This article conducts in-depth research on the thermal runaway behavior of overcharged lithium iron phosphate batteries using simulation methods. By establishing a three-dimensional electrochemical thermal coupling model, the evolution laws of various components in the thermal runaway process are studied and optimized through multi parameter analysis. Research has found that irreversible thermal runaway occurs in lithium iron phosphate batteries at 400 K. The thermal runaway mainly begins with the decomposition of the SEI film, and is most severe at the positive and negative electrodes. Reducing the charging rate, lowering the ambient temperature, and enhancing convective heat transfer can delay thermal runaway. Orthogonal experimental optimization of battery module structure can effectively reduce the risk of thermal runaway. The optimal structure has a thermal runaway time of 13 488 s and a battery capacity of 25.786 Ah/m². The relevant research provides theoretical support for preventing and suppressing battery overcharging and thermal runaway.

The capacity degradation of lithium iron phosphate (LFP) batteries is influenced by working conditions and charge-discharge rates. In new energy systems, LFP batteries may remain idle for extended periods due to lower utilization of renewable energy. To investigate the aging mechanism of LFP batteries as energy storage devices under idle conditions, this study focused on a 20 Ah LFP battery stored at 45 ℃ to simulate idle conditions. Incremental capacity analysis (ICA) was used to study the aging mechanism at different capacity degradation stages. The results indicate that under high-temperature idle conditions, the performance degradation of the battery is mainly related to the loss of positive electrode active materials. Based on this, a relationship between the number of days stored at high temperatures and capacity degradation was established. The research findings provide a basis for predicting the lifespan and economic evaluation of energy storage devices in new energy systems.

This work conducts the charge/discharge cycling tests of graphite||LiFePO₄ pouch batteries at temperatures of 25, 45, 60, 70, and 80 °C to calculate the battery cycling capacity degradation rate. Arrhenius formula is used to calculate the activation energy of LiFePO₄ batteries at different temperatures. Differential capacity vs. voltage (dQ/dV) curves is used for capacity loss analysis. Combined with characterization data such as SEM, ICP, XRD, etc., the results show that when the temperature exceeds 60 °C for cycling test, the growth of the SEI layer at graphite electrode interface accelerates, the microstructure of positive and negative electrode active materials ruptures, and the dissolution/precipitation of transition metal ions aggravates, leading to deterioration of battery performance and accelerated capacity degradation.

Lithium ion batteries are prone to capacity degradation during long-term operation, with varying degrees of degradation and different underlying mechanisms under different operating conditions. Through the study of cycle failure of lithium ion batteries under different conditions, the mechanisms are investigated in order to provide insights for optimizing battery design to enhance the safety and durability of lithium ion battery use. This article summarizes the situation of cycle capacity degradation and failure mechanisms under different temperatures, pressures, charge-discharge rates, overcharging and overdischarging, as well as State of Charge (SOC) cycling ranges. Relevant strategies are proposed to improve the performance of lithium ion batteries and ensure their safe and stable operation.

LiFePO₄ batteries are widely used in new energy vehicles and new energy storage fields due to their high safety and low cost, but their applications are limited by the greatly reduced performance in cold winters, high altitude areas, aviation base stations, and other low-temperature environments. This review focused on the low-temperature performance degradation mechanism of LiFePO₄ batteries, and summarized the recent domestic and international research developments of LiFePO₄ batteries from three aspects: electrode materials modification, electrolyte optimization, and low-temperature heating technology. Finally, a new insight was put forward for improving the low-temperature performance of LiFePO₄ batteries and the future development direction was indicated.

Lifespan and safety are the core challenges for the large-scale application of lithium-ion batteries, and lithium plating is an important cause of safety issues such as accelerated battery life decay and thermal runaway. Therefore, lithium plating detection has always been a research focus in the field of batteries. Electrochemical impedance spectroscopy(EIS) is a non-destructive in-situ electrochemical analysis method that can reveal the electrode kinetics of different time scales inside the battery, including charge transfer reactions, interface evolution, and mass transfer processes that are affected by lithium plating. Therefore, it can be used as a lithium plating detection method. The lithium plating detection methods were summarized based on EIS in recent years, including: static EIS method, dynamic EIS method, and current interruption method. The principles, advantages, and disadvantages of the three methods were reviewed, and the application prospects of the above methods were prospected.

Excessive current density and high roughness of electrode surface during charging and discharging of lithium ion batteries will lead to uneven lithium deposition. The growth of lithium dendrites will puncture the SEI film ( Solid Electrolyte Interface film ) formed by the reaction of the anode material with the electrolyte. Lead to direct contact between lithium dendrites and electrolyte. Part of the dendritic fracture generates lithium metal particles. Part of the electrolyte and the continuous side reaction to produce lithium compounds, that is, dead lithium. It has a great influence on the safety and performance of lithium batteries. At present, the problems such as lithium dendrites and dead lithium in the SEI film are still not effectively solved. In this paper, the formation mechanism of SEI film, lithium dendrites and dead lithium in lithium batteries and some suppression methods proposed at this stage are reviewed. The key problems and future development directions are discussed. It provides a certain theoretical basis and practical guidance for the field of battery research.

Establishing models to evaluate the performance and lifespan of lithium ion batteries under various operating conditions could significantly shorten the design and validation cycle and enable highly reliable, full-lifecycle operational maintenance of batteries. Recent studies have highlighted that preloading forces applied during battery operation have a notable impact on its performance and lifespan. Consequently, integrating electrochemical, thermal, and mechanical fields into coupled modeling frameworks has become a research focal point. This review examines the current state of electrochemical-thermal-mechanical coupling models, detailing methodologies for electrochemical-thermal, electrochemical-thermal-mechanical performance models, as well as aging models. The aim is to provide a comprehensive overview of recent advancements while identifying critical technical challenges that need to be addressed for future model development.

All-solid-state lithium batteries (ASSLBs) are considered to be the preferred choice for next-generation energy storage batteries due to their safety and potential high energy density. Solid-state electrolytes, a key component of ASSLBs, have received much attention in recent years due to their nonflammability and good adaptability to lithium metal anodes. Among the current solid electrolytes, garnet-type oxide composite electrolytes show great potential for application. Due to its combination of the advantages of single-phase inorganic oxide solid electrolytes and polymer solid electrolytes, it not only increases ionic conductivity but also effectively reduces interface resistance, which can effectively improve the safety and energy density of batteries. In this paper, the component composition, composite mode, structure, lithium ion transport mechanism of garnet-type oxide composite solid-state electrolyte and interfacial issues in composite electrolytes were elaborated, the existing problems in the composite solid-state electrolyte were pointed out, and their applications prospects were forecasted.

Some problems in the high nickel/silicon-carbon system of pouch batteries such as gas production at high temperatures and repeated rupture-growth of the solid-electrolyte interphase (SEI), which leads to poor cell cycling and storage performance. In this study, a graphite-based anode blended with 20% silicon-carbon and a ternary NCM811 cathode were employed to investigate the film-forming effect and mechanism of TVSi (Tetravinylsilane), an electrolyte additive, on the surfaces of both the anode and cathode. Experimental results demonstrate that TVSi can preferentially form a dense and stable interfacial film on the surfaces of both electrodes, which significantly enhances the battery's cycle and storage performance. Compared with the general electrolyte, the cell containing TVSi exhibits an increased cycle life by 112 times at 25 ℃, 407 times at 45 ℃, and an improved capacity recovery rate by 3% after 30 days of storage at 60 ℃. SEM and ICP were utilized to characterize the mechanism of TVSi action on the surfaces of both electrodes. The utilization of TVSi additives can address the current calendar life issues in high-nickel silicon-carbon battery systems, accelerating the industrialization of high-energy-density battery products.

At present, the statues of satellite electrical power supply system is to use Agilent 34980A ground power supply and ground power supply distributor for integration. This paper puts forward an intelligent electrical power supply and distribution test equipment design scheme for the integrated and intelligent test requirements for ground power supply test system. It is composed of channel relay module, command sending module, telemetry state acquisition module and staues display module. It has the characteristics of high reliability, strong versatility and good maintenance. It realizes the modularization and miniaturization of electrical power supply and distribution test equipment, as well as remote monitoring, intelligent monitoring and other functions. At present, it has been applied in the satellite platform test system which has played a strong role in supporting the satellite ground automatic test system.

NaTi₂(PO₄)₃ has a NASICON stable structure, an ultra-large three-dimensional open architecture, significant energy density and stability, and has become a hotly researched anode material for aqueous sodium-ion batteries (ASIBs). However, NaTi₂(PO₄)₃ has many problems in ASIBs, such as poor conductivity, side effects with water, and material dissolution. In order to overcome the above problems, nano-materialization, carbon covering, and element doping was usually used to solve the above problems, so as to optimize the performance of the material and make it have high-conductivity and long-cycle performance. This article reviewed the structure, modification method and electrochemical performance of NaTi₂(PO₄)₃ materials to deepen the understanding of the improvement of the NaTi₂(PO₄)₃ structure and the performance optimization technical path and method.

With the rapid development of electric vehicles and portable electronic devices, there is an increasing demand for higher energy density and fast-charging capabilities in lithium-ion batteries. As a result, high-capacity anode materials have garnered significant attention. Common high-capacity anode materials include silicon, phosphorus, and tin, each of which offers advantages for fast charging but shares a common drawback: a high expansion rate during lithiation/delithiation, leading to electrode fracture, pulverization, and detachment during cycling. Although binders constitute only a small portion of the electrode, they play a crucial role in maintaining the structural integrity of the electrode. The current status and challenges of high-capacity anode materials in lithium-ion batteries were introduced, the mechanism by which binders interact with anode materials was explained, and strategies for improving binders in terms of enhancing bonding strength, improving mechanical properties, and enhancing functionality were reviewed. Finally, it discussed the future prospects of binder development.

Energy storage power stations are the key to the use of renewable energy, and their safe operation is essential to achieve the transformation of the energy structure. However, energy storage power stations have safety risks such as fire, gas generation, electric shock and waste battery recycling, especially thermal runaway and improper operation can cause fire accidents. In recent years, there have been frequent safety accidents in energy storage power stations caused by lithium-ion batteries, which have affected the further expansion of the energy storage power station market. This paper summarized the progress of lithium-ion battery safety protection in early warning technology and fire suppression methods, and put forward safety countermeasures and suggestions for energy storage power stations.

Electrolyte is a key factor to ensure the excellent performance of lithium ion batteries, such as long-term cycle stability and high capacity retention. However, the electrolyte is affected by a variety of factors, such as impurity residues, temperature fluctuations, voltage window mismatch, etc., which can lead to Li-ion battery failure and even fire and explosion, and the specific forms of failure are gas production, thermal runaway, aging, liquid leakage, and capacity degradation, etc. These failures seriously affect the performance, stability and safety of lithium ion battery. This study comprehensively summarizes the advanced testing and characterisation techniques adopted for electrolyte failure, and selects a number of typical cases for in-depth analysis, and analyses the causes and phenomena of failure. On this basis, the importance of developing and utilizing in-situ and in-line testing and analysis techniques is emphasized in the paper. Finally, the research prospect of electrolyte failure analysis is envisioned, and the development direction of multilevel failure analysis, simulation and early warning technology is proposed, with a view to providing reference for further research on failure analysis technology and improving battery performance.

基于全球价值链理论与资源依赖理论,系统解构中国在镍钴锂供应链中的“双端依赖”困境——对海外资源的高度进口依赖与对加工环节的过度集中依赖,剖析地缘政治冲突、技术标准博弈、市场周期波动等多维风险的作用机制。研究发现,中国企业通过“资源绑定+技术输出+本地化生产”的三维策略,正在重构全球供应链格局,但仍需突破资源国政策壁垒与高端材料专利封锁。

Dramatic volume changes, particle fragmentation and the continuous damage and reconstruction of the solid electrolyte interface (SEI) film for Si anode seriously hinder its wide use in lithium ion batteries. Herein, a novel electro-active covalent organic framework (COF) material was used to decorate nano Si surface and a high-performance silicon anode material was obtained. On the one hand, the decorated COF layer can effectively buffer the volume expansion of silicon particles. On the other hand, the COF layer helps to tailor the composition of SEI by inducing the generation of more LiF and LiN species. Therefore, the Si particles are well protected and the cycling stability of the Si anode is significantly enhanced. The unique COF decoration broadens the concepts for interfacial engineering for electrode materials in lithium ion batteries.

As the global pursuit of carbon neutrality intensifies, the development prospects for lithium ion battery energy storage technology are promising. However, safety issues remain a significant obstacle to the advancement of lithium ion battery energy storage stations. This paper provides an in-depth analysis of the thermal runaway dynamic characteristics and influencing factors of lithium iron phosphate batteries under different charging rates. By comprehensively analyzing the synergistic characteristics of voltage, temperature, and gas release, the risk stages and safety thresholds during the battery overcharging process are revealed. Utilizing cloud model calculations, a multivariable early warning system based on voltage, temperature, and gas generation is established. This system integrates sensor data through basic probability assignment (BPA) functions and mass functions, enabling a comprehensive assessment of the overcharge risk level of lithium iron phosphate batteries. This provides practical technical support for the safety monitoring and risk management of lithium ion batteries.

The electrochemical energy storage technology represented by lithium ion batteries is the largest and most widely used energy storage technology in the field of energy storage. With the rapid growth of the installed scale of lithium ion battery energy storage system, the safety problem of energy storage systems has become a key bottleneck restricting its large-scale promotion, so it is necessary to research and develop the safety prevention and control technology of energy storage system. The safety prevention and control of lithium ion battery energy storage system runs through battery manufacturing, power station design and construction, power station operation and maintenance, and fire extinguishing. This study comprehensively analyzed and reviewed the recent research progress on lithium battery energy storage safety prevention and control technology, as well as the intrinsic safety of lithium ion batteries, thermal runaway detection and early warning, thermal runaway propagation suppression, thermal management of energy storage system, multi-level security prevention and control of energy storage system.

In the thermal management technology of lithium ion battery packs for electric vehicles, liquid cooling is recognized as the mainstream technique due to its high performance and efficiency. It can be further categorized into indirect liquid cooling and direct liquid cooling. This paper reviews studies on battery pack temperature control utilizing different liquid cooling methods based on battery shape, such as liquid cooling plate (including designs of flow channels and layout), immersion liquid cooling, and composite liquid cooling combined with phase change materials. Temperature control data under different liquid cooling methods are presented, compared, and analyzed. Typically, for prismatic or pouch batteries, liquid cooling plates can be flexibly arranged at the bottom of the cell module, between large surfaces of the batteries, or on the small sides of the batteries. Liquid cooling plates often feature structures such as serpentine channels, biomimetic channels, and fin-shaped structures. For cylindrical batteries, the channels in the liquid cooling plates are often designed in wavy, jacketed, or spiral.

The safety of lithium ion battery energy storage power stations is an important factor restricting energy reform and the realization of the long-term goal of "dual carbon". Once a safety accident occurs in the energy storage power station, the property losses and casualties will be very serious. In view of the thermal safety problem of lithium energy storage battery, this paper comprehensively summarizes the causes of lithium battery thermal runaway, and analyzes the characteristic parameters of lithium battery thermal runaway on this basis. By monitoring the temperature, internal resistance, voltage and characteristic gas of the lithium battery, it can provide the basis for the early warning of the lithium battery thermal runaway. However, the monitoring of these parameters depends on the accuracy and sensitivity of the sensor elements, and higher precision and more reliable sensors are needed. The safety of lithium batteries is fundamentally improved by improving the safety of positive and negative materials of lithium batteries, using additives, non-flammable electrolyte solvents, developing innovative electrolysis systems, and improving the thermal stability and safety of the diaphragm.

This paper investigated an efficient and non-destructive stripping technology for decommissioned lithium iron phosphate (LiFePO₄) batteries, with the aim of achieving an effective and non-destructive separation between the cathode material and the current collector, whilst maintaining the integrity of the materials. It has been found that pre-treatment of failed LiFePO₄ electrode sheets with dimethyl carbonate (DMC) as a solvent can achieve non-destructive recovery of failed LiFePO₄ powder. The use of DMC as a solvent for the pre-treatment of degraded LiFePO₄ cathode materials can maximize the preservation of their original state. This ensures that the electrochemical performance and physicochemical properties of the recovered LiFePO₄ are not compromised, thereby preventing the pre-treatment process from adversely affecting the quality of subsequent repair and regeneration processes. Moreover, this pretreatment method can also effectively remove lithium fluoride from the surface of the degraded LiFePO₄, thereby enhancing the uniformity of material composition and properties, ultimately yielding high-quality degraded LiFePO₄ powder.

Solid oxide fuel cell (SOFC ) has attracted extensive attention from researchers due to its high efficiency and environmental protection characteristics. Perovskite-based materials have excellent conductivity and catalytic activity as potential carriers for SOFC anodes. In this paper, the recent progress on the modification of perovskite oxide anode materials for SOFC was reviewed. The modification mechanisms of metal doping dissolution, surface modification, A/B site defects and their effects on the electrochemical performance of cells such as maximum power density, conductivity and durability were compared. The optimization direction of anode materials was prospected.

The electrode materials constrain the technological advancement of thermal batteries used in advanced weaponry. High-quality electrode materials need to possess high thermal stability, high electronic conductivity, low solubility in molten salt electrolytes, fast discharge kinetics, and low cost. This paper discussed the performance deficiencies of current thermal battery electrode materials from the perspectives of nanoscale structural design, surface modification, and element doping, systematically reviewing the current development status of electrode materials to provide valuable reference directions for the optimization and application development of high specific energy thermal battery electrode materials.

The electrochemical impedance spectroscopy (EIS) of Li-ion battery (LIB) contains abundant internal information of the LIB, which has greater application potential than the commonly used battery parameters such as current, voltage and temperature. Therefore, a method based on EIS to estimate the LIB's state of charge (SOC) was proposed in this paper. Firstly, the EIS data of ternary LIBs under different SOC were obtained through experiments, using a more practical impedance measuring board. Secondly, based on the existing LIB’s equivalent circuit models (ECMs), a new ECM with higher fitting accuracy was proposed. Finally, the parameters of the improved ECM were identified by using the EIS data of the LIBs and the parameter highly related to the SOC was found. By using this parameter, the accurate estimation of the state of charge was successfully realized.

In this paper, Tin doped iron anode materials for iron nickel secondary batteries were prepared by the sol gel method using FeC₂O₄·2H₂O as the iron source, SnO₂ as the tin source, citric acid as the carbon source and reducing agent. The influence of different citric acid contents on anode materials was explored, and the effects of two sulfide additives, NiS and FeS, on the performance of the synthesized anode were investigated. XRD, SEM, CV and EIS were used to characterize the structure, morphology, and electrochemical properties of the synthesized materials. The results show that high temperature sintering of citric acid into carbon provides the main carbon source for the negative electrode material, and when the ratio of metal ions to citric acid was 1∶1.5, the iron specific capacity prepared reaches 523 mAh/g. The addition of appropriate proportions of sulfides can enhance the specific capacity of anode materials. Among them, the anode material with 5% FeS added has a discharge specific capacity of 582 mAh/g, the highest discharge specific capacity, and good cycling stability.

Lithium cobalt oxide cathode material with layered phase structure has high volume energy density, which is widely used in lithium-ion batteries. However, layered lithium cobalt oxide is prone to microstructure deformation in the repeated charging and discharging, which leads to battery degradation and safety risks. Density functional theory was employed to investigate the structure change, lattice atom dissolution, and interfacial reaction mechanism of lithium cobalt oxide cathode under different charging voltages. When the charging voltage exceeds 4 V, the lithium cobalt oxide layer slips, the lattice atoms are rearranged, and the electron orbitals are changed, resulting in a significant relaxation of the bulk structure. The interfacial interaction between lithium cobalt oxide and electrolyte molecules (EC, DMC and LiPF₆) under different charging voltages were investigated. Under 4 V and higher voltages, the electrolyte molecules decompose, and EC and DMC react with the positive surface of lithium cobalt oxide, leading to oxygen dissolution of lithium cobalt oxide crystal. The decomposition of LiPF₆ and the surface and interface of lithium cobalt fluoride can damage the bulk structure of lithium intercalation at the surface and interface. The research results indicate the failure mechanism of lithium cobalt oxide cathode materials, providing basic data and references for the research on transition metal oxide cathode materials.

The demand for the driving range of electric vehicles promotes the improvement of the energy density of lithium-ion batteries. In this paper, high nickel (NCM911) was used as the positive electrode material, and Li-SiO_x and graphite were mixed as the negative electrode material. By optimizing the positive electrode surface density and the mixing ratio of the negative electrode Li-SiO_x and graphite, the high specific energy 21700 cylindrical lithium-ion batteries were successfully prepared. The specific energy reaches ~300 Wh/kg. The battery has good electrochemical performance, satisfying the constant current charging capacity ratio of more than 70% at 5 C charging rate, and improving the low temperature performance of the battery, the first coulomb efficiency is more than 86%, and the capacity retention rate of 1 000 cycles at 1 C rate is more than 80%. By optimizing the positive electrode surface density and Li-SiO_x mixing ratio, the relationship between high specific energy, rate and cycle performance was balanced, which provides a valuable reference for the development of high specific energy lithium-ion batteries.

To address the failure issue of lithium iron phosphate batteries caused by overcharging, this study compares the overcharging curve characteristics of various batches of lithium iron phosphate batteries. Additionally, by utilizing multiple characterization analysis methods, we investigate the failure phenomenon and mechanism of battery caused by overcharging. When the batch B battery was overcharged to 1 070 s, the battery short circuited and caused thermal runaway. The disassembly photos of the R corner of the anode revealed a grayish-black morphology, indicating a severe Fe precipitation reaction. The Fe element originates from rod-shaped impurities containing 33.22% Fe in the cathode. The precipitated Fe metal uniformly fills the base film layer of the separator, causing short circuit during the overcharge of the battery. Short-circuit discharge of the battery can cause Li⁺ to re-intercalate into the positive electrode, resulting in an initial discharge capacity of only 92.21 mAh/g for the cathode. This finding offers a theoretical basis for the design and overcharge tolerance performance improvement of 300 Ah high-capacity and high-safety lithium iron phosphate batteries.

High nickel/high silicon soft pack batteries have the problems of poor calendar life and high temperature storage gas production. The electrochemical stability analysis between the positive and negative electrodes and the electrolyte in full charge state shows that the main source of gas production is the oxidation decomposition of the solvent on the positive electrode side. The research shows that: when 0.5%TPP is added to the electrolyte, the gas production rate of the battery is rapidly reduced from 132% to 6% after being stored at 60 ℃ for 7 days, which is attributed to the fact that TPP additives can build a CEI film with high thermal stability at the positive electrode interface and inhibit solvent oxidation. At the same time, TPP, because it contains 3 unsaturated alkynyl functional groups, co-participates in film formation with FEC on the silicon negative electrode surface, enhancing the toughness of SEI film. The interface impedance of the negative electrode is reduced from 9.45 Ω to 1.19 Ω by 87%.In addition, TPP additive has a significant effect on the high temperature cycle of silicon-based batteries, and the capacity retention rate of 1 000 cycles of 1 C at 45 ℃ increased from 82.3% to 86.9%. Therefore, because of its excellent high-temperature film forming stability, TPP is expected to solve the problem of insufficient calendar life faced by the commercialization of high nickel/high silicon systems, and accelerate the rapid landing of the next generation of high specific energy silicon-based battery products.

Activation is one of the essential processes for proton exchange membrane fuel cells (PEMFCs) to be put into use and achieve optimal performance. Among various activation techniques, online activation stands as a critical step in enhancing the performance of PEMFC stacks. The activation mechanisms of PEMFCs from the perspectives of membrane wetting, transport channel establishment, and microelectrode reconstruction were elucidated. The research findings of domestic and international scholars on online activation processes for PEMFCs were summarized and analyzed, focusing on four main aspects: voltage&current, operational parameters, reactants, and comprehensive control. With the continuous improvement of online activation methods, the output performance of PEMFC stacks were enhanced, and the activation duration was shortened, thereby realizing rapid activation. A comparative analysis of the respective characteristics, advantages, and disadvantages of the four online activation processes was conducted, along with recommendations. It is concluded that the online comprehensive control activation process exhibits advantages such as better activation effects and shorter time, making it one of the promising directions for future online activation research.

In recent years, Si/C anodes have achieved considerable commercial success. However, there is further potential for enhancement of their low-temperature performance. In this work, we proposed a novel additive, ethyl 1-ethyl-3-methylimidazole sulfate (EMIM), which can significantly improve the low-temperature performance of Si/C anode. The study results show that the coin cell containing 3% EMIM exhibits a capacity retention of 78.9% after 100 cycles at room-temperature and 76.05% after 150 cycles at low-temperature (-20 ℃). In addition, characterizations such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and scanning electron microscopy (SEM) all indicate that a SEI formed using an electrolyte containing EMIM exhibits lower interfacial impedance and excellent mechanical properties. These results provide a simple way to improve the low-temperature performance of Si/C anodes and validate a method for commercial lithium-ion batteries that can operate in cold environments.

Silicon anodes has attracted widespread attention due to its extremely high specific capacity. Only minor amounts of Si added in the anode can significantly improve batteries specific capacity, but the huge volume expansion will limit its stability. In full-cells, the utilization rate of anode can be adjusted by changing the N/P ratio, and the lithium insertion depth of the silicon anode can be controlled, thereby changing its energy density and cycling performance. In this work,we produced pouch Li-ion batteries with three N/P ratios of 1.09, 1.06, and 1.03. As the N/P ratio decreased, the battery quality decreased, the total silicon content decreased, the energy density and initial coulombic efficiency of the battery increased. However, during the cycling process, the lithium insertion and extraction depth of the silicon increased, and the volume expansion intensified, ultimately leading to a shortened cycling life. Therefore, introducing silicon into the LFP system and designing an appropriate N/P ratio is expected to improve the energy density of LFP system to 200 Wh/kg at the cost of cycle life.

Traditional thermal battery uses metal sulfide as cathode material. With the increasing demand for high energy density of battery, the need for high-voltage new cathode has become more and more urgent, and the application of high voltage cathode in thermal battery is being explored at home and abroad. In this paper, the research progress of halide and oxide cathode was reviewed, the latest experimental results were reported, and the problems and optimization directions were summarized.

This paper investigated the degradation mechanism of a 280 Ah lithium iron phosphate/graphite battery under high-temperature charge/discharge cycling conditions at 45 ℃. The differential voltage curve (dQ/dV) during cycling was analyzed to identify the sources of capacity loss. By disassembling batteries with 100%, 90%, and 60% state-of-health (SOH) lifetimes, the changes in the morphology, structure, and specific capacity of both the positive and negative electrodes were systematically examined. The comprehensive analysis reveals that the reduction in battery capacity is primarily due to the damage to the graphite structure and the loss of active lithium. The decomposition, reformation, and thickening of the solid electrolyte interphase (SEI) layer are the main mechanisms responsible for the depletion of active lithium.

Pitch coating modification serves as an effective means to enhance the electrochemical performance of graphite anode. The pyrolysis characteristics of pitch and the carbonized structure have a direct impact on the electrochemical properties of anode materials. The electrochemical performance of modified graphite is mainly concerned. However, the pyrolysis characteristics, rheological properties, wettability and carbonization structure of pitch are analyzed, which explains its mechanism in the coating process. The results show that the carbonization process of pitch can be divided into three stages. The low-temperature weight loss stage primarily involves the volatilization of low molecular weight gases, the medium-temperature rapid weight loss stage marks the intense pyrolysis of molecules, and the high-temperature weight loss stage is mainly the polycondensation of macromoleculars. An amorphous carbon material with short-range order, long-range disorder and certain microcrystalline structure is formed, which improves the electrochemical behavior of natural graphite in batteries.

This study conducted a side-heating experiment on a 50 Ah lithium iron phosphate lithium ion battery, analyzing characteristics such as surface temperature changes, flame zone temperature and temperature gradient distribution, mass loss, heat generation, and gas heat release. The study also summarizes the energy flow transmission mechanisms between the battery and the emitted gases during the jet combustion process. The results show that the battery vents at 296 s, with the maximum temperature rise rate reaching 22.7 ℃/s, at 385 s. The peak temperature 693.1 ℃ occurs at 739 s. The peak temperature in the flame zone decreases with increasing height, with the maximum temperature of 865.4 ℃ observed at 10 cm and the maximum temperature gradient of 61.33 ℃/cm at 5 cm. During the entire thermal runaway process, the battery loses 235 g of mass, with the maximum mass loss rate of 4.22 g/s, at 359 s. The total heat generation from the battery and the emitted gases are 2.59 MJ and 4.14 MJ, respectively, with peak heat release rates of 17.3 kW and 49.55 kW at 384 s. There is a critical point 411s in the thermal runaway process, before which the primary source of heat generation is the exothermic reactions within the battery, and after which it is the combustion of the emitted gases. This study aims to provide theoretical references for battery safety design and passive protection strategies.

This article used three different particle sizes of LiFePO₄ (LFP) materials and graphite negative electrodes to assemble laminated soft pack batteries. The conductivity, particle size, and morphology of the materials were analyzed by powder resistivity, laser particle size analyzer, and SEM, and the influence of different particle sizes on the electrochemical performance of the battery was studied. The results show that positive electrode materials with different particle sizes have little effect on material compaction density and battery room temperature performance. However, LFP-W positive electrode materials with smaller particle sizes (initial size <100 nm) had significant advantages at high rates, with a capacity retention rate of up to 74.37% at 3 C. This is due to the smaller particle size shortening the migration path of Li⁺ and improving its migration rate; At the same time, the discharge capacity retention rate of LFP-W battery at low temperature -20 ℃ is 64.36%, demonstrating excellent low-temperature discharge ability. Therefore, LFP positive electrode materials with smaller particle size have better rate performance and low-temperature performance.

The positive electrode, negative electrode and the separator are stacked into a jelly roll by stacking process. The high pressure real density of the positive electrode causes the irrecoverable bending deformation of the positive electrode with the direction of the roll. Due to the requirements of high energy density and high power, the current collector is getting thinner and thinner, and the area of the cutting tab is getting larger and larger, and the mainstream 6μm Cu current collector is extremely easy to fold in the process, resulting in short circuit. In this paper, the bending degree of the positive electrode is improved by using the anti-correction device of the positive electrode to achieve the purpose of flat surface of the positive electrode. The negative electrode adopts the anti-bending mechanism of the tab to press the special shape pattern on the surface of the tab to increase the strength of the foil and prevent the tab from bending and sagging. The above two measurements can effectively improve the electrode status and reduce the occurrence of defects in the production process.