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Life cycle assessment of lithium-ion batteries for greenhouse gas emissions
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Life cycle assessment of lithium-ion batteries for greenhouse gas emissions Yuhan Liang a,b , Jing Su a,b,∗ , Beidou Xi a,b,d,∗ , Yajuan Yu c , Danfeng Ji a , Yuanyuan Sun a , Chifei Cui a , Jianchao Zhu a a
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences. Beijing, 100012, China State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China c Beijing Institute of Technology, Beijing 100081, China d Lanzhou Jiaotong University, Lanzhou 730070,China b
a r t i c l e
i n f o
Article history: Received 1 February 2016 Received in revised form 26 August 2016 Accepted 26 August 2016 Available online xxx Keywords: Lithium ion secondary batteries Carbon footprints Life cycle assessment
a b s t r a c t The optimized design of lithium ion secondary batteries using combination of carbon footprints and life cycle assessment (LCA) was proposed in this study. The carbon footprints of the batteries were obtained by four stages, and relevant reduction strategies were implemented accordingly. The carbon footprints of three different batteries were compared in this study: lithium ion secondary battery, nickel metal hydride battery and solar cell were evaluated. The result indicated that the carbon dioxide equivalence of the assembly process for raw materials sequence was nickel metal hydride battery (124 kg CO2eq ) > solar cell (95.8 kg CO2eq )> lithium ion secondary battery (12.7 kg CO2eq ). The result also proposed the lithium ion batteries’ environmental friendliness with numeric illustration and the calculation of carbon footprints of the product was developed as reference to battery selection for human use. © 2016 Published by Elsevier B.V.
1. Introduction Along with the enhancement of people’s environmental consciousness and the development of carbon label, companies increasingly felt the pressure from low carbon tendency. Thus, the calculation of product carbon footprints and the low carbon management of supply chain will become one of energy conservation and emissions reduction tasks of many brands and retailers in the future. China is now in the beginning of the low carbon economic transformation. With the vigorous promotion of energy conservation and emissions reduction work in the “12th Five-Year-Plan” period, the mechanism of carbon trading and carbon tax has been introduced gradually. It is necessary to reduce product carbon footprints of manufacturing enterprises in China, so as to attract more downstream invents and consumers. The carbon label as the unique identifier to quantitative product carbon footprints is increasingly concerned. Therefore, it is urgent to understand the calculation of product carbon footprints in China.
∗ Corresponding authors at: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences. Beijing, 100012, China E-mail addresses: [email protected] (J. Su), [email protected] (B. Xi).
Carbon Footprint (CFP) originated in ecological footprint (Johnson, 2008), which also considered as carbon emissions, was used to describe the emissions of greenhouse gases (GHGs) from organization, product or individual. Meanwhile, the product carbon footprint, named carbon label, was a research hot spot in all over the world. Wiedmann and Minx (2007) defined CFP as the emissions of CO2 which was caused by an activity during the whole life cycle of a product both directly and indirectly. While, most activities may also emit other kinds of GHGs, that also need to be considered. Therefore, the term carbon dioxide equivalent (CO2eq ) is widely used in CFP assessments. The methods of product carbon footprints are divided into two sorts: “top-to-down” model and “bottom-to-up” model (Wang et al., 2010). Life cycle assessment (LCA) is a kind of “bottom-to-top” method, which includes the process “from start to finish” of the product. It is generally recognized as a quantitative and qualitative analysis tool of environmental impact caused by life cycle of product at the international level. LCA first appeared in the United States, where the company Coca-Cola commissioned a research institution to make a quantitative analysis and track from raw material mining to waste of the beverage container in 1969. LCA is a commonly used tool for evaluating environmental features of electronic products in nowadays.
http://dx.doi.org/10.1016/j.resconrec.2016.08.028 0921-3449/© 2016 Published by Elsevier B.V.
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Lithium ion secondary battery (Wu, 2009) developed as a new battery after nickel cadmium battery, which has become an important technical way to mitigate the crisis of energy and resources and solve environment pollution problems. Lithium-ion battery has been widely used in cell phones, laptops, digital cameras and many other products due to its high energy density, high voltage, low self-discharge, non-memory effect, long cycle life and environmental friendliness. With the increasing market demand for lithium ion battery, further research about its performance is in need. In recent decade, the market share and sales of lithium ion battery continued to soar, which was comparable to that of nickel cadmium battery and nickel metal hydride battery (Battery Industry Association, 2011). The research of product carbon footprints in China is still at the beginning presently, and very few research about carbon footprint assessment of lithium ion battery. However, the secondary environmental problems of widely used lithium ion battery should not be ignored, which requires further research. Recently, there has been many researches on the carbon footprint calculation and the environmental impact assessment of lithium ion battery. Yajun Ge (2008) proposed the LCA method for wasted secondary battery, in which Shenzhen city was used as an example, mainly conducted quantitative assessment on chronic public health impact of nickel cadmium battery, nickel metal hydride battery, lithium ion battery and lead-acid battery. Zackrisson et al. (2010) studied how LCA could be used to the optimization design of lithium-ion batteries for plug-in hybrid electric vehicles, and then the environmental impact of two different solvents batteries were compared. The environmental impact of lithium ion battery used in battery-powered electric cars was measured in Ecoindicator 99 points (Dominic Notter et al., 2010). Majeau-Bettez et al. (2011) made a comparison among nickel metal hydride (NiMH), nickel cobalt manganese lithium-ion (NCM) and iron phosphate lithium-ion (LFP) batteries in three different functional units, which expressed the results through thirteen impact categories. Linda Ager-Wick Ellingsen et al. (2013) evaluated an Li (NixCoyMnz)O2 (NCM) traction battery in three different functional units and compared with preceding researches. Yu et al. (2014) assessed four kinds of cathode active materials, and brought forward a method for assessing cathode active materials that accounts for both the environmental impact and the electrochemical performance to filter cathode active materials that are friendly to environment and with excellent performance. Messagie et al. (2015) first proposed the availability and demand of lithium, then compared a lithium manganese oxide (LMO) and a lithium iron phosphate (LFP) battery by means of LCA, which indicated the whole environmental performance of the battery was strongly dependent on its efficiency and directly tied to the energy mixes associated with its uses. The above researches evaluated the environmental impact of lithium ion battery from different angles. However, there are few studies focusing on the carbon footprint assessment of lithium ion battery products, failing to analyze the impact from each stage. The lithium ion battery was used as an case study and compared with nickel metal hydride battery and solar cell. The carbon footprint assessment of secondary battery product was caculated by LCA method theory. Therefore, the results can be used to provide effective support for managers and evidence for people to choose environmentally friendly products.
Fig. 1. National production of lithium ion battery from 2010 to 2014.
Fig. 2. Production of lithium ion battery in provinces in 2014.
ion battery increased approximate linearly from 2.69 billion to 5.29 billion (CBIW, 2011–2015), as shown in Fig. 1. The long-term consumption growth of electronic products and the substitution effect in the field of electric tools and electric bicycle will lead to steady growth of lithium ion battery. According to the statistics of China Industrial Association of Power Sources (CIAPS), China’s lithium ion battery exports reached 1.32 billion (USD 5.48 billion) in 2014 and 1.13 billion (USD 4.80 billion) in 2013, up by 16.8% (14.1%) from a year earlier. The sales revenue of lithium reached USD 10.7 billion in 2014, up by 21.1% from USD 8.8 billion yuan in 2013. The lithium ion battery used in IT market accounted for 81.1% of the lithium-ion battery market, new energy vehicles and electric bicycles with power lithium ion batteries accounted for 16.8%, and communication and new energy storage with lithium ion batteries took 2.1% of the lithium ion battery market (2015). The production of the lithium ion batteries in 2014 for different provinces in China is shown in Fig. 2. The battery production in Guangdong, Jiangsu and Tianjin ranked top 3, up to 2.02,0.87 and 0.49 billion. At the same time, the production in Fujian, Jiangxi, Guangxi and other places were relatively high, reaching 0.42, 0.38 and 0.34 billion respectively, while the production in Shanxi, Jilin, Sichuan and other places were relatively low. 2.2. Enterprise distribution
2. Lithium ion battery in China 2.1. Production situation In recent years, lithium-ion battery industry is developing rapidly in China. During 2010 and 2014, the production of lithium
The global lithium ion market consists of China, Japan and South Korea, and the lithium ion battery in China is developing rapidly. The battery enterprises are mainly distributed in Guangdong, Jiangsu, Zhejiang Province et al., accounting for 70% of national total. The lithium-ion battery industry (CCID Consulting, 2011) in China is mainly concentrated in the Pearl River Delta repre-
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sented by Guangdong, Yangtze River Delta represented by Jiangsu and Beijing-Tianjin Area represented by Tianjin. The Pearl River Delta is a major production base of materials and assembly for lithium ion battery in China. There are thousands of enterprises in the region, including various types of large battery enterprises such as BYD and MOTTCELL. A large number of cheap labor enabled the rapid development of the labor-intensive assembly link, and Shenzhen BAK has become the production base of lithium ion battery. The Yangtze River Delta is the primary area of battery industry aggregation represented by Shanghai, Jiangsu and Zhejiang Province and occupies an important place in the lithium-ion battery industry. The representative enterprises are Shanghai Yangyang Battery Technology Company and SANYO ENERGY (SUZHOU) Co. Ltd and so on. Jiangsu and Zhejiang are important production bases of materials, which attract a great deal of foreign investment enterprises. Around Bohai Gulf Area represented by Beijing, Tianjin and Shandong Province, as the industry base of materials and power battery, has some typical enterprises such as LISHEN (TIANJIN) and Pulead Technology Industry Co. Ltd. Beijing, relying on the advantages of its technology and talents, had gained great development in cathode material for lithium ion battery. Meanwhile, Tianjin has basically formed a perfect lithium-ion battery industry chain. 3. Methodology 3.1. LCA and environmental product declarations Life Cycle Assessment (LCA) is a quantitative and qualitative analysis method of environment impact caused by life cycle of products, processes and activities. The key point is to analyze the energy consumption and the potential impact on the environment of products from raw materials acquisition, manufacturing, use to recycling of resources, and explain the results of the evaluation, put forward suggestions for energy conservation and emission reductions and improve the environment. EPD2008 is a method for calculating and validating environment data of the products based on LCA and ISO14025, which was posted on the website of Sweden Environmental Management Committee to create environmental product declarations. EPD mainly describes products or manufacturers information for life cycle, determines the functional unit, describes the environmental performance and classifies different effects. In recent years, more and more designers and users in the middle of the products require companies to provide EPD in order to integrate the sustainability information into the product design. This paper mainly studied the EPD2008 to calculate the product’s carbon footprints and analyze the impact on GHGs, and the final results were expressed as carbon dioxide equivalent (CO2eq ). 3.2. Functional unit Lithium iron phosphate (LiFePO4 ) battery was selected as the research object in this paper and the functional unit was defined as 1000 kW h to ensure the comparability of carbon footprints of different batteries. In the second part, three kinds of batteries were compared in the paper to choose low-carbon products. All collected data need to be converted to functional unit to ensure the results comparability. It directly influences the veracity of calculation results. 3.3. System boundary The first stage is to determine each product system and the system boundary, including the production process of product and the initial system boundary. Secondly, research data were collected in accordance with each link of the production process, so as to
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ensure the representativeness, accuracy, completeness, and comparability of the data. The study selected the mode of “enterprise to consumer” for the carbon footprint calculation of lithium-ion battery carbon. The system boundary (S1) was from raw materials acquisition, processing, and manufacturing, transport to use phase except for the recycling process when calculating the carbon label of lithium-ion battery. At the same time, the system boundary (S2) was selected when comparing carbon footprints of three batteries raw materials. Due to various components of the product boundary, PAS2050 required the carbon footprint calculation within the system boundary. The system boundary was defined as follows: of all emissions of GHGs, emission source response to the product life cycle was greater than 1% of its substantial contribution, and the insubstantial emission source are not supposed to exceed 5% of carbon footprints of the product. Life cycle process diagram of the battery is presented in Fig. 3and the system boundary is the respective diagram. 3.4. Battery assembly 3.4.1. Lithium iron phosphate battery Lithium iron phosphate battery is a lithium ion battery produced with lithium iron phosphate cathode materials. Because of higher charge-discharge efficiency, it is mainly used as power battery. Lithium-ion button battery consists of five parts: cathode materials, anode materials, electrolytes, separator and battery shell (Fig. 4). The lithium iron phosphate battery was made in the laboratory of Beijing Institute of Technology in this study. The capacity was 1440 mAh and the charging voltage was 4 V. It was mainly composed of the cathode, anode, electrolytes, separator and battery shell. The cathode included lithium iron phosphate cathode material, acetylene black and aluminum foil. Ferrous oxalate (FeC2 O4 ), ammonium dihydrogen phosphate (NH4 H2 PO4 ) and lithium hydroxide (LiOH) were used to make LiFePO4 by high temperature solid state method. The anode was made of acetylene black, mesocarbon microbeads (MCMB) and binder coated on copper foil. The electrolyte consisted of organic solvent, lithium salt and additives. The organic solvent was a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC), and the lithium hexafluorophosphate (LiPF6 ) was selected as the lithium salt. Moreover, the separator was polyethylene (PE) membrane and the shell was stainless steel. Because of the lack of data, EMC and LiPF6 were traced back to upper-lever. EMC was synthesized by dimethyl carbonate (DMC) and Ethanol (C2H5OH). LiPF6 was made by hydrofluoric acid (HF), phosphorus pentachloride (PCl5 ) and lithium fluoride (LiF). The cathode materials were mixed in an agate mortar according to the proportion, then coating on the aluminum foil and drying under 80◦ for 12 h. After that, the cathode, anode, electrolyte and shell were assembled in the glove box filled with argon. The new battery should let it stand for up to 12 h. Peter Van den Bossche’s research published in 2006 showed that the energy efficiency of lithium ion battery was 90% when its cycle-index was 1000 times. On the premise of the above research results, the study considered the cyclic numbers of battery. Then the quality of the battery’s components were calculated when they produced 1000 kW h electricity. The cathode, anode and electrolyte materials were composed according to certain proportions, and the composition of raw materials and its mass percentage are shown in Table 1. The cathode and anode materials were the main components, accounting for 36.80% and 37.12% of the battery respectively. The electrolyte accounted for a small part, but its contributions to GHGs couldn’t be ignored because of high carbon content. 3.4.2. Nickel metal hydride battery The Nickel metal hydride (Ni-MH) battery is made of hydrogen ion and metal nickel, which mainly used in hybrid electric vehi-
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Fig. 3. Life cycle process diagram and system boundary of the battery.
Fig. 4. The structure diagram of lithium-ion button battery.
Table 1 Components of lithium iron phosphate battery. Component
Raw material
Raw material
Cathode
LiFePO4 Acetylene black Aluminum
FeC2 O4
Anode
Acetylene black MCMB Copper
Electrolyte
Ethylene carbonate(EC) Ethyl methyl carbonate(EMC) LiPF6
Separator
Polyethylene membrane(PE)
Shell
Steel
NH4 H2 PO4
LiOH
Dimethyl carbonate(DMC)Ethanol(C2H5OH) HF PCl5 LiF
Quality/(g/1000 kW h)
Mass percentage
Note
914.35 183.26 3.86
36.80%
5:1
183.26 914.35 13.50
37.12%
5:1
54.01 135.03 293.21
16.11%
2:5 1 mol/L
1.35
0.05%
Outsourcing
297.82
9.92%
Outsourcing
Table 2 Components of the nickel metal hydride battery. Component
Raw material
Raw material
Quality/(kg/1000 kW h)
Mass percentage
Cathode
Ni(OH)2 Nickel foam
NiSO4 NaOHNH3 ·H2 O
4.19 0.03
14.89%
Anode
LaNi5 Nickel foam
La2 O3
4.62 0.04
16.42%
Electrolyte
KOH LiOH 255 carbonyl nickel powder Polytetrafluoroethylene(PTFE)
0.49 1.10 0.29 0.13
7.12%
CHCl3
NiO
HF
Separator
Polypropylene(PP)
0.66
2.33%
Shell
Steel
16.80
59.24%
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Table 3 Components of the solar cell. Component
Raw material
Quality/(g/1000 kW h)
Masspercentage
P-n knot
Silicon Liquid argon Boron-silicon-molybdenum alloy Phosphorus oxychloride(POCl3 )
1004.39 295.76 0.03 1.18
6.4%
Metallic contact
Polyurethane Liquid nitrogen Aluminum slurry Silver pulp
5.07 5466.87 89.98 14.81
27.5%
Antireflection layer
Silicon nitride Silicon carbide Liquid oxygen Silane Liquid ammonia
4.27 5128.80 35.47 3.34 6.20
25.6%
Aluminum alloyed back
Aluminum Tin
339.96 114.86
2.2%
Suede
Ethylene glycol((CH2OH)2) Epoxy resin Hydrofluoric acid(HF) Hydrochloric acid(HCl) Potassium hydroxide(KOH) Nitric acid(HNO3 ) Sodium hydroxide(NaOH)
6118.83 6.62 666.45 302.42 48.05 579.01 21.37
38.2%
Table 4 Energy consumption of the two batteries in different stages. Battery
Phase
Water/m3
Electricity/kW h
Gasoline/L
Lithium iron Phosphate Battery
Production Transport Use
0.02 – –
24.68 – 1111.11
0.007 0.005 –
Ni-MH Battery
Production Transport Use
12.84 – –
705.45 – 1428.57
– 0.05 –
Fig. 5. Carbon footprint flow chart of lithium iron phosphate battery’s raw materials.
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Fig. 6. Carbon footprint flow chart of ni-mh battery’s raw materials.
cles. It has longer service life and is more environmentally friendly than nickel cadmium battery. The studied Ni-MH battery was AA size. The diameter and height of this battery were 13.9 and 50 mm. The capacity was 1800 mAh and the charging voltage was 1.2 V (Tang, 2007). The cathode was made of nickel foam and nickel hydroxide (Ni(OH)2 ) that were prepared by nickel sulfate, sodium hydroxide and ammonia through complex precipitation method. The anode consisted of nickel foam and LaNi5 . The electrolyte was composed of potassium hydroxide (KOH), lithium hydroxide (LiOH), 255 carbonyl nickel powder and polytetrafluoroethylene (PTFE). The separator was polypropylene (PP) and the shell was stainless steel. The energy efficiency of nickel metal hydride battery was 70% when its cycle-index was 1350 times and the quality of Ni-MH battery’s components were calculated when they produced 1000 kW h electricity. The shell was the main component and the mass percentage was 59.24% (Table 2). The anode accounted for 16.42%, followed by the cathode and the electrolyte. The separator was the least. 3.4.3. Solar cell Solar cell is a photoelectric semiconductor wafer, which generates electricity directly from sunlight. The solar cell can be divided into silicon semiconductor battery, multiple compounds thin-film battery, organic materials battery, functional polymer materials preparation of solar cell, nanocrystalline solar cells and so on. The solar cell in the study was a kind of model TPA156 * 156 N monocrystalline silicon solar cell of made in manufacture. The output power was 3.82–4.63 W and the rated voltage was 0.48 V. It consisted of p-n knot, metal contact, antireflection layer, aluminum alloyed back and suede. The p-n knot was a small part, which was made of silicon, liquid argon, boron-silicon-molybdenum alloy and
phosphorus oxychloride (POCl3 ). The metallic contact was synthesized by polyurethane, liquid nitrogen, aluminum slurry and silver pulp, which accounted for 27.5%. The antireflection layer consisted of silicon nitride (Si3 N4 ), silicon carbide (SiC), liquid oxygen, silane and liquid ammonia. The mass percentage of aluminum alloyed back was 2.2%, which included aluminum and tin. Then the suede consisted of ethylene glycol ((CH2 OH)2 ), epoxy resin, hydrofluoric acid (HF), hydrochloric acid (HCl), potassium hydroxide (KOH), nitric acid (HNO3 ) and sodium hydroxide (NaOH). The mass percentage of the suede was 38.2%. The composition of raw materials and its mass percentage are shown in Table 3. The solar cell studied in this paper was used in the northern part of China with relatively little rain. It was assumed that there are 260 sunny days every year and the solar cell receives about six hours’ sunshine daily. In the case of a unified functional unit of 1000 kW h, the conversion of lithium-iron phosphate battery may refer to the Chapter 4.2.1. The power of solar cell was 213.7 w when it produces 1000 kW h of electricity.
3.5. Energy consumption During the entire life cycle of a battery except recycling phase, main energy consumption process includes production, transport and use phase. Under the same 1000 kW h condition, the specific data of stages are shown in Table 4. The transport phase mainly consumed gasoline calculated according to light trucks on the city roads while the use phase consumed electricity the most.
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Fig. 7. Carbon footprint flow chart of solar cell’s raw materials.
3.6. Environmental impact assessment The environmental impact usually can be divided into eleven different impact categories, including carcinogenicity, inhaled organic matter, inhaled inorganic, climate change, radioactive, ozone depletion, ecological toxicity, acid rain and eutrophication, land use, mineral consumption and fossil fuel. This study evaluated the environmental impact of battery from climate change. GHGs were mainly studied and final results were expressed as carbon dioxide equivalent (CO2eq ). 4. Results 4.1. Carbon footprints of different battery raw materials 4.1.1. Lithium iron phosphate battery On the basis of the theory of LCA method, software Simapro was used in the carbon footprint evaluation of raw materials assembly stage. Other related data came from ELCD and CLCD database etc. The carbon footprint flow chart of lithium iron phosphate battery’s raw materials is shown in Fig. 5. From bottom to top, the below is the upstream of the upper. “1 p LiFePO4 Battery” in the graph means a lithium iron phosphate battery when it produced
1000 kW h electricity and “1 p cathode materials” refers to the total cathode materials of a battery. In addition, LiFePO4 , EMC, LiPF6 and other materials used in the preparation of cathode, anode and electrolyte materials were synthesized and expressed in “1 p”. Fig. 5 shows that the carbon footprint of lithium iron phosphate battery’s raw materials is 12.7 kg CO2eq . The carbon footprints of cathode, anode and electrolyte are respectively 4.46 kg CO2eq , 3.67 kg CO2eq and 4.4 kg CO2eq . Meanwhile the carbon footprint of LiFePO4 is 3.85 kg CO2eq , acetylene black is 3.04 kg CO2eq , and EMC and LiPF6 are 1.92 kg CO2eq and 2.38 kg CO2eq respectively. Furthermore, the arrows’ thickness corresponds to the size of qualitative carbon footprints.
4.1.2. Nickel metal hydride battery The carbon footprint flow chart of Ni-MH battery’s raw materials is shown below (Fig. 6). Under the same condition, the carbon footprint of nickel metal hydride battery’s raw materials reaches up to124 kg CO2eq . Among them, the carbon footprints of cathode, anode and electrolyte of Ni-MH battery are respectively 49.7 kg CO2eq , 57.2 kg CO2eq and 10.3 kg CO2eq . Meanwhile the carbon footprint of ammonia is 11.7 kg CO2eq , lanthanum oxide is 16.1 kg CO2eq , and nickel is 66.8 kg CO2eq respectively.
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4.1.3. Solar cell The carbon footprint flow chart of raw materials the solar cell’s raw materials is shown in Fig. 7. It turned out that the carbon footprint of solar cell’s raw materials is 95.8 kg CO2eq . The carbon footprints of antireflection layer, p-n and suede of solar cell are respectively 37 kg CO2eq , 39.8 kg CO2eq and 13.6 kg CO2eq . At the same time, the carbon footprint of silicon carbide is 36.7 kg CO2eq , and silicon is 39.9 kg CO2eq respectively. 4.2. Carbon footprints of different battery 4.2.1. Lithium iron phosphate battery After the carbon footprint evaluation of raw materials assembly stage, the study further calculated the carbon footprints of life cycle. The composition of raw materials and its quality percentage are shown in Table 1 and the main energy consumption process including production, transport and use phase are shown in Table 4. The production phase consumes 0.02 m3 water and 24.68 kW h electricity. The transport phase consumes 0.007 L petrol. The use phase consumes 1111.11 kW h electricity. Finally, the carbon footprint of a lithium iron phosphate battery is 736.35 kg CO2eq after calculation, including 12.7 kg CO2eq from raw materials phase, 15.7 kg CO2eq from production phase and 707.95 kg CO2eq from use phase. 4.2.2. Nickel metal hydride battery For the Ni-MH battery, the production phase consumes 12.84 m3 water and 705.45 kW h electricity. The transport phase consumes 0.05 L petrol. The use phase consumes 1428.57 kW h electricity. So, the carbon footprint of a lithium iron phosphate battery is 1483.72 kg CO2eq after calculation, including 124 kg CO2eq from raw materials phase, 449.5 kg CO2eq from production phase and 910.22 kg CO2eq from use phase. 5. Discussions 5.1. Carbon footprint analysis of lithium iron phosphate battery The research results showed that the carbon footprint of lithium iron phosphate battery’s raw material was 12.7 kg CO2eq . The carbon footprints of cathode, anode and electrolyte of lithium iron phosphate battery accounted for 35.1%, 28.9% and 34.6% respectively, while the corresponding quality accounted for 36.80%, 37.12% and 16.11% respectively. The differences between two kinds of proportions indicated the carbon footprints of battery’s raw materials were greatly influenced by the material type. At the same time, the carbon footprint of a lithium iron phosphate battery was 720.7 kg CO2eq. It consumed large amounts of electricity in use phase and the carbon footprints produced from it account for the most part of the life cycle carbon emissions. Because of the lithium ion battery’s characteristics such as small volume, light weight and so on, the transport phase of a single battery produced few carbon footprints which can be ignored.
95.8 kg CO2eq , registering somewhere in between the two batteries above. LiFePO4 and acetylene black made great contribution to the CO2 equivalent, while GHGs produced by Ni-MH battery mainly came from nickel. The LiFePO4 ’s environmentally friendliness is better than nickel. Solar cell was a new type of energy. However, in the assembly process of raw materials, the use of silicon, carbon and other materials greatly increased the carbon emissions. Therefore, environmentally friendliness should be considered comprehensively. From the perspective of the life cycle of a battery, the carbon footprint of lithium iron phosphate battery and Ni-MH battery were 736.35 kg CO2eq and 1483.72 kg CO2eq . Among them, the carbon footprints of raw materials phase, production phase and use phase of lithium iron phosphate battery accounted for 1.72%, 2.13% and 96.14%. While, the carbon footprints of raw materials phase, production phase and use phase of Ni-MH battery accounted for 8.35%, 30.30% and 61.35%. The environmental impact of use phase was the most part, but differed from different batteries. 6. Conclusions A quantitative analysis of the carbon footprints of battery and carried out carbon identification based on the LCA theory was proposed in this study. The carbon footprints helped enterprises recognize the weak link in the life cycle by itself. Many proposed measures such as improving materials and manufacturing technology, could be taken to reduce GHGs emissions and promote the sustainable development of the product. At the same time, the carbon label would help consumers choose low-carbon products and enjoy low-carbon life. The research demonstrated that under the same functional unit of 1000 kW h, the carbon footprint of lithium iron phosphate battery’s raw materials was 12.7 kg CO2eq , compared to the NiMH battery’s 124 kg CO2eq and the solar cell’s 95.8 kg CO2eq . All above fully illustrates the environmental friendliness of lithium ion battery. However, the regional variations of lithium ion battery manufacture needs more concerns. The life cycle impact assessment found that, different batteries had different producing pollution links. Due to small volume and lightweight, GHGs emissions of lithium iron phosphate battery were less during the raw materials assembly stage, production stage and transport stage. While, the repeated charge-discharge in the use stage made it produce more GHGs. Therefore, the electrochemical performance of battery should be further improved to reduce the loss of charge and discharge. And we can use clean electricity to reduce indirect GHGs emissions as well. The same goes for Ni-MH battery. The carbon footprint of Ni-MH battery is more than the lithium iron phosphate battery, especially for the raw materials phase, production phase and use phase. The result further proved the environmental friendliness and better performance of lithium ion battery.
5.2. Comparison
Acknowledgments
Because of the lacking of data, the study compared the raw materials’ carbon footprints of lithium iron phosphate battery, Ni-MH battery and solar cell and the life cycle carbon footprints of lithium iron phosphate battery and Ni-MH battery on the basis of LCA and the same functional unit to show the environmentally friendliness of lithium ion battery. Under the same condition, the carbon footprint of lithium iron phosphate battery’s raw materials was 12.7 kg CO2eq , compared with the 124 kg CO2eq (the per capita carbon footprint of China was 3900 kg CO2eq ) of Ni-MH battery which was about 10 times of the former. In the meantime, the carbon footprint of solar cell was
This research was supported by the Natural Science Foundation of China (NSFC) (Nos. 51474033 and 41301636), and project from Beijing Municipal Science and technology commission (No D141100004514001). The authors would like to thank Bo Chen and Dong Wang for their help in this paper and appreciate the editor and reviewers for their comments and suggestions to improve the paper. References Battery Industry Association, Industrial Battery Yearbook 2011, Beijing, 2011.
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batteries for plug-in hybrid and battery electric vehicles. Environ. Sci. Technol. 45 (10), 4548–4554. Messagie, M., Oliveira, L., Rangaraju, S., et al., 2015. Environmental performance of lithium batteries: life cycle analysis. Recharg. Lithium Batter., 303–318. Tang, Y.G., 2007. NI-MH Battery, 1st ed. Chemical Industry Press, Beijing. Wang, W., Lin, J.Y., Cui, S.H., et al., 2010. An overview of carbon footprint analysis. Environ. Sci. Technol. 33 (7), 71–78. Wiedmann, T., Minx, J., 2007. A definition of carbon footprints. SA Res. Consult., 9. Wu, F., 2009. Research progress of green secondary battery materials. Mater. China 28 (7–8), 41–49. Yu, Y.J., Wang, D., Huang, K., et al., 2014. Assessment of cathode active materials from the perspective of integrating environmental impact with electrochemical performance. J. Clean. Prod. 82, 213–220. Zackrisson, Mats, Avellán, Lars, Orlenius, Jessica, 2010. Life cycle assessment of lithium-ion batteries for plug-in hybrid electric vehicles—critical issues. J. Clean. Prod. 18, 1519–1529.
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Life cycle assessment of lithium-ion batteries for greenhouse gas emissions Yuhan Liang a,b , Jing Su a,b,∗ , Beidou Xi a,b,d,∗ , Yajuan Yu c , Danfeng Ji a , Yuanyuan Sun a , Chifei Cui a , Jianchao Zhu a a
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences. Beijing, 100012, China State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China c Beijing Institute of Technology, Beijing 100081, China d Lanzhou Jiaotong University, Lanzhou 730070,China b
a r t i c l e
i n f o
Article history: Received 1 February 2016 Received in revised form 26 August 2016 Accepted 26 August 2016 Available online xxx Keywords: Lithium ion secondary batteries Carbon footprints Life cycle assessment
a b s t r a c t The optimized design of lithium ion secondary batteries using combination of carbon footprints and life cycle assessment (LCA) was proposed in this study. The carbon footprints of the batteries were obtained by four stages, and relevant reduction strategies were implemented accordingly. The carbon footprints of three different batteries were compared in this study: lithium ion secondary battery, nickel metal hydride battery and solar cell were evaluated. The result indicated that the carbon dioxide equivalence of the assembly process for raw materials sequence was nickel metal hydride battery (124 kg CO2eq ) > solar cell (95.8 kg CO2eq )> lithium ion secondary battery (12.7 kg CO2eq ). The result also proposed the lithium ion batteries’ environmental friendliness with numeric illustration and the calculation of carbon footprints of the product was developed as reference to battery selection for human use. © 2016 Published by Elsevier B.V.
1. Introduction Along with the enhancement of people’s environmental consciousness and the development of carbon label, companies increasingly felt the pressure from low carbon tendency. Thus, the calculation of product carbon footprints and the low carbon management of supply chain will become one of energy conservation and emissions reduction tasks of many brands and retailers in the future. China is now in the beginning of the low carbon economic transformation. With the vigorous promotion of energy conservation and emissions reduction work in the “12th Five-Year-Plan” period, the mechanism of carbon trading and carbon tax has been introduced gradually. It is necessary to reduce product carbon footprints of manufacturing enterprises in China, so as to attract more downstream invents and consumers. The carbon label as the unique identifier to quantitative product carbon footprints is increasingly concerned. Therefore, it is urgent to understand the calculation of product carbon footprints in China.
∗ Corresponding authors at: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences. Beijing, 100012, China E-mail addresses: [email protected] (J. Su), [email protected] (B. Xi).
Carbon Footprint (CFP) originated in ecological footprint (Johnson, 2008), which also considered as carbon emissions, was used to describe the emissions of greenhouse gases (GHGs) from organization, product or individual. Meanwhile, the product carbon footprint, named carbon label, was a research hot spot in all over the world. Wiedmann and Minx (2007) defined CFP as the emissions of CO2 which was caused by an activity during the whole life cycle of a product both directly and indirectly. While, most activities may also emit other kinds of GHGs, that also need to be considered. Therefore, the term carbon dioxide equivalent (CO2eq ) is widely used in CFP assessments. The methods of product carbon footprints are divided into two sorts: “top-to-down” model and “bottom-to-up” model (Wang et al., 2010). Life cycle assessment (LCA) is a kind of “bottom-to-top” method, which includes the process “from start to finish” of the product. It is generally recognized as a quantitative and qualitative analysis tool of environmental impact caused by life cycle of product at the international level. LCA first appeared in the United States, where the company Coca-Cola commissioned a research institution to make a quantitative analysis and track from raw material mining to waste of the beverage container in 1969. LCA is a commonly used tool for evaluating environmental features of electronic products in nowadays.
http://dx.doi.org/10.1016/j.resconrec.2016.08.028 0921-3449/© 2016 Published by Elsevier B.V.
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Lithium ion secondary battery (Wu, 2009) developed as a new battery after nickel cadmium battery, which has become an important technical way to mitigate the crisis of energy and resources and solve environment pollution problems. Lithium-ion battery has been widely used in cell phones, laptops, digital cameras and many other products due to its high energy density, high voltage, low self-discharge, non-memory effect, long cycle life and environmental friendliness. With the increasing market demand for lithium ion battery, further research about its performance is in need. In recent decade, the market share and sales of lithium ion battery continued to soar, which was comparable to that of nickel cadmium battery and nickel metal hydride battery (Battery Industry Association, 2011). The research of product carbon footprints in China is still at the beginning presently, and very few research about carbon footprint assessment of lithium ion battery. However, the secondary environmental problems of widely used lithium ion battery should not be ignored, which requires further research. Recently, there has been many researches on the carbon footprint calculation and the environmental impact assessment of lithium ion battery. Yajun Ge (2008) proposed the LCA method for wasted secondary battery, in which Shenzhen city was used as an example, mainly conducted quantitative assessment on chronic public health impact of nickel cadmium battery, nickel metal hydride battery, lithium ion battery and lead-acid battery. Zackrisson et al. (2010) studied how LCA could be used to the optimization design of lithium-ion batteries for plug-in hybrid electric vehicles, and then the environmental impact of two different solvents batteries were compared. The environmental impact of lithium ion battery used in battery-powered electric cars was measured in Ecoindicator 99 points (Dominic Notter et al., 2010). Majeau-Bettez et al. (2011) made a comparison among nickel metal hydride (NiMH), nickel cobalt manganese lithium-ion (NCM) and iron phosphate lithium-ion (LFP) batteries in three different functional units, which expressed the results through thirteen impact categories. Linda Ager-Wick Ellingsen et al. (2013) evaluated an Li (NixCoyMnz)O2 (NCM) traction battery in three different functional units and compared with preceding researches. Yu et al. (2014) assessed four kinds of cathode active materials, and brought forward a method for assessing cathode active materials that accounts for both the environmental impact and the electrochemical performance to filter cathode active materials that are friendly to environment and with excellent performance. Messagie et al. (2015) first proposed the availability and demand of lithium, then compared a lithium manganese oxide (LMO) and a lithium iron phosphate (LFP) battery by means of LCA, which indicated the whole environmental performance of the battery was strongly dependent on its efficiency and directly tied to the energy mixes associated with its uses. The above researches evaluated the environmental impact of lithium ion battery from different angles. However, there are few studies focusing on the carbon footprint assessment of lithium ion battery products, failing to analyze the impact from each stage. The lithium ion battery was used as an case study and compared with nickel metal hydride battery and solar cell. The carbon footprint assessment of secondary battery product was caculated by LCA method theory. Therefore, the results can be used to provide effective support for managers and evidence for people to choose environmentally friendly products.
Fig. 1. National production of lithium ion battery from 2010 to 2014.
Fig. 2. Production of lithium ion battery in provinces in 2014.
ion battery increased approximate linearly from 2.69 billion to 5.29 billion (CBIW, 2011–2015), as shown in Fig. 1. The long-term consumption growth of electronic products and the substitution effect in the field of electric tools and electric bicycle will lead to steady growth of lithium ion battery. According to the statistics of China Industrial Association of Power Sources (CIAPS), China’s lithium ion battery exports reached 1.32 billion (USD 5.48 billion) in 2014 and 1.13 billion (USD 4.80 billion) in 2013, up by 16.8% (14.1%) from a year earlier. The sales revenue of lithium reached USD 10.7 billion in 2014, up by 21.1% from USD 8.8 billion yuan in 2013. The lithium ion battery used in IT market accounted for 81.1% of the lithium-ion battery market, new energy vehicles and electric bicycles with power lithium ion batteries accounted for 16.8%, and communication and new energy storage with lithium ion batteries took 2.1% of the lithium ion battery market (2015). The production of the lithium ion batteries in 2014 for different provinces in China is shown in Fig. 2. The battery production in Guangdong, Jiangsu and Tianjin ranked top 3, up to 2.02,0.87 and 0.49 billion. At the same time, the production in Fujian, Jiangxi, Guangxi and other places were relatively high, reaching 0.42, 0.38 and 0.34 billion respectively, while the production in Shanxi, Jilin, Sichuan and other places were relatively low. 2.2. Enterprise distribution
2. Lithium ion battery in China 2.1. Production situation In recent years, lithium-ion battery industry is developing rapidly in China. During 2010 and 2014, the production of lithium
The global lithium ion market consists of China, Japan and South Korea, and the lithium ion battery in China is developing rapidly. The battery enterprises are mainly distributed in Guangdong, Jiangsu, Zhejiang Province et al., accounting for 70% of national total. The lithium-ion battery industry (CCID Consulting, 2011) in China is mainly concentrated in the Pearl River Delta repre-
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sented by Guangdong, Yangtze River Delta represented by Jiangsu and Beijing-Tianjin Area represented by Tianjin. The Pearl River Delta is a major production base of materials and assembly for lithium ion battery in China. There are thousands of enterprises in the region, including various types of large battery enterprises such as BYD and MOTTCELL. A large number of cheap labor enabled the rapid development of the labor-intensive assembly link, and Shenzhen BAK has become the production base of lithium ion battery. The Yangtze River Delta is the primary area of battery industry aggregation represented by Shanghai, Jiangsu and Zhejiang Province and occupies an important place in the lithium-ion battery industry. The representative enterprises are Shanghai Yangyang Battery Technology Company and SANYO ENERGY (SUZHOU) Co. Ltd and so on. Jiangsu and Zhejiang are important production bases of materials, which attract a great deal of foreign investment enterprises. Around Bohai Gulf Area represented by Beijing, Tianjin and Shandong Province, as the industry base of materials and power battery, has some typical enterprises such as LISHEN (TIANJIN) and Pulead Technology Industry Co. Ltd. Beijing, relying on the advantages of its technology and talents, had gained great development in cathode material for lithium ion battery. Meanwhile, Tianjin has basically formed a perfect lithium-ion battery industry chain. 3. Methodology 3.1. LCA and environmental product declarations Life Cycle Assessment (LCA) is a quantitative and qualitative analysis method of environment impact caused by life cycle of products, processes and activities. The key point is to analyze the energy consumption and the potential impact on the environment of products from raw materials acquisition, manufacturing, use to recycling of resources, and explain the results of the evaluation, put forward suggestions for energy conservation and emission reductions and improve the environment. EPD2008 is a method for calculating and validating environment data of the products based on LCA and ISO14025, which was posted on the website of Sweden Environmental Management Committee to create environmental product declarations. EPD mainly describes products or manufacturers information for life cycle, determines the functional unit, describes the environmental performance and classifies different effects. In recent years, more and more designers and users in the middle of the products require companies to provide EPD in order to integrate the sustainability information into the product design. This paper mainly studied the EPD2008 to calculate the product’s carbon footprints and analyze the impact on GHGs, and the final results were expressed as carbon dioxide equivalent (CO2eq ). 3.2. Functional unit Lithium iron phosphate (LiFePO4 ) battery was selected as the research object in this paper and the functional unit was defined as 1000 kW h to ensure the comparability of carbon footprints of different batteries. In the second part, three kinds of batteries were compared in the paper to choose low-carbon products. All collected data need to be converted to functional unit to ensure the results comparability. It directly influences the veracity of calculation results. 3.3. System boundary The first stage is to determine each product system and the system boundary, including the production process of product and the initial system boundary. Secondly, research data were collected in accordance with each link of the production process, so as to
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ensure the representativeness, accuracy, completeness, and comparability of the data. The study selected the mode of “enterprise to consumer” for the carbon footprint calculation of lithium-ion battery carbon. The system boundary (S1) was from raw materials acquisition, processing, and manufacturing, transport to use phase except for the recycling process when calculating the carbon label of lithium-ion battery. At the same time, the system boundary (S2) was selected when comparing carbon footprints of three batteries raw materials. Due to various components of the product boundary, PAS2050 required the carbon footprint calculation within the system boundary. The system boundary was defined as follows: of all emissions of GHGs, emission source response to the product life cycle was greater than 1% of its substantial contribution, and the insubstantial emission source are not supposed to exceed 5% of carbon footprints of the product. Life cycle process diagram of the battery is presented in Fig. 3and the system boundary is the respective diagram. 3.4. Battery assembly 3.4.1. Lithium iron phosphate battery Lithium iron phosphate battery is a lithium ion battery produced with lithium iron phosphate cathode materials. Because of higher charge-discharge efficiency, it is mainly used as power battery. Lithium-ion button battery consists of five parts: cathode materials, anode materials, electrolytes, separator and battery shell (Fig. 4). The lithium iron phosphate battery was made in the laboratory of Beijing Institute of Technology in this study. The capacity was 1440 mAh and the charging voltage was 4 V. It was mainly composed of the cathode, anode, electrolytes, separator and battery shell. The cathode included lithium iron phosphate cathode material, acetylene black and aluminum foil. Ferrous oxalate (FeC2 O4 ), ammonium dihydrogen phosphate (NH4 H2 PO4 ) and lithium hydroxide (LiOH) were used to make LiFePO4 by high temperature solid state method. The anode was made of acetylene black, mesocarbon microbeads (MCMB) and binder coated on copper foil. The electrolyte consisted of organic solvent, lithium salt and additives. The organic solvent was a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC), and the lithium hexafluorophosphate (LiPF6 ) was selected as the lithium salt. Moreover, the separator was polyethylene (PE) membrane and the shell was stainless steel. Because of the lack of data, EMC and LiPF6 were traced back to upper-lever. EMC was synthesized by dimethyl carbonate (DMC) and Ethanol (C2H5OH). LiPF6 was made by hydrofluoric acid (HF), phosphorus pentachloride (PCl5 ) and lithium fluoride (LiF). The cathode materials were mixed in an agate mortar according to the proportion, then coating on the aluminum foil and drying under 80◦ for 12 h. After that, the cathode, anode, electrolyte and shell were assembled in the glove box filled with argon. The new battery should let it stand for up to 12 h. Peter Van den Bossche’s research published in 2006 showed that the energy efficiency of lithium ion battery was 90% when its cycle-index was 1000 times. On the premise of the above research results, the study considered the cyclic numbers of battery. Then the quality of the battery’s components were calculated when they produced 1000 kW h electricity. The cathode, anode and electrolyte materials were composed according to certain proportions, and the composition of raw materials and its mass percentage are shown in Table 1. The cathode and anode materials were the main components, accounting for 36.80% and 37.12% of the battery respectively. The electrolyte accounted for a small part, but its contributions to GHGs couldn’t be ignored because of high carbon content. 3.4.2. Nickel metal hydride battery The Nickel metal hydride (Ni-MH) battery is made of hydrogen ion and metal nickel, which mainly used in hybrid electric vehi-
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Fig. 3. Life cycle process diagram and system boundary of the battery.
Fig. 4. The structure diagram of lithium-ion button battery.
Table 1 Components of lithium iron phosphate battery. Component
Raw material
Raw material
Cathode
LiFePO4 Acetylene black Aluminum
FeC2 O4
Anode
Acetylene black MCMB Copper
Electrolyte
Ethylene carbonate(EC) Ethyl methyl carbonate(EMC) LiPF6
Separator
Polyethylene membrane(PE)
Shell
Steel
NH4 H2 PO4
LiOH
Dimethyl carbonate(DMC)Ethanol(C2H5OH) HF PCl5 LiF
Quality/(g/1000 kW h)
Mass percentage
Note
914.35 183.26 3.86
36.80%
5:1
183.26 914.35 13.50
37.12%
5:1
54.01 135.03 293.21
16.11%
2:5 1 mol/L
1.35
0.05%
Outsourcing
297.82
9.92%
Outsourcing
Table 2 Components of the nickel metal hydride battery. Component
Raw material
Raw material
Quality/(kg/1000 kW h)
Mass percentage
Cathode
Ni(OH)2 Nickel foam
NiSO4 NaOHNH3 ·H2 O
4.19 0.03
14.89%
Anode
LaNi5 Nickel foam
La2 O3
4.62 0.04
16.42%
Electrolyte
KOH LiOH 255 carbonyl nickel powder Polytetrafluoroethylene(PTFE)
0.49 1.10 0.29 0.13
7.12%
CHCl3
NiO
HF
Separator
Polypropylene(PP)
0.66
2.33%
Shell
Steel
16.80
59.24%
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Table 3 Components of the solar cell. Component
Raw material
Quality/(g/1000 kW h)
Masspercentage
P-n knot
Silicon Liquid argon Boron-silicon-molybdenum alloy Phosphorus oxychloride(POCl3 )
1004.39 295.76 0.03 1.18
6.4%
Metallic contact
Polyurethane Liquid nitrogen Aluminum slurry Silver pulp
5.07 5466.87 89.98 14.81
27.5%
Antireflection layer
Silicon nitride Silicon carbide Liquid oxygen Silane Liquid ammonia
4.27 5128.80 35.47 3.34 6.20
25.6%
Aluminum alloyed back
Aluminum Tin
339.96 114.86
2.2%
Suede
Ethylene glycol((CH2OH)2) Epoxy resin Hydrofluoric acid(HF) Hydrochloric acid(HCl) Potassium hydroxide(KOH) Nitric acid(HNO3 ) Sodium hydroxide(NaOH)
6118.83 6.62 666.45 302.42 48.05 579.01 21.37
38.2%
Table 4 Energy consumption of the two batteries in different stages. Battery
Phase
Water/m3
Electricity/kW h
Gasoline/L
Lithium iron Phosphate Battery
Production Transport Use
0.02 – –
24.68 – 1111.11
0.007 0.005 –
Ni-MH Battery
Production Transport Use
12.84 – –
705.45 – 1428.57
– 0.05 –
Fig. 5. Carbon footprint flow chart of lithium iron phosphate battery’s raw materials.
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Fig. 6. Carbon footprint flow chart of ni-mh battery’s raw materials.
cles. It has longer service life and is more environmentally friendly than nickel cadmium battery. The studied Ni-MH battery was AA size. The diameter and height of this battery were 13.9 and 50 mm. The capacity was 1800 mAh and the charging voltage was 1.2 V (Tang, 2007). The cathode was made of nickel foam and nickel hydroxide (Ni(OH)2 ) that were prepared by nickel sulfate, sodium hydroxide and ammonia through complex precipitation method. The anode consisted of nickel foam and LaNi5 . The electrolyte was composed of potassium hydroxide (KOH), lithium hydroxide (LiOH), 255 carbonyl nickel powder and polytetrafluoroethylene (PTFE). The separator was polypropylene (PP) and the shell was stainless steel. The energy efficiency of nickel metal hydride battery was 70% when its cycle-index was 1350 times and the quality of Ni-MH battery’s components were calculated when they produced 1000 kW h electricity. The shell was the main component and the mass percentage was 59.24% (Table 2). The anode accounted for 16.42%, followed by the cathode and the electrolyte. The separator was the least. 3.4.3. Solar cell Solar cell is a photoelectric semiconductor wafer, which generates electricity directly from sunlight. The solar cell can be divided into silicon semiconductor battery, multiple compounds thin-film battery, organic materials battery, functional polymer materials preparation of solar cell, nanocrystalline solar cells and so on. The solar cell in the study was a kind of model TPA156 * 156 N monocrystalline silicon solar cell of made in manufacture. The output power was 3.82–4.63 W and the rated voltage was 0.48 V. It consisted of p-n knot, metal contact, antireflection layer, aluminum alloyed back and suede. The p-n knot was a small part, which was made of silicon, liquid argon, boron-silicon-molybdenum alloy and
phosphorus oxychloride (POCl3 ). The metallic contact was synthesized by polyurethane, liquid nitrogen, aluminum slurry and silver pulp, which accounted for 27.5%. The antireflection layer consisted of silicon nitride (Si3 N4 ), silicon carbide (SiC), liquid oxygen, silane and liquid ammonia. The mass percentage of aluminum alloyed back was 2.2%, which included aluminum and tin. Then the suede consisted of ethylene glycol ((CH2 OH)2 ), epoxy resin, hydrofluoric acid (HF), hydrochloric acid (HCl), potassium hydroxide (KOH), nitric acid (HNO3 ) and sodium hydroxide (NaOH). The mass percentage of the suede was 38.2%. The composition of raw materials and its mass percentage are shown in Table 3. The solar cell studied in this paper was used in the northern part of China with relatively little rain. It was assumed that there are 260 sunny days every year and the solar cell receives about six hours’ sunshine daily. In the case of a unified functional unit of 1000 kW h, the conversion of lithium-iron phosphate battery may refer to the Chapter 4.2.1. The power of solar cell was 213.7 w when it produces 1000 kW h of electricity.
3.5. Energy consumption During the entire life cycle of a battery except recycling phase, main energy consumption process includes production, transport and use phase. Under the same 1000 kW h condition, the specific data of stages are shown in Table 4. The transport phase mainly consumed gasoline calculated according to light trucks on the city roads while the use phase consumed electricity the most.
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Fig. 7. Carbon footprint flow chart of solar cell’s raw materials.
3.6. Environmental impact assessment The environmental impact usually can be divided into eleven different impact categories, including carcinogenicity, inhaled organic matter, inhaled inorganic, climate change, radioactive, ozone depletion, ecological toxicity, acid rain and eutrophication, land use, mineral consumption and fossil fuel. This study evaluated the environmental impact of battery from climate change. GHGs were mainly studied and final results were expressed as carbon dioxide equivalent (CO2eq ). 4. Results 4.1. Carbon footprints of different battery raw materials 4.1.1. Lithium iron phosphate battery On the basis of the theory of LCA method, software Simapro was used in the carbon footprint evaluation of raw materials assembly stage. Other related data came from ELCD and CLCD database etc. The carbon footprint flow chart of lithium iron phosphate battery’s raw materials is shown in Fig. 5. From bottom to top, the below is the upstream of the upper. “1 p LiFePO4 Battery” in the graph means a lithium iron phosphate battery when it produced
1000 kW h electricity and “1 p cathode materials” refers to the total cathode materials of a battery. In addition, LiFePO4 , EMC, LiPF6 and other materials used in the preparation of cathode, anode and electrolyte materials were synthesized and expressed in “1 p”. Fig. 5 shows that the carbon footprint of lithium iron phosphate battery’s raw materials is 12.7 kg CO2eq . The carbon footprints of cathode, anode and electrolyte are respectively 4.46 kg CO2eq , 3.67 kg CO2eq and 4.4 kg CO2eq . Meanwhile the carbon footprint of LiFePO4 is 3.85 kg CO2eq , acetylene black is 3.04 kg CO2eq , and EMC and LiPF6 are 1.92 kg CO2eq and 2.38 kg CO2eq respectively. Furthermore, the arrows’ thickness corresponds to the size of qualitative carbon footprints.
4.1.2. Nickel metal hydride battery The carbon footprint flow chart of Ni-MH battery’s raw materials is shown below (Fig. 6). Under the same condition, the carbon footprint of nickel metal hydride battery’s raw materials reaches up to124 kg CO2eq . Among them, the carbon footprints of cathode, anode and electrolyte of Ni-MH battery are respectively 49.7 kg CO2eq , 57.2 kg CO2eq and 10.3 kg CO2eq . Meanwhile the carbon footprint of ammonia is 11.7 kg CO2eq , lanthanum oxide is 16.1 kg CO2eq , and nickel is 66.8 kg CO2eq respectively.
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4.1.3. Solar cell The carbon footprint flow chart of raw materials the solar cell’s raw materials is shown in Fig. 7. It turned out that the carbon footprint of solar cell’s raw materials is 95.8 kg CO2eq . The carbon footprints of antireflection layer, p-n and suede of solar cell are respectively 37 kg CO2eq , 39.8 kg CO2eq and 13.6 kg CO2eq . At the same time, the carbon footprint of silicon carbide is 36.7 kg CO2eq , and silicon is 39.9 kg CO2eq respectively. 4.2. Carbon footprints of different battery 4.2.1. Lithium iron phosphate battery After the carbon footprint evaluation of raw materials assembly stage, the study further calculated the carbon footprints of life cycle. The composition of raw materials and its quality percentage are shown in Table 1 and the main energy consumption process including production, transport and use phase are shown in Table 4. The production phase consumes 0.02 m3 water and 24.68 kW h electricity. The transport phase consumes 0.007 L petrol. The use phase consumes 1111.11 kW h electricity. Finally, the carbon footprint of a lithium iron phosphate battery is 736.35 kg CO2eq after calculation, including 12.7 kg CO2eq from raw materials phase, 15.7 kg CO2eq from production phase and 707.95 kg CO2eq from use phase. 4.2.2. Nickel metal hydride battery For the Ni-MH battery, the production phase consumes 12.84 m3 water and 705.45 kW h electricity. The transport phase consumes 0.05 L petrol. The use phase consumes 1428.57 kW h electricity. So, the carbon footprint of a lithium iron phosphate battery is 1483.72 kg CO2eq after calculation, including 124 kg CO2eq from raw materials phase, 449.5 kg CO2eq from production phase and 910.22 kg CO2eq from use phase. 5. Discussions 5.1. Carbon footprint analysis of lithium iron phosphate battery The research results showed that the carbon footprint of lithium iron phosphate battery’s raw material was 12.7 kg CO2eq . The carbon footprints of cathode, anode and electrolyte of lithium iron phosphate battery accounted for 35.1%, 28.9% and 34.6% respectively, while the corresponding quality accounted for 36.80%, 37.12% and 16.11% respectively. The differences between two kinds of proportions indicated the carbon footprints of battery’s raw materials were greatly influenced by the material type. At the same time, the carbon footprint of a lithium iron phosphate battery was 720.7 kg CO2eq. It consumed large amounts of electricity in use phase and the carbon footprints produced from it account for the most part of the life cycle carbon emissions. Because of the lithium ion battery’s characteristics such as small volume, light weight and so on, the transport phase of a single battery produced few carbon footprints which can be ignored.
95.8 kg CO2eq , registering somewhere in between the two batteries above. LiFePO4 and acetylene black made great contribution to the CO2 equivalent, while GHGs produced by Ni-MH battery mainly came from nickel. The LiFePO4 ’s environmentally friendliness is better than nickel. Solar cell was a new type of energy. However, in the assembly process of raw materials, the use of silicon, carbon and other materials greatly increased the carbon emissions. Therefore, environmentally friendliness should be considered comprehensively. From the perspective of the life cycle of a battery, the carbon footprint of lithium iron phosphate battery and Ni-MH battery were 736.35 kg CO2eq and 1483.72 kg CO2eq . Among them, the carbon footprints of raw materials phase, production phase and use phase of lithium iron phosphate battery accounted for 1.72%, 2.13% and 96.14%. While, the carbon footprints of raw materials phase, production phase and use phase of Ni-MH battery accounted for 8.35%, 30.30% and 61.35%. The environmental impact of use phase was the most part, but differed from different batteries. 6. Conclusions A quantitative analysis of the carbon footprints of battery and carried out carbon identification based on the LCA theory was proposed in this study. The carbon footprints helped enterprises recognize the weak link in the life cycle by itself. Many proposed measures such as improving materials and manufacturing technology, could be taken to reduce GHGs emissions and promote the sustainable development of the product. At the same time, the carbon label would help consumers choose low-carbon products and enjoy low-carbon life. The research demonstrated that under the same functional unit of 1000 kW h, the carbon footprint of lithium iron phosphate battery’s raw materials was 12.7 kg CO2eq , compared to the NiMH battery’s 124 kg CO2eq and the solar cell’s 95.8 kg CO2eq . All above fully illustrates the environmental friendliness of lithium ion battery. However, the regional variations of lithium ion battery manufacture needs more concerns. The life cycle impact assessment found that, different batteries had different producing pollution links. Due to small volume and lightweight, GHGs emissions of lithium iron phosphate battery were less during the raw materials assembly stage, production stage and transport stage. While, the repeated charge-discharge in the use stage made it produce more GHGs. Therefore, the electrochemical performance of battery should be further improved to reduce the loss of charge and discharge. And we can use clean electricity to reduce indirect GHGs emissions as well. The same goes for Ni-MH battery. The carbon footprint of Ni-MH battery is more than the lithium iron phosphate battery, especially for the raw materials phase, production phase and use phase. The result further proved the environmental friendliness and better performance of lithium ion battery.
5.2. Comparison
Acknowledgments
Because of the lacking of data, the study compared the raw materials’ carbon footprints of lithium iron phosphate battery, Ni-MH battery and solar cell and the life cycle carbon footprints of lithium iron phosphate battery and Ni-MH battery on the basis of LCA and the same functional unit to show the environmentally friendliness of lithium ion battery. Under the same condition, the carbon footprint of lithium iron phosphate battery’s raw materials was 12.7 kg CO2eq , compared with the 124 kg CO2eq (the per capita carbon footprint of China was 3900 kg CO2eq ) of Ni-MH battery which was about 10 times of the former. In the meantime, the carbon footprint of solar cell was
This research was supported by the Natural Science Foundation of China (NSFC) (Nos. 51474033 and 41301636), and project from Beijing Municipal Science and technology commission (No D141100004514001). The authors would like to thank Bo Chen and Dong Wang for their help in this paper and appreciate the editor and reviewers for their comments and suggestions to improve the paper. References Battery Industry Association, Industrial Battery Yearbook 2011, Beijing, 2011.
Please cite this article in press as: Liang, Y., et al., Life cycle assessment of lithium-ion batteries for greenhouse gas emissions. Resour Conserv Recy (2016), http://dx.doi.org/10.1016/j.resconrec.2016.08.028
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Please cite this article in press as: Liang, Y., et al., Life cycle assessment of lithium-ion batteries for greenhouse gas emissions. Resour Conserv Recy (2016), http://dx.doi.org/10.1016/j.resconrec.2016.08.028