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Power loss is a limiting factor for batteries and individual cells. The resulting heat generation due to the power loss leads to reduced battery performance and, thus, lower efficiency. These losses are largely due to the internal resistance of the cells. Therefore, it is important to accurately determine the value of the internal resistance of lithium–ion cells. From the literature, it was found that there are three widely used internal resistance-measurement methods (current step method, direct-energy-loss method, and calorimeter measurement), with negligible research on their comparison demonstrating the most efficient method. Henceforth, to find the most optimal method, this research adopts all three methods on a variety of cell chemistries, including Lithium-ion Manganese Oxide (LMO), Lithium Iron Phosphate (LFP), Nickel Manganese Cobalt (NMC), and Lithium Titanium-Oxide (LTO) for different c-rates (1 C, 2 C, and 3 C), with a wide temperature range (from 0 °C to 40 °C). [ABSTRACT FROM AUTHOR]

At present, most synthetic graphite materials commonly used as anode active ingredients in lithium‐ion cells are produced by graphitization of petroleum cokes. The carbon footprint associated with synthetic graphite production is significant. Thus, bio‐derived and cheap precursors, such as saccharides, would be an attractive alternative for the sustainable production of graphitic carbons. However, they are non‐graphitizing at temperatures as high as 3000 °C, preserving the curved, fullerene‐like structure of graphene layers and microporosity. Consequently, many lithium ions are consumed during the formation of solid electrolyte interphase films and passivated in the nanovoids. Here, a method for the production of pure, crystalline, graphitic materials based on sucrose disposed of microporosity is presented, which also works with a variety of saccharides and other organic precursors of hard carbons—generally considered incapable of such transformation. This process employs catalytic graphitization by Si particles at high temperatures. The electrochemical response of such derived sucrose‐based graphite in Li‐ion half‐cells demonstrated its feasibility to serve as an anode active material for rechargeable Li‐ion batteries. [ABSTRACT FROM AUTHOR]

This study investigates the potential link between the increasing prevalence of single-use vapes (SUVs) and the rising frequency of waste and recycling fires in the UK. Incorrectly discarded Li-ion cells from SUVs can suffer mechanical damage, potentially leading to thermal runaway (TR) depending on the cells' state of charge (SOC). Industry-standard abuse tests (short-circuit and nail test) and novel impact and crush tests, simulating damage during waste management processes, were conducted on Li-ion cells from two market-leading SUVs. The novel tests created internal short circuits, generating higher temperatures than the short-circuit test required for product safety. The cells in used SUVs had an average SOC ≤ 50% and reached a maximum temperature of 131 °C, below the minimum ignition temperature of common waste materials. The high temperatures were short-lived and had limited heat transfer to adjacent materials. The study concludes that Li-ion cells in used SUVs at ≤50% SOC cannot generate sufficient heat and temperature to ignite common waste and recycling materials. These findings have implications for understanding the fire risk associated with discarded SUVs in waste management facilities. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are a feasible solution to store energy efficiently. However, in safety-critical environments such as the suborbital rockets, the introduced technologies do not may compromise safety. This research explores the possibility of replacing Ni-MH batteries with Li-ion batteries. However, before replacing technologies, the reliability of Li-ion cells needs to be evaluated, and the potential benefits must be considered against the risks to ensure the mission’s success. The main objective is to ensure the safety and integrity of suborbital missions during the technology transition. To assess the technology exchange, a method where the battery cell experiences a sequence of tests that cover aspects of safety encountered during the vehicle missions, such as vacuum, capacity, short circuit behavior, over-current discharge, behavior at higher environment temperature, and pulsed discharge behavior. To experience the proposed method, two Li-ion cells commercial off-the-shelf (COTS) from different manufacturers are evaluated. The results indicated that only one of the two cell models evaluated can substitute the Ni-MH. This research concludes that replacing Ni-MH cells with Li-ion cells is feasible, for such an application. The proposed acceptance flow design based on the test collectively validates the replacement, showing that the Li-ion cells can offer reliability, safety, and efficiency to suborbital vehicles to fulfill this mission profile. [ABSTRACT FROM AUTHOR]

As a core component of new energy vehicles, accurate estimation of the State of Health (SOH) of lithium-ion power batteries is essential. Correctly predicting battery SOH plays a crucial role in extending the lifespan of new energy vehicles, ensuring their safety, and promoting their sustainable development. Traditional physical or electrochemical models have low accuracy in measuring the SOH of lithium batteries and are not suitable for the complex driving conditions of real-world vehicles. This study utilized the black-box characteristics of deep learning models to explore the intrinsic correlations in the historical cycling data of lithium batteries, thereby eliminating the need to consider the internal chemical reactions of lithium batteries. Through Pearson correlation analysis, this study selects health indicators (HIs) from lithium battery cycling data that significantly impact SOH as input features. In the field of lithium batteries, this paper applies ABC-BiGRU for the first time to SOH prediction. Compared with other recursive neural network models, ABC-BiGRU demonstrates superior predictive performance, with maximum root mean square error and mean absolute error of only 0.016799317 and 0.012626847, respectively. [ABSTRACT FROM AUTHOR]

Transitioning to more ambitious electrode formulations facilitates developing high-energy density cells, potentially fulfilling the demands of electric car manufacturers. In this context, the partial replacement of the prevailing anode active material in lithium-ion cells, graphite, with silicon-based materials enhances its capacity. Nevertheless, this requires adapting the rest of the components and harmonizing the electrode integration in the cell to enhance the performance of the resulting high-capacity anodes. Herein, starting from a replacement in the standard graphite anode recipe with 22% silicon suboxide at laboratory scale, the weight fraction of the electrochemically inactive materials was optimized to 2% carbon black/1% dispersant/3% binder combination before deriving an advantage from including single-wall carbon nanotubes in the formulation. In the second part, the recipe was upscaled to a semi-industrial electrode coating and cell assembly line. Then, 1 Ah lithium-ion pouch cells were filled and tested with different commercial electrolytes, aiming at studying the dependency of the Si-based electrodes on the additives included in the composition. Among all the electrolytes employed, the EL2 excelled in terms of capacity retention, obtaining a 48% increase in the number of cycles compared to the baseline electrolyte formulation above the threshold capacity retention value (80% state of health). [ABSTRACT FROM AUTHOR]

The rapid advancement in Lithium‐ion battery technology has significantly boosted the electric vehicle market worldwide. These batteries are highly sought after by automobile manufacturers and researchers due to their exceptional energy storage and power capabilities. However, efficient working temperatures ranges from 15°C to 35°C, making it essential to implement battery cooling and heating methods to maintain optimal performance. This study primarily focuses on battery cooling. The automotive manufactures have focused on ethylene glycol, water and synthetic oils as commonly used coolants for keeping the lithium‐ion battery pack within working temperature limits. However, these fluids have lower heat conduction, leading to reduced heat transfer rates and diminished cooling performance. To address this issue, nano‐enhanced fluids, which are engineered fluids containing suspended nanospheres, have been explored. The heat transfer properties of conventional coolants are increased using nano‐enhanced fluids, thereby improving heat conduction and promoting efficient heat transfer within the battery. The study compares the temperature‐related characteristic of different nano‐enhanced fluids, including oxides of copper (CuO), titanium (TiO2), aluminum (Al2O3), silicon (SiO2), and zinc (ZnO), when added to base fluids such as synthetic oils, water and ethylene glycol. The importance to capacity of specific heat, conductivity of fluid thermally, fluid resistance to flow and fluid volumetric mass which are affected by changes in temperature limits are stressed upon. Depending on the specific application and test conditions, the effectiveness of one nano‐enhanced fluid may outperform the others. In conclusion, the thermo physical properties of nanofluids play a critical role in maintaining the battery pack temperature within operating temperature limits. The selections of nanofluids for particular battery thermal management system depends upon its arrangement along the battery pack and cell geometry. The cooling performance using nanofluids as coolant is 10% to 15% higher than the conventional used fluids. This nano‐enhanced fluid show great promise in enhancing the cooling capabilities of battery cooling systems, contributing to improved Lithium‐ion battery performance in electric vehicles. [ABSTRACT FROM AUTHOR]

The significant heat generated during the operation of lithium‐ion batteries raises the battery temperature thereby leading to performance degradation and thermal runaway in a thermal abuse environment. Therefore, a simple but effective battery thermal management system (BTMS) is crucial to achieve the permissible operating temperatures. In this work, the performance of air‐cooled BTMS is evaluated by changing the arrangement of cells under discharging conditions. Seven distinct arrangements (trapezoidal, slanted, cross, aligned, staggered, tilted square, and zigzag) of lithium‐ion cells are investigated in a rectangular battery pack. Two‐way coupling of 1D electrochemical model and 2D conjugate thermal‐fluid model is employed. The increasing Reynolds number reduces the cell temperature due to augmented convective effects. Under otherwise identical conditions, the zigzag cell arrangement outperforms the other cell arrangements but at the expense of the highest pressure drop (≈threefold). Particularly, the values of average and maximum cell temperature are reduced by ≈5K and ≈4K, respectively, for Re = 1000 at 1C in comparison to the aligned cell arrangement. Similarly, the least favorable performance is predicted by the trapezoidal, slanted, and cross‐cell arrangements. Finally, a performance plot is suggested considering the trade‐off between the power requirement and the cooling enhancement. [ABSTRACT FROM AUTHOR]

Lithium‐ion cells with graphite anodes and nickel–manganese–cobalt oxide (NMC622) cathodes are filled with three different amounts of electrolyte. During formation, incremental capacity analysis indicates small differences in the formation processes between cells with insufficient electrolytes to fill all pores and those with an electrolyte volume above the total pore volume of the cell. Complimentary analysis of the gases developed during formation shows that the composition of these cells differs from the cells with a sufficient electrolyte. The aging of cells under high temperature (60 °C) and high constant voltage of 4.2 V is studied. During aging, cells with higher amounts of electrolyte degrade substantially slower. Based on data available from electrical tests, a theory explaining the volume‐dependent rise of resistance and capacity decay is proposed. [ABSTRACT FROM AUTHOR]

Abstract To improve the discharge equalization efficiency of the battery and prevent the occurrence of overdischarge, in this paper, the 18,650 ternary lithium battery is taken as the object of investigation, and an alternating equalization control system for the discharge process of serial cells is proposed. The system implements the alternating discharge of serial cells by switching on and off, using state of charge (SOC) as the equalization variable, and eventually completes the equalization control of the entire battery pack. Discharge simulations were performed in Matlab/Simulink for faulty and normal operating conditions of the battery pack, respectively. The findings indicate that even in the presence of a malfunction, the battery pack can continue to operate continuously for a while; in contrast, under ideal circumstances, the battery pack is capable of maintaining SOC balance throughout the discharge process. Eventually, five batteries are used to construct the experimental platform for the alternating equalization system. The battery pack can still perform selective discharge under fault conditions until the battery pack reaches the discharge cutoff condition. Under normal conditions, the maximum SOC difference of all five batteries can stabilize at about 1%. The experimental results show that the proposed equalization control system can achieve the equalization of battery discharge and prolong the discharge time, and can prevent the occurrence of battery over discharge.

Power loss is a limiting factor for batteries and individual cells. The resulting heat generation due to the power loss leads to reduced battery performance and, thus, lower efficiency. These losses are largely due to the internal resistance of the cells. Therefore, it is important to accurately determine the value of the internal resistance of lithium–ion cells. From the literature, it was found that there are three widely used internal resistance-measurement methods (current step method, direct-energy-loss method, and calorimeter measurement), with negligible research on their comparison demonstrating the most efficient method. Henceforth, to find the most optimal method, this research adopts all three methods on a variety of cell chemistries, including Lithium-ion Manganese Oxide (LMO), Lithium Iron Phosphate (LFP), Nickel Manganese Cobalt (NMC), and Lithium Titanium-Oxide (LTO) for different c-rates (1 C, 2 C, and 3 C), with a wide temperature range (from 0 °C to 40 °C).

This study investigates the potential link between the increasing prevalence of single-use vapes (SUVs) and the rising frequency of waste and recycling fires in the UK. Incorrectly discarded Li-ion cells from SUVs can suffer mechanical damage, potentially leading to thermal runaway (TR) depending on the cells’ state of charge (SOC). Industry-standard abuse tests (short-circuit and nail test) and novel impact and crush tests, simulating damage during waste management processes, were conducted on Li-ion cells from two market-leading SUVs. The novel tests created internal short circuits, generating higher temperatures than the short-circuit test required for product safety. The cells in used SUVs had an average SOC ≤ 50% and reached a maximum temperature of 131 °C, below the minimum ignition temperature of common waste materials. The high temperatures were short-lived and had limited heat transfer to adjacent materials. The study concludes that Li-ion cells in used SUVs at ≤50% SOC cannot generate sufficient heat and temperature to ignite common waste and recycling materials. These findings have implications for understanding the fire risk associated with discarded SUVs in waste management facilities.

To improve the discharge equalization efficiency of the battery and prevent the occurrence of overdischarge, in this paper, the 18,650 ternary lithium battery is taken as the object of investigation, and an alternating equalization control system for the discharge process of serial cells is proposed. The system implements the alternating discharge of serial cells by switching on and off, using state of charge (SOC) as the equalization variable, and eventually completes the equalization control of the entire battery pack. Discharge simulations were performed in Matlab/Simulink for faulty and normal operating conditions of the battery pack, respectively. The findings indicate that even in the presence of a malfunction, the battery pack can continue to operate continuously for a while; in contrast, under ideal circumstances, the battery pack is capable of maintaining SOC balance throughout the discharge process. Eventually, five batteries are used to construct the experimental platform for the alternating equalization system. The battery pack can still perform selective discharge under fault conditions until the battery pack reaches the discharge cutoff condition. Under normal conditions, the maximum SOC difference of all five batteries can stabilize at about 1%. The experimental results show that the proposed equalization control system can achieve the equalization of battery discharge and prolong the discharge time, and can prevent the occurrence of battery over discharge. [ABSTRACT FROM AUTHOR]

This paper presents the problem of identifying the parameters of the LFP-type lithium-ion cell model. A 2nd order circuit model is presented for the analysis of electrical signals at the terminals of the cell. Laboratory experimental tests were carried out and used for identification. In order to obtain a match between the model and the measurements, a proprietary computer application was developed, which, using a genetic algorithm, finds optimal solutions in the form of a set of parameters of the elements of the equivalent scheme as a function of the cell's state of charge. The identification results obtained were then visualized and compared to the measurements. [ABSTRACT FROM AUTHOR]

Nickel‐rich (Ni‐rich) layered oxides are considered as the most promising cathode candidates for lithium‐ion cells owing to their high theoretical specific capacity. However, the higher nickel content endows structural deformation through unwanted phase transitions and parasitic side reactions that lead to capacity fading upon prolonged cycling. Hence, a deep understanding of the chemistry and structural behaviour is essential for developing Ni‐rich Lithium Nickel Cobalt Manganese oxide (NCM) cathode‐based high‐energy batteries. The present review focuses on the different challenges associated with Ni‐rich NCM materials and surface modification as a strategy to solve the issues associated with NCM materials, assessment of several coating materials, and the recent developments in the surface modification of Ni‐rich NCMs, with an in‐depth discussion on the impact of coating on the degradation mechanism. [ABSTRACT FROM AUTHOR]

Electric vehicles surged into the automobile industry due to increasing emissions and future extinction of fossil fuels which resulted due to their unforeseen utilization all over the globe. Battery is important components for manufacturing of electric vehicles (EVs). Currently lithium‐ion (Li‐ion) cells are the most advanced and efficient cell technology developed till date. These cells work well within an operating temperature range of 15° C to 35°C. Thus, many battery cooling techniques were developed such as air, liquid, phase change material (PCM) and heat pipe based cooling system. Liquid cooling was found to be the most efficient, adoptable and convenient system used in EVs. The current paper focuses on development of an active indirect liquid cooling system using nanofluids as coolant. Different performance parameters such as mass flow rate, nanoparticle concentration and maximum temperature of battery pack were varied and simulation results were validated using experimental results. The results concluded that nanofluids show improved and enhanced cooling as in comparison with other coolants such as water and ethylene glycol. Al2O3‐water nanofluid is the most preferable to use in EVs as coolants due to its efficient cooling, low cost and environmental friendly nature. On increasing the mass flow rate of the coolants, flowing into the cooling tube increases the cooling performance and reduces the temperature of battery pack within the battery operating zone. The cooling performance using nanofluids increased by 40% as in comparison with water and ethylene glycol as coolants when tested experimentally. [ABSTRACT FROM AUTHOR]

Transitioning to more ambitious electrode formulations facilitates developing high-energy density cells, potentially fulfilling the demands of electric car manufacturers. In this context, the partial replacement of the prevailing anode active material in lithium-ion cells, graphite, with silicon-based materials enhances its capacity. Nevertheless, this requires adapting the rest of the components and harmonizing the electrode integration in the cell to enhance the performance of the resulting high-capacity anodes. Herein, starting from a replacement in the standard graphite anode recipe with 22% silicon suboxide at laboratory scale, the weight fraction of the electrochemically inactive materials was optimized to 2% carbon black/1% dispersant/3% binder combination before deriving an advantage from including single-wall carbon nanotubes in the formulation. In the second part, the recipe was upscaled to a semi-industrial electrode coating and cell assembly line. Then, 1 Ah lithium-ion pouch cells were filled and tested with different commercial electrolytes, aiming at studying the dependency of the Si-based electrodes on the additives included in the composition. Among all the electrolytes employed, the EL2 excelled in terms of capacity retention, obtaining a 48% increase in the number of cycles compared to the baseline electrolyte formulation above the threshold capacity retention value (80% state of health).

Battery cells are the main components of a battery system for electric vehicle batteries. Depending on the manufacturer, three different cell formats are used in the automotive sector (pouch, prismatic, and cylindrical). In the last 3 years, cylindrical cells have gained strong relevance and popularity among automotive manufacturers, mainly driven by innovative cell designs, such as the Tesla tabless design. This paper investigates 19 Li-ion cylindrical battery cells from four cell manufacturers in four formats (18650, 20700, 21700, and 4680). We aim to systematically capture the design features, such as tab design and quality parameters, such as manufacturing tolerances and generically describe cylindrical cells. We identified the basic designs and assigned example cells to them. In addition, we show a comprehensive definition of a tabless design considering the current and heat transport paths. Our findings show that the Tesla 4680 design is quasi-tabless. In addition, we found that 25% of the cathode and 30% of the anode are not notched, resulting in long electrical and thermal transport paths. Based on CT and post-mortem analyses, we show that jelly rolls can be approximated very well with the Archimedean spiral. Furthermore, we compare the gravimetric and volumetric energy density, the impedance, and the heating behavior at the surface and in the center of the jelly rolls. From the generic description, we present and discuss production processes focusing on format and design flexible manufacturing of jelly rolls. [ABSTRACT FROM AUTHOR]

The development and scale‐up of lithium‐ion battery (LIB) production for a sustainable energy supply is advancing very rapidly and in versatile directions. Manufacturing processes and production steps are constantly developed and optimized to improve production efficiency. To integrate new machinery into a production line while conforming to the DIN EN ISO 9001 standards of certification, it is necessary to define the procedures for assuring product quality. Herein, a quality assurance concept is designed for an innovative flexible stacking process currently under development. Critical sources of errors are identified by employing the failure process matrix approach. On this basis, it is described how these errors are either avoided by suitable design of the machine components and its control or by which inspection technology is integrated to detect defective intermediate products. In the resulting quality assurance concept, a digital twin of the stacking machine is employed to constantly surveil process and product properties and also to facilitate the change of the produced products on the machine. Evaluating the quality management already in the design phase of the machine saves resources and enables a deeper understanding of the stacking process. [ABSTRACT FROM AUTHOR]

In order to make electric transportation more accessible, the cost of lithium‐ion batteries must decrease. One way to achieve this is by increasing the production rates, especially in the time‐consuming steps of electrolyte filling and cell formation. Within this work, lithium‐ion pouch and hardcase cells are filled with electrolyte and the formation is started at varying wetting degrees. Data from the formation, stabilization, and life cycle testing are analyzed to determine the effect of an incomplete wetting degree on the cell quality. Additionally, postmortem analysis is performed to help understand the mechanisms induced when a cell with incomplete wetting is subjected to a current. The pouch cells demonstrate a linear capacity fade, regardless of the wetting degree, but feature strong lithium plating which becomes visible during postmortem analysis. In contrast, the hardcase cells display a clear correlation between the cell quality and the wetting degree in both the life cycle test and the postmortem analysis. It is shown that a wetting degree of 98% is required before starting the formation to avoid lithium plating in the cell. [ABSTRACT FROM AUTHOR]

Li‐ion cells of the industrially relevant 21700 format are investigated experimentally by systematic variation of their tab design. To observe the effects of the tab design only, the cells are built on pilot scale using the same electrodes, electrolyte, and separator. Tabs are varied regarding 1) conventionally welded tabs and 2) tabs made from the electrodes' foils ("foil tabs"), as well as the tab number. Conclusions are drawn on cell impedances, rate capability (0.5C–3C), heating behavior, and cycling aging. Cells with a multitab design show a reduced impedance (1 kHz) by 62%, an improved charging rate capability by ≈17% for 3C, an improved cycle stability by 26.5%, and charge throughput by 22.8%. For the check‐ups at C/10, improvements in cycle life and charge throughput of 51.1% and 42.4% are observed, respectively. The improved cycle life is due to the reduction of inhomogeneities in the jellyrolls as observed by X‐ray computed tomography. The data are put into context with cells from other studies to conclude the order of magnitude of the effects of tab design variation. Based on experimental findings, estimations are made for 46800 format cells regarding energy content and impedance. [ABSTRACT FROM AUTHOR]

The deployment of battery-powered electric vehicles in the market has created a naturally increasing need for the safe deactivation and recycling of batteries. Various deactivating methods for lithium-ion cells include electrical discharging or deactivation with liquids. Such methods are also useful for cases where the cell tabs are not accessible. In the literature analyses, different deactivation media are used, but none include the use of calcium chloride (CaCl2) salt. As compared to other media, the major advantage of this salt is that it can capture the highly reactive and hazardous molecules of Hydrofluoric acid. To analyse the actual performance of this salt in terms of practicability and safety, this experimental research aims to compare it against regular Tap Water and Demineralized Water. This will be accomplished by performing nail penetration tests on deactivated cells and comparing their residual energy against each other. Moreover, these three different media and respective cells are analysed after deactivation, i.e., based on conductivity measurements, cell mass, flame photometry, fluoride content, computer tomography and pH value. It was found that the cells deactivated in the CaCl2 solution did not show any signs of Fluoride ions, whereas cells deactivated in TW showed the emergence of Fluoride ions in the 10th week of the insertion. However, with the addition of CaCl2 in TW, the deactivation process > 48 h for TW declines to 0.5–2 h, which could be an optimal solution for real-world situations where deactivating cells at a high pace is essential. [ABSTRACT FROM AUTHOR]

All autonomous electrically powered devices require a continuous power supply from batteries. Increasing the discharge performance is the top priority in the Lithium-Ion (Li-Ion) battery field and pulsed discharge is proving numerous advantages. In this paper, the maximum efficiency of pulsed discharge method on a constant load while the cells are alternately switched with dead-time is thoroughly studied. Therefore, a novel Li-Ion charge/discharge and measurement device (SWD) using fast switching MOSFET was designed and fabricated. The device can alternately switch up to 8.3 kHz two Li-Ion 18650 batteries, generating continuous power to the programmable load and monitor the parameters that impact the capacity of the battery. An EIS (Electrochemical Impedance Spectroscopy) analysis is employed to evaluate the impedance and the behavior of the cells at frequencies up to 10 kHz. Experimental results reveal that a maximum discharge time is determined when two cells are switched at a frequency of 5.8 kHz. As a consequence, the total capacity of two switched batteries in a single discharge cycle is increased by 16.6%. Pulsed discharge efficiency is visible starting from 70% State of Charge (SOC) and is correlated with the rest time, reduced heat loss and inductance, respectively. [ABSTRACT FROM AUTHOR]

The development of electric transport is inextricably linked with the modernization of the associated infrastructure, and one of the factors for the slow introduction of electric transport in Russia is the small number of charging stations. But most of the existing solutions in the field of charging stations have a drawback – the lack of mobile installations. The team of Kazan State Power Engineering University (KSPEU) and Production Association "Zarnitsa" is developing a mobile electric vehicle charge units (MSCEU). At the design stage, a problem has arisen with the fact that it would be difficult to conduct constant tests on a full-fledged prototype of the MSCEU due to the weight and size parameters of the equipment. At the same time, there is a need for preliminary confirmation of the compliance of the MSCEU with the climatic (UHL1) and mechanical performance (M3) groups. To accomplish this task, it was decided to simulate the work of the MSCEU in the COMSOL software. For solving this problem, it is necessary to simulate a module of four rechargeable batteries in order to confirm the manufacturer's parameters, and thus verify the resulting model. Based on these results, a complete MSCEU model consisting of 1,200 batteries can be implemented, which can be used to check compliance with the given conditions. For thermal calculations, it is necessary to check the pre-selected parameters of the air conditioning power, and to select the thickness of the thermal insulation. As a result a 3D model has been implemented in COMSOL, the parameters of all materials used have been determined, the connections of solutions have been built, physics of processes and the type of a solver have been selected. Based on the simulation, the insulation thickness has been chosen, the results of simulation of operating the air conditioning system to maintain the operating temperature of the batteries have been obtained, and the results have been demonstrated that confirm the mechanical reliability of the MSCEU.

Despite lithium‐ion battery (LIB) and supercapacitor materials have gone through numerous enhancements, achieving high energy density as well as power density together is still a dream for the industries. In this scenario, herein we report, boric acid coated α−MnO2 anode with 1288 mAh g−1 at 0.1 C at the initial cycle and of an average discharge capacity of 570 mAh g−1 at 0.1 C over 20 cycles, high‐rate capability and 100 % Coulombic efficiency after 60 cycles for LIB. The Li+ diffusion coefficient estimated from GITT and EIS measurements reveals that the H3BO3 coated α−MnO2 electrode has superior Li‐ion kinetics (DLi+ ${{D}_{{{\rm L}{\rm i}}^{+}}}$ ∼10−10 cm2 s−1) than bare α−MnO2. Coin cells with boric acid coated α−MnO2 electrode are able to power up red and blue LEDs continuously for about 24–32 hours. The ex‐situ investigations reveal an interesting self‐assembled active electrode‐electrolyte interfacial bridging Li4B2O5 layer formation. This significant active layer allows free migration of lithium ions across interface that leads to good cyclability. In flexible supercapacitor, the boric acid coated α−MnO2 yields excellent cyclability over 500 cycles with specific capacitance of 35 F g−1 at 1 A g−1 and further 200 cycles at 30° acute angle with 21 F g−1 at 1 A g−1. The research overthrows the significance of boric acid in conversion reactions for active interfacial bridging layer in LIB and hydroxyl ion capturing agent in flexible supercapacitor. [ABSTRACT FROM AUTHOR]

When considering the mechanism of the batteries, the capacity reduction at storage (when not in use) and cycling (during use) and increase of internal resistance is because of degradation in the chemical composition inside the batteries. To optimize battery usage, a battery management system (BMS) is used to estimate possible aging effects while different load profiles are requested from the grid. This is specifically seen in a case when the vehicle is connected to the net (online through BMS). During this process, the BMS chooses the optimized load profiles based on the least aging effects on the battery pack. The major focus of this paper is to design an algorithm/model for lithium iron phosphate (LiFePO4) batteries. The model of the batteries is based on the accelerated aging test data (data from the beginning of life till the end of life). The objective is to develop an algorithm based on the actual battery trend during the whole life of the battery. By the analysis of the test data, the complete trend of the battery aging and the factors on which the aging is depending on is identified, the aging model can then be recalibrated to avoid any differences in the production process during cell manufacturing. The validation of the model was carried out at the end by utilizing different driving profiles at different C-rates and different ambient temperatures. A Linear and non-linear model-based approach is used based on statistical data. The parameterization was carried out by dividing the data into small chunks and estimating the parameters for the individual chunks. Self-adaptive characteristic map using a lookup table was also used. The nonlinear model was chosen as the best candidate among all other approaches for longer validation of 8-month data with real driving data set. [ABSTRACT FROM AUTHOR]

Precise lifetime predictions for lithium‐ion cells are crucial for efficient battery development and thus enable profitable electric vehicles and a sustainable transformation towards zero‐emission mobility. However, limitations remain due to the complex degradation of lithium‐ion cells, strongly influenced by cell design as well as operating and storage conditions. To overcome them, a machine learning framework is developed based on symbolic regression via genetic programming. This evolutionary algorithm is capable of inferring physically interpretable models from cell aging data without requiring domain knowledge. This novel approach is compared against established approaches in case studies, which represent common tasks of lifetime prediction based on cycle and calendar aging data of 104 automotive lithium‐ion pouch‐cells. On average, predictive accuracy for extrapolations over storage time and energy throughput is increased by 38% and 13%, respectively. For predictions over other stress factors, error reductions of up to 77% are achieved. Furthermore, the evolutionary generated aging models meet requirements regarding applicability, generalizability, and interpretability. This highlights the potential of evolutionary algorithms to enhance cell aging predictions as well as insights. [ABSTRACT FROM AUTHOR]

In order to meet consumer demands for electric transportation, the energy density of lithium-ion batteries (LIB) must be improved. Therefore, a trend to increase the overall size of the individual cell and to decrease the share of inactive materials is needed. The process of electrolyte filling involves the injection of electrolyte liquid into the cell, as well as the absorption of the electrolyte into the pores of the electrodes and the separator, which is known as wetting. The trend towards larger-format LIB challenges the electrolyte filling due to an increase in wetting distance for the electrolyte as well as a decrease in the void volume of the cell. The optimization of the process via numerical simulation promises to reduce costs and ensure quality during battery production. The two models developed in this study are based on a commercial computational fluid dynamics (CFD) program to study the effect of process parameters, such as pressure and temperature, on the filling process. The results were verified with neutron radiography images of the dosing process and a feasibility study for a wetting simulation is shown. For all simulations, specific recommendations are provided to set up the electrolyte filling process, based on which factors generate the greatest improvement. [ABSTRACT FROM AUTHOR]

Machine learning (ML) models are increasingly being used in metrology applications. However, for ML models to be credible in a metrology context they should be accompanied by principled uncertainty quantification. This paper addresses the challenge of uncertainty propagation through trained/fixed ML regression models. Analytical expressions for the mean and variance of the model output are obtained/presented for certain input data distributions and for a variety of ML models. Our results cover several popular ML models including linear regression, penalised linear regression, kernel ridge regression, Gaussian Processes (GPs), support vector machines (SVMs) and relevance vector machines (RVMs). We present numerical experiments in which we validate our methods and compare them with a Monte Carlo approach from a computational efficiency point of view. We also illustrate our methods in the context of a metrology application, namely modelling the state-of-health of lithium-ion cells based upon Electrical Impedance Spectroscopy (EIS) data. • Novel analytical results for uncertainty propagation through kernel-based models. • Our methods offer an alternative to Monte Carlo sampling approaches. • Benefits include greater accuracy, transparency and reproducibility. • The computational efficiency of analytical and Monte Carlo approaches is compared. • We illustrate our methods on state-of-health modelling of lithium-ion cells. [ABSTRACT FROM AUTHOR]

Abstract Precise lifetime predictions for lithium‐ion cells are crucial for efficient battery development and thus enable profitable electric vehicles and a sustainable transformation towards zero‐emission mobility. However, limitations remain due to the complex degradation of lithium‐ion cells, strongly influenced by cell design as well as operating and storage conditions. To overcome them, a machine learning framework is developed based on symbolic regression via genetic programming. This evolutionary algorithm is capable of inferring physically interpretable models from cell aging data without requiring domain knowledge. This novel approach is compared against established approaches in case studies, which represent common tasks of lifetime prediction based on cycle and calendar aging data of 104 automotive lithium‐ion pouch‐cells. On average, predictive accuracy for extrapolations over storage time and energy throughput is increased by 38% and 13%, respectively. For predictions over other stress factors, error reductions of up to 77% are achieved. Furthermore, the evolutionary generated aging models meet requirements regarding applicability, generalizability, and interpretability. This highlights the potential of evolutionary algorithms to enhance cell aging predictions as well as insights.

Nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) is one of the most promising Li-ion battery cathode materials and has attracted the interest of the automotive industry. Nevertheless, storage conditions can affect its properties and performance. In this work, both NMC811 powder and electrodes were storage-aged for one year under room conditions. The aged powder was used to prepare electrodes, and the performance of these two aged samples was compared with reference fresh NMC811 electrodes in full Li-ion coin cells using graphite as a negative electrode. The cells were subjected to electrochemical as well as ante- and postmortem characterization. The performance of the electrodes from aged NM811 was beyond expectations: the cycling performance was high, and the power capability was the highest among the samples analyzed. Materials characterization revealed modifications in the crystal structure and the surface layer of the NMC811 during the storage and electrode processing steps. Differences between aged and fresh electrodes were explained by the formation of a resistive layer at the surface of the former. However, the ageing of NMC811 powder was significantly mitigated during the electrode processing step. These novel results are of interest to cell manufacturers for the widespread implementation of NMC811 as a state-of-the-art cathode material in Li-ion batteries. [ABSTRACT FROM AUTHOR]

Battery cells are the main components of a battery system for electric vehicle batteries. Depending on the manufacturer, three different cell formats are used in the automotive sector (pouch, prismatic, and cylindrical). In the last 3 years, cylindrical cells have gained strong relevance and popularity among automotive manufacturers, mainly driven by innovative cell designs, such as the Tesla tabless design. This paper investigates 19 Li-ion cylindrical battery cells from four cell manufacturers in four formats (18650, 20700, 21700, and 4680). We aim to systematically capture the design features, such as tab design and quality parameters, such as manufacturing tolerances and generically describe cylindrical cells. We identified the basic designs and assigned example cells to them. In addition, we show a comprehensive definition of a tabless design considering the current and heat transport paths. Our findings show that the Tesla 4680 design is quasi-tabless. In addition, we found that 25% of the cathode and 30% of the anode are not notched, resulting in long electrical and thermal transport paths. Based on CT and post-mortem analyses, we show that jelly rolls can be approximated very well with the Archimedean spiral. Furthermore, we compare the gravimetric and volumetric energy density, the impedance, and the heating behavior at the surface and in the center of the jelly rolls. From the generic description, we present and discuss production processes focusing on format and design flexible manufacturing of jelly rolls.

All autonomous electrically powered devices require a continuous power supply from batteries. Increasing the discharge performance is the top priority in the Lithium-Ion (Li-Ion) battery field and pulsed discharge is proving numerous advantages. In this paper, the maximum efficiency of pulsed discharge method on a constant load while the cells are alternately switched with dead-time is thoroughly studied. Therefore, a novel Li-Ion charge/discharge and measurement device (SWD) using fast switching MOSFET was designed and fabricated. The device can alternately switch up to 8.3 kHz two Li-Ion 18650 batteries, generating continuous power to the programmable load and monitor the parameters that impact the capacity of the battery. An EIS (Electrochemical Impedance Spectroscopy) analysis is employed to evaluate the impedance and the behavior of the cells at frequencies up to 10 kHz. Experimental results reveal that a maximum discharge time is determined when two cells are switched at a frequency of 5.8 kHz. As a consequence, the total capacity of two switched batteries in a single discharge cycle is increased by 16.6%. Pulsed discharge efficiency is visible starting from 70% State of Charge (SOC) and is correlated with the rest time, reduced heat loss and inductance, respectively.

The deployment of battery-powered electric vehicles in the market has created a naturally increasing need for the safe deactivation and recycling of batteries. Various deactivating methods for lithium-ion cells include electrical discharging or deactivation with liquids. Such methods are also useful for cases where the cell tabs are not accessible. In the literature analyses, different deactivation media are used, but none include the use of calcium chloride (CaCl2) salt. As compared to other media, the major advantage of this salt is that it can capture the highly reactive and hazardous molecules of Hydrofluoric acid. To analyse the actual performance of this salt in terms of practicability and safety, this experimental research aims to compare it against regular Tap Water and Demineralized Water. This will be accomplished by performing nail penetration tests on deactivated cells and comparing their residual energy against each other. Moreover, these three different media and respective cells are analysed after deactivation, i.e., based on conductivity measurements, cell mass, flame photometry, fluoride content, computer tomography and pH value. It was found that the cells deactivated in the CaCl2 solution did not show any signs of Fluoride ions, whereas cells deactivated in TW showed the emergence of Fluoride ions in the 10th week of the insertion. However, with the addition of CaCl2 in TW, the deactivation process > 48 h for TW declines to 0.5–2 h, which could be an optimal solution for real-world situations where deactivating cells at a high pace is essential.

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Commercial coin cells with LiNi0.6Mn0.2Co0.2O2 positive electrode material were investigated using an accelerating rate calorimeter and a Tian-Calvet calorimeter. After cycling and charging to the selected states of charge (SOCs), the cells were studied under thermal abuse conditions using the heat-wait-seek (HWS) method with the heating step of 5 K and a threshold for self-heating detection of 0.02 K/min. The onset temperature and the rate of the temperature rise, i.e., the self-heating rate for thermal runaway events, were determined. The morphology of the positive electrode, negative electrode and the separator of fresh and tested cells were compared and investigated with scanning electron microscopy (SEM). Furthermore, the microstructure and the chemical compositions of the individual components were investigated by X-ray diffraction (XRD) and inductively coupled plasma with optical emission spectrometry (ICP-OES), respectively. In the Tian-Calvet calorimeter, the coin cells with the selected SOCs and the individual components (positive electrode, negative electrode and separator) were heated up with a constant heating rate of 0.1 °C/min (ramp heating mode). Simultaneously, the heat flow signals were recorded to analyze the heat generation. The combination of the three different methods—the HWS method using the ES-ARC, ramp heating mode on both cells and the individual components using the Tian-Calvet calorimeter—together with a post-mortem analysis, give us a complete picture of the processes leading to thermal runaway. [ABSTRACT FROM AUTHOR]

The contribution presents examples for electrochemical impedance spectroscopy data taken on automotive lithium‐ion battery cells. Discharge was done with the help of an external load. The measurements were done with an initial state of charge of about 97 %, at 23 °C and from 5000–0.1 Hz. Spectra were fitted with an equivalent circuit containing two RC elements and an inductance. For load currents up to 20 A and in certain regions of the used frequency range, it is possible to measure impedance spectra also under load that almost coincide with load‐free spectra. [ABSTRACT FROM AUTHOR]

Lithium-ion (Li-ion) cells are the optimal choice of energy storage for battery electric vehicles. As the Li-ion cells must operate in a temperature range of 15–45 °C for optimal performance and life, thermal control of the cells is paramount. The study uses infrared imaging to investigate the temperature dynamics of two lithium-ion pouch cells with two energy capacities, 60 Ah and 20 Ah under different operational scenarios with natural convection. Experimental analysis conducted at ambient temperatures of 27 °C, 35 °C, and 40 °C reveals the necessity of cooling for the 20 Ah cell at temperatures exceeding 40 °C and C-rates beyond 1C. Similarly, thermal management is recommended for the 60 Ah cell at ambient temperatures of 35 °C and above, as temperatures surpass the 45 °C desirable threshold during charging and discharging rates of 1C and higher. Further studies are concentrated on the 60 Ah cell due to its increased cooling demands in comparison to the 20 Ah cell. The 60 Ah cell is modelled using NTGK and ECM electrochemical models and validated against experimental data, showing a good agreement within ±10% between both models and the experimental study. Finally, numerical simulations explain the efficacy of localized cooling with forced convection of liquid and performance metrics are introduced to evaluate the cooling efficiency of design configurations. Based on performance metrics, the T-shaped cold plate design, with an inlet coolant temperature of 30 °C, achieved the highest performance index of 1.13. This design notably decreased the maximum temperature and maximum temperature difference by 41.8% and 31.8%, respectively, compared to natural convection. This improvement is observed during the discharge of 60 Ah cell at 2C in a 40 °C environment, where the cell demands substantial cooling measures. Therefore, implementing localized cooling for the cell demonstrates its effectiveness in regulating temperature increase, leading to a significant decrease in the infrastructure requirements and weight of the thermal management system. • IR thermography captures the temperature characteristics of high capacity pouch cells at different ambient temperatures. • NTGK & ECM models captured cell temperature dynamics but showed discrepancies in reproducing the temperature distribution. • Localized cooling designs significantly reduce the cell's maximum temperature and temperature nonuniformity. • T-shaped cold plate proved the most effective localized cooling design for battery thermal management and reduce weight. [ABSTRACT FROM AUTHOR]

The environment has gained significant importance in recent years, and companies involved in several technology fields are moving in the direction of eco-friendly solutions. One of the most discussed topics in the automotive field is lithium-ion battery packs for electric vehicles and their battery thermal management systems (BTMSs). This work aims to show the most used lithium-ion battery pack cooling methods and technologies with best working temperature ranges together with the best performances. Different cooling methods are presented and discussed, with a focus on the comparison between air-cooling systems and liquid-cooling systems. In this context, a BTMS for cylindrical cells is presented, where the cells are arranged in staggered lines embedded in a solid structure and cooled through forced convection within channels. The thermal behavior of this BTMS is simulated by employing a computational fluid dynamics (CFD) approach. The effect of the geometry of the BTMS on the cell temperature distribution is obtained. It is shown that the use of materials with additives for the solid structure enhances the performance of the system, giving lower temperatures to the cells. The system is tested with air-cooling and water-cooling, showing that the best performances are obtained with water-cooling in terms of cell packing density and lowest cell temperatures. [ABSTRACT FROM AUTHOR]

In order to meet consumer demands for electric transportation, the energy density of lithium-ion batteries (LIB) must be improved. Therefore, a trend to increase the overall size of the individual cell and to decrease the share of inactive materials is needed. The process of electrolyte filling involves the injection of electrolyte liquid into the cell, as well as the absorption of the electrolyte into the pores of the electrodes and the separator, which is known as wetting. The trend towards larger-format LIB challenges the electrolyte filling due to an increase in wetting distance for the electrolyte as well as a decrease in the void volume of the cell. The optimization of the process via numerical simulation promises to reduce costs and ensure quality during battery production. The two models developed in this study are based on a commercial computational fluid dynamics (CFD) program to study the effect of process parameters, such as pressure and temperature, on the filling process. The results were verified with neutron radiography images of the dosing process and a feasibility study for a wetting simulation is shown. For all simulations, specific recommendations are provided to set up the electrolyte filling process, based on which factors generate the greatest improvement.

In the coming decade, a multitude of small, carry-on payloads in the form of miniature rovers, scientific instruments and surface deployed stand-alone systems will provide many new and exciting possibilities for lunar exploration. For these system, the survival of and operation in the extreme cold of the lunar night will be the biggest challenge, as most will be purely battery driven and unable to rely on radioisotope heaters. Maximizing battery lifetime in these conditions requires a trade-off between energy density, low-temperature performance and insulation, but comparable temperature and current dependent discharge capacities of batteries and other energy storage devices are often not reported in datasheets or literature. For this reason, a selection of energy storage devices was chosen and tested to determine their low-temperature performance in a representative environment. Based on this data, the theoretical lifetime per battery weight and optimal operational temperature for varying degrees of insulation was determined. It was shown that the selection of the optimal energy storage device and operational temperature depends on the insulation, emphasizing the need for multi-disciplinary design optimization. • Night survival is the greatest challenge for small lunar surface systems. • Temperature dependent capacity for a selection of energy storage devices. • Temperature dependent capacity determines the optimum operation temperature. • Optimal operational temperatures for batteries depend on insulation. • Majority of energy storage devices survive cryogenic temperatures. [ABSTRACT FROM AUTHOR]

Besides high energy density, fast‐charging capability, and costs, safety of Li‐ion batteries is fundamentally important – even after long‐term usage or abusive conditions. In this paper, a new combination of accelerating rate calorimetry (ARC) coupled with a mass spectrometer (MS), as well as cell resistance and audio recording was applied to study commercial 18650‐type Li‐ion cells. This novel ARC‐MS setup allows following the electrochemical and thermal behavior simultaneously to the evolved gases during cell venting and thermal runaway. The tested cells were (i) unaged, (ii) aged by low temperature cycling (main mechanism: Li deposition), as well as (iii) overcharged. The aged and the overcharged cells show an early onset‐of‐self‐heating at 36 °C whereas the self‐heating started at 96 °C for the unaged cells. The rank of the time until explosion of the cells is in the order of overcharged cell

There is a large demand for models able to predict the future capacity retention and internal resistance (IR) of Lithium-ion battery cells with as little testing as possible. We provide a data-centric model accurately predicting a cell’s entire capacity and IR trajectory from one single cycle of input data. This represents a significant reduction in the amount of input data needed over previous works. Our approach characterises the capacity and IR curve through a small number of key points, which, once predicted and interpolated, describe the full curve. With this approach the remaining useful life is predicted with an 8.6% mean absolute percentage error when the input-cycle is within the first 100 cycles.

Nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) is one of the most promising Li-ion battery cathode materials and has attracted the interest of the automotive industry. Nevertheless, storage conditions can affect its properties and performance. In this work, both NMC811 powder and electrodes were storage-aged for one year under room conditions. The aged powder was used to prepare electrodes, and the performance of these two aged samples was compared with reference fresh NMC811 electrodes in full Li-ion coin cells using graphite as a negative electrode. The cells were subjected to electrochemical as well as ante- and postmortem characterization. The performance of the electrodes from aged NM811 was beyond expectations: the cycling performance was high, and the power capability was the highest among the samples analyzed. Materials characterization revealed modifications in the crystal structure and the surface layer of the NMC811 during the storage and electrode processing steps. Differences between aged and fresh electrodes were explained by the formation of a resistive layer at the surface of the former. However, the ageing of NMC811 powder was significantly mitigated during the electrode processing step. These novel results are of interest to cell manufacturers for the widespread implementation of NMC811 as a state-of-the-art cathode material in Li-ion batteries.

The performance and lifetime of lithium‐ion batteries are strongly influenced by the temperature distribution within the cells, as electrochemical reactions, transport properties, and aging effects are temperature dependent. However, thermal analysis and numerical simulation of the temperature inside the cells can only be as accurate as the underlying data on thermal transport properties. This contribution presents a numerical and analytical model for predicting the thermal conductivity of porous electrodes as a function of microstructure parameters. Both models account for the morphology of the electrode structures and bulk material properties of the constitutive components. Structural parameters considered in both models alike are the porosity of the electrode coatings, particle size distribution, particle shape, particle contact areas, and binder carbon black distribution. The numerical model is based on the well‐established finite volume discretization, allowing for detailed 3D analyses. The analytical model is an extension of the well‐known Zehner–Bauer–Schluender approach for solid packing and provides fast predictions of the effects of parameter variations. The results of both models have been successfully verified against each other and compared to literature data and experimental measurements. [ABSTRACT FROM AUTHOR]

Lithium‐ion batteries are an essential technology with extensive use in numerous electric applications. A complete understanding of the simultaneous effects of charging factors such as state‐of‐charge (SOC), C‐rate, and rest period is essential to manage lithium‐ion batteries. This study aims to determine the significant charging factors influencing the battery dynamics to provide detailed insights into the relationship between the selected charging factors and the battery dynamics. The cathodic charge transfer resistance and the ohmic resistance are substantially affected by the C‐rate, whereas the SOC dominantly contributes to only the Rt;c. The effect of the SOC on the ohmic resistance and the cathodic charge transfer resistance depends on the C‐rate. The cathode charge transfer resistance is the most sensitive dynamic parameter to charging factors. The solid electrolyte interphase formation charge transfer resistance is the most stable battery dynamic parameter. The sensitivity analysis expressly shows the part of the lithium‐ion battery that needs to be improved to provide better performance under the implemented charging protocols. Comprehensive analysis of the simultaneous effects of charging factors on battery dynamics can also be used in a battery management system to measure changes in battery dynamics that will support lithium‐ion battery controls. [ABSTRACT FROM AUTHOR]

Herein, individual cell currents in parallel connected battery strings are measured using micro‐Hall‐effect sensors. Cells are routinely connected in electrical series and parallel to meet the power and energy requirements of automotive and consumer electronics applications. Cells connected in series have been extensively studied; however, cells in parallel are often assumed to be a "black box" in battery management systems. Poor pack design can result in positive feedback between current and temperature differentials along the parallel string, driving greater levels of heterogeneous behavior and uneven degradation. Herein, a noninvasive multisensor array board using Hall‐effect sensors is used to individually record the current passing through eight parallel connected cells in two different electrical configurations, showing highly heterogeneous current distribution. Characteristic "waves" of current and temperature are found to propagate along the parallel battery string and cell rebalancing is found to occur over hundreds of seconds with individual cell currents of up to 1 C rate. [ABSTRACT FROM AUTHOR]

The significance of the heat of mixing is poorly understood in the context of lithium-ion cells. In this work, we propose a local thermo-electrochemical pseudo-two-dimensional model accounting for the heat of mixing in the electrodes to analyse the spatial and temporal variations of different heat generation components. The proposed model analyses the relative contribution of various heat generation sources under different operating conditions for a lithium-ion cell. In our simulations, the heat of mixing amounted to 9%–16% for 1C–5C discharge current and 38%–48% for 2C–5C charge current of the total heat. We show that the heat of mixing can be equally significant over a wide range of operating current conditions. Several sources, including the ohmic heat, irreversible heat of reaction, and the heat of mixing, increase with current, and the net interplay between these sources determines which component becomes dominant at high currents. Moreover, the effects of the diffusion time scale of electrodes and current on the heat of mixing are analysed. We demonstrate that the heat of mixing can significantly contribute to the cell's total heat generation under poor diffusion dynamics or high current conditions. • Volume-averaged spatial definition for heat of mixing formulated. • Constituent-wise heat generation analysis performed using thermo-electrochemical model. • Heat of mixing contribution is comparatively greater during charging. • Electrode diffusion time scale strongly affects the heat of mixing component. [ABSTRACT FROM AUTHOR]

Herein, the effects of charge rate in coin cells containing NMC532/1506‐T graphite are investigated. The cells are cycled at room temperature using charge rates of 1‐, 2‐, 4‐, and 8‐C and discharged at the 1‐C rate for 50 cycles. The amounts of lithium and LiF are found to be highly correlated with charge time. Three decomposition products are identified in the organic electrolyte. The proposed, empirical formulae for these compounds are C14H33O15P3, C16H37O15P3, and C11H22O7PF; all are most likely organophosphates formed by the reaction of organic electrolyte decomposition products with LiPF6 or P(=O)F3. The relative concentrations of these organics do not display sensitivity to charge rate. These results imply that a new performance fade mechanism is not introduced by electrolyte decomposition. [ABSTRACT FROM AUTHOR]