Lithium-ion Secondary Cells Research Articles

Alternating Si/C Thin-Films as Model Anode Material for Lithium-Ion Batteries

Graphite is currently the state-of-art material for the anode-side of lithium-ion batteries (LIB) with a theoretical capacity of 372 mAh g-1. However, its technological potential is already largely exhausted, shifting research focus to other materials, such as silicon (Si) with its high theoretical capacity (3579 mAh g-1) [1]. However, Si cannot be used on its own because of its low electrical conductivity. Moreover, it suffers from a strong increase in volume and amorphization during lithiation, which is the primary origin of several degradation mechanisms, e.g. as pulverization, delamination and an unstable solid electrolyte interface. There are various approaches to counteract these issues, amongst them the structuring of Si into nanowires or hollow structures [2]. Silicon is most often used with graphite in a composite material, due to decades of experience in graphite synthesis an application [3].In this work we investigate anodes consisting of alternating Si and C thin-films with a layer thickness of a few hundred nanometers each. In general, Si thin-film anodes show a higher performance than its bulk counterparts [4]. The layers are produced by deposition from the gas phase. This process enables good adhesion between the particles and the substrate, which can counteract delamination and provide a longer cycle life. Additionally, it can also be performed in a binder-free fashion, thereby reducing the need for inactive electrode components.The alternation of carbon and silicon layers improves the electrical conductivity and also separates the silicon layers from each other aiding to reduce the mechanical stress caused by volume expansion. The characterization of the layers is done by cross sectional SEM, EDX and AFM. Furthermore, the crystallinity of the deposited layers is determined via XRD. The manufacturing process influences the morphology of the layers, which in turn affects the electrochemical properties. For this reason, galvanostatic cycling and electrochemical impedance spectroscopy are subsequently carried out in a coin cell type Swagelok half-cell setup with 2- and 3-electrode arrangements. Constant current cycling is used to investigate the long-term stability of the cells in order to analyze the change in the respective Si layers as a function of their distance from the surface. In addition, the electrodes are analyzed post-mortem via SEM and XRD to investigate which degradation mechanisms play a role in the observed behavior.[1] Kasavajjula, U. et al., Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells, J. of Power Sources 163 (2), 1003 – 1039, 2007.[2] Wu, H., Cui Y., Designing nanostructured Si anodes for high energy lithium ion batteries, Nano Today 7 (5), 414 – 429, 2012.[3] You, S. et al., Design Strategies of Si/C Composite Anode for Lithium-Ion Batteries, Chem. Eur. J. 27 (48), 12237 – 12256, 2021 [4] Graetz, J. et al., Highly reversible Lithium storage in nanostructures Silicon, Electrochem. Solid-State Lett. 6 (9), A194, 2003.

A Study on dFMEA-based Fire Risk Assessment of Lithium-ion Secondary Battery Testing Cells

In this study, Design Failure Mode and Effects Analysis (dFMEA) was performed to evaluate the fire risk of lithium-ion secondary battery testing cells used during the research and development stage. dFMEA was used for the failure risk analysis, risk assessment, and risk priority analysis of the anode, cathode, separator, electrolyte, and cell design of the testing cell. In addition, the evaluation criteria, including severity, occurrence, and detection, was reorganized into three categories and optimized for the testing cell application. Based on the failure risk analysis, a total of 11 causes of failure were identified. In particular, explosion and thermal runaway were predicted when a nickel-cobalt-manganese (NCM)-based anode material with a high nickel content was used, the separator had a high thermal contraction rate and low tensile strength characteristics, and there were errors in the electrolyte composition optimization. This cause of failure was classified as a moderate risk with a high fire risk by the risk priority analysis. Therefore, at the research and development stage, it is critical to evaluate the mutual reactivity and preliminary physical properties of battery materials and to construct safety equipment to reduce fire damage.

Effect of Temperature on Silicon-Based and Silicon-Rich Anodes for Li-Ion Batteries

Several governments are committed to fight against climate change and, reducing the pollution derived from the utilization of fossil fuel powered cars is considered as a part of the solution. Therefore, environmentally friendly electric vehicles (EVs) keep on gaining importance [1], [2] . Nevertheless, in order to extend the autonomy range of EVs to that achieved by internal combustion cars, next-generation lithium-ion batteries (LIBs) with larger specific capacities and subsequent higher energy densities are required.Replacing graphite, the anode widely used in current LIBs, with other materials capable of providing much larger capacities, is a well-known strategy to boost the specific capacity of this technology [3], [4] . In this sense, silicon is one of the most promising materials, not only because it can deliver a capacity (~3579 mAh/g) approximately 10 times that of graphite (~370 mAh/g) [5], [6] , but also because it is an affordable substitute anode material for LIBs, since it is the second most abundant element in the earth’s crust [7] .Numerous scientific investigations have been carried out in silicon anodes for LIBs, however, a parameter that has not been assessed and would be crucial in its real performance in EVs is the effect that temperature would have over its cyclability. To determine such effect, we have conducted galvanostatic tests with silicon-based and silicon-rich anodes in half-cells at different temperatures. Besides, the absence or presence of fluoroethylene carbonate (FEC) as electrolyte additive has also been evaluated. The different capacities and cycle-lifes observed, along with the possible kinetic mechanisms behind them, will be here discussed. We gratefully acknowledge support from the U. S. Department of Energy (DOE), Vehicle Technologies Office. Argonne National Laboratory is operated for DOE Office of Science by UChicago Argonne, LLC, under contract number DE-AC02-06CH11357. The U.S. government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the government. [1] M. Armand and J-M. Tarascon. Nature 2008, 451, 652-657. Building better batteries. [2] C. C. Chan. EEE 1999 International Conference on Power Electronics and Drive Systems, PEDS’99, Hong Kong. The Past, Present and Future of Electric Vehicle Development. [3] W-J. Zhang, J. Power Sources 2011, 196 (1), 12-24. A review of the electrochemical performance of alloy anodes for lithium-ion batteries. [4] V. Etacheri, R. Marom, R. Elazari, G. Salitra and D. Aurbach. Energy Environm. Sci. 2011, 4, 3243-3262. Challenges in the development of advanced Li-ion batteries: a review. [5] X. Su, Q. Wu, J. Li, X. Xiao, A. Lott, W. Lu, B. W. Sheldon and J. Wu. Adv. Energy Mater. 2014, 4, 1300882. Silicon-Based Nanomaterials for Lithium-Ion Batteries: A Review. [6] H. Wu and Y. Cui. Nanotoday 2012, 7(5), 414-429. Designing nanostructured silicon anodes for high energy lithium ion batteries. [7] U. Kasavajjula, C. Wang and A. J. Appleby. Journal of Power Sources 2007, 163, 1003. Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells.

Stable SEI Formation on Al-Si-Mn Metallic Glass Li-Ion Anode

Alloying anodes are of great interest as a replacement for graphite in lithium-ion batteries (LIBs) since they can store one or more Li atoms per host atom. Si has received the most attention in this regard due to its very high theoretical specific capacity (3579 mAh/g, ~8300 mAh/cm3)1 and relatively low cost. However, the durability of batteries with high Si content is limited due to the unstable solid-electrolyte interphase (SEI) on Si2 and its large volume change upon lithiation and delithiation which leads to cracking and pulverization3, 4. Among alloying anodes, amorphous materials generally outperform crystalline materials5, 6. The absence of grain boundaries can improve passivity7-9, and amorphous materials generally lithiate in a continuous manner, which eliminates phase boundaries and the mechanical strains associated with them. In addition, amorphous materials composed solely of metals and/or metalloid elements, termed metallic glasses, have been shown to exhibit exceptional hardness, yield strength, and fracture toughness7-9.This study explores an Al-Si-Mn glass as an alternative LIB anode. Si-based metallic glasses are appealing because they maintain Si, which can alloy with up to 3.75 Li6, 10, as the main Li-binding element, but distribute it homogeneously within an amorphous matrix. A dense amorphous Al64Si25Mn11 metallic glass (a-AlSiMn) was successfully produced via splat quenching, a rapid cooling technique that is scalable and commonly used to produce amorphous materials for a variety of applications. This process is shown schematically in the figure below. The a-AlSiMn glass exhibits greater specific capacity (>900 mAh/g) than graphite and a low lithiation potential, making it suitable for high-energy density LIBs. The glass remains amorphous throughout cycling, maintaining any improved mechanical properties conferred by the amorphous structure.Crucially, parasitic electrolyte reduction is found to be much reduced in comparison to pure Si or Al, and comparable to that on Cu. The charge consumed by electrolyte reduction in each cycle is given in the figure below for a-AlSiMn and an amorphous Si reference anode. The resulting SEI on a-AlSiMn is very thin, and rich in fluorinated species such as LiF, F-P-O groups, and fluorinated oxides of silicon and aluminum, whereas very few organic species are present. In particular, lithium ethylene decarbonate (LiEDC), which plays a large role in SEI formation on Si, is entirely absent, and a thinner, more stable SEI results. This study shows that metallic glasses can become a viable new class of alloying anode materials for LIBs with improved surface passivity. Li, J.; Dahn, J. R., An In Situ X-Ray Diffraction Study of the Reaction of Li with Crystalline Si. Journal of The Electrochemical Society 2007, 154 (3), A156.Yin, Y.; Arca, E.; Wang, L.; Yang, G.; Schnabel, M.; Cao, L.; Xiao, C.; Zhou, H.; Liu, P.; Nanda, J.; Teeter, G.; Eichhorn, B. W.; Xu, K.; Burrell, A. K.; Ban, C., Non-Passivated Silicon Anode Surface. ACS applied materials & interfaces 2020.Kasavajjula, U.; Wang, C.; Appleby, A. J., Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells. Journal of Power Sources 2007, 163 (2), 1003-1039.Liang, B.; Liu, Y.; Xu, Y., Silicon-based materials as high capacity anodes for next generation lithium ion batteries. Journal of Power Sources 2014, 267, 469-490.Beaulieu, L. Y.; Hatchard, T. D.; Bonakdarpour, A.; Fleischauer, M. D.; Dahn, J. R., Reaction of Li with Alloy Thin Films Studied by In Situ AFM. Journal of The Electrochemical Society 2003, 150 (11), A1457.Hatchard, T. D.; Topple, J. M.; Fleischauer, M. D.; Dahn, J. R., Electrochemical Performance of SiAlSn Films Prepared by Combinatorial Sputtering. Electrochemical and Solid-State Letters 2003, 6 (7), A129.Chen, M., A brief overview of bulk metallic glasses. NPG Asia Materials 2011, 3 (9), 82-90.Jafary-Zadeh, M.; Praveen Kumar, G.; Branicio, P. S.; Seifi, M.; Lewandowski, J. J.; Cui, F., A Critical Review on Metallic Glasses as Structural Materials for Cardiovascular Stent Applications. Journal of Functional Biomaterials 2018, 9 (1), 19.Telford, M., The case for bulk metallic glass. Materials Today 2004, 7 (3), 36-43.Fleischauer, M. D.; Dahn, J. R., Combinatorial Investigations of the Si-Al-Mn System for Li-Ion Battery Applications. Journal of The Electrochemical Society 2004, 151 (8), A1216. Figure 1

Si Nanoparticles inside a Carbon Matrix As an Anode for Next Generation LIB

1. Introduction Lithium-ion batteries (LIB) are used in many applications such as cellular phones, mobile computers and electrical vehicles since they have high capacity and long cycle life. There is a continuing demand for advanced LIBs with higher energy density. However, graphite, conventional anode materials for commercial LIBs, are approaching their theoretical capacity limits. In this context, Si anodes have attracted much attention for the alternatives of graphite anodes because of their high capacity, low cost and environmental benignity. However, Si anodes suffer from drastic volume change and huge stress generation during the lithiation and delithiation process, which causes fracture of Si and deformation of the electrode. Such unfavorable phenomena arising from the severe volume change results in the poor cycle ability of Si anodes. These crucial problems hamper the direct utilization of Si anodes for next-generation LIBs.Amorphous SiO x (x<2) anodes have shown the cycle performance improvement since the amorphous structure and SiO2 phase serve as the buffer layer which suppresses the volume expansion during the lithiation delithiation process. However, the irreversible capacity of the first cycle is large due to the formation of inactive Li-Si-O phase from SiO2 phase. [1-2]Much research on composite anodes containing Si and graphite has been investigated, and improvement of the cycle performance of composite electrodes have been demonstrated. However, the amount of Si in the composite electrode is limited since there is a strong trade-off relationship between the capacity and the cycle performance in the composite electrode. [3-4]Recently, we have successfully synthesized Si nanoparticles inside a Carbon Matrix (SCM). Here, we show the electrochemical Li storage performance of SCM. 2. Experimental Synthesis of Si nanoparticles with Voids inside a Carbon Matrix (SCM) We synthesized SCM through chemical techniques. The cross-sectional SEM image of SCM is shown in Fig. 1. Si nanoparticles with voids inside the carbon matrix are observed. Electrode preparation SCM powder as active material, carbon powder as conductive additive and polyacrylate as binder at a mass ratio of 92:1:7 were mixed in water to form slurry. The slurry was coated onto Cu foil (10μm thickness) and dried at 90 ºC for 5 min, and then heated in vacuum at 100 ºC overnight. The electrode was punched into discs typically with a diameter of 13.8 mm. The weight of active material in the electrode is ranged from 3.0 to 4.0 mg. CR2032 cell preparation Coin type cell (CR2032) was assembled in the Ar-filled glove box. Li metal (Honjyou metal) was used as the counter electrode. Polypropylene was used as the separator. The liquid electrolyte used was 1.2 M LiPF6 in ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1 vol %) with fluoroethylene carbonate (FEC) (2 vol %). 3. Results First charge –discharge curves of the SCM electrode with current rate of 0.1 C is shown in Fig. 2. During the first cycle, the electrode exhibited a reversible capacity of 680 mAhg-1 with an efficiency of 75.6 %. Cycle performance of the SCM electrode and shape of the SCM particle after cycling will be reported and discussed. 4. Reference [1] J. Yang et al. SiOx-based anodes for secondary lithium batteries. Solid State Ionics 152-153, 125-129 (2002).[2] M. N. Obrovac et al. Alloy Negative Electrodes for Li-Ion Batteries. Chem. Rev. 114, 11444−11502 (2014).[3] Y. liu et al. Silicon/carbon composites as anode materials for Li-ion batteries. Electrochem. Solid State Lett. 7 (10), A369-372 (2004).[4] U. Kasavajjula et al. Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells. J. Power Sources 163, 1003-1039 (2007) Figure 1

Optimization of Si/Gr Based Anode Formulation for High Energy Density Li-Ion Batteries

In need of increasing automotive applications, it is necessary to find both higher capacity and higher-capacity retention electrode materials for Li-ion batteries. Among the candidates for negative electrode [1], silicon appears as an attractive alternative to graphite due to its natural abundance, high specific gravimetric capacity (3579 mAh.g-1 vs. 372mAh.g-1 for graphite) and a large volumetric capacity (2081 mAh.cm-3 vs. 779 mAh.cm-3). Silicon based electrodes nevertheless suffer from poor cyclability usually due to dramatic volume expansion of the electrode during the cycling and electrolyte reduction [2]. As a consequence, irreversible capacity losses are not limited to the first few cycles, but may continue to deteriorate cell performance and life [3, 4]. On one hand, previous studies demonstrated that the formulation [5], the processing [6] of the composite electrode and the adhesion to the current collector are critical for Si with respect to the electrochemical performance. The design of a flexible network of shaped conductive additives bonded with an aqueous binder to silicon particles through an optimized ratio of covalent and hydrogen bonds greatly help in facilitating a homogeneous functioning of the electrode that minimizes electrolyte reduction and keep the mechanical integrity of the electrode. On the other hand, using a combined silicon/graphite material also help in mitigating volume variations expected to occur upon cycling, especially for high mass loading electrodes (>3-4 mg). In this study, we use both approaches by tuning the binder incorporation in the case of a 50/50 %wt Silicon/Graphite composite electrodes. We focus here in particular on the electrode formulation, using a polyacrylic acid polymer binder thanks to its grafting mechanism to silicon particles enabling a strong mechanical cohesion even in the case of high-loaded electrodes. [7] pH and viscosity adjustments of the electrode slurry will be discussed, as they seem to have a remarkable effect at the interface between electrode and current collector. In fact, the longer drying process (due to thicker coating) exacerbate different corrosion mechanisms and migration phenomena that were not observed previously for thin electrodes usually studied. Characterizations on this interface were carried out, combining XPS and SEM, in order to offer a further comprehension of Si/Gr cycling performance as a function of electrode preparation. Reference : 1) Kasavajjula, U., Wang, C. & Appleby, A. J. Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells. 163, 1003–1039 (2007). 2) Obrovac, M. N. & Chevrier, V. L. Alloy negative electrodes for Li-ion batteries. Chem. Rev. 114, 11444–11502 (2014). 3) Ryu, J. H., Kim, J. W., Sung, Y. & Oh, S. M. Failure Modes of Silicon Powder Negative Electrode in Lithium Secondary Batteries. Electrochem. Solid-State Lett. 7, 306–309 (2004). 4) Beaulieu, L. Y. et al. Colossal Reversible Volume Changes in Lithium Alloys service Colossal Reversible Volume Changes in Lithium Alloys. Electrochem. Solid-State Lett. 4, A137 (2001). 5) Mazouzi, D. et al. Critical roles of binders and formulation at multiscales of silicon-based composite electrodes. J. Power Sources 280, 533–549 (2015). 6) Nguyen, B. P. N., Chazelle, S., Cerbelaud, M., Porcher, W. & Lestriez, B. Manufacturing of industry-relevant silicon negative composite electrodes for lithium ion-cells. J. Power Sources 262, 112–122 (2014). 7) Mazouzi, D., Lestriez, B., Roué, L. & Guyomard, D. Silicon Composite Electrode with High Capacity and Long Cycle Life. Electrochem. Solid-State Lett. 12, A215 (2009).

Temperature Influence on Silicon-Based Anodes for Li-Ion Batteries

Nowadays, with the aim of reducing the pollution derived from the utilization of fossil fuel powered cars, the environmentally friendly hybrid (HEVs) and electric vehicles (EVs) are gaining importance[1], [2]. Although EVs already circulate on the roads, the search for next-generation lithium-ion batteries (LIBs) with larger specific capacity and, therefore, higher energy density is necessary to achieve similar driving performance (e.g., range and power) to those provided by internal combustion engines. A strategy to upgrade the specific capacity of current LIBs consists of replacing graphite, the anode par excellence in this technology, with other materials that can supply much larger capacities[3], [4]. In this sense, silicon is postulated as one of the most promising anode materials, since it is capable of delivering a capacity (~3579 mAh/g) almost 10 times larger than that of graphite (~370 mAh/g)[5], [6]. Additionally, silicon is the second most abundant element in the earth’s crust, making it an affordable substitute of carbonaceous anode materials for LIBs[7]. However, although numerous scientific studies have been performed on silicon anodes for LIBs, a parameter that has not been evaluated and that would be of interest is the impact that temperature would have on its cycle-life. To fill in this gap, we have performed galvanostatic experiments at different temperatures with silicon-based anodes in half-cells with and without fluoroethylene carbonate (FEC) as electrolyte additive. The different capacity fading behavior observed and the possible kinetic mechanisms behind them will be discussed here. We gratefully acknowledge support from the U. S. Department of Energy (DOE), Vehicle Technologies Office. Argonne National Laboratory is operated for DOE Office of Science by UChicago Argonne, LLC, under contract number DE-AC02-06CH11357. The U.S. government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the government. [1] M. Armand and J-M. Tarascon. Nature 2008, 451, 652-657. Building better batteries. [2] C. C. Chan. EEE 1999 International Conference on Power Electronics and Drive Systems, PEDS’99, Hong Kong. The Past, Present and Future of Electric Vehicle Development. [3] W-J. Zhang, J. Power Sources 2011, 196 (1), 12-24. A review of the electrochemical performance of alloy anodes for lithium-ion batteries. [4] V. Etacheri, R. Marom, R. Elazari, G. Salitra and D. Aurbach. Energy Environm. Sci. 2011, 4, 3243-3262. Challenges in the development of advanced Li-ion batteries: a review. [5] X. Su, Q. Wu, J. Li, X. Xiao, A. Lott, W. Lu, B. W. Sheldon and J. Wu. Adv. Energy Mater. 2014, 4, 1300882. Silicon-Based Nanomaterials for Lithium-Ion Batteries: A Review. [6] H. Wu and Y. Cui. Nanotoday 2012, 7(5), 414-429. Designing nanostructured silicon anodes for high energy lithium ion batteries. [7] U. Kasavajjula, C. Wang and A. J. Appleby. Journal of Power Sources 2007, 163, 1003. Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells.

Thermal characteristics of 80 °C storage-degraded 18650-type lithium-ion secondary cells

It is important for large-scale lithium-ion secondary cells to function in a safe and stable manner. Little information is available on the parameters determining the transitions between non-heating, self-heating, and thermal runaway processes of degraded lithium-ion secondary cells. Thermal characterization of the degraded cells is important to identify the impact of degradation on the safety limits of these cells. Accelerating rate calorimeter (ARC), operated in a heat-wait-search mode, is capable of characterizing the thermal behavior of lithium-ion cells. Here, the self-heating and relative heat generation rates of storage-degraded lithium-ion cells during thermal runaway are investigated. Twenty-five 18650-type LiCoO2-based secondary cells are degraded during storage at 80 °C with various states of charge (SOCs), then the thermal behavior of the cells was analyzed by carrying out ARC measurements. The correlations between the onset temperature of thermal runaway, self-heating rate, and heating rate of each cell are investigated. It was found that the self-heating rate correlates linearly with the onset temperature of thermal runaway, while the relative heat generation rate correlates with it exponentially. The cells charged to 100% SOC presented the lowest onset temperatures of thermal runaway.

Temperature Influence on Silicon-Based Anodes for Li-Ion Batteries

Environmentally friendly hybrid, plug-in hybrid and full-electric vehicles (EVs) are gaining importance [1]. However, to gain further acceptance by the consumer, it is essential to extend the autonomy range of EVs to be similar to that of a gasoline-fueled car. There is a need for finding next-generation lithium-ion batteries (LIBs) with larger specific capacity and, therefore, higher energy density. Undoubtedly, one of the most direct strategies to boost the specific capacity of LIBs is to replace the widely used graphite anode with other materials capable of delivering much larger capacities.[2] Among potential candidates, silicon is one of the most promising anode materials, since it offers a theoretical capacity (~3579 mAh/g) approximately 10 times higher than that of graphite (~370 mAh/g) [3], [4]. Besides, silicon is the second most abundant element in the earth’s crust, which positions it as a commercial-friendly substitute of carbon materials for anodes of LIBs[5]. Nevertheless, silicon anodes display pronounced capacity fade upon cycling and, thus, presents a great challenge to battery design 3 , 4 , 5. Another aspect that so far has not been considered nor explored is the influence that temperature would have over the cyclability of silicon anodes in LIBs. To understand its effect, we performed galvanostatic experiments at different temperatures with silicon-based anodes in half-cells. In addition, the effect of using fluoroethylene carbonate (FEC) as an additive was also investigated. The different capacity fading observed and the possible kinetic mechanisms behind that distinct behavior will be discussed here. We gratefully acknowledge support from the U. S. Department of Energy (DOE), Vehicle Technologies Office. Argonne National Laboratory is operated for DOE Office of Science by UChicago Argonne, LLC, under contract number DE-AC02-06CH11357. The U.S. government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the government. [1] M. Armand and J-M. Tarascon. Nature 2008, 451, 652-657. Building better batteries. [2] V. Etacheri, R. Marom, R. Elazari, G. Salitra and D. Aurbach. Energy Environm. Sci. 2011, 4, 3243-3262. Challenges in the development of advanced Li-ion batteries: a review. [3] X. Su, Q. Wu, J. Li, X. Xiao, A. Lott, W. Lu, B. W. Sheldon and J. Wu. Adv. Energy Mater. 2014, 4, 1300882. Silicon-Based Nanomaterials for Lithium-Ion Batteries: A Review. [4] H. Wu and Y. Cui. Nanotoday 2012, 7(5), 414-429. Designing nanostructured silicon anodes for high energy lithium ion batteries. [5] U. Kasavajjula, C. Wang and A. J. Appleby. Journal of Power Sources 2007, 163, 1003. Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells.

Alginate Based Binder Materials for High Capacity Silicon Anodes

Lithium-ion secondary cells are one of the most advanced energy storage systems currently available, and the battery concept with the highest specific energy and energy density. Due to rapidly falling cost following mass production, Li-ion batteries are making a significant impact on markets previously dominated by other technologies, including stationary storage. However, new materials are urgently required in order to address the need for higher energy density, longer cycle/calender life, and improved safety, while satisfying very demanding cost and sustainability targets. Silicon as an anode material is among the most promising materials having a very high theoretical specific charge capacity of about 3600 mAh/g. In addition, it is a low cost, non-toxic and readily available material. For both electrodes, binders are necessary to maintain electrode structure. The state of the art binder material is PVDF, which requires toxic solvents such as NMP. For materials, such as silicon, which have large volume changes during (de)alloying there is a need for new binders which can accommodate such volume changes. Recently, there have been several reports on alginates [1-3] as binder material for anodes in Li ion batteries; however the alginate materials itself used in the studies reported were poorly characterized. The overall content and distribution of the repetition units, mannuronate and guluronate (M/G) in the alginate have an impact on the 3D structure and properties. Na alginates with varying levels of G are evaluated. 1) Na alginate with approx. 70% G obtained from brown seaweed containing long G-blocks. 2) Na alginate with approx. 47% G obtained from brown seaweed containing shorter G-blocks 3) Na alginate produced from Pseudomonas fluorescens with approx. 25% G, and where the G residues are only present as single G's i.e. there are no G-blocks present. Also, the molecular weight (MW) of the alginate is an important determinant for the chemical and physical properties (e.g. viscosity in solution), hence the effect of MW on binder properties of the above mentioned alginates is examined. Here we present a systematic study where different alginate samples are characterized in order to identify the best possible combinations of active anode material and the binder component. Both in-house prepared and commercial Na alginate based binder materials are used to understand how the properties of the different alginate binders effect the overall electrode structure. Seaweed alginates are obtained from FMC Biopolymer, whereas bacterial alginates are prepared at SINTEF using well established methods, including fermentation and extraction. The materials are evaluated as binders for anodes using commercial available silicon materials from Elkem. In addition, the electrochemical performance of Na alginate based electrodes are compared to other proposed binders such as CMC, PVA and PAA. [1] Z.-H. Wu, J.-Y. Yang, B. Yu, B.-M. Shi, C.-R. Zhao, Z.-L. Yu, Self-healing alginate–carboxymethyl chitosan porous scaffold as an effective binder for silicon anodes in lithium-ion batteries, Rare Metals, (2016) 1-8. [2] M.-H. Ryou, S. Hong, M. Winter, H. Lee, J.W. Choi, Improved cycle lives of LiMn2O4 cathodes in lithium ion batteries by an alginate biopolymer from seaweed, J Mater Chem A, 1 (2013) 15224. [3] I. Kovalenko, B. Zdyrko, A. Magasinski, B. Hertzberg, Z. Milicev, R. Burtovyy, I. Luzinov, G. Yushin, A Major Constituent of Brown Algae for Use in High-Capacity Li-Ion Batteries, Science, 334 (2011) 75-79.

Si Nanoparticles-Embedded Nitrogen-Doped Carbon Nanofibers for Lithium Ion Battery Anodes

In recent years, the increased demands such as a higher capacity, power, and cycle stability are importantly issued to realize next generation Li-ion batteries (LIBs). The design and choice of electrode materials (i.e., anode and cathode materials) can be of key factors to satisfy and to improve such electrochemical performance of LIBs. Among the anode materials, silicon (Si) has been considered as a pormising candidate because of the highest theoretical capcity of 4200 mA h g-1 (based on Li-alloying/dealloying reaction: Si + 4.4Li ↔ Li4.4Si), low electrochemical potential (< 0.5 V vs. Li/Li+), and abundance, nevertheless the practical application in LIBs is still challenging due to its limitation; a severe volume change (~400%) during the Li-alloying/dealloying reaction and thereby leading to a crack and pulverization, resulting in a rapid capacity facding.1 To overcome this drawback, tailoring of unique nanostructures and/or nanocomposite such as Si-carbon composites can be an effective approach.2 Herein, we design the fabric-like nanocomposite based on Si nanoparticles-embedded nitrogen-doped carbon nanofibers (Si@N-CNFs) that are synthesized via a facile single-nozzle electrospinning followed by carbonization process, and report their Li-storage performance along with an effect on use with and without polyethylene glycol (PEG). To make Si@N-CNFs nanocomposite, the spinnable solution, including urea, PEG (w/wo), polyacrylonitrile (PAN), and polyvinly butyral (PVB), are first prepared. The urea and PEG are used as a source for N-doping and a non-ionic surfactant to give highly dispersed Si nanoparticles into the solution, respectively. The weight ratio of Si to PEG here is 1 to 8. The as-prepared final solution was poured into the 10 mL plastic syringe and electrospinning was carried out by appling a voltage of 14 kV at single-nozzle electrospinning system. Complete w-Si@N-CNFs nanocomposite is obtained through the stabilization of the as-spun Si@N-CNF at 280 oC in for 2 hr in air and subsequent carbonization at 800 oC for 2 hr in N2 atmosphere, which is clearly confirmed by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). As the conuterpart, wo-Si@N-CNFs nanocomposite that is obtained without PEG is also prepared with the same procedure.Field-emission electron microscopy (FE-SEM) observation shows that both as-spun w-Si@N-CNFs and wo-Si@N-CNFs nanocomposites are a fabric-like formation consisting of one-dimensional (1-D) nanofibers with c.a. 400 nm in diameter. However, as for wo-Si@N-CNF, aggregated Si particles developed a droplet like structures with diameter of over 1 µm in the middle of nanofibers, randomly. After carbonization, the morphology of w-Si@N-CNFs was reminiscent of as-spun w-Si@N-CNFs with a shruken diameter of 300 nm due to a decomposition of some elements (i.e., H and O) in CNFs at 800 oC (Figure 1a) and that of wo-Si@N-CNFs represented similar fabric morphology to w-Si@N-CNFs with grainy texture on the surface of CNFs (Figure 1b). More importatnly, the enlarged FE-SEM image (inset of Figure 1a and b) reveals obviously that the well-dispersed Si nanoparticles are embedded uniformly into N-CNFs, whereas some of Si nanoparticles are aggreagted and/or isolated in their counter part (wo-Si@N-CNFs), which induce the grainy texture on surface of wo-Si@N-CNFs.We evaluated the Li-storage performance of w-Si@N-CNFs nanocomposite anodes. w-Si@N-CNF nanocomposite exhibits the reversible capacity of 1,045 mA h g-1 at a current density of 200 mA g-1, the excellent capacity retention of 61% after 200 cycles, and a high initial coulombic efficiency of 97% at second cycle, compared to Si nano-particles (Figure 1c). The great eletrochemical performance of w-Si@N-CNFs nanocomposite can be associated with the advantageous geometrical features of the uniform encapsulation of highly dispersed Si nanoparticles into N-CNFs with using PEG as well as network of carbon fabric structures, and thereby offering both high electrical conductivity and soft buffer platform for preventing the huge volume expansion of Si nanoparticles. references 1. U. Kasavajjula, C. Wang, and A. J. Appleby, Nano- and Bulk-Silicon-Based Insertion Anodes for Lithium-Ion Secondary Cells. J. Power Sources, 163, 1003, (2007). 2. N. Liu, H. Wu, M. T. McDowell, Y. Yao, C. Wang, and Y. Cui, A Yolk-Shell Design for Stabilized and Scalable Li-Ion Battery Alloy Anodes. Nano Lett., 12, 3315, (2012). Figure 1. Low- and high FE-SEM images of (a) w-Si@N-CNFs and (b) wo-Si@N-CNFs. (c) Cyclic performances of w-Si@N-CNFs and Si nano-particles at a current density of 200 mA g-1. Figure 1

Self-supported Porous Silicon Nanotube Arrays As Anode Material for Li-ion Batteries

Li-ion batteries (LIBs) have been used as a power source ranging from microelectronics to electrical vehicles. However, the use of graphite as anode material for next generation LIBs is unsuitable because of the low Li+ storage capacity (372 mAh.g-1). Various alternative, such as Si, Sn, Ge, has been considered as alternative due to their superior specific gravimetric capacity (for example Si = 4200 mAh.g-1) resulting in high power/energy densities1. However, these materials are intrinsically prone to large volume change during alloying/dealloying mechanism resulting in pulverization, thick SEI formation, loss of electrical contact and active material2. The use of nanostructure has been widely studied to address this problem. Recently, our group has developed techniques to fabricate ultrathin crystalline silicon nanotube arrays (Si NTAs). In comparison to previous works which focus on sealed SiNTs3 and larger size SiNTs (> 400 nm)4, our Si NTAs are ultrathin (10 nm) with porous side walls5. Fig.1 a & b, shows the SEM and TEM images of the Si NTAs fabricated by three step template directed method. The first step is the formation of sacrificial ZnO into stainless steel substrates followed by the deposition of Si onto the ZnO nanowires. The last step is the removal of the sacrificial ZnO nanowire templates to obtain the Si NTAs with porous side wall structure. Fig. 1 (a) SEM and (b) TEM image of Si NTAs. Fig. 2 shows the gravimetric capacity of Si NTAs as a function of cycle number. The electrochemical tests were performed in two electrode Swagelok cell. The half-cells were assembled by using Si NTAs as a working electrode, Li foil as a counter electrode, and a Whatman glass microfiber soaked in 1 M LiPF6 in EC:DEC electrolyte as separator. The cell was cycled at C/20 in a potential window of 0.01 – 1.75 V vs Li/Li+. It delivers a specific capacity of 1670 mAh.g-1 after 30 cycles. The high capacity values are attributed to the 3D porous structure of the Si NTAs. During this work, the improved electrochemical performance of Si NTAs will be discussed. Fig. 2. Gravimetric capacity vs cycle number for Si NTAs at C/20. Reference 1. Liang, B.; Liu, Y.; Xu, Y., Silicon-based materials as high capacity anodes for next generation lithium ion batteries. Journal of Power Sources 2014, 267, 469-490. 2. Kasavajjula, U.; Wang, C.; Appleby, A. J., Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells. Journal of Power Sources 2007, 163 (2), 1003-1039. 3. Song, T.; Xia, J.; Lee, J.-H.; Lee, D. H.; Kwon, M.-S.; Choi, J.-M.; Wu, J.; Doo, S. K.; Chang, H.; Park, W. I., Arrays of sealed silicon nanotubes as anodes for lithium ion batteries. Nano letters 2010, 10 (5), 1710-1716. 4. Wu, H.; Chan, G.; Choi, J. W.; Yao, Y.; McDowell, M. T.; Lee, S. W.; Jackson, A.; Yang, Y.; Hu, L.; Cui, Y., Stable cycling of double-walled silicon nanotube battery anodes through solid-electrolyte interphase control. Nature nanotechnology 2012, 7 (5), 310-315. 5. Huang, X.; Gonzalez-Rodriguez, R.; Rich, R.; Gryczynski, Z.; Coffer, J. L., Fabrication and size dependent properties of porous silicon nanotube arrays. Chemical Communications 2013, 49 (51), 5760-5762. Figure 1

Evaluation by year of the valuable/hazardous material content of lithium-ion secondary battery cells and other components of notebook computer battery packs

Our objective was to provide the information necessary to efficiently recover metals from end-of-life lithium-ion secondary batteries by assessing the metal content by year of production. In addition, we analyzed the concentrations of Sn and the toxic metals Pb, Cr, and Cd in battery pack components, including printed circuit boards and cables. Li and Co were the only active substances in the cathode materials of lithium-ion secondary batteries produced from 1997 to 2005. Ni and Mn also were used in cathode materials of batteries produced from 2007 to 2011. However, Ni became the main constituent in 2012, and Mn was not detected in batteries from that year. For printed circuit boards and cables, Pb concentrations from 1997 to 2004 ranged from 6451 to 12,107 mg/kg, but from 2005 onward maximum concentrations were 513 mg/kg, clearly showing that substitution for Pb had been completed a year before the EU Restriction on Hazardous Substances (RoHS) Directive came into effect.

Internal Impedance of the Lithium-Ion Secondary Cells Used for Reimei Satellite after the Eleven Years Operation in Space

The lithium-ion secondary batteries have been widely used for the space programs, today. Among them, REIMEI was one of the first satellites using lithium-ion secondary battery. In 2005, the satellite was launched, and injected into the low earth polar orbit. Eleven years has passed since the launch and over 60,000 cycles of charge and discharge was experienced in space.The lithium-ion secondary cell of the REIMEI battery was designed using spinel manganese oxide type material for the positive electrode, and the graphitized type carbon for the negative electrode. The cell case was made of aluminium laminated film and the structure was reinforced by the epoxy resin and aluminium housing. After the operation of eleven years, the cells still maintain the appropriate uniform balance and operative. In order to identify the internal condition of the battery/cell, we calculated the ac impedance by the pulse duration to the on-board battery.

Amorphous Silicon Nitride Thin Film Anodes for Li-Ion Batteries

Silicon has proven to have a great potential as anode material for lithium ion batteries due to its high theoretical capacity, however; there are several obstacles that need to be overcome in order to make it a commercially viable option. Two of the main issues stem from the fact that silicon undergoes a large volume change during lithiation and delithiation (1). This makes forming a stable solid electrolyte interphase (SEI) difficult, resulting in a continuous loss mechanism of electrolyte and lithium as SEI is formed and broken each cycle. Uneven expansion and contraction causes the silicon to fracture, both exposing new surface on which more SEI might form, as well as electrically disconnecting material from the electrode, rendering it inactive. In this work we investigate the use of amorphous silicon nitride as an alternative to pure silicon anodes. Silicon nitride is believed to form lithiated silicon and lithium nitride or one of several lithium silicon nitride ternary phases during the initial lithiation (2, 3). The resulting material is therefore believed to combine the high lithium ion conductivity of lithium containing nitrides with the high capacity of silicon. In a sufficiently fine structure, we hypothesize the silicon would be able to expand and contract with little to no fracturing owing to dimensional stabilization, short diffusion distances, and fast lithium diffusion in the surrounding lithium nitride, resulting in a high cycling stability. We investigate this theory using a thin film electrode system. For this purpose, a-SiNx:H thin films are deposited on copper foil substrates using plasma enhanced chemical vapor deposition (PECVD) with silane (SiH4) and ammonia (NH3) as precursors. By changing the flow ratio of the precursor gases in the plasma, SiNxfilms with five different compositions were made (x = 0, 0.36, 0.63, 0.88 and 1.00). Films of different thicknesses were also made to be able to separate surface and bulk irreversible capacities, and to evaluate the kinetics of the material. Ellipsometry and transmission electron microscopy (TEM) were used to determine the thickness, composition, structure and quality of the pristine films. Electrochemical tests were conducted in 2032 coin cells, with a lithium metal counter electrode, using a commercial electrolyte with 5% FEC and 1% VC, and cycling is conducted between 50 mV and 1 V. The variation of the first cycle specific charge capacity as function of different stoichiometries is studied, as well as the stability of the resulting material. Figure 1 shows the charge capacity and Coulombic efficiency of three 40 nm thick SiN1.00 thin film electrodes which were primed at C/6 for 6 cycles and cycled at 1C for 750 cycles. These had an average charge capacity of 1126±40 mAh/g on the first 1C cycle, and experienced only a slight increase in capacity during the first 230 cycles, peaking at 1259±33 mAh/g before leveling out. After finishing 750 cycles the cells still retained an average capacity of 1245±19 mAh/g. Voltage-capacity curves for a selection of cycles can be seen in the figure 2, showing the large difference between the first conversion cycle and the subsequent cycles. By comparing the first cycle irreversible capacities of SiN1.00 films with different thicknesses (40 nm, 80 nm, 120 nm, 160 nm, and 200 nm), it has been determined that the conversion reaction of this nitride composition consumes approximately 565 mAh/g, while the initial formation of SEI consumes 0.021 mAh/cm2. These experiments also demonstrated that increasing the thickness of the films had no significant adverse effects on their performance, but rather improved the first cycle irreversible capacity and increased the long term (cycles 10-100) average Coulombic efficiency from 99.6% (40 nm) to >99.9% (80 nm, 120 nm, 160 nm and 200 nm). 1. Kasavajjula U, Wang C, Appleby AJ. Nano-and bulk-silicon-based insertion anodes for lithium-ion secondary cells. Journal of Power Sources. 2007;163(2):1003-39. 2. Ahn D, Kim C, Lee J-G, Park B. The effect of nitrogen on the cycling performance in thin-film Si1−xNx anode. Journal of Solid State Chemistry. 2008;181(9):2139-42. 3. Suzuki N, Cervera RB, Ohnishi T, Takada K. Silicon nitride thin film electrode for lithium-ion batteries. Journal of Power Sources. 2013. Figure 1

Nanostructured Si-Based Anodes for Lithium-Ion Batteries

High capacity electrode materials are searched for commercial applications due to the increase in energy density and power density requirements for lithium-ion secondary cells. Silicon has triggered significant research effort because of its low Li-uptake potential and the high theoretical capacity. However, volume changes during cycling cause pulverization and capacity fade, which is an obstacle of the application of silicon as an anode. Here we present a review of research progress on silicon-based anode materials for lithium-ion batteries, focusing on the effects of the morphology and compound on the electrochemical properties. The reasons of poor cycle performance are discussed. It is pointed out that to control the huge volume change and solid electrolyte interface growth during cycling is an effective way to improve the cycle performance. Outlook for the future development of silicon-based composite anode materials for the application of silicon anodes are finally outlined.

Silicon Nitride Coated Silicon Thin Films As Anodes for Li-Ion Batteries

Silicon has proven to have a great potential as anode material in lithium-ion batteries due to its high theoretical electrochemical capacity. However, silicon anodes deteriorate quickly during cyclic charging and discharging, rendering them useless in only a few cycles [1]. This has been attributed to the stresses induced by the large volume change of the material during cycling. Numerous attempts have been made to reduce these stresses, e.g. by using nanoparticles, nanorods, nanowires, thin films and porous structures, with a varying degree of success [2, 3]. While using finely structured materials aids in the intercalation of lithium by reducing the necessary diffusion distance, it also has the unfortunate effect of greatly increasing the specific surface area of the silicon. When using nano-sized materials, silicon’s ability to form a thin and stable solid electrolyte interphase (SEI) therefore becomes increasingly important. There are a number of factors that have a large influence on the SEI formation, making the process notoriously difficult to analyze, but also makes it possible to manipulate. Coating silicon with different nitrides and oxides, e.g. TiN and TiO, have previously been shown to enhance the cycling stability and Coulombic efficiency of the material [4, 5]. In this project the effect of coating the surface of silicon thin films with a thin (< 4-5 nm) layer of silicon nitride is investigated, as well as the effect of varying the stoichiometry of the silicon nitride. By itself silicon nitride has been shown to function as a conversion electrode material, forming elemental silicon and lithium nitride during the initial cycle, with thin films exhibiting capacities of up to 1800 mAh/g [6].40 nm silicon thin films were deposited by PECVD on copper foil using silane as precursor. The nitride was formed by addition of ammonia to the gas flow in the late stages of the deposition, and different stoichiometries were obtained by changing the ratio of these gases. By varying the flow rate of ammonia, coatings with four different compositions were made; pure silicon (A), stoichiometric Si3N4(D) and two intermediate compositions (B and C). Three electrodes were punched from each of the resulting films and mounted in coin cells with lithium metal counter electrodes and cycled at a current rate of C/3 for 150 cycles. During cycling, all the cells exhibited an initial increase in capacity, peaking at close-to-theoretical capacity within 10-40 cycles before beginning a slow decline. The average charge capacity for each series after 50, 100 and 150 cycles is presented in the figure, showing that the capacity retention increases with increasing nitrogen content for series A, B and C, and then decreases for series D. This indicates that a nitrogen coating has a positive effect on the deterioration mechanisms of the electrode, and that this effect increases with increasing nitrogen content of the coating, as long as a stoichiometric nitride is not formed.1. Kasavajjula, U., C. Wang, and A.J. Appleby, Nano-and bulk-silicon-based insertion anodes for lithium-ion secondary cells. Journal of Power Sources, 2007. 163(2): p. 1003-1039.2. Wu, H. and Y. Cui, Designing nanostructured Si anodes for high energy lithium ion batteries. Nano Today, 2012. 7(5): p. 414-429.3. Ge, M., et al., Scalable preparation of porous silicon nanoparticles and their application for lithium-ion battery anodes.Nano Research, 2013: p. 1-8.4. Memarzadeh Lotfabad, E., et al., ALD TiO2 coated silicon nanowires for lithium ion battery anodes with enhanced cycling stability and coulombic efficiency. Physical chemistry chemical physics : PCCP, 2013. 15(32): p. 13646-57.5. Kohandehghan, A., et al., Silicon nanowire lithium-ion battery anodes with ALD deposited TiN coatings demonstrate a major improvement in cycling performance. Journal of Materials Chemistry A, 2013. 1(41): p. 12850-12861.6. Suzuki, N., et al., Silicon nitride thin film electrode for lithium-ion batteries. Journal of Power Sources, 2013. 231(0): p. 186-189.

Lithium Ion Secondary Cell Prepared by a Printing Procedure, and Its Application to All-Solid-State Inorganic Lithium Ion Cells

We have developed a straightforward printing method for preparation of a lithium secondary cell. LiCo1/3Ni1/3Mn1/3O2 and Li4Ti5O12 viscous printable pastes were used for the cathode and anode, respectively. Electrochemical measurement was used to characterize the capacitance of each cell, and field-emission scanning electron microscopy and particle size measurements were used to characterize particle size and morphology. These film electrodes functioned stably both in a standard liquid electrolyte and in an Li2SiO3 solid electrolyte, although the capacitance of the all-solid-state cell was significantly lower than that of the cell containing liquid electrolyte. When liquid electrolyte was used, the capacity decreased by 36% after 50 cycles. However, the capacity of 0.2 mA h/g remained almost the same even after 50 charge–discharge cycles, demonstrating the stability and strength of the all-solid-state lithium ion cell. It was also found that the cell resistance mostly arose from the electrode/electrolyte interface and not from the bulk electrolyte. Addition of a sol–gel to the solid electrolyte printable paste improved cell performance.

State of Charge Dependency of Graphitized-Carbon-Based Reactions in a Lithium-ion Secondary Cell Studied by Electrochemical Impedance Spectroscopy

Li-ion insertion/deinsertion reactions of the anode of a Li-ion secondary cell incorporating a reference electrode were analyzed by electrochemical impedance spectroscopy (EIS) at different temperatures and state of charges (SOCs). The cell uses graphitized carbon as anode electroactive material. Impedance spectra fittings were carried out using an equivalent circuit, so that the reaction kinetics could be evaluated accurately. The dependencies of the Li-ion conduction (Rsl1), Li-ion solvation/desolvation (Rsl2) and charge transfer (Rct) reactions on the SOC and anode potential were evaluated. The results were compared with a dQ/dE vs. E curve of graphite to analyze how the structural changes of graphite affect the Li-ion insertion process. The charge transfer process was found to be dependent on the SOC and anode potential. On the other hand, Li-ion conduction and Li-ion solvation/desolvation processes did not depend on the SOC and anode potential.

Thermal characteristics of lithium ion secondary cells in high temperature environments using an accelerating rate calorimeter

The analysis of the thermal behavior of Li-ion secondary cells in high temperature environments is one of the most important issues for the application of these batteries in electric vehicles. In this study, by using an accelerating rate calorimeter (ARC), we monitored the exothermic and thermal runaway behaviors of two lithium ion secondary cells using different cathode materials, lithium cobalt oxide (LCO) and lithium manganese oxide (LMO). Also, the internal resistance and open circuit voltage of the cells were recorded. As a result of the thermal runaway tests, it was found that the amount of heat released from the cell using LMO as the cathode material was lower when compared to the cell using LCO. In general, LMO exhibits a high thermal stability. This is mainly due to differences between the cathode materials. In addition, a sudden increase in the internal resistance and decrease in the open circuit voltage of the cells were detected, which seemed to be due to the shutting down of the cell separators. As already described, by combining the ARC tests and electrochemical measurements, we were able to identify the thermal and electrochemical characteristics, including the thermal runaway, based on the materials used in the Li-ion secondary cells.