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.

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%.

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.

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.

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.

Lithium ion battery dominates the market of portable electronic products and electric vehicles and energy storage. However, more and more attention has recently been paid to the cost and resource availability of lithium. Sodium ion batteries are considered to be the ideal choice for grid-level energy storage systems. There are still various challenges need to be overcome, however, before its commercial application. Among them, the low initial coulombic efficiency is a critical issue that seriously limits the improvement of practical energy density of the sodium ion full battery. This review analyzed the influence factors of low initial coulomb efficiency, such as the solid electrolyte interphase formed due to the decomposition of electrolyte during the first cycle, and the poor reversibility of sodium ion insertion/deintercalation process, as well as the defects and surface functional groups. Also, the paper summarized the emerging strategies to improve the initial coulomb efficiency of sodium ion batteries, such as electrolyte optimization, structure/morphology design, surface modification, and binder optimization, which is of great significance for promoting and realizing the practical application of high energy sodium ion batteries.

Using FePO₄ as the iron source,the LiFePO₄ was prepared by carbothermaI reduction. By changing the feed rate and crushing pressure,the final product LiFePO₄ has different particle size distributions. The current collector made up the cell,which contains the final product LiFePO₄ conductive agents and binders. The results show that the D_max of final product LiFePO₄ is whthin 20 μm and the granularity of mixed liquids is within 35 μm. The compacting density of the coating layer is greater than 2.44 g/m³ and the 0.1 C discharge specific capacity exceeds 159 mAh/g. The final product LiFePO₄ has good performance in practicability.

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.

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.

Despite their wide range of applications, lithium-ion batteries (LIBs) are severely degraded in terms of capacity, rate capability and lifetime at low temperatures, which greatly limits their applications in low-temperature fields. A number of factors cause poor low-temperature performance of LIBs. The microscale processes occurring near the electrode/electrolyte interface, particularly the increased energy barrier for lithium ion (Li⁺) desolvation at the solid electrolyte interphase (SEI) and the slow transport of Li⁺ through the SEI, play a crucial role in the low-temperature performances of LIBs. Therefore, the improvement and development of electrolytes is of significant importance for the further exploration of low-temperature LIBs. This review started by examining the factors that limit the low-temperature kinetics of LIBs, and analyzed the low-temperature rate-determining steps. It then further explored how solvents, salts, and additives improve the low-temperature performances in different battery systems. This Review is expected to provide the informative outlook for the design of the next-generation low-temperature LIBs.

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.

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.

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.

Using high nickel ternary cathode material and silicon carbon anode material, 3.6Ah 18650 lithium ion battery was successfully prepared through the selection of anode material and optimization of electrode surface density parameters. The 18650 battery has a volumetric energy density of 751 Wh/L, can be discharged at 3 C multiplication rate, and has an operating temperature range of –40~60 ℃. The battery has good multiplicity performance, cycling performance, low temperature discharge performance and high temperature discharge performance, with good overall performance, which can meet the requirements of wide temperature range and long cycle use.

Thermal runaway of lithium ion batteries is one of major problems hindering the development of higher energy density batteries and their large-scale application. The thermal safety of lithium ion batteries not only depends on the electrode material and battery design, but also varies by their aging modes and degrees. The degradation of electrochemical performance and thermal runaway behavior of aged lithium ion batteries during cyclic aging at high temperature were investigated in this work. The NCM lithium ion batteries were cyclic aged at 72 ℃ and 25 ℃ under 1 C current at CC-CV mode. The electrochemical performances of fresh and aged batteries were first compared, then ARC was used to perform thermal runaway test on fresh and aged batteries to explore the thermal safety variations of batteries after cyclic aging at high temperature, finally, the post analysis of aged batteries was carried out to investigate their aging mechanism. Related results have shown that the electrochemical performance of batteries deteriorated seriously due to the loss of large amounts of active materials in both positive and negative electrodes. During the ARC tests, both fresh and aged batteries occurred thermal runaway. However, the dynamic process of thermal runaway was slowed down due to the consumption of large amounts of electrolyte in aged batteries, thus the overall harm of thermal runaway by high-temperature aged batteries was alleviated.

The potential of lithium difluorophosphate as an electrolyte additive for enhancing the performance of lithium-ion batteries has been extensively investigated. Specifically, its superior low impedance effect has garnered significant interest. The latest research on the use of lithium difluorophosphate in regulating the impedance of solid electrolyte interphase (SEI) and improving the stability of batteries at low temperature, high rate, and high temperature was reviewed. Furthermore, the challenges and possible solutions associated with the practical application of lithium difluorophosphate were introduced. The effect mechanisms of lithium difluorophosphate was elaborated and the development of low-impedance electrolyte additives was prospected.

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 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.

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.

Solid-state lithium metal battery has become the most promising lithium battery technology for its outstanding safety and high theoretical specific capacity. For building a system with high specific energy density, the main obstacle is the interfacial issues and the compatibility between cathode and solid electrolyte. Through the introduction of modification strategies on film mechanical property, cathode/electrolyte interface properties and its integrated preparation technology, and theoretical calculation, etc, the progress of cathode/electrolyte interfacial modification techniques such as physical contact optimization, cathode/electrolyte permeability enhancement, interface compatibility improvement and cathode electrolyte interphase construction were reviewed. The development trend of interface modification technology for solid-state lithium metal batteries was also prospected.

The cascading utilization of retired power lithium batteries (with a rated capacity of over 80%) can effectively alleviate the pressure of battery recycling and environmental pollution, and improve resource utilization efficiency and economic benefits. However, conducting rapid, non-destructive, and accurate state assessment of the retired batteries remains a challenge. Compared with other reported methods, electrochemical alternating current measurement of batteries and collecting data to draw impedance spectra are the core methods for studying battery states, which have two advantages: fast and non-destructive. The battery detected in this way can establish internal impedance and state correlation, and quickly complete battery state evaluation. The analysis methods of electrochemical impedance spectroscopy mainly include predicting impedance based on measurement data and machine learning methods, analyzing the changes in various equivalent components of the circuit based on equivalent circuit diagrams, and using integration algorithms to convert impedance spectroscopy into a more intuitive relaxation time distribution spectroscopy. These methods all provide analytical methods for the internal aging of batteries, providing an electrochemical basis for the relationship between the internal impedance and health status of batteries. Based on this, this article reviewed the latest research progress in combining electrochemical impedance spectroscopy with machine learning to evaluate the state of power lithium batteries both domestically and internationally, with a focus on summarizing and exploring the relationship between electrochemical impedance spectroscopy, equivalent circuit models, relaxation time distribution, and machine learning.

As the core energy storage component of flexible electronic devices, fiber shaped lithium ion batteries show the advantages of high flexibility, light weight and weaving. The electrode materials prepared by the traditional process usually use the metal current collector to coat the active material, which is easy to cause the active material to crack and fall off under various deformations. This method affects the stability of the energy storage performance. Carbon fiber (CF) has the advantages of high conductivity, good flexibility, strong mechanical properties, and weaving. It has received extensive attention as a conductive skeleton for flexible self-supporting electrodes. Carbon nanotubes (CNT) are conductive nanomaterials commonly used in the field of electrodes with large aspect ratio and large specific surface area. Arrayed carbon nanotubes (VACNTs) can also provide a highly ordered conductive structure and improve the mechanical strength of the electrode. Herein, VACNTs were grown in situ on CF as a flexible self-supporting conductive skeleton, and hydrothermally loaded lithium iron phosphate and lithium titanate as positive and negative electrodes respectively, and assembled into a fiber full battery. At a charge-discharge rate of 0.2 C, the initial discharge line specific capacity reaches 1.38 mAh/cm, and the line energy density is as high as 2.62 mWh/cm.

Voltage reversal due to insufficient fuel supply severely restricts the lifespan of proton exchange membrane fuel cells (PEMFCs). In order to study and solve this problem, this work used bi-functional PtIr alloys as anode catalyst to fabricate membrane electrode assembly (MEA) and performed polarization performance, reversal tolerant performance and electrochemical impedance spectroscopy (EIS), etc. The results show that the peak power density of PtIr/C electrode can reach 1.49 W/cm², which is 2.1% higher than that of Pt/C-IrO₂ (50%) electrode (1.46 W/cm²). The reversal tolerant results show that PtIr/C electrode presents an anti-electrode time of 725 s, which is slightly worse than that of Pt/C-IrO₂ (50%) electrode, and lower absolute reversal voltage during the whole process, as well as higher structural stability which remained unchanged after reversal test. After the reversal, the peak power density of the PtIr/C electrode decreases to 1.18 W/cm² with an attenuation of about 20.80%, while the peak power density of the Pt/C-IrO₂ (50%) electrode decreases to 1.09 W/cm² with an attenuation of about 25.34%. In summary, compared with the Pt/C electrode doped with IrO₂, the PtIr electrode had better initial polarization performance and excellent anti-electrode ability. This research is of great significance for the design of high-performance and durable catalytic layers of fuel cell MEA.

In order to predict the aging of proton exchange membrane fuel cells (PEMFCs) under dynamic operating conditions and improve the prediction ability of the gated recurrent unit network (GRU), this paper proposes a TCN-GRU-A prediction method that combines time convolutional network (TCN), attention mechanism, and GRU. By introducing the TCN layer to enhance the feature extraction ability of GRU, the attention mechanism is used to weight the output features of GRU to improve the accuracy of the prediction. Validated using a PEMFC dynamic durability test dataset, a comparison with various deep learning models' predictions indicates that the proposed method demonstrates lower prediction errors and better fitting, whether applied to full-current load data or constant-current load data.

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.

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.

Power battery management technology is the core and key to ensuring the efficient, safe, and reliable operation of new energy vehicles. The State of Charge (SOC) of power batteries is the foundation of power battery management technology. However, there are too many uncertain factors affecting the SOC of power batteries, and how to accurately estimate the SOC of power batteries has become a key issue. Regarding the difficulty in accurately obtaining SOC for power batteries, this paper establishes a power battery testing platform, conducts routine performance testing and power battery life testing, establishes a fractional order model of power batteries based on fractional order theory, and then combines multiple innovation theory with fractional order model unscented Kalman filtering algorithm to propose fractional order model multiple innovation unscented Kalman filtering (FOMIUKF) algorithm, and uses this algorithm to estimate the SOC of power batteries. Comparative analysis was conducted on the estimation accuracy of power battery SOC based on different algorithms under different environmental temperatures, dynamic operating conditions, and initial SOC values. The results show that the average absolute error (MAE) and root mean square error (RMSE) of the power battery SOC estimation results are the smallest based on the FOMIUKF algorithm. Under different dynamic operating conditions, the maximum MAE of the power battery SOC estimation results using the FOMIUKF algorithm is about 1.04%, and the maximum RMSE of the power battery SOC estimation results is about 0.858 6%. This indicates that the accuracy of the FOMIUKF algorithm for power battery SOC estimation results is higher than that of the EKF, UKF, and FOUKF algorithms.

For secondary battery electrode materials, high-entropy design can achieve better structural stability, bulk electronic conductivity, and ion diffusion rate. The high-entropy modified electrode materials in lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), potassium-ion batteries (PIBs), and aqueous zinc-ion batteries (ZIBs) in recent years were reviewed. The constitutive relationship between superior electrochemical performance and high-entropy structure was analyzed. The current status of the development of high-entropy electrode materials and the challenges was systematically summarized. This paper also gave the insights into the design of high-entropy materials to provide a reference for the industrialization of high-entropy electrode materials for secondary batteries. The reference for promoting the industrialization of high-entropy electrode materials for secondary batteries was provided.

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.

With the increasing power demand of satellites, high-voltage and high-power equipment such as electric propulsion is widely used on satellites, which makes it difficult for the traditional 100 V bus electrical architecture to meet the increasing demand of satellites. This paper proposes a novel high-voltage conversion module for direct-driving Hall electric propulsion equipment. It adopts a two-stage circuit which can realize the functions of Maximum Power Point Tracking (MPPT), constant current charging for battery and bus voltage stabilization.

Accurately and real-time monitoring the internal temperature of lithium batteries is crucial for preventing thermal runaway. However, there is currently no effective method for online monitoring of the internal temperature of batteries. Therefore, in this study, a miniaturized impedance testing system is utilized to perform impedance testing experiments on lithium ion batteries at various temperatures and state of charge (SOC) levels. The influence of battery temperature and SOC on impedance is investigated, aiming to identify characteristic frequencies strongly correlated with temperature and weakly correlated with SOC. On this basis, a lithium battery internal temperature estimation algorithm is proposed using the Support Vector Regression (SVR) technique, enabling non-destructive and accurate estimation of the internal temperature without the need for additional sensors.

Lithium metal anode has become a research hotspot in the field of rechargeable batteries due to its extremely high specific capacity (3 860 mAh/g) and low electrochemical potential (–3.04 V). However, the instability of lithium metal can promote the formation of dendrites, and the uncontrolled interface reaction during charge and discharge can cause the generated solid electrolyte interphase (SEI) to be unstable, affecting the battery cycling life. By introducing artificial SEI (ASEI), the mechanical and electrochemical properties are improved. The goal is to prepare lithium metal batteries (LMBs) with long cycle life and high energy density. Polymers are highly flexible and capable of designing their structures to meet specific needs, making them ideal materials for artificial SEI. In this paper, the properties and functions of artificial SEI are summarized. According to the types and functions of different functional groups of polymers, the research progress of artificial SEI is summarized, and the future research direction and development prospect are prospected.

Solid-state lithium-ion batteries have the potential to surpass traditional lithium-ion batteries in terms of safety and energy density. As an important part of the battery, developing composite negative electrodes with high performance is of great significance. And the charge transfer ability in the electrode is key to preparing high-performance solid-state composite negative electrodes. Hard carbon has the characteristics of small volume change during cycling, which helps maintain the interfacial contact between active materials and solid electrolyte during cycling, and improves ion conduction in the electrode, thus achieving stable cycling. In this paper, hard carbon was used as the active material, and composite of lithiated Nafion (Li-Nafion) and Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) was used as binders as well as solid state electrolyte to prepare a hard carbon composite negative electrode for the first time. The irreversible capacity in solid-state composite anode was explored by electrochemical testing and XPS characterization. By adjusting the composition and structure of the electrode, the charge transfer ability in the electrode was improved. The composite negative electrode treated by pre-lithiation showed good rate performance and cycle stability at 70 ℃. The full-cell assembled with LiFePO₄ cathode and hard carbon negative electrode cycled at 70 ℃ for 400 cycles with an average coulombic efficiency of 99.80%. Moreover, the solid-state pouch cell assembled with pre-lithiated hard carbon composite negative electrode and single crystal LiNi_0.6Co_0.1Mn_0.3O₂ (NCM613) also cycle 30 cycles stably with an average coulombic efficiency of 98.51%.

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.

Long term peak shaving and frequency modulation of lithium iron phosphate energy storage batteries can lead to a decrease in electrode activity and a decrease in battery life. By conducting charging and discharging experiments on lithium iron phosphate energy storage battery modules under peak shaving and frequency modulation conditions, the relaxation behavior was analyzed, and the changes in relaxation voltage under different SOC, different charging and discharging methods, and different charging and discharging rates were compared. The voltage offset rate was proposed as an indicator to measure the voltage's recovery ability. The analysis of experimental results shows that the voltage recovery time of frequency modulation mode is greater than that of peak modulation mode, and the larger the current magnification, the longer the relaxation time. In peak shaving mode, after each charging and discharging cycle, intermittently soak for 540~660 s, while in frequency modulation mode, soak for 900~1 100 s after each cycle, which is beneficial for voltage's recovery.

The rapid development of renewable energy sources such as photovoltaic also brings great challenges to the frequency stability of microgrid system, in order to solve the frequency stability problems caused by the power imbalance between the source and load of microgrid, a two-layer multi-timescale frequency optimization scheduling model based on islanded photovoltaic microgrid has been established, and the optimal regulation of the system frequency has been considered comprehensively in terms of both system planning and operation, and a function of economic gain has been constructed in the upper-layer model. In the upper-layer model, a function with the economic return as the objective is constructed to optimize the long-term energy storage configuration of the microgrid system. In the lower-layer model, a multi-objective function with the operating cost and the root-mean-square of the frequency deviation is constructed to establish a day-ahead optimal dispatch model with the photovoltaic dynamic load shedding standby and the coordinated frequency regulation of the energy storage, and gold search algorithm is introduced to solve the double-layer multi-timescale optimization model, which gives the optimal energy storage configuration as well as the operating characteristics of each unit. Finally, the correctness and validity of the proposed model are verified by simulation example.

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.