Environmental impact of spent lithium ion batteries and green recycling perspectives by organic acids – A review

Environmental impact of spent lithium ion batteries and green recycling perspectives by organic acids – A review

Journal Pre-proof Environmental impact of spent lithium ION batteries and green recycling perspectives by organic acids – A review Pratima Meshram, Ab...

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Journal Pre-proof Environmental impact of spent lithium ION batteries and green recycling perspectives by organic acids – A review Pratima Meshram, Abhilash Mishra, Abhilash, Rina Sahu PII:

S0045-6535(19)32531-7

DOI:

https://doi.org/10.1016/j.chemosphere.2019.125291

Reference:

CHEM 125291

To appear in:

ECSN

Received Date: 6 June 2019 Revised Date:

31 October 2019

Accepted Date: 1 November 2019

Please cite this article as: Meshram, P., Mishra, A., Abhilash, , Sahu, R., Environmental impact of spent lithium ION batteries and green recycling perspectives by organic acids – A review, Chemosphere (2019), doi: https://doi.org/10.1016/j.chemosphere.2019.125291. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Ltd.

Battery Materials are less prone to affect the food chain, and efficient utilisation might resurrect the metal depletion imbalance

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ENVIRONMENTAL IMPACT OF SPENT LITHIUM ION BATTERIES AND GREEN RECYCLING

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PERSPECTIVES BY ORGANIC ACIDS – A REVIEW

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Pratima Meshram1, Abhilash Mishra2, Abhilash1, Rina Sahu2

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CSIR-National Metallurgical Laboratory, Jamshedpur

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2

National Institute of Technology, Jamshedpur

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Tel: +91-657-2345274; Fax: +91-657-2345213; Email: [email protected]

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Abstract: The huge usage of rechargeable batteries in electronics has added to a recurrent

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problem worldwide in generating tonnage of spent lithium-ion batteries (LIBs). The inadequacy

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of the resources of the depleting critical metals has also been described in vogue. The

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environmental assessment of the life cycle of the LIBs has been elucidated vis-a-vis the effects

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of raw material supply, transportation, and recycling. Based on the available work for recycling

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technologies, this review also attempts to elicit the various methods practiced in

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discharging/dismantling, classification, and separation of components followed by metal

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recovery. The authors have reviewed the major developments in the area of recycling of

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cathode material by using various acids for extraction of metals from spent LIBs, compared the

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merits and demerits of acids used and presented a comprehensive outlook to the processes

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formulated vis-à-vis imperative need for using green techniques. The necessity for benign

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recycling methods is stressed upon to alleviate the need for high temperature and oxidative

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acid leaching conditions. The various green lixiviants (organic acids) attempted to extract

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metals from spent LIBs have been discussed in detail with respect to the mechanism, efficacies

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as well as the various factors (selectivity, cost, etc.) that govern the use of organic acids in

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battery recycling. It was ascertained that the GHG emissions to extract Co using organic acids

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stand 1/8 of that using an inorganic acid leaching process. Efforts need to be envisaged in

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separating the leached metals from these lixiviants ensuring economics and environmental

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benefits.

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Keywords: environmental assessment; spent LIBs; recycling; pretreatment; metal; organic acids 1

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1. Introduction

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Every year the LIBs production increase rapidly and the production of LIBs all over the world has

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reached 7.8 billion in 2016, which is grown by 40% as compared to 5.6 billion in 2015 (Zheng et

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al., 2018). Lithium-ion batteries (LIBs) have been introduced by Sony Corp. in 1991, after which

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it gains more attention as compare to any other available batteries (Zou et al., 2013; Georgi-

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Maschler et al., 2012). Spent LIBs recycling gain remarkable attention in the past few years due

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to the rapid increase in demand for critical metals and negative impact on environmental from

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solid hazardous waste scrapping and disposal. Lithium-ion batteries find their applications

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mainly in portable electronic devices such as mobile phones, power banks, laptops and cameras

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due to their advantageous features including, large range of operating temperatures, high

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energy density, long life cycles, and sensible discharge resistance. LIBs are not only dominating

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the portable electronic markets like mobile phone and laptop but also become the first choice

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for electronic automobiles in the future. Automakers like Nissan, Toyota, Honda, General

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Motors and Volkswagen announced plans to utilize LIBs in upcoming electric and hybrid

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vehicles (Ferreira et al, 2009). LIBs technologies are more advanced than other batteries in

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terms of energy density and higher voltage per cell, which is a crucial factor for hybrid and

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electric vehicles (Zou et al., 2013; Li et al., 2012).

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Spent LIBs not only contain significant quantities of valuable materials but also contain

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hazardous materials. The release and fate (i.e., transport and transformation) of metals in these

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batteries or the batteries as such into the environmental system is a very important issue for

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discussion. The uncontrolled disposal of these batteries creates a major risk to health, the

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environment, and a significant waste of valuable resources. Although a few organizations, such

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as Portable Rechargeable Battery Association (PRBA), Rechargeable Battery Recycling

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Corporation (RBRC) and European Portable Battery Association (EPBA) and some more

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organizations in the USA and Europe are involved in collection and recycling of batteries but at

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present there are no such legislation and regulations of collecting and recycling of batteries in

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most of the developing countries. Battery metals such as lithium, nickel, cobalt, and manganese

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as well as the electrolytes may have adverse human health and environmental effects. The

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amount and the form in which the respective component material is present in the battery can

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determine the quantum of risk associated with the batteries. Disposal in landfills or by

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incineration is preferred often during the phase-out of technologies, but green recycling is

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unanimously the better option as it can diminish the adverse effect (if any) on the environment

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and landfill.

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LIBs cell is predominantly composed of three different layers that are cathode layer, an

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anode layer, a separator (PVC), electrolyte, and polymer enclosed with metallic shells (Gratz et

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al., 2014). The composition of different parts of LIBs vis-à-vis its percentage weight distribution

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per battery is shown in Table-S1. The cathode material in LIBs is mostly metal oxide in the form

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of LixMyOz such as lithium cobalt oxide, lithium manganese oxide and many more coated on

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aluminum foil. Among these the recycling of spent batteries comprising LiCoO2 as the electrode

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material has many positive aspects since the cobalt and lithium in it can be an alternative

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resource for the future. The anode is the negative active material coated with active material

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(graphite) on copper foil. The electrolyte salts used include LiPF6 and LiBF4. Lithium hexafluoride

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phosphate (LiPF6) is preferably used lithium salt in most of the LIBs (Zeng, et al., 2014). A

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separator is mainly used between anode and cathode layers to maintain the space and avoid

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contact between them. Separator (a microporous film) is made up of polymers like

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polypropylene (PP) or polyethylene. The function of separator is to avoid short circuits between

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the electrodes as well as it also used as a safety purpose by sealing the electrodes when the cell

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is overheating. Around 85% of the lithium-ion batteries used in worldwide have a size in

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between the range of 5 to 25 g and around 15% have sizes between 25 to 75 g. Espinosa, et al.,

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(2004) mentioned that every laptop usually consists of four to six cells and the average weight

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of single cell is 45 g, whereas mobile phones having a single cell with 22 g of average size. Table-

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1 shows the weight of different parts of mobile and laptop LIBs. The differences in composition

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matter for the economics of processing of the different types of batteries; but the

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environmental effects are mostly similar. In recent years, there have been few comprehensive

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reviews on the subject of LIB green recycling. Zhang et al. (2018) emphasized on the various

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aspects of recycling and leaching of LIBs including the process steps, and separation of metals

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followed by LCA of the process methods. Huang et al (2018) do emphasize similar aspects but

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mostly focused on product manufacturing from recycled LIBs. Kim et al. (2018) strictly discuss

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end-of-life battery management and material flow analysis in South Korea instead of a global

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perspective. Boxall et al. (2018) reviewed the projections of LIB waste generation and potential

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for innovation for LIB recycling only for Australia. Zeng et al. (2014) attempt to review the

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status of the recycling processes of spent LIBs, introduce the structure and components of the

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batteries, and the problems encountered. However, no of these reviews have been able to

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assess the environmental impact during raw material production, battery production,

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distribution and transportation, usage and green recycling in a collective mode.

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2. Environmental Assessment

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The life cycle of lithium-ion battery (Fig.1) defines the complexity in disposition of spent LIBs

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due to presence of various interim routes like reuse in batteries, use of remanufacturing

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material in batteries, and regeneration of cathode before recycling for use as battery grade

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material by stoichiometric additions. A detailed environmental assessment for the production

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of LIBs as well as their recycling has been put forth with the need to pinpoint the precise unit

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operation that contributes maximum towards environmental degradation and emission of

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greenhouse gases. The environmental impacts of the production of several different batteries

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were presented by McManus (2012), who reported that the materials required in lithium-ion

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battery production have the most significant contribution to greenhouse gases and metal

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depletion. The energy requirement for the production of these batteries was reported to about

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90 MJ per Kg and 12.5 kg of CO2 equivalent emitted for per Kg of LIBs. Ordoñez et al., (2016)

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reported that about 1100 t of heavy metals and 200 t of toxic electrolytes were generated from

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4000 t of spent LIBs. Apart from this, there are many occupational hazards during disposal and

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recycling of LIBs vis-à-vis components, which is depicted in Table-2. The major contributors to

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environmental and health impact start from its raw material production followed by battery

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production, its distribution, and transportation requirements, uses, charging and maintenance

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and finally recycling and waste management (Corbus and Hammel, 1995). Recycling efforts are

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mainly focused on cathode materials because of their relative mass and presence of critical

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metals (Kim et al., 2018; Song et al., 2019). The cradle to grave pathway via all these stages

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needs minimization ensuring a shift to adoption of a circular economy approach to preventing

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the environment and health effects.

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2.1. Effects of raw material production: The raw material production for batteries have a huge

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ramifying effect. Mostly the raw materials used in LIBs are extracted from their respective ores

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with mainly focusing on lithium, cobalt, nickel, and manganese as they are used in the

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production of cathode materials in the lithium-ion batteries. Cobalt is mainly extracted from its

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ores accompanied by nickel or copper along with the little amount of arsenic and silver as well.

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The worldwide scenario of cobalt generation mainly includes 44% from the copper industry,

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50% from the nickel industry and remaining production are from primary cobalt operations. The

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approximate reserve of cobalt is about 7,100,000 MT (USGS, 2018). African countries,

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Democratic Republic of Congo (DRC) and Zambia are the main producers of cobalt while Russia,

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Australia, China, Cuba, Canada, and Madagascar are the other important producers as shown in

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Fig. 2 and the location of reserves are presented in Table-3. Lithium is an important metal as it

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shares the largest market in the production of LIBs. Chile, Australia, and Brazil are the main

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producers of lithium while other important producers include Argentina, Portugal, the U.S., and

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China. The estimated reserves for lithium are about 16,000,000 MT, out of which Chile has

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about 53% and Argentina has 14% (USGS, 2018). The estimated reserves for manganese is

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about 680,000 MT (USGS, 2018). South Africa (75% of world resources), Ukraine (10%),

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Australia, and China are the major producers and suppliers of manganese, while other

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important producers include Brazil, India, and Indonesia. Cuba and Australia are the major

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producers of nickel across the worldwide while Brazil, Russia, the Philippines, and Indonesia are

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also important producers of nickel. The estimated reserve for nickel is about 74,000,000 MT. It

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is estimated that cobalt and lithium will be going to face a serious deficiency in the upcoming

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years. In the year 2016, the consumption rate of Co for batteries has increased to 13.7% and

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will reach 20.3% in 2018 (Lv et al., 2018). According to USGS, 2018 the reserve for valuable

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metals like Li and Co is 53 million tons and 5 million tons respectively. Apart from metals, it is

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important to consider graphite recycling especially in countries with less primary production

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(Song et al., 2019).

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Mining, mineral processing, smelting, leaching, and refining are the major processes applied for

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the conversion of the metal and components to the specific form of material utilized in the

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batteries. Taking into consideration a LIB for EVs, the production of wrought aluminum

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consumes 2-3kg CO2 equivalents per kg of battery, surpassing it more than an actual alumina

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refinery. The electrode viz., LiMn2O4, production consumes nearly 800-1000 kg CO2 equivalents

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per kg of battery. Even the consumption is 100-500 kg CO2 equivalents per kg of battery for

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production of electrolytes like DMC, LiFP6, which after discharging of batteries pose high threats

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of being emanated into the environment (Kang et al., 2013; Dunn et al., 2016). However,

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currently owing to the stringent regulation and environment pollution acts these days, all the

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unit operation in the production of raw materials releases fewer emissions.

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2.2. Effects during battery production: Water pollution, air emission, and solid wastes may

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generate during LIBs manufacturing, which is harmful to health as well as the environment. Due

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to the increasing demand for these types of batteries, the Greenhouse gas (GHG) emission

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associated with its production has become a major concern. Recently Hao et al., (2017)

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reported the GHG emission for the three types of most commonly used cathode materials of

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LIBs. According to their report, for the production of a 28 kWh battery of LFP, NMC and LMO

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cathode materials, about 3061 KgCO2-eq, 2912 kgCO2-eq, and 2705 kgCO2-eq GHG emissions is 7

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generated respectively. A more detailed perspective id shown in Table-4, which describes the

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energy consumption vis-à-vis type of cathode chemistry and its share on contribution to GHG

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emissions. Though used prevalent and economically suitable, LCO’s contribute 80% to GHG

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emissions. The emitted gas contains 40% carbon monoxide (CO), 20% carbon dioxide (CO2) and

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30% hydrogen (H2) as well as traces of <3% hydrogen fluoride (HF) and nearly 7% hydrocarbons.

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2.3. Effect due to transportation and distribution: Battery waste management is imperatively

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affected by sorting, packing, storage and transportation. To avoid fire or incident, the batteries

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must be packaged according to stringent requirements. A non-conductive material should be

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used to prevent the short-circuiting against each other as well as the sides of metal packaging.

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Approved packaging container viz., metal drum, wooden box, fiberboard or other materials are

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used for this purpose. Separated packing is required for leakage of vented cells (Miller and Bill

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McLaughlin, 2001). The batteries are then placed into an approved packaging group II container

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with suitable cushioning (vermiculite) to reduce vibration and shock. The inside of the

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packaging should be lined with a heavy plastic/polypropylene liner. The outside of the package

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should be labeled with a "Miscellaneous" Class 9 label.

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2.4. Effect during battery usage and maintenance: By increasing roundtrip efficiency and,

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minimizing the amount of energy that is lost during these charging cycles, the environmental

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impacts incurred by the energy used to charge batteries could be reduced.

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2.5. Effects during recycling: Numerous companies around the world are licensed and currently

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working in the field of battery recycling. The major firms engaged in LIBs recycling are Accurec,

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Umicore process, Batrec AG, Sony-Sumitomo, Toxco and many more as mentioned in Table-6.

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The primary aim of recycling batteries at the industrial and laboratory is to extract metals like

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cobalt, lithium, nickel, and manganese. Recycling of lithium-ion batteries is more common than

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Ni-Cd and Ni-MH batteries (Ellis and Mirza, 2011).

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The advanced battery chemistries of LIBs offer improved systems because they incorporate less

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hazardous materials and may use hydrometallurgical rather than pyrometallurgical or smelting

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processes for recycling. In addition to increasing efficiency in the use of resources, recycling

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provides direct environmental benefits. For instance, the GHG emissions of an LMO lithium-ion

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battery could be reduced by up to 50% over its lifetime if it uses recycled cathode, aluminium,

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and copper instead of virgin materials (Dunn et al., 2012). Moreover, recycling LCO batteries

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results in a reduction in SOx emissions by almost 100%, largely because it avoids the SOx-

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intensive smelting step of virgin cobalt recovery (Dunn et al., 2015). LCA analysis when

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compared among the outputs of battery production from pyro-metallurgy and hydrometallurgy

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via-a-vis raw material production, pyro-metallurgy exceeding production from raw materials in

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electricity consumption and double release of PM2.5 and VOCs than that of hydrometallurgy

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(Arambarri et al., 2019).

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Another very important parameter that should become an integral part of the life cycle and

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environmental impact assessment study for batteries is the form of the material in the battery

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system itself. While evaluating the effects of battery materials, the focus presumably shifts to

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the toxic nomenclatures of Ni, Co, Cd, Mn, Zn as they translocate easily in the environment. The

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battery manufacturers frequently modify their battery chemistries, which makes it difficult to

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incorporate recovered materials. For example, the compound normally used in a Ni-Cd battery

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is an insoluble cadmium oxide but assumptions are made based on the highly soluble cadmium

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chloride existing in the literature on toxicology. The MnO2 and Mn3O4 phase of manganese,

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ZnMn2O4 phases of zinc and LiNiO2 phase of nickel in spent LIBs are not so easily soluble in

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normal temperature and pressure, and thus must be a decisive factor when assessing their

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effects too. This problem is yet to be addressed in life cycle analyses of battery systems, and it

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is difficult to state how much it might affect them when it is addressed. The new chemistries

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replace the old ones irrespective of geographical locations. Apart from Europe and China, India

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has become a prominent destination for e-waste recyclers. Indian mobile manufacturing

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industry is expected to touch Rs 160,000 crore by the end of 2019. In 2017, the Indian mobile

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manufacturing industry produced 22 million mobile phones and the industry would produce 50

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million mobile phones by 2020. The service life of LIBs is generally 3 - 4 years or average life is

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1000 cycles (Chen et al., 2018).

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3. The necessity of environmentally benign recycling methods

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Several methods have been proposed for the extraction of valuable metals from waste/spent

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LIBs. These can be categorized into pyrometallurgy, hydrometallurgy, and bio-hydrometallurgy.

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Out of these, hydrometallurgy is a superior process in terms of high concentration of recycled

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metal, low energy cost, and low emission. Nowadays the use of LIBs tends to increase rapidly

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for the upcoming years, hence new recycling techniques should be developed and existing 10

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processes should be optimized to treat spent Li-ion batteries to obtain sustainability (Renault et

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al., 2014). Numerous researchers have developed techniques for extraction of metals from

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waste LIBs by using inorganic acids like HCl (Wang et al., 2009; Shuva and Kurny, 2013; Guzolu

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et al., 2017), HNO3 (Lee and Rhee, 2002) and H2SO4 (Meshram et al., 2014; Chen and Ho, 2018).

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To diminish the negative impact of inorganic acids, reducing environmental pollution and to

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find environmentally friendly treatment, many researchers in recent years use green recycling

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tools like organic acids viz., citric acid (C6H8O7) (Zheng et al., 2016; Fan et al., 2016), oxalic acid

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(H2C2O4) (Sun and Qui, 2012; Zeng et al., 2015), DL-malic acid (C4H5O6) (Li et al., 2010a; Sun et

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al., 2017), L-tartaric acid (C4H6O6) (He et al., 2017; Cheng, 2018). To reduce the hazardous risks

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to humans as well as to the environment, in recent times some effort has been made by the

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researcher to develop an efficient and eco-friendly technique for extracting valuable metals and

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recycle the spent LIBs. The use of organic acid for leaching to dissolve valuable metals like

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lithium, cobalt, nickel, and manganese from waste LIBs have to gain more attention.

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Nonetheless, this overview also gives a comprehensive record of comparison between

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inorganic and organic acid along with, extensive usage of organic acid as green leaching

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reagents for recycling and extracting metals from spent of LIBs. Gao et al (2018) compare both

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the lixiviants to stress upon the use of inorganic media for higher extraction and organic media

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for better selectivity based on the pH and dissociation constant, however the mechanism

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missing is evident in this review. Lv et al., (2017) describe the procedure for recycling lithium-

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ion is divided into two basic categories of the simple procedure and combination process as

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shown in Fig.3.

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3.1. Discharging and dismantling and pre-treatment of LIBs: This is an important component in

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battery recycling in general. The first basic step before dismantling is to discharge the LIBs

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completely to avoid explosion or self-ignition. Different researchers have opted various

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methods as described in Table-S2. LIBs can be dismantled manually using a plier and a

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screwdriver (generically can be referred as cutting device) and split into components like plastic

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shells, metallic shells, polymer, PVC, anodes foil, and cathodes foil. Metallic components, plastic

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parts, and separators can be directly recycled. The high purity plastic and metallic crusts and

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the organic separators comprise relatively homogeneous components. They can be directly

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centrally collected, compacted, and then sent to specialized plants for further reuse in new

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products. Most of the researchers preferred a single-stage pretreatment technique for

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dismantling of LIBs by directly crushing them into small sizes, followed by magnetic separation

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to separate metallic parts. In the end, fine crushing and sieving process was employed to obtain

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cathode active material as a feed to the leaching process. The dismantling process vis-à-vis the

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components is presented in Fig.4. Many researchers employed different methods for extracting

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cathode material from Al foil and concluded that pretreatment methods always play a vital role

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which includes solvent dissolution method, ultrasonic separation, thermal treatment method,

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and mechanical methods which are shown in Table-S3 along with its merits and demerits. With

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the rapid development of mechanization, the mechanical and automatic dismantling of WEEE is

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recently becoming a hot spot. Nowadays some new attempts to automatically disassemble

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mobile phones are emerging (Zhang et al., 2018). Elaborative dismantling via full automatic

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machines is expected to be the desired ideal operation for spent LIB recycling.

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After separating cathode active material from Al foils, it is used for subsequent leaching process

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as feed. Table-6 shows the composition of different cathode active material used by different

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researchers. The literature survey shows that mechanical treatment, hydrometallurgy

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(Meshram et al., 2014), pyrometallurgy (Paulino et al., 2008), and biotreatment (Brandl and

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Faramarzi, 2006; Kim et al., 2016) are the main available recycling methods for extracting the

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valuable metals from waste LIBs. Apart from these methods, metals can also be extracted by

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bacteria and fungi (Horeh et al., 2016; Mishra et al., 2008; Xin et al., 2009). Among all the

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available recycling approaches, hydrometallurgy method dominates due to being simple, high

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recovery and options of closed-loop operations. Biotreatment has also created some attention

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due to the selective and green recovery of some metals from the waste lithium-ion batteries.

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3.2. Hydrometallurgical Processing of LIBs: Hydrometallurgical processing of spent LIBs is a

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simple and efficient method for extracting all valuable metals. In the hydrometallurgical

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technique, number of processes are carried out to dissolve and extract metals from an aqueous

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medium; i.e., acid leaching (Meshram et al., 2015a; Paulino et al., 2008), chemical precipitation

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(Guzolu et al., 2017; Yang et al., 2017), solvent extraction (Yang et al., 2017; Paulino et al.,

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2008), and electrochemical separation (Chagnes and Pospiech, 2013; Garcia et al., 2017; Xu et

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al., 2008; Zhang et al., 2013). The first basic step is to dissolve Co, Li, Ni, and Mn by acid

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leaching, and then these metals are extracted from the solution (leach liquor) by a suitable

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method. Fig.5 shows the typical flowchart for the recycling of waste lithium-ion batteries

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through the hydrometallurgical process.

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hydrometallurgical treatments to extract valuable metals from solution as they are more

There

13

are lots

of

advantage

by

using

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flexible and reliable, eco- friendly, energy consumption is less, good rate of reaction, high purity

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and extract all the metals present in spent LIBs (Garcia et al., 2017; Sun and Qiu, 2011; Sun et

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al., 2017). The most widely used method to extract valuable metals from waste LIBs is acid

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leaching. There are different parameters on which the leaching rate of different metals like

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cobalt, lithium, nickel, and manganese depends on lixiviant concentration, pulp density,

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reaction temperature, time.

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The lixiviants are mainly classified as inorganic and organic acids; merits and demerits of which

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are described in Table-7. The use of inorganic acids can lead to high consumption of water,

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chemicals, and in long term adding to the corrosion of equipment and generation of secondary

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wastes (Tesfaye et al., 2017; Innocenzi et al., 2017). Rocchetti et al., (2013) also explained the

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gas emission from the inorganic acid to recycle waste LIBs, and conclude that the gas like CO2,

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Cl2, SO2, ethane, and phosphorus will be emitted. Another disadvantage of using inorganic acid

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is the pH of the solution (leach liquor) is very low and metals cannot be extracted directly from

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the solution hence the process becomes more complicated (Yao et al., 2018). With inorganic

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acids, disposal of water containing acid,

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problems leading to economic and energy losses.

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Whereas organic acids termed as “GREEN LIXIVIANTS” are easy to manage, as they are

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biodegradable, do not emits harmful gases to the atmosphere (He et al., 2017; Li et al., 2018).

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Chen et al., (2015); Horeh et al., (2016); explain about the advantage of organic acid and the

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use of organic acids as eco-friendly and efficient lixiviant, more to that there are no harmful

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gases emitted, delayed the corrosion of equipment as well as it is for the operators, and few

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organic acids gives selective leaching of valuable metals present in waste LIBs. A most

hazardous fumes, acidic leachates are the main

14

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important factor associated with organic acids is, they can be recycled after leaching processes

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(Chen et al., 2015). Golmohammadzadeh et al., (2017) and Rocchetti et al., (2013) reported that

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organic acids are costlier than the inorganic acids, still it's usage is cost-effective as it avoids

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negative impact on the environment which is mostly associated with inorganic acids.

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Numerous researchers used inorganic acid like sulfuric acid (Meshram et al., 2015b; Chen and

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Ho, 2018), hydrochloric acid (Guzolu et al., 2017; Wang et al., 2009; Shuva and Kurny, 2013),

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nitric acid (Lee and Rhee, 2003; ), Phosphoric acid (Pinna et al., 2017) and hydrofluoric acid

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(Suarez et al., 2017) as a leaching reagent and showed very high recovery of metals from spent

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lithium-ion batteries. Some selected work is listed in Table-8 using inorganic acid as a lixiviant

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for spent LIBs, and Fig.6 shows the schematic recovery process by using different inorganic acid

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as the lixiviant.

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Hydrochloric acid has an excellent leaching efficiency as compared to another inorganic acid

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(Joulie et al., 2014), but Cl2 was produced and leads to a potential environmental problem as

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shown in Eq. (1).

326 327

2LiCoO2 + 8HCl 2CoCl2 + Cl2 + 2LiCl + 4H2O

(1)

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Sulfuric acid is mostly used in the presence of hydrogen peroxide (H2O2) as a reducing agent as

330

it enhances the leaching efficiency. Eq. (2) shows the chemical reaction of cathode active

331

material with hydrogen peroxide:

332

2LiCoO2 + 3H2SO4+ 3H2O2  2CoSO4 + Li2SO4

(2)

333

15

334

In spite of the fact inorganic acids are stronger oxidants than organic ones; the latter is

335

thermally stable, leaves no negative impact on the environment, and usually form strong

336

chelates (Deng et al., 2015). Different organic acids, including oxalic acid (Sun and Qui, 2012;

337

Zeng et al., 2015), DL-malic acid (Sun et al., 2018; Li et al., 2013), tartaric acid (Chen et al., 2018;

338

Cheng, 2018; He et al., 2017) and citric acid (Li et al., 2010b; Fan et al., 2016; Chen et al., 2015;

339

Zheng et al., 2016) shows similar leaching performance as with inorganic acids, which signifies

340

that these eco-friendly lixiviants can efficiently recover metals from spent LIBs. Few reviews

341

(Zhang et al. 2018, Huang et al. 2018, Zeng et al., 2014) have emphasized the merits of selected

342

work on the use of organic acids in recycling of spent LIBs; however, the following section

343

attempts to discuss and deliberate all such work carried out and their mechanism using organic

344

lixiviants.

345 346

3.2.1. Citric Acid: Some of the research that used citric acid for leaching of LIBs vis-à-vis

347

conditions is summarized in Table-9. A hydrometallurgical process to recover metals by using

348

citric acid and H2O2 based on leaching was introduced by Li et al., (2010b). Citric acid can leach

349

90% of cobalt and 100% of lithium by using 1% H2O2, citric acid of 1.25M at 90 oC with 20 g/L

350

pulp density in 30 min. The extraction of Li and Co from waste LIBs in presence of C6H8O7·H2O

351

and H2O2 can be presented by Eq. (3)

352 353 354

6H3Cit (aq) + 2LiCoO2 (s) + H2O2 (aq) 2Li+ (aq) + 6H2Cit- (aq) + 2Co2+ (aq) + 4H2O + O2 (g)

355

16

(3)

356

Comparison of citric acid with two different organic acid namely aspartic and malic is reported

357

by Li et al. (2013) by using hydrogen peroxide as a reducing reagents and reported that 100 % Li

358

and > 90% Co were recovered using malic and citric acids whereas by using aspartic acid the

359

recovery is very low because of its low acidity. Golmohammadzadeh et al. (2017) reported by

360

comparing four different organic acids (DL-malic, oxalic, citric and acetic acid) finds the best

361

sequence is citric acid > DL-malic > acetic > oxalic acid, in terms of their efficiency to recover

362

cobalt and lithium from spent LIBs.

363

Extraction of valuable metals by hydrometallurgical process from cathode active material

364

(LiNi1/3Co1/3Mn1/3O2) of spent LIBs using citric acid was investigated by Chen and Zhou, (2014). It

365

was observed that about 98% Ni, and Mn, 89% Li and 97% Co was recovered by using 2 M citric

366

acid in presence of 2% H2O2 and 50 g/L pulp density in 80 min at 70 oC. For the recovery

367

process, a combined method of selective precipitation and solvent extraction was performed to

368

separate and recover each metal from the leach solution. Firstly, cobalt and nickel were

369

selectively precipitated by ammonium oxalate ((NH4)2C2O4) and dimethylglyoxime (C4H8N2O2)

370

sequentially Fig. 7. Then manganese was extracted by Na-D2EHPA and stripping was carried out

371

with sulfuric acid. The manganese was recovered as MnSO4 in the aqueous phase and D2EHPA

372

could be reused after saponification. Finally, lithium was precipitated by 0.5 M Na3PO4 and

373

about 89% of the lithium was recovered as Li3PO4.

374

Several researchers work on citric acid and proposed that 90 °C is the optimum temperature for

375

extraction of cobalt and lithium (Fan et al., 2016; Li et al., 2010b; Li et al., 2013; Zheng et al.,

376

2016). To avoid the negative influence related to high-temperature, several researchers

377

reported that 60-80 oC as the preferred temperature range for extraction of valuable metals

17

378

like cobalt and lithium (Chen et al., 2015; Golmohammadzadeh et al., 2017). While Aaltonen et

379

al., (2017) investigated that at room temperature (25 oC) citric acid is able to leach 97% of

380

cobalt, 89% of lithium along with 98%, and 93% of manganese and nickel respectively by using 1

381

% H2O2, with 50 g/L pulp density in 24 h. Recently, Ma et al., (2017) reported that the citric acid

382

is beneficial for the selective dissolution of metals in the mixed battery waste as compared to

383

the sulfuric acid as leaching reagent. They reported that citric acid with hydrogen peroxide as

384

oxidant favored valuable metals dissolution (Co and Ni) but not promoted the dissolution of

385

Mn, Fe, Zn, and the other metals. They also showed with thermodynamic calculations that

386

metals precipitate more easily in a sulfuric acid system than in the citric acid system. Recently,

387

Musariri et al (2019) used citric acid to evaluate their effect on metal leaching rate from spent

388

LIBs. They concluded that with the increase in the acid concentration of citric acid from 1M to

389

1.5M at 95 °C, an increase in metal leaching rate was observed. Maximum recovery of 95% Co,

390

97% Li and 99% Ni recoveries within 30 min were obtained in 1.5M citric acid.

391 392

3.2.2. Tartaric Acid: Tartaric acid acts as a good buffer in a wide pH range 2.1-7.4

393

(Golmohammadzadeh et al., 2018). The acid has been reported as an efficient chelating agent.

394

Very few researchers have been worked on tartaric acid in the recovery of metals from waste

395

lithium-ion batteries as mentioned in Table-10.

396 397 398

18

399

The leaching reaction of tartaric acid with LiCoO2 in presence of H2O2 can be represented in Eq.

400

(4):

401 402

2LiCoO2 (s) +3C4H6O6 (aq) + H2O2 (aq)

403 404

C4H4O6Li2 (aq) + 2C4H4O6Co (aq) + 4H2O (l) + O2 (g)

(4)

405 406

For increasing the rate of dissolution, the addition of reducing reagent (H2O2) was essential.

407

H2O2 helps in the dissolution of cobalt and lithium as two metals are contained in the same

408

oxide compound. In the absence of H2O2, the aforementioned recoveries were about less than

409

31%, while with 4 % H2O2 at 70 o C in 30 min and 17 g/L pulp density, the recoveries of all the

410

metals (Co, Mn, Ni, and Li) increased to > 98% (He et al., 2017). Results also showed that

411

tartaric acid produces a solution environment with lower pH as compared to ascorbic acid, DL-

412

malic acid, succinic acid, and L-aspartic acid.

413

Nayaka et al., (2016) dissolve more than 95% of LiCoO2 in presence of tartaric and ascorbic acid

414

by employing a reductive complexing mechanism. Eq. (5) shows the dissolution process of

415

LiCoO2 with C4H4O6 and confirms the reduction of Co(III)-tartrate (CoC4H5NO4) to form Co(II)-

416

tartrate (CoC4H2O4), followed by cobalt precipitation as cobalt oxalate.

417 418

4LiCoO2 + 12C4H4O6  4LiC4H3O6+ 4 Co(C4H3O6)2+ 6 H2O

419

The effect of different reductants (glucose, ascorbic acid, and hydrogen peroxide) on leaching

420

of lithium and cobalt from LIBs in tartaric acid solution was reported by Cheng et al (2018). The

19

(5)

421

group reported that among these three reducing agents, hydrogen peroxide exhibits a higher

422

ability to convert Co3+ of the cathode active materials to soluble Co2+. The recovery rate of Li

423

and Co was 98% and 97% respectively in the presence of 0.6 M tartaric acid with 3 % H2O2 at 80

424

°C in 30 min.

425 426

3.2.3. Malic Acid: An environmental friendly recycling technique for recovery of lithium and

427

cobalt from waste LIBs by using malic acid was reported by Li et al., (2010a) and results showed

428

that 93% Co and 94% Li can be leached using 1.5 M DL-malic acid in presence of 2.0 % H2O2, 20

429

g/L pulp density in 40 min at 90

430

recovery by using malic acid. Result also showed that the leaching efficiency of Li and Co

431

increases with an increase in reaction time and temperature. The leaching reaction of waste

432

LiCoO2 with malic acid can be represented in Eq. (6) as follows:

o

C. Table-11 summaries the optimal condition for metal

433 434

4LiCoO2(s) + 12C4H6O5 (as)  4LiC4H5O5 (aq) + 4CoC4H5O5 (aq) + 6H2O (l) + O2 (g)

(6)

435 436

Li et al., (2010a) also confirmed that for increasing the rate of dissolution, the addition of

437

reducing reagent (H2O2) was essential because the two metals were present in the same oxide

438

phase. Eq. (7) shows the reaction of waste cathode powder in the presence H2O2:

439 440 441

2LiCoO2(s) + 6C4H6O5 (aq) +H2O2 4LiC4H5O5 (aq) + 2CoC4H5O5 (aq) + 4H2O (l) + O2 (g)

442

20

(7)

443

Under similar conditions by just decreasing the reaction time from 40 min to 30 min, Li et al

444

(2013) reported the extraction of Li and Co from waste LIBs with DL-malic acid as leaching

445

reagent. With pure malic acid, ~54% Li and 37% Co could be extracted. However, by adding 2 %

446

H2O2, the recovery rate increased drastically to 99% Li and 90% Co adding to the embodied

447

energy of the process. The presence of two carboxyl functional groups and its higher solubility

448

in water improved the metal solubilization from spent LIBs (Li et al., 2010a).

449

Sustainable extraction of metals from spent LIBs in the presence of malic acid was investigated

450

by Sun et al (2017). At 40g/L pulp density, 80 oC in 30 min, 98.9 % Li and 94.3 % Co were

451

extracted using 1.2 M acid concentration. Golmohammadzadeh et al (2017) used room

452

temperature to extract 90.9 % Li and 80% Co and elucidated the two-step mechanism of

453

leaching in Eq. (8) and Eq. (9), where two moles of H+ released from DL-malic acid plays a vital

454

role to enhance the efficiency of leaching (Li et al., 2014).

455 456

H2C4H4O5  HC4H4O5- + H+

(8)

HC4H4O5-  C4H4O52- + H+

(9)

457 458 459 460

Musariri et al (2019) used malic acid to evaluate their effect on metal leaching rate from spent

461

LIBs. Malic acid concentration did not affect leaching, and 1M concentration was most

462

appropriate to achieve 98% Co, 96% Li and 99% recoveries in 30min.

463

21

464

3.2.4. Oxalic Acid: Oxalic acid has been a widely used leaching agent for extraction and

465

chelation of metals from various secondary wastes, especially WEEE. Oxalic acid acts as an

466

agent for leaching as well as precipitation in hydrometallurgical studies. In this view, Zeng et al

467

(2015) attempted to extract Li and Co from waste LIBs by synchronous leaching and

468

precipitation using 2 M oxalic acid with 15 g/L pulp density at 95 °C for 150 min, achieving a

469

high recovery rate of 98% Li and 97% Co. Similarly, combined oxalate leaching and vacuum

470

pyrolysis for recovery of Li and Co from the waste LIBs were reported by Sun and Qiu (2012).

471

They used oxalate ion as a leaching agent to achieve 98% leaching efficiency using 1M oxalic

472

acid with 15% H2O2 (Eqs. 10 and 11) and 25 g/L pulp density at 80 °C for 120 min. The

473

separation was aided by differences in the solubility properties of lithium oxalates and cobalt

474

oxalates; as latter was insoluble in acid and thus precipitated, whereas the former being soluble

475

could be separately precipitated at high pH. Table-12 summaries the examples of various work

476

done to use oxalic acid for metal recovery from LIBs.

477 478

4H2C2O4 +2LiCoO2  LiHC2O4 +2CoC2O4 (s) +4H2O + 2CO2 (g)

(10)

3H2C2O4 +2LiCoO2 (s) +H2O2  Li2C2O4 +2CoC2O4 (s) +4H2O+O2 (g)

(11)

479 480 481 482

Recently, Aaltonen et al (2017) reported leaching of metals at room temperature using 1M

483

oxalic acid along with 1% H2O2 and found that oxalic acid can selectively recover lithium. This

484

value falsifies the claims of many researchers (Sun and Qiu, 2012, Zeng et al., 2015).

485

22

486

3.2.5. Other organic acids: Some other commonly used acids, though significantly less applied

487

to leach of spent LIBs, are succinic acid, ascorbic acid, aspartic acid, lactic acid, formic acid.

488

Table-13 mentions the optimized conditions for metal extraction from spent LIBs by using

489

different organic acids.

490

Li et al (2012) developed a hydrometallurgical process using ascorbic acid for the extraction of

491

lithium and cobalt from waste LIBs, where ascorbic acid worked as a leaching as well as the

492

reducing agent. Ascorbate ion with high reducing potential can avoid the use of deleterious

493

hydrogen peroxide to enhance leaching efficiency. Nearly 98.5% Li and 94.8% Co was recovered

494

as respective metal ascorbates using 1.25 M ascorbic acid with 25 g/L pulp density at 75 °C in 20

495

min. The leaching reaction is represented in Eq. (12) as follows:

496 497

4C6H8O6 + 2LiCoO2  C6H6O6 + C6H6O6Li2 + 2C6H6O6Co + 4H2O

(12)

498 499

Succinic acid was also used as a leaching reagent for cathode active material of LIBs. Li et al

500

(2015) reported nearly 100% Co and 96% Li extraction in presence of 1.5 M succinic acid, 4%

501

H2O2 and 15 g/L pulp density at 70 oC in 40 min. However, in the absence of reducing agent

502

(H2O2), only 41.98% Li and 19.72% Co were recovered in similar conditions.

503

Li et al. (2013) reported that due to the weak acidity and low solubility of aspartic acid in the

504

water, it is an inefficient agent for recovery of lithium and cobalt from spent LIBs and recovered

505

only 60 % lithium and cobalt. A closed-loop process for recovery of lithium carbonate from

506

cathode scrap of spent LIBs by using formic acid and it can be used as leachate and reductant

507

(Gao et al., 2017). The recovery rates of Li, Ni, Co, and Mn were found to be 95.46%, 98.22%,

23

508

99.96%, 99.96%, and 99.95% respectively. The chemical reactions during the leaching process

509

can be described in Eq. (13)

510 511

6LiNi1⁄3Co1⁄3Mn1⁄3O2(s)+21HCOOH(aq) →2C2H2NiO4(aq)+2C2H2CoO4(aq)+2C2H2MnO4(aq)

512

+6CHLiO2(aq)+3CO2 (g)+12H2O(aq) (13)

513 514 515

Recently, in a few studies, the leaching of LIBs with an acetic acid solution in the presence of

516

H2O2 is also reported (Natarajan et al., 2018; Gao et al., 2018). The reaction of the LCM type of

517

cathode material in acetic acid in the presence of H2O2 can be represented by equation (14) as

518

follows:

519 520

Li2CoMn3O8(s) + 10CH3COOH(aq) + 10H2O2(aq)  2CH3COOLi(aq)+ Co(CH3COO)2(aq) +

521

3Mn(CH3COO)2 (aq) + 8 H2O + 3O2

(14)

522 523

Natarajan et al. (2018) used acetic acid as lixiviant and H2O2 as a reductant for leaching of

524

mobile phone batteries. It was found that with 3 M Acetic acid and 7.5 vol % H2O2 as reducing

525

agent 99.9% Li, 98.7% Co, and 99.5% Mn were leached out from cathode material in 40 min at

526

70 oC and a pulp density of 20 g/L. Finally, Cobalt was recovered as cobalt sulfide with 99.2%

527

purity, and, MnCO3 and Li2CO3 being 98.7% and 99.4% pure respectively. Similarly, Gao et al.,

528

(2018) also use acetic acid as a lixiviant for selective recovery of valuable metals from spent

529

lithium-ion batteries and reported that the introduction of reductant accelerates the leaching

24

530

speed but decreases the influence of the acid concentration and S/L ratio. About 93.62% Co,

531

99.97% Li, 96.32% Mn and 92.67% Ni were recovered using 3.5 M acetic acid and 4% H2O2 in 1 h

532

at 60 oC with S/L ratio of 40 g/L. Li2CO3 was precipitated by adding a saturated Na2CO3 solution.

533

Lactic acid, which is widely distributed in nature and miscible with water, is also chosen for the

534

leaching of LIBs. The industrial production of lactic acid is also a green process, mainly through

535

fermentation. Given this, a green process was developed for the recycling of cathode material

536

of spent lithium-ion batteries using lactic acid (Li et al., 2017). The results showed that the

537

leaching efficiencies of Li, Ni, Co, and Mn reached >97% using 1.5 M lactic acid in presence of

538

0.5% H2O2 at 20 g/L pulp density in 20 min at 70 °C.

539

The examples of proven work on the use of green reagents in leaching of spent LIBs highlight

540

the organic acids as effective lixiviants and they have the potential to replace inorganic acids

541

owing to environmentally benign for processing of spent LIBs. The most important reason for

542

recycling batteries is to reduce environmental burden apart from meeting critical metal

543

demand. Thus, environmental impact assessment of the recycling process must be clearly

544

understood before choosing a process for it to be less energy-intensive as compared to virgin

545

processes to get the raw materials. The energy consumption is mainly affected by the choice of

546

leachant used. Inorganic leaching uses a reductant along with oxidizing acids, which increases

547

the embodied energy of the process as their production sustains environmental encumbrances.

548

As reported by Li et al., 2013, the energy consumption in producing citric acid is 35MJ/kg which

549

is 1/10 of the energy required to produce same concentration of sulfuric acid or butane. Apart

550

from this, the need for high temperatures is very less using organic acids. It is also possible to

551

recover the acid for recycling by decreasing the solution pH, causing the metals to precipitate

25

552

and reviving the acid by filtration. The waste organic acid would not pose a serious

553

environmental threat because it is a relatively benign substance used in foods, beverages, and

554

detergents. The use of inorganic acids with high concentration and temperature would result in

555

process emissions like sulfur, chloride, and nitrous oxides. The energy consumption of the

556

process of recycling with organic acids (Fig.7) vis-à-vis inorganic acid (sulfuric) was calculated as

557

9.3 and 14 MJ/kg (Li et al., 2013). There are possibilities to increase process energy efficiency by

558

further optimizing acid concentrations, and maximizing acid recycling.

559

The energy intensity of NMC cathode material manufacturing from virgin materials is 132

560

MJ/kg, which is nearly 25% less by organic acid-based recycling. Finally, using organic acid

561

enables this process to be competitive with producing virgin cobalt on an energy consumption

562

basis. The GHG emissions to extract 90% Co using a process with organic acids stands to be

563

close to 500 g/CO2

564

leaching process.

565

The selectivity for leaching Li over Co by oxalic acid is an additional advantage for processing

566

LiCoO2 cathodes. There lies another advantage of acids like citric and aspartic, which can avoid

567

oxidants and their effects during downstream processing. The onus now lies on developing

568

optimized process flow sheets to recover the extracted metals from the leach solutions as

569

saleable products.

570

4. Future Directions of Research

571

With the rise in the application of LIBs in electronics, the number of spent LIBs generated also

572

surmounts which need a recycling process to conserve the sustainable resource and save the

573

environment. Based on the above assessment, it can be ascertained that the being hazardous

eq

per kg Co, which is nearly 4000g/CO2eq per kg Co using an inorganic acid

26

574

term with batteries, if handled and processed properly, can't be generically applied. The various

575

portals of battery processing ranging from raw material extraction to recycling in a closed-loop

576

cycle have its merits and demerits; but with the advent of technological changes and processing

577

options, battery recycling by safe mode is not a hard task to accomplish. Each cathode material

578

will be processed by a definite route, which governs its economics, energy consumption and

579

impact. We cannot recycle all LIBs by one technique, which ultimately leads to complications in

580

downstream processing and thus paves way for proper segregation of its type and properties.

581

Owing to large scale discarding of used LIBs, few successful examples worldwide can be a good

582

reference point for waste battery management for the developing world. By targeting a

583

complete waste battery collection system, improving EPR and promoting consumers to submit

584

spent batteries to assigned collection points; the uncontrolled collection issue can be sorted.

585

Battery dismantling must employ mechanized ways to separate crusts from cathode material.

586

The available literature survey related to recycling of spent LIBs highlights that mechanical

587

treatment, pyro-metallurgy, hydrometallurgy, and bio-treatment are the main major routes for

588

recycling of the waste lithium-ion batteries, hydrometallurgy dominates as compare to other

589

recycling technique as it an exploitable technology for the extraction of precious metals from

590

waste LIBs. Organic acids (effective and environmentally green leaching agents) have been

591

demonstrated to play a vital role in the extraction of lithium, nickel, cobalt, and manganese

592

from spent LIBs. Though they are weaker than inorganic ones, still organic acids have been

593

examined to a greater extent for leaching of spent LIBs thus helping to avoid oxidizing agents,

594

lowering complexity of managing the pregnant liquor and thus diminishing the energy loss. The

595

GHG emissions to extract 90% Co using a process with organic acids stands to be close to 500

27

596

g/CO2

597

process. Efforts need to be envisaged in separating the leached metals from these organic acid

598

media, to create a win-win situation of economics and environmental benefits.

eq

per kg Co, which is nearly 4000g/CO2eq per kg Co using an inorganic acid leaching

599 600 601 602

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Figure Captions Fig.1: Life cycle assessment of lithium ion battery Fig.2: World map showing the reserves of Li, Co, Mn, Ni, and Graphite Fig.3: Different processes for recycling of spent LIBs Fig.4: Dismantling process for spent lithium-ion batteries Fig.5: Hydrometallurgical processing of spent LIBs Fig.6: Schematic recovery process by using different inorganic acid as lixiviant (Pinna et al., 2017; Qadir and Gulshan, 2018; Suarez et al., 2017; Shuva and Kurny, 2013; Guzolu et al., 2017; Chen and Ho, 2018; Chen et al., 2017) Fig.7: Schematic recovery process by using citric acid as lixiviant Table Captions Table-1: Weight of the component of the lithium-ion battery Table-2: Occupational standards for materials present in LIBs Table-3: Location of reserves of Li, Ni, Co, Mn and graphite globally Table-4: Energy consumption for various cathode chemistries in LIB production (Modified from Dunn et al., 2014) Table-5: Commercial process and companies engaged in recycling of batteries Table-6: Composition of different cathode active material used (Li et al., 2010b; Chen et al., 2011; Li et al., 2013; Jha et al., 2013; Meshram et al., 2015b; Khan et al., 2016; Fan et al., 2016; He et al., 2016; Sun et al., 2017; Gao et al., 2018; Golmohammadzadeh et al., 2018; Chen and Ho, 2018; Meshram et al., 2018) Table-7: Salient differences among processing parameters among organic and inorganic acid Table-8: Selected literature work on different inorganic acids as a lixiviant for LIBs Table-9: Summary of various published work on metal recovery from LiBs using citric acid Table-11: Summary of selective work on metal recovery from LIBs using tartaric acid Table-11: Summary of selective work on metal recovery from LIBs using malic acid Table-12: Summary of selective work on metal recovery from LIBs using oxalic acid Table-13: Summary of selective work on metal recovery from LIBs using other organic acids Supplementary Table Captions Table-S1: Parts and Composition of LIBs (Zhu et al., 2012; Gratz et al., 2014; Zeng et al., 2014; Younesi et al.,2015; Rojas and Zea, 2016; Toma et al., 2017; Horeh et al., 2017; Zhang et al., 2018; Qadir and Gulshan, 2018) Table-S2: Different discharging processes of LIBs Table-S3: Different pre-treatment process and their merits and demerits.

Table-1: Weight of the component of the lithium-ion battery Component

Total Battery assembly Plastic shell Metallic shell Cu electrode Al electrode Cathode material Polymer electrolyte

Weight of component Mobiles Laptops (Rojas and Zea, 2016) (Qadir and Gulshan, 2018) g % g % 17.8 316 1.8 5.2 50 15.8 4.3 12.2 51 16.1 3.5 9.8 17.2 5.4 7.5 2.4 5.4 15.1 130.9 41.4 0.6 1.8 6.8 2.2 1.8 5 20.9 6.6

Table-2: Occupational standards for materials present in LIBs Component Anode

Species

Hazardous Effects

Copper foil

Gastrointestinal issues in form of dust and mist irritate the eyes and mucous membranes Lung damaged by inhalation Respiratory effects, congestion, edema, and hemorrhage of the lung. Lung damage

Graphite

Cathode oxide

Aluminium foil Cobalt oxide

Manganese (VI) oxide

Nickel oxide Lithium

Electrolyte

Binders

LiPF6

Polypropylene

Polyvinylidene fluoride

Limits/Standard/Permissible Exposure Limits 0.1 mg/m3 as fume 1.0 mg/m3 as a dust or mist

Vimmerstedt et al., 1995

15 mg/m3 total particulates

15 mg/m3 as dust 5 mg/m3 as metal 1.0 * 104 TO 1.7 * 106 ng/m3

0.1 mg /m3 (TWA) 5 mg/m3 for manganese compounds as Mn 0.2 mg/m3 for manganese (TWA) 1 mg/m3 (TWA)

Skin carcinogenesis Non-hazardous if ingested with food or water

Toxic fume while heating/burning, (HF, PF5) Decomposes to irritating fumes when burnt Mild toxic when inhaled; Toxic fume while heating/burning (HF, PF5)

References

2.5 mg/m3 as F (long-term value) 15 mg/m3

2.5-5 TWA mg/m3

IARC, 1991; Barceloux, 1999; IARC, 2006

Vimmerstedt et al., 1995

Nordberg et al., 2011 Aral and VecchioSadus, 2008 Kang et al., 2013

Table-3: Location of reserves of Li, Ni, Co,Mn and graphite globally S. No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

Location Greenbushes, AUS Mt Marion, AUS Mt Cattlin, AUS Euriowie, AUS Finniss, AUS Zhabuye, China Qinghai, China DXC, China Jaijika, China Yichun, China Clayton, USA Searles lake, USA Great salt lake, USA Fox Creek, USA Bernic Lake, Canada Fox creek, Canada Wekusko, Canada La Motte, Canada La Corne, Canada H’ Muerto, Argentina Rincon, Argentina Olaroz, Argentina Cauchari, Argentina Bikita, Zimbabwe Atacama, Chile Maricunga, Chile Ethiudna, AUS Mount Gunson, AUS Akkarga, Russia Kola Peninsula, Russia Norilsk, Russia Kolwezi, DRC Kakanda, DRC Kamoya, DRC Konkola, Zambia Nchanga, Zambia Mufulira, Zambia

S. No. 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74

Location S. No. Nkana, Zambia 75 Keely-Frontier, Canada 76 TemagamiLorrain, 77 Canada Blackbird mine, USA 78 Ldaho mine, USA 79 Miramar, Cuba 80 La vega de Taco, Cuba 81 Palawan, Phillipines 82 Surigao, Phillipines 83 Ambatovy , Madagascar 84 Sudbury, Canada 85 Manitoba, Canada 86 Montreal, Canada 87 Québec, Canada 88 Kola Peninsula, Russia 89 Norilsk , Russia 90 Rio Tuba, Phillipines 91 Palawan, Phillipines 92 Toamasina, Madagascar 93 Ambatovy, Madagascar 94 Taolagnaro, Madagascar 95 Vale, Indonesia 96 Halmahera, Indonesia 97 Kidd Creek, S.A 98 Sudbury, S.A 99 Nkomati mine, S.A 100 Queensland, Aus 101 Tasmania, Aus 102 Yilgarn Craton, AUS 103 Taco bay, Cuba 104 Goiás, Brazil 105 Bahia, Brazil 106 Carajás , Brazil 107 Jinchang, China 108 Altay, China 109 Sundergarh, India 110 Balaghat, India 111

Location Ratnagiri, India Durg, India Saldanha Bay, S.A Hotazel, S.A Sishen mine, S.A Richards Bay, S.A Tarkwa Banso, Ghana Franceville, Gabon Nikopol, Ukraine Ushkatyn, Kazakhastan Jezkazgan, Kazakhastan Azul mine, Brazil Espigão d’Oesto, Brazil Corumbá, Brazil Pará, Brazil Port Hedland, AUS Woodie Woodie, AUS Bootu Creek mine, AUS Guiyang, China Wafangzi mine, China Jammu and Kashmir, India Jharkhand, India Kerala, India Tamil Nadu, India Liumao mine, China Pingdu mine, China Bahia, Brazil Tanga, Tanzania Merelani Hills, Tanzania Epanko, Tanzania Sonora, Mexico BalІkesir, Turkey Yozgat, Turkey Konya, Turkey Muğla, Turkey Graphmada, Madagascar Andapa, Madgascar

Table-4: Energy consumption for various cathode chemistries in LIB production (Modified from Dunn et al., 2014) Cathode Structure Weight Energy Preaparation Step Major Chemistry of consumption Energy Contribution contributor to battery (mmBtu/ton) energy consumption of total pack consumption (mmBtu/ton) (%) (kg) NMC Planar/layered 180 135 4.5 3 NiO LMR-NMC

Planar/layered

LCO (Solid state) LCO (Hydrothermal) LFP (Hydrothermal) LFP (Solid state) LMO

Planar/layered

140

Contribution (%)

40

100

3.0

3

CoO

30

150

2.6

2

CoO

88

251

32

13

CoO

53

48

35

71

LFP preparation

71

39

6

16

Fe3O4

40

26

15

56

LMO preparation

56

170 Planar/layered Olivine 230 Olivine Spinel

220

Table-5: Commercial process and companies engaged in recycling of batteries Process Hydrometallurgy

Pyrometallurgy

Pyro Hydrometallurgy

Company (Name and Location) IPGNA Ent. (Recupyl), France

Raw material

Outcome

All Batteries

LiCoO2 and Co(OH)2

Sumitomo-Sony, Japan Toxco, Canada

LIBs Li, Ni-based battery

Co(OH)2 LiCoO2

Eurodieuze, France Zimaval, France

Ni, Cd and steel Zn and Mn

Dowa, Japan Batrec AG, Switzerland

All Zn, Mn, Hg based battery All Batteries Li, Hg based battery

Umicore, Belgium

LIBs and Ni-MH

Co and Ni

Nippon Recycling center, Japan Accurec GmbH, Germany

Ni-Cd, Ni-MH, LIBs

Ni, Co, Cd, Al, Cu

All

Ni, Cd, Fe, LiCO3

INMETCO, US

Ni-Cd

Cd, Ni, Zn

Glencore Plc., Switzerland

LIBs and EV

Cu, Ni, Zn, Li

Ni, Co -

References Saloojee and Lloyd, 2015 Ellis and Mirza, 2011 Kushnir, 2015 Saloojee and Lloyd, 2015 Saloojee and Lloyd, 2015 Zhang et al., 2013 Kushnir, 2015 Ellis and Mirza, 2011 Ellis and Mirza, 2011 Zhang et al., 2013. Ellis and Mirza, 2011 Saloojee and Lloyd, 2015 Zhang et al., 2013 Kushnir, 2015 Ellis and Mirza, 2011 Ellis and Mirza, 2011 Kushnir, 2015 Saloojee and Lloyd, 2015 Zhang et al., 2013 Saloojee and Lloyd, 2015 Zhang et al., 2013 Ellis and Mirza, 2011

Table-6: Composition of different cathode active material used (Li et al., 2010b; Chen et al., 2011; Li et al., 2013; Jha et al., 2013; Meshram et al., 2015b; Khan et al., 2016; Fan et al., 2016; He et al., 2016; Sun et al., 2017; Gao et al., 2018; Golmohammadzadeh et al., 2018; Chen and Ho, 2018; Meshram et al., 2018) Metals (wt. %) Cathode Material LiCoO2 LiCoO2 LiCoO2 LiCoO2 LiCoO2 LiCoO2 NCM LiNi1/3Co1/3Mn1/3O2 LiNi1/3Co1/3Mn1/3O2 LiCoO2 LiCoO2 NCM

Co 53.8 26.77 57.94 23.67 74.6 58.76 35.52 20.26 18.65 58.11 25.83 35.8

Li 4.48 3.34 6.76 2.87 4.09 6.78 6.28 7.08 6.15 6.69 8.31 6.5

Ni 0.80 0.34 0.76 0.26 0.58 11.85 20.19 18.32 0.39 26.29 10.6

Mn 0.97 1.1 0.91 0.76 8.15 18.89 17.57 0.14 14.41 11.6

Table-7: Salient differences among processing parameters among organic and inorganic acid Parameters Selectivity Emission of gas Corrosion of equipment’s Separation/ Recovery Free energy (∆ Go) Flammable Overall Cost Example

Inorganic Acid No selectivity can be seen Cl2, Co, CO2 Possible Easy Low Highly flammable Low as compare to organic acid HNO3, HCl, H2SO4, etc.

Organic Acid Selectivity is possible No No Difficult High Non flammable High Citric acid, oxalic acid, etc.

Table-8: Selected literature work on different inorganic acids as lixiviant for LIBs Composition (Wt. %)

Lixiviant

LiCoO2

1 M HNO3

LiCoO2

4 M HCl

Co=20.56 Li=3.43 Mn=12.3 Ni=0.72 Co=35.8 Li=6.5 Mn=11.6 Ni=10.06 Co=6.43 Li=4.37

5 M HCl

Leaching Parameter Time Temp S/L o (min) C (g/L) 75 1020 60 80 20

Co

Recovery % Li Mn

Ni

95

95

-

-

97

97

98

97

98

-

-

70

95

10

99

240

95

50

66.2

1.5 M H2SO4 + 15% H2O2

60

60

40

94.07 98.1

Li=4.8, Co=41.5, Mn=2.1 LiCoO2

2% H3PO4

60

90

8

99

15% HF

120

75

20

98

Co=25.83 Li=8.31 Mn=26.2 Ni=14.41

2 M H2SO4 +10% H2O2

-

70

33.3

98.5

1M H2SO4

References

93.4 50.2 96.3

Lee and Rhee, 2003 Wang et al., 2009 Guzolu et al., 2017

Meshram et al., 2015b

-

-

Latif and Ahmed, 2016

88

-

-

80

-

-

Pinna, et al., 2017 Suarez et al., 2017 Chen and Ho, 2018

99.8 98.6 98.6

Table-9: Summary of various published work on metal recovery from LiBs using citric acid Composition (Wt. %)

Lixiviant

Recovery (%)

References

Li-4.48 Co-53.8 Mn-0.97 Ni-0.80 LiCoO2

1.25M Acid + 1% H2O2

30 min

Co=90, Li=100

Li et al., 2010b

1.25M Acid+ 2%H2O2 1.25M Acid+ 1% H2O2

30 min 35 min

90

20

Co=90 Li=100

Li et al., 2013

90

60

Co=90.2, Li=98

Fan et al., 2016

2M Acid+ 2% H2O2

80 min

70

50

Co=99, Li=93

Chen and Zhou, 2014

1M Acid

90 min

80

30

Co=97, Ni=93, Mn=98, Li=89

Chen et al., 2015

2.5M Acid+ 5%H2O2

2h

85

40

Ma et al., 2017

1M Acid+ 1% H2O2

24 h

25

50

Co=85.1 Ni=100 Mn=28.3 Co=97, Ni=93, Mn=98, Li=89

LiCoO2

1% H2O2

5h

90

15

Co=97, Ni=93, Mn=98, Li=89

Zheng et al., 2016

LiCoO2

2M Acid+ 1% H2O2 1.5M citric acid

5h

50

30

Li=99.80 Co=96.46

30min

95

10

Li=97 Co=95 Ni=99

Golmohammadzadeh et al., 2017 Musariri et al., 2019

Li-6.78 Co-58.76 Mn-0.76 Ni-0.58 Li-4.48 Co-53.8 Mn-0.97 Ni-0.80 Li-6.81 Co-58.79 Mn-0.76 Ni-0.58 Co-0.24 Ni=1.01 Mn-35 Co-23 Li-3 Ni,Mn-5

Li-9.73 Co-28.82 Mn-24.39 Ni-33.91 Cu-0.11 Al-1.48

Time

Parameters Temp. Pulp (oC) density (g/L) 90 20

Aaltonen et al., 2017

Table-10: Summary of selective work on metal recovery from LIBs using tartaric acid Composition (Wt. %)

Lixiviant

Reductant

Li-6.28 Co-35.52 Ni-11.85 Mn-8.15 LiCoO2

0.4M Acid

----

300

80

-

LiCoO2

1M Acid

20 g/L Glucose

90

80

10

Li-6.69 Co-58.11 Ni -0.39 Mn-0.14

4% H2O2

Parameters Time Temp. S/L (min) (o C) ratio(g/L) 30 70 17

0.6M Acid + 3 H2O2%

Recovery (%)

References

Co=98.64 Li=99.07 Ni=99.31 Mn=99.3 Co>95

He et al., 2017

Li=82.7 Co=46.6

30 g/L Ascorbic

Li=84.3 Co=47.3

10% H2O2

Li=82.4 Co=53.2 Co=98 Li=97

30 ---

80

33.3

Nayaka et al., 2016 Cheng, 2018

Chen et al., 2018

Table-11: Summary of selective work on metal recovery from LIBs using malic acid Composition (Wt. %)

Li 7.08 Co 20.26 Mn 18.89 Ni 20.19

Lixiviant Time (min)

Parameters Temp. Pulp (o C) density (g/L) 80 40

Recovery (%)

References

Li=98.9 Co=94.3

Sun et al., 2017

1.2M Acid + 1.5% H2O2

30

Li 4.48 Co 53.8

1.5M Acid +2% H2O2

40

90

20

Li=100 Co=90

Li et al., 2010a

LiCoO2

1.5M Acid + 2% H2O2

30

90

20

Li=100 Co=90

Li et al., 2013

LiCoO2

1M Acid

-

25

15

Li=90.89 Co=80.22

Li-9.73 Co-28.82 Mn-24.39 Ni-33.91 Cu-0.11 Al-1.48

1M acid

30min

95

10

Li=96 Co=98 Ni=99

Golmohammadzadeh et al., 2017 Musariri et al., 2019

Table-12: Summary of selective work on metal recovery from LIBs using oxalic acid Composition (Wt. %)

Lixiviant

Parameters Temp. Pulp (oC) density (g/L) 120 80 50 min

LiCoO2

1M Acid + 15%, H2O2

Co- 24.5 Li-3.52

1 M Acid

150 min

95

Co-23 Li-3 Ni and Mn-5

1M Acid +1% H2O2

24 h

25

Recovery (%)

References

98

Sun and Qui., 2012

15

Li=98, Co=97

Zeng et al., 2015

5

Li=74 Co=2

Aaltonen et al., 2017

Time

Table-13: Summary of selective work on metal recovery from LIBs using other organic acids Composition (Wt. %)

Lixiviant

LiCoO2

1.25M Ascorbic acid

20

Parameters Temp. Pulp (oC) density (g/L) 70 25

Li=6.76, Co=57.94, Ni=0.76, Mn=0.91 LiCoO2

1.5 M Succinic Acid + 4% H2O2

40

70

1.5M Aspartic Acid + 2%H2O2

30

Li=6.79, Co=17.68, Mn=16.46, Ni=17.58

1.5M Lactic acid + 0.5 % H2O2

Li=6.15, Co=18.65, Mn=17.57, Ni=18.32 Li=6.15, Co=18.65, Mn=17.57, Ni=18.32

Time (min)

Recovery (%)

References

Li=98.5 Co=94.8

Li et al., 2012

15

Li=96 Co=96

Li et al., 2015

90

20

Li =60 Co=60

Li et al., 2013

20

70

20

Li= 97.7 Co=98.9 Mn=98.4 Ni=98.2

Li et al., 2017

2M Formic Acid + 2% H2O2

120

70

50

Gao et al., 2017

3.5M Acetic Acid + 4% H2O2

60

60

40

Li= 99.97 Co=93.97 Mn=96.32 Ni=92.67 Li= 99.97 Co=93.97 Mn=96.32 Ni=92.67

Gao et al., 2018

Fig.1: Life cycle assessment of lithium ion battery

Fig. 2: World map showing the reserves of Li, Co, Mn, Ni, and Graphite

Fig 3: Different processes for recycling of spent LIBs

Fig.4: Dismantling process for spent lithium ion batteries

Fig 5: Hydrometallurgical processing of spent LIBs

Fig. 6: Schematic recovery process by using different inorganic acid as lixiviant (Pinna et al., 2017; Qadir and Gulshan, 2018; Suarez et al., 2017; Shuva and Kurny, 2013; Guzolu et al., 2017; Chen and Ho, 2018; Chen et al., 2017)

Fig 7: Schematic recovery process by using citric acid as lixiviant

Research Highlights •

Global distribution of Li, Ni, Co, Mn and graphite depicted



Major ongoing processes vis-à-vis strategies described



Discussed about various organic acids used and mechanism of leaching



An overview on green processing perspective of LIBs recycling is presented.

To, The Co-Editor-in-Chief(s) Chemosphere

Dated: 24th Sep 2019

Subject: Declaration of No-Conflict of Interest (CHEM63222) Dear Sir, I am glad to submit the revision to the review article entitled “ASSESSMENT OF ENVIRONMENTAL IMPACT OF SPENT LITHIUM ION BATTERIES AND GREEN RECYCLING PERSPECTIVES BY ORGANIC ACIDS”, authored by Pratima Meshram, Abhilash Mishra, Abhilash, and Rina Sahu, for consideration to publication in “Chemosphere” Journal. We declare to have no conflict of interest and certify that the manuscript has been revised and submitted with our concurrence. Thanking You, Yours faithfully, (Pratima Meshram) (Abhilash Mishra) (Abhilash) (Rina Sahu)