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.

The development status, application achievements, and directions of hydrogen fuel cell technology in China, were reviewed and analyzed, which covered aspects such as the construction of standard systems, demonstration application policies, diversification of application scenarios, and cutting-edge technologies. The results show that China has established a standard system covering hydrogen energy, complete vehicles, key components and materials. Relying on the five major demonstration city clusters, it has successfully promoted the large-scale application of the fuel cell technology. Fuel cell vehicles have achieved a significant leap in key performance indicators such as driving range and power density. The localization rate of key components such as fuel cell stacks and air compressors has exceeded 90%, and the localization process of key materials such as proton exchange membranes, carbon paper, and catalysts is accelerating. Meanwhile, application scenarios are expanding into areas such as marine, rail transportation, power generation, etc, which demonstrates technical feasibility and emission reduction benefits.In the future, key development directions for hydrogen fuel cell technology will include advanced hydrogen storage methods-such as liquified hydrogen, hydrogen swapping, and solid-state storage-alongside the advancement of low-cost, high-power, and highly durable fuel cells, as well as their deep integration with artificial intelligence; the maturity of new refueling modes such as liquified hydrogen and hydrogen swapping, the breakthrough of low-cost and long-lifetime technology routes, the in-depth integration of artificial intelligence with fuel cell technology, and the application and promotion of fuel cell passenger vehicles will become the key directions, which will drive China's hydrogen fuel cell technology towards larger-scale development.

The complex high-energy particles and electromagnetic radiation in the space environment require solar cells to not only possess a high power-to-weight ratio but also exhibit excellent radiation resistance and reliability. Perovskite solar cells (PSCs), with their low cost, superior radiation tolerance, and lightweight properties, show great potential for space applications. Researchers have conducted extensive exploratory studies and empirical work on the space application of PSCs. The latest research progress in this field and the main technical bottlenecks were reviewed, aiming to provide valuable references for the development of related technologies. The experimental research outcomes of PSCs under complex conditions such as particle irradiation high vacuum, and strong light exposure were summarized, existing space measurement cases were analyzed, the challenges faced by PSCs in space applications were outlined, and potential solutions and future research directions were proposed.

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。

The hybrid power system composed of hydrogen fuel cells(PEMFC) and battery power sources involves the collaborative optimization of system design and energy management strategies, which is crucial for enhancing overall efficiency, prolonging system lifespan, and improving dynamic response performance. This paper first systematically summarizes the classification and application of the topology of the fuel-lithium hybrid power system, and analyzes the key issues of different topologies. Based on these issues, a "topology-control" logical relationship is established to provide a foundation for the optimization design of energy management strategies. The research and analysis focus on the energy management methods of the parallel and hybrid topologies: for the parallel hybrid power system with the fuel cell as the main power supply unit, the application and optimization design are studied, emphasizing the need to comprehensively optimize the working state of the fuel cell to improve the efficiency and stability of the hybrid power system. For the hybrid power system, the analysis is conducted around four key aspects: power demand prediction, energy scheduling, battery health management, and system optimization. An adaptive energy management system with multi-objective optimization is proposed. Through the combination of case studies and engineering applications, the energy economy of the hybrid power system is improved. The research shows that intelligent energy management strategies, with their online learning and adaptive characteristics, are an important research direction for achieving a performance leap in hybrid power systems in the future.

With the large-scale application of lithium-ion batteries for energy storage, the gas diffusion behavior during thermal runaway(TR) and its early detection have received extensive attention. Thermal runaway experiments were conducted triggered by external heating on 280 Ah LiFePO₄ batteries, the gas compositions released during the thermal runaway process were analysed, and the characteristics of thermal runaway under different states of charge(SOC) were explored. The experimental results show that under high SOC conditions, the thermal runaway triggering time of the battery is short, the surface temperature rise rate is higher, and the proportion of H₂ in the thermal runaway gases released from 100% SOC batteries is as high as 44.84%. In contrast, the thermal runaway process of low SOC batteries is more moderate and mainly releases CO₂(78.41% of CO₂ in the thermal runaway release gas of 0% SOC batteries). In addition, the diffusion behavior of gases during the thermal runaway process of lithium iron phosphate batteries in energy storage systems was simulated using ANSYS Fluent software. The simulation results show that there are significant differences in the gas diffusion paths under different SOC conditions: under high SOC, the gas mainly rises rapidly along the vertical direction and diffuses in the top region, whereas under low SOC, the gas first accumulates at the bottom and then gradually diffuses to the whole space. The influence of SOC on the thermal runaway characteristics and gas diffusion behavior of lithium iron phosphate batteries was revealed, which provided an important theoretical reference for the safe and optimal design of lithium-ion energy storage systems.

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.

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.

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.

Lithium iron phosphate (LiFePO₄) with olivine structure has the advantages of high safety, long cycle life and low cost. However, the low conductivity caused by intrinsic defects in its crystal structure limits its widespread application. Carbon coating can effectively improve the conductivity of LiFePO₄ and is the core strategy to enhance its electrochemical performance. This article reviews the research progress of carbon coating on the surface of LiFePO₄ and summarizes the methods of carbon coating, types of carbon sources and optimization strategies for carbon coating.

As a new type of power source with low emissions and zero pollution, hydrogen fuel cells have been favored by various industries and have been applied in road transportation, shipping, aviation and other fields. However, the application of related technologies in railway transportation equipment is still in its infancy. The current application status of hydrogen energy in the rail transit field is introduced. In response to the high power and multi-condition requirements of railway transportation equipment, research has been conducted on multi-stack integration technology of hydrogen fuel cells and power source distribution technology, and vehicle-mounted verification has been carried out.

The reliability of the proton exchange membrane fuel cell (PEMFC) sealing system is crucial to its operation and commercialization, and related research has been carried out from three aspects. At the material level, the characteristics of silicone rubber, fluoroelastomer and other materials were compared, and the application value of new sealants such as UV light-curing adhesive and anaerobic adhesive was discussed. In terms of structural design, based on the interfacial stress and assembly process, the advantages and disadvantages of direct sealing, MEA/PEM wrapping and rigid frame structures were analyzed. In the durability assessment, the chemical degradation, fatigue and stress relaxation mechanisms of the sealing system under acid corrosion, heat-wetting cycle, and dynamic load are described. Future research can focus on composite material design, interface mechanics optimization and multi-scale life prediction, and provide theoretical and practical guidance for the optimization of sealing systems.

Solid oxide fuel cells(SOFC) have advantages such as high power generation efficiency, high-quality waste heat, and environmental friendliness. The commercialization of SOFC technology will provide an energy-saving and carbon-reducing pathway for achieving carbon peak and carbon neutrality goals in the future. The current domestic demonstration application status, patent layout, policy guidance, market situation, and emission advantages were reviewed. Currently, the industry is in the phase of technology importation, and there are very few demonstration projects in the industry, especially more than 100 kW SOFC systems. Local governments are gradually introducing policies to promote the development of SOFCs, additionally, R&D project policies at the national level are guiding the expansion toward large-scale commercial equipment. Overall industry investment in R&D resources is increasing, and the patent landscape is exhibiting rapid growth.

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.

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.

Battery technology, as the central pillar for efficient storage and utilization of clean energy, confronts several critical challenges—prolonged research‑and‑development cycles, difficulty in accurate lifetime forecasting, insufficient safety assurances, and low recycling efficiency. Artificial intelligence, through the construction of data‑driven models and intelligent optimization algorithms, has accelerated advancement across multiple stages. Looking ahead, a closed “physical entity—virtual mapping—intelligent decision” loop centered on digital twins, augmented by explainable AI and lightweight algorithms, promises end‑to‑end coverage from molecular design and manufacturing optimization to online monitoring and second‑life reuse. Realizing this intelligent‑fusion paradigm in practice will require the establishment of shared data platforms to break down data silos and demystify model black boxes, as well as strengthened interdisciplinary collaboration—thereby delivering high safety, low cost, and sustainable battery systems to propel the intelligent transformation and green development of the new energy sector.

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.

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.

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.

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.

In view of the problems such as slow equalization speed and single equalization path existing in the current equalization circuit topologies and control strategies, a battery pack equalization control circuit topology based on the asymmetric Buck-Boost circuit was proposed. The principles of implementing single-single and multi-asymmetric multi-cell equalization control by the asymmetric Buck-Boost circuit were analyzed. Subsequently, taking the state of charge (SOC) of lithium-ion batteries as the equalization variable, a state- space model of the battery pack was constructed, and the quadratic programming algorithm was used to iteratively optimize the equalization current. Finally, the SOC equalization of the lithium-ion battery pack was achieved by adjusting the duty cycle of the switching transistors. The model of the asymmetric Buck-Boost circuit and the active equalization control strategy was built on the MATLAB/Simulink simulation platform. The simulation verification was carried out for the publicly available lithium-ion battery charge-discharge experimental dataset of the University of Maryland. The results show that the equalization topology of the asymmetric Buck-Boost circuit and the active equalization control strategy model can quickly achieve the SOC equalization of the lithium-ion battery pack. Compared with the traditional topologies and control strategies, the equalization time is shortened by more than 30.9%.

Electroactive organic materials (EOMs) have garnered widespread attention due to their superior solubility, low cost, and synthetically tunable. Herein, based on the solubility statistics from the EPI Suite™ database, outstanding EOMs candidates are screened and designed for bipyridinium based single redox flow battery (SRFB), enabling the selected 2,2'-bipyridinium electrolyte to achieve stable charge/discharg process at saturated concentrations. Thanks to this design, a high reversible capacity of 2,2'-bipyridinium-based electrolytes has been realized. The SRFB based on saturated concentration of 2,2'-bipyridinium exhibits a reversible electrolyte capacity of up to 56.0 Ah/L at a current density of 40 mA/cm², the coulombic efficiency is 99.99%. This study significantly enhances the reversible capacity of bipyridinium-based electrolytes, providing a promising and safe RFB technology that can be adapted to various application scenarios.

In recent years, the recycling and treatment of waste lithium ion batteries and lithium iron phosphate (LFP) cathode materials in the field of new energy have attracted widespread attention. In addition to reducing the pollution of harmful components in waste batteries to the environment, the regeneration of battery materials is also crucial for resource utilization and economic benefits. This article reviews the research progress of LFP direct regeneration methods such as solid-phase method, hydrothermal method, eutectic method, and electrochemical regeneration method. At the same time, it introduces a groundbreaking new LFP regeneration technology. Finally, this article briefly introduces the commercialization process of direct recycling of waste lithium ion battery materials, discusses the advantages and disadvantages of LFP direct regeneration method, and some challenges encountered in the current regeneration process. It also looks forward to the future development of this field, laying a good foundation for further realizing the industrial production of LFP battery recycling.

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.

As an emerging post-lithium-ion battery technology, aqueous zinc ion batteries (AZIBs) have the advantages of low redox potential, high theoretical capacity, abundant resources, good environmental protection and high safety, and show great potential in large-scale energy storage systems due to their unique advantages. As the host material for storing Zn²⁺, the type and structure of AZIBs cathode materials determine the electrochemical reaction mechanism, and largely determine the output voltage, rate performance, energy and cycle life of the battery. Therefore, in order to improve the efficiency of AZIBs, it is of great significance to develop cathode materials with excellent electrochemical properties. Through the discussion of relevant literature, the research progress of manganese-based cathode, vanadium-based cathode, organic cathode and Prussian blue analogue of the main cathode material systems of AZIBs was expounded, the current development status of this field was demonstrated, and the future direction of AZIBs cathode material technology research was prospected, hoping to provide a reference for the wide application of AZIBs phase cathode materials in the field of next-generation energy storage, and develop high-performance cathode materials.

Li⁺ de-solvation at the solid electrolyte interphase (SEI) is a critical step governing the fast charging and low-temperature performance of lithium-ion batteries. The Li₃P, LiF, and Li₃PO₄ interfacial phases were designed on graphite anode by liquid-phase coating, respectively, which promoted the de-solvation of Li⁺ and constructed an inorganic-rich SEI membrane, thus accelerating the Li⁺ transport at the electrode interfaces and between the interfaces. From the EIS impedance, it can be clearly found that the low-temperature internal resistance is significantly reduced with the addition of the additive LiF compared with conventional graphite. The battery using PHG-Q anode can guarantee 49.57% charging capacity share at -20 ℃@0.2 C. At -40 ℃@0.2 C, the charging capacity share is improved by 7.29% with conventional graphite. Cycling LiF additives at low temperature -40 ℃@0.05 C facilitates Li⁺ de-solvation effect, and the capacity retention rate can be maintained at 93.95% for 800 cycles.

With advancing automotive electrification, battery management systems (BMS) are crucial for intelligent electric vehicle (EV) operation. However, accurate state estimation relies on effective battery model selection. Fractional-order models (FOM) show promise, balancing computational efficiency and accuracy. Therefore, this paper primarily reviews the modeling of FOMs. First, this paper outlined the modeling mechanisms of different battery models. It then focused on the principles, structures, advantages, and application scenarios of FOMs compared to others. Next, the potential of FOM-thermal model coupling for precise, synergistic monitoring of battery temperature and electrochemical performance was explored. Finally, future FOMs research directions and challenges in battery management were discussed. Overall, this review aims to provide a reference for FOMs theoretical research and engineering applications. It seeks to promote their integration into advanced BMS.

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.

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.

Proton exchange membrane fuel cells are power generation devices that convert chemical energy into electrical energy. Developing a high-efficiency and environmentally friendly proton exchange membrane is essential to meet people's demand for clean energy. Nafion membrane is a commercially available proton exchange membrane, but it is prone to swelling under high humidity. In order to improve the proton conductivity of the Nafion membrane, small molecule inorganic acids can be simply doped into it. However, this can easily lead to leakage of the exchange membrane. In order to simultaneously improve the mechanical properties and proton conductivity of Nafion proton exchange membrane, this paper synthesized covalent organic frameworks (COFs, TpPa-PO₃H₂) containing phosphate groups through the interfacial method and incorporated them into the Nafion matrix. A series of TpPa-PO₃H₂/Nafion composite proton exchange membranes were prepared by a solution casting method, and the structure and performance of the membranes were systematically investigated. The addition of TpPa-PO₃H₂ can reduce the crystallinity of the composite membrane and significantly increase its water absorption. At the same time, the strong electrostatic interaction between the TpPa-PO₃H₂ and the Nafion matrix improves the mechanical properties and thermal stability of the composite membrane, and reduces its swelling ratio. The results showed that the proton conductivity of the composite membrane can be increased by 101% compared with the pure Nafion membrane, and the power density can be increased by 81.2%. The TpPa-PO₃H₂ proton exchange membranes with excellent comprehensive performance was promising for the application in PEMFCs.

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.

Electrochemical impedance spectroscopy (EIS) is one of the important parameters reflecting the performance of lithium-ion batteries, and the EIS can be used for online assessment of lithium battery working condition and fault warning. For the online monitoring of electrochemical impedance spectra of lithium-ion batteries, an EIS online monitoring system based on an embedded microcontroller, a battery management IC and upper computer software, was designed. This system is able to collect the wide-band impedance characteristics of lithium-ion batteries and realize the online measurement of AC impedance in the frequency range of 0.12-7 812.52 Hz. The maximum relative impedance deviation is only 0.61% (@0.48 Hz) by five repetitive tests on lithium-ion batteries. The EIS static tests of lithium-ion batteries at different SOCs were performed using this system and electrochemical workstation respectively, and the maximum relative error is only 5.91% (@7 812.52 Hz, 30% SOC). Through the dynamic tracking of the battery working conditions, the dynamic curve of EIS during charging and discharging was analyzed, and it is proposed that the amplitude change rate of 0.61 mΩ/s was taken as the threshold value of the battery over-discharge, which can be carried out in advance of 180 s for the early warning of over-discharge. This EIS online monitoring system designed has the advantages of data visualization, simple hardware structure, high detection efficiency and low cost, which can be easily integrated into the battery management system (BMS), and has the prospect of application in the online estimation of the state of lithium-ion batteries and early warning of failures.

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.

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.

A 46-type cylindrical battery based on Ni-rich NCA/graphite+Si was selected, and the capcacity fading mechanism during fast-charging cycle of which was studied. Firstly, trickle discharging and dV/dQ curve were adopted for non-destructive and semi-quantitatve analysis. Then, XRD, ICP, semi-cell and other measurements were performed to precisely quantify the compositions of capcacity loss. It was found that the main factors of capacity loss are the active lithium loss in anode and the polarization loss which acount for 55.8% and 39.4% respectively. The causes of active lithium loss in anode are the repeated swelling-shrinkage behavior of anode and high temperature induced SEI growth and side reaction. The main reason of polarization loss is the break of cathode particles induced cell resistance growth. This study provides the direction to improve the fast-charging cycle life of 46-type cylindrical battery.

The poor thermal stability and detrimental gas release characteristics of ternary cathode materials significantly affect the safety performance of lithium ion batteries. Aimed at exploring the intrinsic relationship between performance failure, structural failure, and safety stability of the ternary cathode, the in-situ electrochemical mass spectrometry and differential scanning calorimetry analyses were conducted on the aged (A-NCM) and fresh (O-NCM) LiNi_0.5Co_0.2Mn_0.3O₂ cathodes to investigate their safety stability. The results show that, under an upper cutoff voltage of 4.7 V, significant CO₂ and H₂ harmful gas signals were detected for A-NCM during electrochemical cycling. Additionally, when the thermal decomposition reaction between the electrode and the electrolyte was initiated, A-NCM electrode would release more heat, further increasing the battery temperature and posing safety hazards. This research helps to construct the relationship between "battery aging and battery safety", providing a theoretical basis for intelligent battery safety management.

In this study, organic sulfide lipoic acid (α-ALA) and polyethylene glycol diacrylate (PEGDA) monomers were used as raw materials to prepare a chemically stable three-dimensional cross-linked polymer P(A_x-P_y) by reverse vulcanization reaction under high temperature (without initiator) conditions. Then it was blended with polyethylene oxide (PEO) to obtain a solid-state electrolyte membrane P(A_x-P_y)-PEO. P(A_x-P_y)-PEO can assist in constructing an SEI layer that enables stable cycling of the battery. The conductivity of P (A₃-P₃)-PEO electrolyte at 60℃ reaches 1.85×10^–3 S/cm with an electrochemical window of up to 4.5 V. When the current density is 0.1 mA/cm², the Li|P(A₃-P₃)-PEO|Li cell can stably cycle for more than 1600 hours, and the Li|P(A₃-P₃)-PEO|SPAN cell has a discharge-specific capacity of 719 mAh/g and a coulombic efficiency of up to 99%. The results indicate that the polymer electrolyte prepared in this study has great potential for improving ion transport and battery cycling stability.