Electrochemical Power Research Articles

Numerical Analyses on Transient Thermal Behavior of Micro Heat Pipe Array-Air Cooling Battery Thermal Management System

Power battery provides energy source for electric vehicles, and is an important part of electric vehicles. The performance of power battery directly restricts the output power, system safety and economy of electric vehicles: specific energy determines the driving mileage of electric vehicle; specific power determines the maximum climbing capacity and maximum speed and battery cycle life directly affects the automobile economy. Among many kinds of power batteries, lithium-ion battery has strong advantages in power output, mileage and service life. It is the mainstream technology of existing vehicle power battery, and is the focus of current research and development. Lithium-ion power system is an electrochemical power source with complex flow and heat transfer process, temperature is one of the key factors affecting the system performance. Temperature and temperature distribution directly affect the electrical performance, charge/discharge efficiency, output power and cycle life. Overall, the effect of temperature on the battery is mainly reflected in three aspects: (1) When temperature is too high, the recession will aggravate the battery capacity and output power, high temperature will even cause thermal runaway. (2) When temperature is too low, the discharge capacity of the battery will be attenuated and the charge/discharge efficiency decreased; (3) inconsistence in temperature distribution will further exacerbate the inconsistency between the cells and the uneven rate of aging, and cause cycle life decay. The best working temperature range of lithium ion battery is about 25-40℃, and the temperature difference between cells should be controlled below 5℃. Therefore, it is necessary to design a reasonable thermal management system structure and to develop advanced control strategy, in order to ensure the power battery operate within the suitable temperature range, and effectively control the battery temperature difference, in order to improve the performance of power battery and ensure the efficient operation of electric vehicles. Traditional battery thermal management method mainly adopts air cooling and liquid cooling structure. However, it is difficult for air cooling system to control the battery temperature and meet heat dissipation requirement under high discharge rate. The liquid cooling system has complicated structure, which may lead to an increase in weight and reduces the energy density of the battery system. Compared with the traditional air cooling and liquid cooling, heat pipe has advantages of high heat transfer coefficient, simple structure, light weight, and in the large current discharge conditions, which can achieve efficient heat dissipation enhancement and ensure smaller temperature difference. Therefore, battery thermal management system based on heat pipe technology is the choice of future HEV/EV. A heat pipe-air cooling coupled heat dissipation system was designed in this paper. Micro heat pipe array (MHPA) was used as it has flat surface to ensure the contact surface and low contact resistance for better heat transfer efficiency. A fin structure was installed on the MHPA to enhance heat transfer. Simulation was conducted for both one battery cell and a battery pack using MHPA cooling system. First, one cell-MHPA-fin structure was studied. A first order equivalent circuit model was used in the approach to predict the dynamics of the cell electrical performance. The electric model was then coupled with a lumped thermal model to describe the dynamics of heat generation of the battery cell. 3D CFD calculation was conducted to simulate the thermal response when the battery is operating under a variable operating condition with heat pipe cooling. Results show that MHPA-fin air cooling system has quick response for the sudden change of current. Comparison results showed that the cooling rate of battery with MHPA is twice than that with liquid cooling. Secondly, a battery pack of 36 cells was studied. MHPA-fin system was installed between two adjacent cells. Same model with one cell analysis was adopted in this study. Results showed that the temperature of all cells within the pack responses nearly identical with a temperature difference below 3℃. Finally, the cycle life of the battery cell with the above MHPA-air cooling system was analyzed. Under 1C discharge rate, the cell can work for more than 800 cycles with a capacity fading less than 20%.

Influence of Aluminum Addition to Catalytic Behavior of Bismuth Ruthenate for Oxygen Electrode Reactions

Electrochemical power sources that use oxygen as a reactant may play an essential role in the future energy needs of the society. In particular, fuel cells, aqueous metal-air batteries, and metal hydride (MH)/air batteries hold promise as power sources beyond lithium-ion batteries (LIBs). For such electrochemical power sources, an alkaline solution is often employed as the electrolyte and an oxygen electrode reaction occurs at the cathode. However, the development of highly active catalysts (i.e., with low activation overpotential) for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) remains challenging. We then have devoted to investigate the electrode catalyst which decreases in the overpotential for both ORR and OER. To the best of our knowledge, a pyrochlore type metal oxide including bismuth ion as the A-site (Bi2Ru2O7, BRO) is one of the most promising bifunctional catalysts and the overpotentials and Tafel slopes were reported in “Electrocatalysis (Vol. 9, 146-152, 2018)”. In order to further decrease in the overpotential and Tafel slopes, we attempted to addition of Al ion to BRO (ABRO) and have evaluated. BRO and ABRO were prepared by a precipitation method. Bi(NO3)3, RuCl3 and NaOH aqueous solutions were used for preparation of BRO. Al(NO3)3 was added to investigate the aluminum addition. Finally, the precipitates were made for calcination under atmospheric air at 500 and 600oC for 3 h. X-ray diffraction (XRD) was used to characterize the products. The weight change during the calcination was investigated by Thermo-gravimetry. The oxygen contents of the products were estimated by using modified temperature-programmed reduction (TPR). The product was put into a quartz tube furnace and was heated up to 700 °C in a hydrogen atmosphere. Water, which was produced by the reaction of hydrogen and oxygen in BRO, was quantified by using Karl Fischer moisture meter. The catalytic behavior for both ORR and OER was investigated by a rotating ring disk electrode (RRDE). The disk and ring electrodes were made by a glassy carbon (GC) and Pt, respectively. The product was dispersed on GC and fixed with a thin film of anion-exchange-membrane (corresponding ionomer solution: AS-4, TOKUYAMA K.K.). Hg|HgO reference electrode and a Ni mesh counter electrode were placed in a perfluoroalkoxyalkane beaker cell. The electrolyte solution was 0.1 mol dm-3 KOH aqueous solution. The XRD pattern of the product was assigned to Bi2Ru2O7 after the calcination at 500oC. When the calcination temperature was at 600oC, it was likely to assign to Bi1.9Ru2O6.92 These results indicated that oxygen and bismuth were made elimination between 500oC and 600oC. The lattice constant of the product obtained at 500oC is very close to that of Bi2Ru2O7; therefore, we reasonably considered that the product was Bi2Ru2O7. In the case of ABRO, there were no peaks for impurity compounds like as the aluminum compounds. Hereafter, we call BRO that obtained at 500oC and 600oC as BRO-500 and BRO-600, respectively. Similar to this, we named ABRO-500 and ABRO-600 for ABRO. TPR results showed that the oxygen contents of BRO and ABRO were depended on the calcination temperature, which corresponds to the XRD results. The oxygen content of BRO decreased with increase in the calcination temperature; whereas opposite tendency was recognized for ABRO. Figure 1 (a) and (b) shows the hydrodynamic voltammograms of BRO for ORR and OER, respectively. The overpotential is around 0.31 V and around 0.16 V for ORR and OER, which shows that overpotential is not related to the calcination temperature in this study. On the other hand, Tafel slope for OER decreased with an increase in the calcination temperature. Fig. 1 (c) and (d) also shows voltammograms for ABRO. The OER overpotential of ABRO-600 was greatly low as around 0.07 V, which suggests that the addition of aluminum during the preparation of BRO gives the influence on the catalytic activity. This work was supported by “Advanced Low Carbon Technology Research and Development Program (ALCA)” of Japan Science and Technology Agency (JST). The authors express gratitude to Tokuyama Corporation for supplying AS-4. Figure 1

Social capital selection framework of public-private partnership project of electrochemical storage power station under linguistic environment

The social capital selection is one of the most important issues in public-private partnership project of electrochemical storage power station. However, two problems reducing the decision-making rationality and accuracy exist in the present multi-criteria decision analysis. First, the existing evaluation index system does not can reflect the technological characteristics of electrochemical storage power station; second, some information distortion and loss are caused by the uncertainty in the evaluation values and the criteria weights. In order to overcome these deficiencies, the innovations of this paper are as follows: ①this paper built a social capital selection evaluation index system specifically targeted at electrochemical storage power station, the results of social capital selection are more in line with the actual needs of power station construction and operation; ② trapezoidal interval type-2 hesitant fuzzy number as the mathematics symbol of linguistic terms are used to established a evaluation model, which can balance the convenience of opinion expression and the accuracy of evaluation value; ③ the maximizing deviations principle was used to handle the interval weights under the linguistic environment, it not only allowed the experts to express subjective weights as possible as they can, but also realized objective weights’ information mining by using the deviations of evaluation data. The aforementioned innovations together constitute a social capital selection framework of electrochemical storage power station. Finally, the effectiveness of decision framework was verified based on a case study of China.

Integration of supercapacitors into printed circuit boards

Abstract Physically integrated energy storage devices are gaining increasing interest due to the rapid development of flexible, wearable and portable electronics technology. For the first time, supercapacitor components have been integrated into a printed circuit board (PCB) construct. This proof-of-concept study paves the way for integrating supercapacitors into power electronics devices and hybridising with PCB fuel cells. Commercial Norit activated carbon (NAC) was used as the electrode material and was tested in two types of electrolytes, sodium sulfate (Na2SO4) aqueous electrolyte, and Na2SO4-polyvinyl alcohol (Na2SO4-PVA) gel electrolyte. Electrochemical measurements compare the SC-PCBs to standard two-electrode button-cell supercapacitors. A volumetric energy density of 0.56 mW h cm−3 at a power density of 26 mW cm−3 was obtained in the solid-state SC-PCB system, which is over twice the values acquired in the standard cell configuration. This is due to the removal of bulky components in the standard cell, and/or decreased thickness of the overall device, and thus a decrease in the total volume of the SC-PCB configuration. The results show great potential for embedding supercapacitors into PCBs for a broad range of applications. In addition, further advantages can be realised through close physical integration with other PCB-based electrochemical power systems such as fuel cells.

Ultrahigh rate and long-life nano-LiFePO4 cathode for Li-ion batteries

LiFePO4 is one of the most promising cathode materials for Li-ion batteries. However, its low electronic conductivity and slow Li-ion diffusion rate lead to poor electrochemical performance, especially poor rate performance. The hybrid of LiFePO4/Nitrogen and Sulfur co-doped graphene is successfully synthesized via a self-assembly method. Given its Nitrogen and Sulfur co-doped graphene matrix, the hybrid exerts a significantly impact on the electron conductivity of LiFePO4, resulting in excellent electrochemical properties and power density. The LiFePO4 composite has reversible capacity of 106.1 mAhg −1 at 10 C and 94.6 mAhg−1at 15 C. Moreover, with less than 5% loss of discharge capacity after 500 cycles at 10 C, the Nitrogen and Sulfur co-doped graphene can effectively improve the electrochemical performance of LiFePO4.

Influence of porosity parameters and electrolyte chemical composition on the power densities of non-aqueous and ionic liquid based supercapacitors

Influence of specific surface area (SDFT), total pore volume (Vtot) and other porosity characteristics on the electrochemical parameters and power density of two electrode electric double layer capacitors based on 1 M 3-ethyl-methylammonium tetrafluoroborate (Et3MeNBF4) solution in acetonitrile and on 1-ethyl-3-methylimidazolium tetrafluoroborate (EtMeImBF4) has been analysed. The pore size distribution data calculated from nitrogen, CO2 and Ar adsorption isotherms using mainly Carbon 2D non-local density functional theory for heterogeneous surface (2D-NLDFT-HS) model have been compared with crystallographic characteristics obtained by Raman, X-ray diffraction, photoelectron spectroscopy, etc. methods. It was shown that, chemical composition and crystallographic structure of precursor material, synthesis and activation conditions have decisive influence on the shape (spherical, cylindrical or slit-shape pores) and hierarchical porous structure and electrical conductivity of the carbon materials. Noticeable increase in series and parallel capacitances from 50 to 138 F g−1 in 1 M Et3MeNBF4 and up to 155 F g−1 in EtMeImBF4, gravimetric power density (up to 35 kW kg−1) and volumetric power density (up to 25 kW dm−3, both at discharge time 3.6 s in 1 M Et3MeNBF4 + AN electrolyte) for optimised EDLC has been demonstrated. For EtMeImBF4 based cells lower gravimetric (25 kW kg−1) and volumetric (10 kW dm−3) power densities have been achieved. For completing the EDLCs with high power and energy densities, highly micro-and mesoporous materials with optimum specific surface area (1200–1500 m2 g−1) but maximum (meso) pore volume (Vtot > 1.5 cm3 g−1) should be applied. Only for optimised EDLCs the very short characteristic charging/discharging times (lower than 0.3 s in Et3MeNBF4 + AN and 1.0 s in EtMeImBF4) can be achieved.

Facile preparation of fullerene nanorods for high-performance lithium-sulfur batteries

Lithium-sulfur batteries have been considered as one of the most promising electrochemical power sources due to its extremely high energy density and high theoretical specific capacity. However, poor cycling life due to the dissolution of lithium polysulfides hinders its practical application. In this paper, C60 nanorods are prepared by a facile, scalable and repeatable antisolvent induced precipitation method at an ambient temperature and used as a novel interlayer material for lithium-sulfur batteries. It was proved that C60 nanorods could efficiently inhibit the diffusion of lithium polysulfides via both physical adsorption and strong chemical bonding. Lithium-sulfur batteries with C60 interlayer delivered a capacity of 725 mAh g−1 and a capacity retention of 154.5% after 500 cycles at 4800 mAg−1 with a coulombic efficiency around 100%.

Fabrication of Microtubular Solid Oxide Fuel Cells by Film Compaction and Co-Sintering

The microtubular design of solid oxide fuel cells (SOFCs), which are promising electrochemical power sources, has a number of significant advantages over traditional planar and tubular designs: increased resistance to the cell (stack) heating rate and packing density of cells in a stack. The paper presents results on the development of a microtubular SOFC (MT-SOFC) fabrication method based on compaction and co-sintering a set of films. The formation of an anode-supported MT-SOFC having a Ni-cermet collector (support) and functional layers of about 300 and 50 μm thick, respectively; a Zr0.84Y0.16O2–δ solid electrolyte layer (40 μm); and a cathode based on La0.7Sr0.3MnO3–δ has been developed. The outer diameter and length of the MT-SOFC were 3.9 and 12 mm, respectively. The maximum specific power generated by the MT-SOFC at 850°C was 0.21 W/cm2.

Paired Electrolysis for Amide Formation Catalyzed By Vitamin B12 Model Complex Under Aerobic Condition

Electroorganic synthesis is currently expanding into various interdisciplinary fields because of its versatile application to molecular transformations as well as sustainable and economical advantage. Electroorganic synthesis is especially recognized as green process in synthetic organic chemistry since redox process of substrate is progressed by electric current without chemical reagent and waste after the reaction. Among the various methods in electroorganic synthesis, paired electrolysis is excellent method that electrochemical power is used both on the working electrode and the counter electrode to form synthetic useful compounds.1-4 Here we report the paired electrolysis mediated by vitamin B12 derivative,5 cobalt complex, under aerobic condition to form various amide compounds from trichloromethylated organic compounds and tertiary amines. Reference A. Paddon, M. Atobe, T. Fuchigami, P. He, P. Watts, S. J. Haswell, G. J. Pritchard, S. D. Bull, F. Marken, J. Applied Electrochem., 2006, 36, 617.J. Llorente, B. H. Nguyen, C. P. Kubiak, K. D. Moeller, J. Am. Chem. Soc., 2016, 138, 15110.Senboku, K. Nagakura, T. Fukuhara, S. Hara, Tetrahedron, 2015, 71, 3850.Kim, R. Uchiyama, Y. Kitano, M. Tada, K. Chiba, J. Electroanal. Chem., 2001, 507, 152.H. Shimakoshi, Y. Hisaeda, Current Opinion in Electrochemistry, 2018, in press. Figure 1

Portable Generator Based on Direct-Flame Metal-Supported Solid Oxide Fuel Cells (MS-SOFCs)

Metal-Supported solid oxide fuel cells (MS-SOFCs) tolerate rapid thermal cycling [1,2]. This makes them ideally suited for applications requiring rapid start-up time, or tolerance to thermal fluctuations arising from load-following or intermittent fuel flow. In direct flame mode, SOFCs are heated by a flame impinging on the anode side of the cell, and the flame also partially oxidizes the fuel to electrochemically- active species (such as hydrogen and carbon monoxide) [3–6]. In this work, we have developed a prototype consumer product by retrofitting MS-SOFCs to a commercial propane-fueled camping stove (Figure 1). The power produced by the fuel cells is conditioned by a simple microelectronic circuit to provide LED lighting and USB mobile phone charging. Previous efforts [7] to systematically characterize the behavior of MS-SOFCs in direct-flame mode in carefully controlled lab environment will be summarized, including the impact of: air-to-fuel ratio in the flame, fuel flow velocity, burner-to-MS-SOFC distance, catalyst composition, and application of thermal insulation to the cell. The insight from these experiments was used in the present work to guide the design of a free-standing prototype, including cell size and stacking arrangement, and interaction with the stove flame and microelectronics. The prototype performance is shown in Figure 2. The MS-SOFC stack can be heated up from room temperature to delivery of useful power in less than 10 seconds. Operation points in LED mode and USB-charger mode fall on the overall operating curve of the MS-SOFC stack, and successful charging of smartphones is demonstrated. [1] M.C. Tucker, Progress in metal-supported solid oxide fuel cells: A review, J. Power Sources. 195 (2010) 4570–4582. doi:10.1016/j.jpowsour.2010.02.035. [2] J. Mougin, A. Brevet, J.-C. Grenier, R. Laucournet, P.-O. Larsson, D. Montinaro, L.M. Rodriguez-Martinez, M.A. Alvarez, M. Stange, L. Bonneau, E. Concettoni, L. Stroppa, Metal Supported Solid Oxide Fuel Cells: From Materials Development to Single Cell Performance and Durability Tests, ECS Trans. 57 (2013) 481–490. doi:10.1149/05701.0481ecst. [3] M. Horiuchi, S. Suganuma, M. Watanabe, Electrochemical Power Generation Directly from Combustion Flame of Gases, Liquids, and Solids, J. Electrochem. Soc. 151 (2004) A1402. doi:10.1149/1.1778168. [4] M.M. Hossain, J. Myung, R. Lan, M. Cassidy, I. Burns, S. Tao, J.T.S. Irvine, Study on Direct Flame Solid Oxide Fuel Cell Using Flat Burner and Ethylene Flame, ECS Trans. 68 (2015) 1989–1999. doi:10.1149/06801.1989ecst. [5] M. Vogler, M. Horiuchi, W.G. Bessler, Modeling, simulation and optimization of a no-chamber solid oxide fuel cell operated with a flat-flame burner, J. Power Sources. 195 (2010) 7067–7077. doi:10.1016/j.jpowsour.2010.04.030. [6] K. Wang, R.J. Milcarek, P. Zeng, J. Ahn, Flame-assisted fuel cells running methane, Int. J. Hydrogen Energy. 40 (2014) 4659–4665. doi:10.1016/j.ijhydene.2015.01.128. [7] M.C. Tucker, A.S. Ying, Metal-Supported Solid Oxide Fuel Cells Operated in Direct-Flame Configuration, J. Power Sources. (2017). Figure 1

Understanding Chemical Stability Issues between Different Solid Electrolytes in All-Solid-State Batteries

It is commonly accepted that today’s Li-ion technologies might have issues addressing future long term targets.1 Hence there is an increasing focus on novel cell designs. Solid electrolytes (SE) have attracted growing interest as they could enable the use of lithium metal. They feature several advantages over liquid electrolytes, such as a rigid and non-leaking structure, non-flammability as well as a larger temperature operation range.2 All-solid-state batte­ries thus have great potential to enhance safety, lifetime and energy density compared to established Li-ion cell technologies.3 Sulfide-based SEs like crystalline Li10GeP2S12 (LGPS) or glass-ceramic 70Li2S∙30P2S5 (LPS), feature high ionic conductivity exceeding that of current liquid electrolytes. Moreover, their softness allows for good contacting, thus providing lower grain-boundary and interfacial resistance compared to oxide-based SEs.1 However, chemical insta­bility towards air and moisture as well as Li metal remains as critical issue.3 Moreover, recent studies revealed that their electrochemical stability has generally been overesti­mated so far.4–6 The rather narrow stability demands for protection on both cathode and anode side.1 While coating of the active material is a common strategy to prevent degradation of the SE at the cathode side, diffe­rent approaches aim for overcoming decomposition issues at the Li metal anode. Numerous examples of sputtering thin interlayers onto the SE and lithium metal, respective­ly, have been reported in the literature.7–11 However, most sputtering techniques are expensive and thus less attractive for large-scale applications. An alternative approach con­sists in application of a thin polymer interlayer, which has already been successfully tested for Li1+xAlxTi2-x(PO4)3, an oxide-based SE that is known to rapidly decompose in contact with lithium metal.12 The chemical stability of Li10SnP2S12 (LSPS), the tin-deri­vate of LGPS, towards PEO has been investigated in a different context. Blanga et al. demonstrated a composite electrolyte of PEO and LSPS with improved cycling beha­vior and safety in lithium/sulfur batteries.13 The authors stated that addition of the salt LiI results in the formation of a novel Li10+xIxSnP2S12/P(EO)3/LiI electrolyte. In the present study, we analyzed the compatibility of LSPS with PEO-LiTFSI membranes by both looking into electrochemical properties and performing XPS as well as further analytics of the aged interfaces. We will give experimental evidence for the chemical reactivity of LSPS in contact with PEO. In particular, the formation of poly­sulfides as well as sulfite will be proven by a combination of various techniques. Potential reasons for the observed decomposition will be critically discussed and a possible degradation mechanism will be proposed. References J. Janek and W. G. Zeier, Nat. Energy 2016, 1 (9), 16141.W. Weppner. in Encyclopedia of Electrochemical Power Sources, p. 162, Elsevier B.V. 2009.F. Mizuno, C. Yada and H. Iba. in Lithium-Ion Batteries, p. 273, Elsevier B.V. 2014.S. Wenzel, D. A. Weber, T. Leichtweiss, M. R. Busche, J. Sann and J. Janek, Solid State Ionics 2016, 286, 24–33.S. Wenzel, S. Randau, T. Leichtweiss, D. A. Weber, J. Sann, W. G. Zeier and J. Janek, Chem. Mater. 2016, 28 (7), 2400–2407.Y. Zhu, X. He and Y. Mo, ACS Appl. Mater. Interfaces 2015, 7 (42), 23685–23693.W. C. West, J. Whitacre and J. Lim, J. Power Sources 2004, 126 (1-2), 134–138.K.-i. Chung, W.-S. Kim and Y.-K. Choi, J. Electroanal. Chem. 2004, 566 (2), 263–267.M. Ogawa, R. Kanda, K. Yoshida, T. Uemura and K. Harada, J. Power Sources 2012, 205, 487–490.K. Nagao, A. Hayashi, M. Deguchi, H. Tsukasaki, S. Mori and M. Tatsumisago, J. Power Sources 2017, 348, 1–8.A. Kato, A. Hayashi and M. Tatsumisago, J. Power Sources 2016, 309, 27–32.S.-D. Lee, K.-N. Jung, H. Kim, H.-S. Shin, S.-W. Song, M.-S. Park and J.-W. Lee, ChemSusChem 2017, 10 (10), 2175–2181.R. Blanga, M. Goor, L. Burstein, Y. Rosenberg, A. Gladkich, D. Logvinuk, I. Shechtman and D. Golodnitsky, J. Solid State Electrochem. 2016, 20 (12), 3393–3404.

(Invited) Multiscale Morphological and Electrical Characterization of Charge Transport and Charge Transfer Limitations to Power Performance of Positive Electrode for Li-Ion Batteries

Composite materials consisting of several interpenetrated and percolating phases are widely used as electrodes for a variety of electrochemical cells. Such electrodes are generally mixed ionic−electronic conductors, in which ions and electrons are confined to transport within the specific conducting network. In particular, for electrochemical storage and energy transformation devices, the transport properties play critical roles in determining their performance, which is pivotal to improve them for service as power sources. To reach this goal, an increased fundamental understanding of the factors that play on the transport properties within such composite materials is still required. The transport of the electrons and ions through Li-ion battery electrode and their transfer to the active matter depend on the electrode architecture (nano- and microstructure) through the interfacial areas, materials connectivity, and the transport length scales. Novel opportunity for progressing in this direction and exploring relationships between electrode architecture, charge transport and electrochemical performance is implementation of X-ray computed tomography (XRCT) and focused ion beam in combination with scanning electron microscopy (FIB-SEM) techniques to characterize and quantify the 3D architecture of composite electrodes. In particular, tortuosity, a critical parameter with respect to ionic transport, has been exhaustively studied. Comparatively, factors that play on the electrons transport and wiring to the active mass have been much less considered. Moreover, attempts to correlate quantified 3D geometries with measured electrochemical power performance or electrical transport properties of same real electrodes remain rare. We intend to fill this gap in this presentation. We have undertaken exhaustive characterizations of 3D geometries of LiNi1/3Mn1/3Co1/3O2 (NMC), LiFePO4 (LFP), and NMC/LFP blended electrodes and rationally interpreted their measured electrical properties and electrochemical performance. A combination of X-Ray tomography and FIB-SEM tomography are used for a multiscale analysis of electrodes 3D geometries, in particular the distribution of the conductive additive and the binder that perform as electronic wires, the tortuous pores distribution, which after electrolyte impregnation perform as ionic wires, and the inter-connectivity between the active matter phase and the electronic and the ionic wires [1]. The electrical properties (permittivity and conductivity) are measured from low (a few Hz) to microwave (a few GHz) frequencies by the broadband dielectric spectroscopy technique [2]. This one is very sensitive to the different scales of the electrode architecture involved in electronic transport, from interatomic distances to macroscopic sizes, as well as to the morphology at these scales, coarse or fine distribution of the constituents [2,3]. In addition to the geometry of the electrode architecture, the interfaces (adsorption of ions to the surface of active material and carbon nanoparticles), and interactions at such interfaces lead to a reciprocal influence of ionic and electronic transfers at the different scales of the electrode [4]. Finally, discharge rate performance is analyzed by simple, yet efficient methods. This approach allows discriminating between the contributions of the electronic and ionic wiring networks as the performance limiting factors, depending on the electrode geometry and discharge rate. [5] Acknowledgements Financial funding from the ANR Program No. ANR-15-CE05-0001-01 (PEPITE) is acknowledged. We also thank the CLYM (Centre Lyonnais de Microscopie) supported by the CNRS, the “Grand Lyon” and the Rhône-Alpes Region for use of the Zeiss NVision40 FIB/SEM. The IMD (Institut de la Mobilité Durable – Sustainable Mobility Institute) is also acknowledged for financial support.

Extracting Lithium and Metals from Spent Batteries

Compared with nickel-cadmium (NiCd), nickel-metal hydride (NiMH), lead-acid, or other secondary batteries, Lithium Ion Batteries (LIBs) have found wide application as electrochemical power sources in mobile communications and portable electronic devices due to their high power and energy density, long storage life, low self-discharge rate, high cell voltage, and wide operating temperature range. However, less than 5% of spent lithium-ion batteries are recycled today. The currently best available technology cannot recover critical components like lithium. As Lithium-ion batteries continue to electrify our world, over 11 million tons of spent Lithium-ion batteries will be discarded through to 2030. Only 5% of spent Lithium-ion batteries reach recycling facilities globally. The remaining 95% often reach landfills or are dangerously stockpiled in many cases. Smelting followed by refining is the currently best available technology for recycling Lithium-ion batteries. These processes, however, often have unprofitable unit economics, cannot recover lithium economically, and are limited by maximum recycling efficiencies of 30-40%. As an important cathode active material, layered LiCoO2 is usually employed in commercial LIBs. As a result, the consumption of lithium and cobalt has increased dramatically in parallel with the growth in demand for electronic equipment. Both lithium and cobalt are regarded as significant strategic metals that are expensive. Cobalt, in particular, is of relatively low abundance and costly. In addition, the tremendous expansion of the LIB market has resulted in a great deal of battery waste. In this paper, a green chemistry process will be presented that can be used to recover and recycle lithium and other electrode metals from spent lithium batteries. A few years after the development of lithium-ion technologies, Contestabile et al. [1] published one of the early papers devoted to the description of a multi-step process for the treatment and recovery of spent lithium primary batteries [2]. Since then, many researchers have applied various methods to the development of recovery processes for spent LIBs batteries [3]. Iizuka et al. [4] separated lithium and cobalt from spent LIBs by bipolar membrane electrodialysis coupled with chelation. Li et al. [5] recycled lithium and cobalt from used LIBs with natural organic acids as leaching reagents. Zhu et al. [6] used sodium citrate and acetic acid to leach the paste components of spent LIBs. It is important to note that, because LiCoO2 has become the leading and typical cathode active material of LIBs, most of the established recovery technologies have concentrated on the treatment of LiCoO2. The process uses an organic solvent to achieve high extraction efficiencies of lithium and metals and allows the organic solvent to be effectively recycled back, instead of being wasted. We have developed a hydrometallurgical method involving natural succinic acid leaching for recovery of lithium and cobalt from the cathode active materials of spent LIBs. This method has three main steps: dismantling of the battery, anode/cathode separation, and metals leaching. Our experimental data clearly show that the amount of ozone, the initial acid concentration, the S/L ratio, the temperature, and the leaching time have marked influence on the leaching efficiency of the metals. We determined that nearly 100% of cobalt and more than 96% of lithium are leached under optimized conditions: succinic acid concentration of 1.5 mol/L, ozone content of 4 vol.%, S/L ratio of 15 g /L, temperature of 70oC, and reaction time of 40 min. These conditions result in low energy consumption, low chemical consumption, and better percentage leaching. In particular, the leaching efficiency of cobalt, which is an extremely expensive chemical, in succinic acid aqueous solution was higher than reported in earlier studies.

3D hierarchical Co/CoO/C nanocomposites with mesoporous microsheets grown on nickel foam as cathodes for Li-O2 batteries

Li-O2 batteries are of great promise for next generation electrochemical power sources. However, they are significantly restricted by their low charge/discharge efficiency, inferior rate capability and poor cycle stability. Herein, a hierarchically porous Co/CoO/carbon nanocomposite is in situ grown on three dimensional nickel foam (denoted as Co/CoO/C@Ni) by the solvothermal deposition and subsequent pyrolysis of metal organic framework. This nanocomposite is found to be composed of free-standing microsheets with abundant mesopores. In comparison with Super P cathode, the Co/CoO/C@Ni architecture as a unique bifunctional cathode for Li-O2 batteries shows enhanced electrochemical performances: the charge overpotential dramatically drops by 0.5 V; the discharge capacity reaches 8000 mAh g−1 at a current density of 0.1 mA cm−2; the superior cycle stability of up to 70 cycles as well as good rate capability is obtained. This enhancement is mainly ascribed to the 3D hierarchically porous structure, which facilitates the diffusion of oxygen and electrolyte, and provides large space for Li2O2 deposition. Meanwhile, the synergy of Co and CoO contributes positively to the reaction kinetics. In addition, the high electronic conductivity of 3D Ni foam substrate ensures fast electron transport. Accordingly, the hierarchically porous Co/CoO/C@Ni architecture is a promising cathode for Li-O2 batteries.

Electrode Materials Based on Porous Silicon with Platinum Nanoparticles for Chemical Current Sources

Composites on porous silicon with platinum nanoparticles were prepared with the aim of developing structural materials for electrochemical power sources. The size and shape of the nanoparticles in the silicon matrix were examined by atomic force and high-resolution transmission electron microscopy. The catalytic activity of the nanomaterials in hydrogen oxidation and oxygen reduction was evaluated. The models based on the composite electrodes prepared were tested under the conditions of operation of hydrogen–air fuel cells.

Development of continuously variable transmission and multi-speed dual-clutch transmission for pure electric vehicle

Pure electric vehicles, as a promising alternative to conventional fossil fuel–powered passenger vehicles, provide outstanding overall energy-utilizing efficiency by omitting the internal combustion engine. However, because of lower energy density in battery energy storage, the driving range per charge is limited by this electrochemical power source, leading to a so-called range phobia and presenting a major barrier for large-scale commercialization. The widely adopted single-reduction gear in pure electric vehicles typically do not achieve the diverse range of functional needs that are present in multi-speed conventional vehicles, most notably acceleration performance and top speed requirements. Consequently, special-designed multi-speed pure electric vehicle–powertrains have been compared and investigated for these applications in this article. Through the optimizing of multiple gear ratios and creating special shifting strategies, a more diverse range of functional needs is realized without increasing the practical size of the electric motor and battery. This article investigates the performance improvements of pure electric vehicle realized through utilization of multi-speed dual-clutch transmissions and continuously variable transmissions. Results reveal that there can be significant benefits attained for pure electric vehicles through multi-speed transmissions. Simulation results shows that continuously variable transmission and two-speed transmission are the two most promising transmissions for pure electric vehicle in different classes, respectively.

Conductivity of Inorganic Perchlorates Dissolved in Aprotic Solvents

Electrolytes in modern electrochemical power sources are based on the usage of aprotic highly polar solvents. We have to keep in mind, that lithium ion battery (LIBs), sodium ion batteries (SIBs) and electrochemical supercapacitors (SC) cannot work without solutions of corresponding ionic compounds in them. LIBs use standard lithium salt electrolyte 1 M LiPF6 in EC/DMC. The goal was to find sodium salt electrolyte(s) with electric conductivity values similar to lithium salt electrolytes. In this study the electric conductivity of 288 different samples of lithium salts (LiClO4, LiBF4, and LiPF6) electrolytes in different concentrations, sodium salts (NaClO4, NaBF4 and NaPF6) electrolytes in different concentrations and fluorinated salts ((C2H5)4N(BF4) and (CH3)4N(BF4)) electrolytes in different concentrations was measured. The electric conductivity and the electrochemical behaviour of the electrolyte samples were measured at a lab room temperature using impedance spectroscopy (EIS) and linear voltammetry (LSV) measurement methods.

Special topic on electrochemical power sources

Special topic on electrochemical power sources

Technology of Electrochemical Micromachining Based on Surface Modification by Fiber Laser on Stainless Steel

In order to fabricate the micro cavity with complex structure on stainless steel, the technology of micro electrochemical machining based on surface modification by fiber laser is adopted. Heating scan on the surface of 304 stainless steel by using fiber laser can realize marking. In the process of laser heating and metal melting on the surface of 304 stainless steel, oxide layer can be formed and phase transformation can also occur, and the corrosion resistance layer with predefined pattern is formed. In the next process of micro electrochemical machining, the laser masking layer severs as the protective layer to realize micro machining of micro cavity. A newly developed device of electrochemical micro machining based on surface modification by fiber laser can meet the micro machining requirement. After laser masking processing through laser scanning on the surface of the 304 stainless steel, the passivation electrolyte and high-frequence-pulse electrochemical machining power supply were adopted, and the samples with typical structures by using electrochemical micromachining with fiber laser masking were fabricated.

Electrochemical Carbon Separation in a SOFC–MCFC Polygeneration Plant With Near-Zero Emissions

The modularity and high efficiency at small-scale make high temperature (HT) fuel cells an interesting solution for carbon capture and utilization at the distributed generation (DG) scale when coupled to appropriate use of CO2 (i.e., for industrial uses, local production of chemicals, etc.). The present work explores fully electrochemical power systems capable of producing a highly pure CO2 stream and hydrogen. In particular, the proposed system is based upon integrating a solid oxide fuel cell (SOFC) with a molten carbonate fuel cell (MCFC). The use of these HT fuel cells has already been separately applied in the past for carbon capture and storage (CCS) applications. However, their combined use is yet unexplored. The reference configuration proposed envisions the direct supply of the SOFC anode outlet to a burner which, using the cathode depleted air outlet, completes the oxidation of the unconverted species. The outlet of the burner is then fed to the MCFC cathode inlet, which separates the CO2 from the stream. This layout has the significant advantage of achieving the required CO2 purity for liquefaction and long-range transportation without requiring the need of cryogenic or distillation plants. Furthermore, different configurations are considered with the final aim of increasing the carbon capture ratio (CCR) and maximizing the electrical efficiency. Moreover, the optimal power ratio between SOFC and MCFC stacks is also explored. Complete simulation results are presented, discussing the proposed plant mass and energy balances and showing the most attractive configurations from the point of view of total efficiency and CCR.