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Materials for energy conversion
Sci. Bull. (2016) 61(8):585–586 DOI 10.1007/s11434-016-1047-5
www.scibull.com www.springer.com/scp
Editorial
Materials for energy conversion Ned Djilali
Published online: 19 March 2016 Ó Science China Press and Springer-Verlag Berlin Heidelberg 2016
Advances in material science and engineering are critical to the development of economically viable technologies to address some of the grand socio-economic challenges of the twenty first century. Materials are at the core of emerging clean energy conversion and storage technologies [1] that can be used to capitalize on available renewable energy resources. These technologies range from solar cells and batteries, to storage of heat and hydrogen. Photovotaic cells for instance have the potential to meet a large portion of global energy needs, but though they already achieve acceptable energy return on investment [2], further cost reductions and improvements in efficiency are required to enhance their competitiveness. Large scale power generation using solar and other variable renewable energy resources requires suitable storage of energy either directly in the form of electricity or in the form of hydrogen generated via electrolysis. Both batteries and hydrogen storage technologies require progress in energy densities, performance and durability. These two technologies are in turn central to the electrification and decarbonization of the transportation sector via electric vehicles using batteries and/or fuel cells. The range of challenges that must be addressed in developing higher performance, more durable and cheaper materials for these energy technologies requires not only
SPECIAL TOPIC: Materials for Energy Conversion N. Djilali (&) Institute for Integrated Energy Systems, University of Victoria, Victoria, BC V8W 2Y2, Canada e-mail: [email protected] N. Djilali Renewable Energy Research Group, King Abdulaziz University, Jeddah, Saudi Arabia
the development and synthesis of improved and new materials but also understanding and eventual control of the underlying processes, transport properties and degradation phenomena. The Special Topic section of this issue of the Science Bulletin presents four contributions by leading research groups from Asia, Europe and North America addressing some challenges related to batteries, hydrogen storage, and fuel cell materials. Much of the current effort in battery research is directed at improving electrode materials to enhance cyclic stability and energy density. In their contribution, Liu et al [3], report on an exploratory experimental study on Lithium trivanadate (LVO), a material with relatively large reversible lithium ion insertion/extraction capacity that was particularly promising for moderate-voltage lithium ion batteries. The study investigates the introduction of surface defects to improve the lithium ion intercalation properties using controlled annealing in a reducing gas. The results of Liu et al. [3] show that electrodes annealed in nitrogen atmosphere have improved electrochemical properties compared to those annealed in air, discuss underlying causes, and lay some ground for future study of nitrogen annealing and nickel doping to further improve electrode performance. Hydrogen is an important energy carrier for long term sustainability [4] but its storage is challenging. One of the promising avenues for lowering thermodynamic requirements and achieving significant storage densities is through adsorption materials. The adsorption isotherms are important in determining the storage characteristics of such materials. Available adsorption models typically require prescription of a number of adjustable parameters to cover the full range of temperature and pressure. To address this issue, Durette et al. [5] perform grand canonical Monte Carlo simulations to determine the high density limit of the
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adsorption isotherms of hydrogen in metal–organic framework materials, and obtain physical insights on the fluid phase density in the pores of these materials. Fuel cells–as well as batteries and electrolyzers–rely on the use of judiciously designed materials to ensure effective transport of reactant and products to and from the reaction sites [6]. This is typically achieved through porous electrodes that have a complex structures and whose performance is characterized by macroscopic parameters such as permeability, effective diffusivity and tortuosity [6]. Khabbazi et al. [7] present a theoretical analysis of the impact of geometry of the solid phase of a porous material on tortuosity. Using lattice Boltzmann modelling (LBM), they determine the impact of particle aspect ratio on the intrinsic tortuosity–porosity relationships of two-dimensional porous media composed of rectangular particles, and provide insight for tailoring of stochastic porous media encountered in energy conversion and storage. While much effort in fuel cell development is currently centered on acidic systems using polymer electrolyte membranes, challenges related to water management, sluggish oxygen reduction reaction (ORR) kinetics and the high cost of platinum based catalysts have prompted renewed interest in alkaline systems that have inherently higher ORR kinetics and can operate with non-precious metal catalysts [8]. Uhlig et al. [9] use a combination of experimental characterization techniques to investigate the stability, activity and preferred pathways of the ORR in cobalt oxide catalysts for anion exchange membrane fuel cells (AEMFC). The results are promising but point to the
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Sci. Bull. (2016) 61(8):585–586
need for improved selectivity to mitigate the higher amount of by-product hydroperoxide generated with the cobalt oxide catalyst.
References 1. Xiong J, Han C, Li Z et al (2015) Effects of nanostructure on clean energy: big solutions gained from small features. Sci Bull 60:2083–2090 2. Mann SA, de Wild-Scholten MJ, Fthenakis VM et al (2014) The energy payback time of advanced crystalline silicon PV modules in 2020: a prospective study. Prog Photovolt 22:1180–1194 3. Liu YG, Zhang CP, Liu CF et al (2016) The effect of nitrogen annealing on lithium ion intercalation in nickel-doped lithium trivanadate. Sci Bull 8:587–593 4. Andrews J, Shabani B (2014) The role of hydrogen in a global sustainable energy strategy. WIREs Energy Environ 3:474–489 5. Durette D, Be´nard P, Zacharia R et al (2016) Investigation of the hydrogen adsorbed density inside the pores of MOF-5 from path integral grand canonical Monte Carlo at supercritical and subcritical temperature. Sci Bull 8:594–600 6. Lange KJ, Carlsson H, Stewart I et al (2012) PEM fuel cell CL characterization using a standalone FIB and SEM: experiments and simulation. Electrochim Acta 85:322–331 7. Khabbazi A, Hinebaugh J, Bazylak A (2016) Determining the impact of rectangular grain aspect ratio on tortuosity–porosity correlations of two-dimensional stochastically generated porous media. Sci Bull 8:601–611 8. Peng SK, Xu X, Lu SF et al (2015) A self-humidifying acidicalkaline bipolar membrane fuel cell. J Power Sources 299:273–279 9. Uhlig LM, Sievers G, Bru¨ser V et al (2016) Characterization of different plasma-treated cobalt oxide catalysts for oxygen reduction reaction in alkaline media. Sci Bull 8:612–618
www.scibull.com www.springer.com/scp
Editorial
Materials for energy conversion Ned Djilali
Published online: 19 March 2016 Ó Science China Press and Springer-Verlag Berlin Heidelberg 2016
Advances in material science and engineering are critical to the development of economically viable technologies to address some of the grand socio-economic challenges of the twenty first century. Materials are at the core of emerging clean energy conversion and storage technologies [1] that can be used to capitalize on available renewable energy resources. These technologies range from solar cells and batteries, to storage of heat and hydrogen. Photovotaic cells for instance have the potential to meet a large portion of global energy needs, but though they already achieve acceptable energy return on investment [2], further cost reductions and improvements in efficiency are required to enhance their competitiveness. Large scale power generation using solar and other variable renewable energy resources requires suitable storage of energy either directly in the form of electricity or in the form of hydrogen generated via electrolysis. Both batteries and hydrogen storage technologies require progress in energy densities, performance and durability. These two technologies are in turn central to the electrification and decarbonization of the transportation sector via electric vehicles using batteries and/or fuel cells. The range of challenges that must be addressed in developing higher performance, more durable and cheaper materials for these energy technologies requires not only
SPECIAL TOPIC: Materials for Energy Conversion N. Djilali (&) Institute for Integrated Energy Systems, University of Victoria, Victoria, BC V8W 2Y2, Canada e-mail: [email protected] N. Djilali Renewable Energy Research Group, King Abdulaziz University, Jeddah, Saudi Arabia
the development and synthesis of improved and new materials but also understanding and eventual control of the underlying processes, transport properties and degradation phenomena. The Special Topic section of this issue of the Science Bulletin presents four contributions by leading research groups from Asia, Europe and North America addressing some challenges related to batteries, hydrogen storage, and fuel cell materials. Much of the current effort in battery research is directed at improving electrode materials to enhance cyclic stability and energy density. In their contribution, Liu et al [3], report on an exploratory experimental study on Lithium trivanadate (LVO), a material with relatively large reversible lithium ion insertion/extraction capacity that was particularly promising for moderate-voltage lithium ion batteries. The study investigates the introduction of surface defects to improve the lithium ion intercalation properties using controlled annealing in a reducing gas. The results of Liu et al. [3] show that electrodes annealed in nitrogen atmosphere have improved electrochemical properties compared to those annealed in air, discuss underlying causes, and lay some ground for future study of nitrogen annealing and nickel doping to further improve electrode performance. Hydrogen is an important energy carrier for long term sustainability [4] but its storage is challenging. One of the promising avenues for lowering thermodynamic requirements and achieving significant storage densities is through adsorption materials. The adsorption isotherms are important in determining the storage characteristics of such materials. Available adsorption models typically require prescription of a number of adjustable parameters to cover the full range of temperature and pressure. To address this issue, Durette et al. [5] perform grand canonical Monte Carlo simulations to determine the high density limit of the
123
586
adsorption isotherms of hydrogen in metal–organic framework materials, and obtain physical insights on the fluid phase density in the pores of these materials. Fuel cells–as well as batteries and electrolyzers–rely on the use of judiciously designed materials to ensure effective transport of reactant and products to and from the reaction sites [6]. This is typically achieved through porous electrodes that have a complex structures and whose performance is characterized by macroscopic parameters such as permeability, effective diffusivity and tortuosity [6]. Khabbazi et al. [7] present a theoretical analysis of the impact of geometry of the solid phase of a porous material on tortuosity. Using lattice Boltzmann modelling (LBM), they determine the impact of particle aspect ratio on the intrinsic tortuosity–porosity relationships of two-dimensional porous media composed of rectangular particles, and provide insight for tailoring of stochastic porous media encountered in energy conversion and storage. While much effort in fuel cell development is currently centered on acidic systems using polymer electrolyte membranes, challenges related to water management, sluggish oxygen reduction reaction (ORR) kinetics and the high cost of platinum based catalysts have prompted renewed interest in alkaline systems that have inherently higher ORR kinetics and can operate with non-precious metal catalysts [8]. Uhlig et al. [9] use a combination of experimental characterization techniques to investigate the stability, activity and preferred pathways of the ORR in cobalt oxide catalysts for anion exchange membrane fuel cells (AEMFC). The results are promising but point to the
123
Sci. Bull. (2016) 61(8):585–586
need for improved selectivity to mitigate the higher amount of by-product hydroperoxide generated with the cobalt oxide catalyst.
References 1. Xiong J, Han C, Li Z et al (2015) Effects of nanostructure on clean energy: big solutions gained from small features. Sci Bull 60:2083–2090 2. Mann SA, de Wild-Scholten MJ, Fthenakis VM et al (2014) The energy payback time of advanced crystalline silicon PV modules in 2020: a prospective study. Prog Photovolt 22:1180–1194 3. Liu YG, Zhang CP, Liu CF et al (2016) The effect of nitrogen annealing on lithium ion intercalation in nickel-doped lithium trivanadate. Sci Bull 8:587–593 4. Andrews J, Shabani B (2014) The role of hydrogen in a global sustainable energy strategy. WIREs Energy Environ 3:474–489 5. Durette D, Be´nard P, Zacharia R et al (2016) Investigation of the hydrogen adsorbed density inside the pores of MOF-5 from path integral grand canonical Monte Carlo at supercritical and subcritical temperature. Sci Bull 8:594–600 6. Lange KJ, Carlsson H, Stewart I et al (2012) PEM fuel cell CL characterization using a standalone FIB and SEM: experiments and simulation. Electrochim Acta 85:322–331 7. Khabbazi A, Hinebaugh J, Bazylak A (2016) Determining the impact of rectangular grain aspect ratio on tortuosity–porosity correlations of two-dimensional stochastically generated porous media. Sci Bull 8:601–611 8. Peng SK, Xu X, Lu SF et al (2015) A self-humidifying acidicalkaline bipolar membrane fuel cell. J Power Sources 299:273–279 9. Uhlig LM, Sievers G, Bru¨ser V et al (2016) Characterization of different plasma-treated cobalt oxide catalysts for oxygen reduction reaction in alkaline media. Sci Bull 8:612–618