Solid-state sulfide electrolytes have high room-temperature ionic conductivities, but their poor mechanical strength makes it difficult to prepare practical electrolyte layers. Herein, the present work proposed a strategy of pre-fiberizing polymer adhesives to achieve the solvent-free preparation of sulfide electrolyte composite membranes at room temperature, thereby enhancing the performance of all-solid-state batteries. Pre-fiberized PTFE fiber powder was prepared by the demulsification of PTFE emulsion followed by drying. An ultrathin sulfide solid electrolyte composite membrane (~35 μm) with high ionic conductivity (3.17 mS/cm) was successfully prepared using Li₆PS₅Cl electrolyte and roller pressing at room temperature. Using lithium cobalt oxide coated with lithium niobate (LCO@LNO) as the cathode material, a composite cathode membrane comprising the positive electrode material, electrolyte, and conductive agent was prepared via the same solvent-free process as electrolyte membranes at room temperature. An all-solid-state thin-film battery was prepared by stacking ultra-thin lithium indium alloy, electrolyte composite membrane, and cathode composite membrane, which achieves a reversible specific capacity of 134.1 mAh/g, an energy density of 188Wh/kg, and 100 stable cycles.

Lithium ion batteries (LIB) are widely used for mobile energy storage due to their high energy density and long cycle life. However, the limited resources of lithium severely limit its application in large-scale energy storage. In recent years, sodium ion batteries (SIB) have become a promising alternative to LIB due to their low cost and high safety. Hard carbon, with its low redox potential, stable structure, large layer spacing and relatively low cost, is widely used as an anode material for SIB. However, the poor multiplicative performance and low initial Coulomb efficiency of hard carbon anode limit the performance of SIB. This paper reviews the research progress of hard carbon anode for sodium ion batteries, including the mechanism of sodium storage in hard carbon, selection of precursors and the effect of preparation process on the performance of hard carbon.

ZIF-67 was prepared by colloidal chemical synthesis with cobalt nitrate hexahydrate Co(NO₃)₂·6 H₂O and 2-methylimidazole (MeIm) as raw material at room temperature, and it was used as wet seeds. ZIF-8 formed by zinc acetate dehydrate C₄H₆O₄Zn·2 H₂O and 2-methylimidazole (MeIm) was coated around ZIF-67 by in-situ growth method to prepare the material of core-shell structure ZIF-67@ZIF-8. The morphology and structure of the synthesized materials were characterized by FE-SEM, TEM and XRD. The molar ratio of raw metal ions was changed by the control variable method, and the samples with different ratios were obtained. The obtained samples were selected as the active substance of working electrodes, and the electrochemical tests such as cyclic voltammetry and constant current charge and discharge were carried out in a three-electrode system. The results show that when the molar ratio of raw metal ions (namely Co²⁺ and Zn²⁺) is 1∶1, the prepared material has higher specific capacitance of 1 144.4 F/g at the current density of 1 A/g and good cycling stability in constant current charge-discharge testing.

The energy storage performance of ternary lithium battery at different temperatures was researched by measuring the charge/discharge capacity and pulse test. The results show that during the discharging process, the discharge platform voltage and discharge capacity decrease with the temperature drops from 55 ℃ to -10 ℃. The discharge capacity at high temperature (55 ℃) is 105.0% of the rated capacity, and the discharge capacity at low temperature (-10 ℃) is only 83.9% of the rated capacity. With the decrease of temperature, the heat production of the battery increases gradually, the internal resistance increases, and the discharge power decreases, affecting the normal use of the battery. During the charging process, the charge platform voltage increases with the temperature drops from 55 ℃ to -10 ℃, the internal resistance and the charge power increase, affecting the battery charging efficiency.

Lithium ion batteries are widely used in energy storage systems with high energy density, high power density and long service life. The accurate estimation of the usable capacity in the long-term operation state is the key for the energy storage system to participate in power regulation. In order to solve this problem, this paper proposes a method for estimating the usable capacity loss of lithium ion batteries based on Singular Value Decomposition-Double Adaptive Unscented Kalman Filter (SVD-DAUKF) algorithm, which firstly constructs the expression of battery usable capacity considering aging, and then uses the SVD-DAUKF algorithm combined with the equivalent circuit model to identify the model parameters and estimate the state of charge. Finally, combined with the parameter identification results and the definition of usable capacity, the estimation results of usable capacity loss are verified at 1 C, and the estimation error of usable capacity loss is less than 4%.

In order to solve the problem of appearance deformation in the production process of the pouch cell, the possible deformation mechanism in the whole process of the cell production was analyzed, and then a series of solutions were put forward, such as reducing the capacitance current, pressurizing the capacitance and full electrochemical formation. The experimental results show that the heating and pressurization can effectively optimize the bad appearance, reduce the stack thickness of the cell, and improve the interface to enhance the cycle performance of the cell. However, the aging stage after full electrochemical process will consume active substances, resulting in a decrease in cell capacity. Therefore, the loss of cell capacity can be reduced by further adjusting and reducing the charge state of the cell after the cell is fully electrolyzed to improve its appearance, so as to achieve the best improvement effect.

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.

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.

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.

This study focused on a prismatic LiFeO₄ lithium-ion battery pack and proposed an optimized design of the parallel-tilted channel liquid cooling plate instead of the traditional parallel channel liquid cooling plate. A 6 C discharge rate liquid cooling simulation was conducted to compare the heat dissipation performance of the battery pack under the two cooling plates. Then, a single-factor analysis was conducted on the parallel-tilted channel liquid cooling plate to investigate the impact of different cooling liquid mass flow rates and cooling plate structural parameters (channel width, inlet width, and channel tilt angle) on the heat dissipation performance of the battery pack. Finally, an orthogonal experiment was designed to conduct a range analysis on the simulation results. The analysis results show that the optimal combination of structural parameters for the parallel-tilted channel liquid cooling plate is a channel width of 12 mm, an inlet width of 15 mm, a channel angle of 70°, and a mass flow rate of 30 g/s. At the same 30 g/s mass flow rate, the maximum temperature and maximum temperature difference of the battery pack and the pressure drop of the liquid cooling plate are decreased by 0.45%, 2.96% and 29.08%, respectively, for the optimal combination of structural parameters compared with the parallel channel liquid cooling plate structure.

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 exhibit capacity decay during charge-discharge cycles, followed by a sharp decline near end-of-life. Knee points can cause malfunctions and premature aging, necessitating the development of a multi-scale feature fusion approach for the prediction of cycle life and knee points in lithium-ion batteries, ensuring the safe utilization of such systems. Primarily, a multi-scale convolutional neural network (CNN) was employed to extract health-related features from raw data, including discharge voltage, current, and temperature, spanning various temporal scales. Subsequently, the long short-term memory (LSTM) neural network was employed to capture the long-term dependencies of these features. Furthermore, fitting of degradation trajectories in the early and late stages of battery operation enabled the identification of knee points. Lastly, the effectiveness and accuracy of the proposed model were validated using the Stanford-MIT dataset. The results demonstrate that the model, utilizing the first 80 cycles of data, accurately predicts both the cycle life and turning points of the battery. The RMSE for cycle life prediction is below 30 cycles, while for knee points, it is below 60 cycles. Additionally, the MAPE is below 2% for cycle life prediction and below 5% for knee points. Accurate prediction of knee points proves advantageous for continuous improvement of battery performance and lifespan, making it vital for effective battery health management.

In photovoltaic power generation systems, the output power of photovoltaic cells is susceptible to environmental factors such as light intensity and temperature, and has typical nonlinear characteristics. Therefore, in order to improve the efficiency of photovoltaic cells, the photovoltaic cells required a real-time tracking so as to ensure the maximum power output. This paper summarized the current research status of MPPT algorithms for photovoltaic arrays at home and abroad, introduced the algorithms for tracking maximum power points of photovoltaic arrays under uniform lighting and local shading conditions, analyzed the principles and compared their advantages and disadvantages, refined the existing problems, and sorted out the next research ideas. Finally, the current research direction of MPPT was discussed, and its future development trends were pointed out for readers' reference.

In recent years, with the rapid development of the new energy industry, the high-nickel ternary cathode materials (NCM/NCA) have become widely used in the lithium battery industry due to their high specific capacity and energy density. Increasing nickel content can enhance the reversible capacity and energy density, but introduce some challenges, such as cation mixing (Li⁺ and Ni²⁺), lattice oxygen release, electrolyte decomposition, and decreased thermal stability. These factors contribute to the performance degradation and safety risks. In order to address these issues, recent research has focused on the surface coating, micro/nanostructure design, and element doping to improve the battery performance and safety by protecting particle surfaces or optimizing crystal structures and particle morphology. These improvement strategies for high nickel cathode materials were summarized and compared.

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.

Silicon-based anode materials have problems of volume expansion, surface instability or low electron conductivity. In this paper, porous silicon-carbon composites are obtained by Si morphology control, conductive net-work design, porous structure construction and carbon coating. Si nanosheets can be obtained via balling based on different cleavage energies in different facets of Si. Spray drying of the well-distributed slurry containing silicon nanosheets, carbon nanotubes, and graphite yields porous structures. Liquid state carbon coating of the porous structures leads to the entire carbon coating on both the surfaces of the silicon nanosheets and the whole composites. Coin test shows the composite deliver a specific capacity of 1 000.8 mAh/g and a high initial coulombic efficiency of 93.9%. Full cell tests display high rate property at 1 C and good cycling behavior. These good performances are derived from the conductive net-work structure, the porous structure construction, and the dual-carbon coating of the composite.

Hydrogen fuel cell is an electrochemical energy conversion device. Compared with conventional combustion engines, it is characterized by fast startup speed, low operating temperature, high efficiency, environment-friendly, low noise and low characteristic signal. Therefore, it is very suitable for city transportation, space and underwater applications. However, poor durability hinders the large-scale commercialization of hydrogen fuel cell. The reasons for bad durability can be divided into two aspects, including adverse operation protocols and unsuitable operation conditions. This review summarizes the attenuation mechanisms and advances researches about membrane electrode assemblies (including catalyst layer, gas diffusion layer, proton exchange membrane) under start up and shut down protocol, dynamic protocol, idle protocol, water management, thermal management, cold start, gas toxicity, and clamping force.

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.

In order to clarify the thermal runaway explosion process and its hazards of lithium-ion batteries at different state of charge (SOC), 18650 lithium-ion batteries were selected as the research object, and the thermal runaway experiments of the batteries at different SOC were conducted in a 20 L standard container. The temperature, pressure, and quality data of the explosion process were recorded and analyzed. The results show that there are two stages (injection and explosion) in the thermal runaway explosion process of lithium-ion batteries. The duration time of injection decreases with the increase of SOC. The injection stage lasts for 10.1 s at 25% SOC, while it only lasts for 0.03 s at 100% SOC. The explosion mass loss is 14% of the original battery mass at 25% SOC, and reaches 67.8% at 100% SOC. With the increase of SOC, the mass loss of the battery increases significantly. The maximum explosion pressure p_max is negatively correlated with the maximum surface temperature q_max of batteries at 75% and 100% SOC, while the p_max and q_max at 25% and 50% SOC are both larger. The results of the study are helpful to clarify the thermal runaway explosion process of lithium-ion batteries, and have some guiding significance for the structure design and safety evaluation of lithium-ion batteries.

Owning to the low cost and eco-friendliness, water-based processing for the preparation of electrode films is attractive in Li-ion battery industry. A composite binder suitable for water-based processing of Li-rich layered oxide cathodes(LLOs) was prepared by sodium alginate(SA) and polyacrylic acid(PAA). The result demonstrats that adjusting the mass ratio of SA and PAA can control the degree of cross-linking between the hydroxyl group of SA and the carboxyl group of PAA, thus regulating the electrode structure and improving the electrode kinetics. The LLOs electrode films prepared by the water-based processing has excellent electrochemical performance when the mass ratio of SA/PAA is 3∶1. The LLOs‖Li half-cells have a discharge specific capacity of 293.8 mAh/g(4.8 V), and 179.2 mAh/g at a high current density of 3 C. The study will help to design and optimize binders for 4.8 V high voltage LLOs.

This paper presents an original solution to the issue of the silicon-based negative electrode's high volume expansion and ease of detachment from the collector during battery cycling: a modified copper foil collector with graphene coating. The graphene coating makes the collector's surface rougher, which improves adhesion between the collector and the active material and prevents the phenomena of collector detachment from active material. The rate performance and cycle stability of batteries with modified collectors coated with graphene are significantly better than those with Cu foil collectors. At a high rate of 2 C, the silicon-based negative electrode with the improved collector covered with graphene had a discharge specific capacity of 467.2 mAh/g. After 80 cycles at 0.2 C, retention of capacity is still above 50%. In contrast, the one with normal copper foil collector only retained 18.2% of capacity.

During the cycle aging process of lithium-ion batteries, the side reactions occur, such as the structure collapse of the active material in cathode and anode and the decomposition and gas production of electrolyte, leading to the battery swelling and capacity degradation. Studying the evolution law of battery swelling force during its life cycle has great engineering significance for strengthening battery life management. However, there are few literature reports on this field of research. The evolution trend of swelling force and life of lithium-ion batteries during the aging process was explored. It’s found that after differentiating the charging peak value of the swelling force and capacity value during cycling, the absolute values of both show simultaneously the increase trend, indicating a strong correlation between battery swelling force and cycling life. Introducing the swelling force into the battery life prediction model can improve the accuracy of lithium-ion battery life warning model.

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.

Photovoltaic power prediction has significance for power grid dispatching. This article focuses on the characteristics of volatility and instability in photovoltaic power, proposes a combination forecasting model using the long short-term Memory (LSTM) network optimized by ant lion optimization (ALO) algorithm based on ensemble empirical mode decomposition (EEMD) and Kmeans clustering algorithm(Kmeans). First, the photovoltaic power data is decomposed by EEMD. The corresponding intrinsic mode functions and residual are obtained. Then, the decomposed sequence is reconstructed by Kmeans clustering to reduce the sequence complexity and the number of decomposed components. Finally, the reconstructed subsequence is input into the LSTM model optimized by ALO for prediction, and the prediction results of each sequence are simply summed as the final prediction value. Compared with the currently widely used EEMD-LSTM algorithm, the prediction accuracy of the EEMD-Kmeans-LSTM and EEMD-Kmeans-ALO-LSTM algorithms have been improved to a certain extent.

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.

For fixed-type large-scale ground solar power projects, how to choose the installation tilted angle and spacing has a significant impact on the economics of the project. This article mainly introduces how to optimize the system's optimal tilted angle and pitch based on the conditions of a specific project. The conventional methods are analyzed and compared. In order to achieve the purpose of reducing the LCOE of the project, the optimization can be implemented according to the characteristics of the project during the execution of a project.

Anode-free lithium metal battery has become an academic hotspot due to its high theoretical capacity, energy density and low cost. However, due to the lithium-sparse property of copper foil and the high activity of lithium metal, the lithium deposition/stripping is not uniform, resulting in many problems such as lithium dendrites and excessive lithium consumption, which limits the practical application. In this paper, the advantages, challenges and solutions of anode-free lithium metal batteries were comprehensively reviewed. Four improvement strategies were discussed in detail, including modifying the current collector, constructing a stable solid electrolyte interface(SEI) film, introducing lithium supplementation technology and optimizing the electrolyte. The mechanism of the negative side affecting the deposition / stripping of lithium metal, the advantages of the positive side additional lithium source and the influence of the electrolyte on the reversibility of the anode-free lithium metal battery were discussed. The advantages and disadvantages of the four strategies and the future development direction were summarized.

It is of great practical significance of conducting experimental research on the safety of lithium ion battery modules under liquid cooling conditions considering their unique characteristics. In this study, the thermal runaway experiments on 280 Ah lithium iron phosphate batteries, induced by overcharge, external short circuit and overheating were performed on a submerged liquid cooling system test platform to explore the thermal behavior in both the thermal runaway process induced by liquid cooling of individual batteries and modules. Additionally, this study also scrutinized the distinctions in thermal runaway behavior between the conditions induced by liquid cooling and those governed by natural convection. It has revealed that submerged liquid cooling process can diminish the initial heating temperature, mitigates the temperature escalation triggered by overcharge-induced uncontrolled heating, lowers the peak temperature following such incidents, effectively dampens the rate of temperature increase during the process, and delays the onset of uncontrolled heating in the case of battery thermal runaway. Furthermore, in the thermal runaway experiment induced by overheat, utilizing submerged liquid cooling with a 2 kW heater plate attached to the heating, the battery reached a maximum temperature of 90 °C, indicating effective thermal control in preventing thermal runaway.

The thermal characteristics of 18650 type lithium iron phosphate batteries with different SOC adiabatic conditions were studied by means of accelerating rate calorimeter (ARC), and the batteries after ARC experiment were dissected. The results show that the lithium-iron phosphate batteries under 10%SOC and 50%SOC do not go into thermal runaway due to the pressure relief and heat dissipation of valves breaking down at 159 ℃. At 100% SOC, the temperature drops slightly at 159 ℃, and then keeps rising; from 174 ℃, the temperature heating rate continues to rise; when the temperature reaches 191 ℃, the heating rate is 1 ℃/min; when the temperature reaches 220 ℃, the heating rate is 2.4 ℃/min(0.04 K/s); soon afterwards, the temperature rises sharply, and the thermal runaway occurs following the maximum temperature of 340 ℃. With the increase of SOC, the mass loss of the battery caused by ARC experiment increases, and the damage degree of separator increases. The separator will close at 10% SOC, is damaged at 50% SOC, and is melted at 100% SOC.

In real-world vehicle operational scenarios, battery temperature distribution within a battery pack demonstrates non-uniform attributes. Particularly, under elevated operating temperatures, the pace of battery degradation escalates, potentially resulting in accelerated diminishment of both capacity and power. This study centers on lithium-ion batteries and employs extended cycles of 1 C charge-discharge to methodically characterize and assess battery pack attributes including temperature distribution, degradation behavior, and current dispersion. Furthermore, a comparison is drawn with individual baseline cells. Research findings unveil that all batteries within the battery pack encounter elevated temperature elevation and manifest a swifter degradation rate when contrasted with the baseline cell. In particular, following 1 815 cycles, the capacity of the central battery within the pack diminishes to 61.2% of its initial capacity, whereas the baseline cell sustains 86.5% of its capacity. Additionally, both resistance and current distribution within the battery pack manifest comparable patterns of alteration. Through experimental quantification of the influence of non-uniform temperature distribution on battery degradation, this study enhances the comprehension of the degradation tendencies of modular lithium-ion batteries subjected to temperature gradients. These insights bear substantial implications for the optimization of battery design, enhancement of battery performance, and extension of battery lifespan.

In recent years, lithium ion batteries(LIBs) are the state-of-the-art battery technology, which has been widely used in portable electronic devices, electric vehicles, energy storage systems. However, there are still some problems that result the decay of energy and power density of LIB under low-temperature condition, restricting its application in extreme working condition for the following reasons: the diffusion of Li⁺ in the electrode material, the charge transfer and desolvation process at the interface are relatively slow. The increase of the viscosity of the electrolyte results in the deterioration of the wettability of the active material and separator. In addition, charging under low-temperature may lead to the growth of lithium dendrites, which trigger internal short circuit and thermal runaway accidents in the worst case. Based on years of experience in the development of low-temperature LIB and related literature reports, the strategies were reviewed to improve low-temperature performance from the perspective of electrolyte, focusing on the effects of co-solvents with low viscosity and wide liquid range, new lithium salts with high conductivity and low desolvation energy, and additives to form thin and dense SEI, and their challenges on low-temperature performance. Moreover, the future development direction of low temperature LIB was prospected.

Since the commercial application of lithium-ion batteries (LIBs), the capacity decline of lithium-ion batteries working in low temperature has attracted much attention from scholars. This paper analyzed and discussed the influencing factors of poor performance of LIBs in low temperature, and summarized the methods to improve the dynamics of low-temperature batteries in recent years from four aspects: electrolyte design, cathode material modification, anode material modification and battery heating technology. Finally, the methods to improve the performance of low-temperature LIBs were summarized and new insights and schemes were put forward to promote the sustainable development of high-performance low-temperature LIBs.

FeF₃-FeF₂ cathode material was prepared by solvothermal and high temperature calcination methods, and its physical and electrochemical properties were characterized. The test results show that the specific surface area of FeF₃-FeF₂ cathode materials is 11.8 m²/g, which is much larger than FeS₂ (0.5 m²/g). The initial thermal decomposition temperature of FeF₃-FeF₂ cathode materials is 850 ℃, which is about 300 ℃ higher than FeS₂ and about 200 ℃ higher than CoS₂. The no-load voltage of FeF₃-FeF₂ single cell battery is 3.22 V, which is much higher than the no-load voltage of FeS₂ (2.05 V). The initial discharge voltage of LiB/LiF-LiCl-Li₂SO₄/FeF₃-FeF₂ single cell battery is 2.65 V at the current density of 150 mA/cm². When the cut-off voltage is 1.5 V, it can discharge for 308 s. The specific discharge capacity of LiB/LiF-LiCl-Li₂SO₄/FeF₃-FeF₂ single cell battery reaches 160.4 mAh/g, which is 75.3% and 43.5% higher than the LiCl-KCl and LiF-LiCl-LiBr electrolyte systems, exhibiting a longer working time. Therefore, for the development of high voltage, high specific energy, and high specific power thermal batteries, FeF₃-FeF₂ is a promising cathode material for thermal batteries.

In order to achieve the specific energy increase of lithium ion batteries, the use of silicon-based materials to increase the capacity of the negative electrode is a common method for high specific energy lithium ion batteries. SiO_x has been used in power batteries because of its excellent cycling performance. However, in the process of charging and discharging, the volume expansion and contraction rate of the SiO_x particle is large, which often affects the cycle life of the battery. It is helpful to improve the cycle life of silicon-containing high specific energy system to investigate the relationship between particle pulverization and the transition growth of SEI film and the preloading force during the process of expansion and contraction of SiO_x particles. In this paper, the failure mechanism of SiO_x particles was analyzed by analyzing the failure state of silicon anode particles after high specific energy lithium ion battery cycling under different stress conditions.

Capacity fading of LiFePO₄/graphite (LFP) cell was investigated at different temperatures and an optimal cycling temperature range was found for this type of battery. Also, by using dV/dQ-Q curve, it is found that when capacity loss is 20% of its initial value, the main factor is the loss of active lithium (LLI), which occupies more than 80% of the total loss. The loss of anode material is between 12% and 14% and the loss of cathode material was about 4%-6%. This result provides a theoretical basis for designing and improving of cycle performance of LFP battery. Further, the cycle life was fitted and could be predicted by using temperature acceleration model. And the prediction model is very accurate in the specific temperature range.

Aiming at the heat dissipation problem of cylindrical lithium-ion battery pack under harsh working conditions, a thermal management system of battery pack with composite phase change material(PCM ) coupling liquid cooling was designed. The optimum mass fraction of silicon carbide (SIC) in PCM is 5%. A PCM coupled wavy microchannel liquid cooling battery thermal management system was designed. The designed thermal management system can control the maximum temperature of the battery to be 49.88 ℃ at 40 ℃ ambient temperature and 2 C discharge rate. The maximum module temperature difference is 5.14 ℃, and the maximum monomer temperature difference is 4.34 ℃. Compared with the natural convection and PCM single cooling method, the maximum temperature of the battery pack with the designed thermal management system decreases by 26.95 and 3.55 ℃, respectively. The results show that the designed PCM coupled liquid cooling battery thermal management system can ensure the normal operation of the battery pack under harsh conditions.

CF_x serves as an important positive electrode material, has high energy density, long storage life, and excellent safety in lithium primary batteries. In recent years, researchers have identified the problems existing in CF_x materials by studying the working mechanism of Li/ CF_x and have carried out a series of modification treatments based on these issues, such as plasma treatment, surface coating, and atomic doping. Furthermore, researchers have also changed the surface structure through methods like surface defluorination and nanoscale engineering to enhance conductivity and lithium ion transport rate, further improving its energy density. These research achievements provide new insights and approaches for the application of CF_x in lithium primary batteries. This article mainly introduced the working mechanism of Li/CF_x batteries and the current issues with CF_x materials, summarized and analyzed the modification methods for CF_x materials, and provided a detailed introduction and outlook on the applications of Li/CF_x batteries in aerospace, national defense, and military fields.