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.

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.

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%.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Lithium-sulfur batteries (LSBs) are considered to be one of the most promising new battery systems due to their high theoretical energy density and low price. However, there are some problems in practical application, such as poor electrical conductivity, easy volume expansion and poor cycle stability. Metal organic frameworks (MOFs) are used for LSBs due to the characteristics of large specific surface area and high porosity, which can inhibit the dissolution of sulfur and improve the utilization rate of sulfur to achieve high cyclic stability of LSBs. Adding carbon materials with excellent electrical conductivity can improve the overall conductivity of the electrode. Therefore, the application of composite materials based on C/MOFs and their derivatives in LSBs cathodes has become a current research hotspot in LSBs. This article summarized some recent research progress on C/MOFs and their derivatives in LSBs cathode materials. The application of MOFs and their derivatives in LSBs electrodes was summarized and prospected.

The high potential generated by the cell reversal causes irreversible carbon corrosion damage to the microporous layer, which greatly shortens the durability of PEMFC. So the study of carbon corrosion in the microporous layer caused by the cell reversal has important scientific significance to strengthen the durability of PEMFC. In this study, four kinds of commercial carbon black with different degrees of graphitization were selected to prepare microporous layer, and their properties before and after high-potential corrosion were analyzed. The results show that increasing the graphitization degree of carbon black and decreasing its specific surface area, the degradation degree of physical properties such as surface hydrophilicity, surface morphology and pore structure of GDL after corrosion was alleviated, and the degradation degree of cell performance was also alleviated. The corrosion resistance of the four kinds of carbon black is acetylene black>XC-72>Ketjen Black> BP2000. The physical properties of GDL prepared by acetylene black has almost no degradation after corrosion, and the performance of cell has a lower degradation degree. This provides an important theoretical basis for developing excellent reversal tolerant anode microporous layer and improving the durability of PEMFC.

A state of charge (SOC) estimation method of lithium battery based on SABO-GRU- Attention (subtraction average based optimizer-gate recurrent unit-attention) was proposed. The subtraction average based optimization algorithm was used to adaptively update the hyper-parameters of GRU neural network, and SE (sequence and exception) attention mechanism was used to adaptively allocate the weights of each channel to improve learning efficiency. The University of Maryland battery data set was preprocessed to input voltage and current parameters, and lithium battery charge and discharge simulation experiments were carried out, and the lithium battery state of charge experimental platform was built for the charge and discharge experiments of energy storage lithium batteries. The lithium battery state of charge experimental platform was built for charging and discharging experiments of energy storage lithium battery. The results show that the proposed SOC neural network estimation model is obviously superior to LSTM, GRU and PSO-GRU models, and has high estimation accuracy and application value.

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.

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.

Compared with sulfide, fluoride as cathode material for thermal battery, possessing high theoretical discharge voltage and specific discharge capacity. Among them, the theoretical discharge voltage of NiF₂ cathode material is 2.96 V, and the specific discharge capacity is 554 mAh/g. However, due to the low intrinsic conductivity of NiF₂, the rate capability is poor, and the capacity attenuation phenomenon appears obviously at the current density of 1A/cm²; in addition, the actual discharge voltage of NiF₂ is much lower than the theoretical value. NiCl₂ cathode material has excellent rate performance, when it is combined with NiF₂ as additive, the polarization phenomenon of NiF₂ can be significantly improved under high current density, and the discharge time of thermal battery can be prolonged.

The efficient recycling and utilization of spent lithium-ion battery cathode materials aligns with China's new low-carbon development goals and promotes energy recycling. The capacity failure mechanism and pretreatment methods of spent lithium-ion batteries were introduced. The research status of traditional recycling methods such as pyrometallurgical recycling, hydrometallurgical recycling for the cathode materials obtained were analyzed. Direct recycling is the most ideal method for cathode materials of spent lithium-ion batteries. The characteristics of solid-phase regeneration, hydrothermal restoration, molten salts repairing, electrochemical regeneration methods were described, and the advantages and disadvantages of each method were summarized. Finally, the problems and challenges that recycling of spent lithium-ion batteries may face from multiple perspectives were discussed.

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.

The effects of the ratio of active substance (NCM811) in the positive electrode coating and the compaction density of the coating on the performance of the positive electrode were studied by using charge-discharge motor, AC impedance technology, SEM electron microscope technology and half-cell technology. Compared with 90% and 93.5% of NCM811 in the coating, when the ratio of NCM811 is 97.3%, the discharge specific capacity of the active substance is significantly reduced, which is due to the lack of conductive agent and strong ohmic polarization. When the ratio of NCM811 is 93.5%, the discharge specific capacity of the coating is the highest, because it has relatively less non-active substances and relatively high discharge specific capacity of active substance. When the ratio of NCM811 is 97.3%, the NCM811 particles appear pulverization after cycling, which is the result of the joint action of anisotropic stress and Joule heat. The compaction density of the coating increased from 3.325 g/cm³ to 3.675 g/cm³, and the discharge specific capacity of NCM811 increased at first and then decreased, which is the result of the joint action of ohmic polarization and electrochemical polarization. The cycle stability gradually improved, because rolling stabilized the internal structure of the coating, can resist anisotropic stress of active materials, and reduce the ohmic resistance of the electrode.

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.

In this paper, the crystal silicon cell was taken as the research object, and the fingers darkening area of the cell was analyzed. SEM scanning, EDS elemental analysis and oven simulation vulcanization acceleration were used to confirm that the fingers darkening was caused by silver vulcanization, and the influencing factors of this vulcanization phenomenon were analyzed. It is proved to be related to the sulfur content on the surface of the cell, the ambient temperature of the cell after packaging, and the packaging materials. The results show that the higher the sulfur content in the environment, the easier the cell is to vulcanize. The higher the storage or transportation temperature, the easier the cells are vulcanized; In the packaging materials, EVA foam as a whole is multi-layer porous structure, which can promote the occurrence of vulcanization reaction, and the surface of hollow plate is planar structure, which can inhibit the occurrence of vulcanization reaction. Vulcanization of the solar cell fingers will not affect the power performance and reliability of the modules. The analysis of this paper is helpful for the cell manufacturers to solve the problem of vulcanization, and help the component manufacturers in the encountering of a vulcanized module to analyze the modules performance.

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.

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.

MoS₂ is a typical two-dimensional layered material with grapheme-like structure, the thermal decomposition of high-purity MoS₂ can reach about 800℃, showing outstanding thermal stability. The supercritical water system is used to synthesis MoS₂, and its microstructure, thermal stability and discharge performance as a cathode material for thermal battery are analyzed. The results show that the flower-shaped MoS₂ can be prepared by supercritical water system, and the 1T- MoS₂ component can occupy 30.8% of the total crystalline phase. When used as the cathode materials of thermal battery, MoS₂ shows satisfied electrochemical performance.

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.

Aiming at the distribution of electrode surface current and cell surface temperature under the forward current injection condition of photovoltaic cells, the COMSOL Multiphysics simulation software was used to establish and analyze the three-dimensional model of photovoltaic cell. Through the numerical simulation of the carriers transport process of photovoltaic cells under the condition of large current injection, the distribution of carrier current density along the busbar was obtained. The simulation results show that the transverse current density at the edge of the fingers reaches the peak due to the transverse transport process of the carriers inside the cells. Moreover, the total current density concentrate on the direction of the busbar and the fingers. With the increase of the applied voltage, the surface temperature of the cell also increases, and the highest point of the surface temperature concentrates on the root of the secondary busbar. The maximum allowable forward voltage threshold is calculated theoretically.

Lithium metal has a great potential in the field of energy storage due to its high theoretical capacity. However, the lithium dendrites caused by the uneven deposition of lithium metal in lithium metal batteries, may cause battery short circuits and restrict their current practical application. Three-dimensional current collector, due to their high specific surface area and abundant lithiophilic sites, can control lithium metal deposition through kinetic principles, thereby reducing local current density and improving lithium ion transfer rate and metal nucleation rate. In this paper, the research progress of 3D current collector in lithium metal batteries including metal, carbon, composites and the modification of 3D current collector in recent years were reviewed, and some issues needed to be solved and future developments in the field were also discussed.

Taking 280 Ah lithium iron phosphate(LFP) battery as the research object, the discharge curve of the battery under the current rate of 0.5 C was measured in the standard environment. First, the battery was discharged at 0.5 C to the state of charge(SOC) of 30% and rested for 3 h to record the stable open circuit voltage(OCV). Then the battery was discharged from 30%SOC to 10%SOC at 0.5 C, meanwhile the test was interrupted after every single step of 2%SOC and rested for 3 h to record the corresponding stable OCV. Finally the SOC-OCV curve was obtained. The result shows that the SOC-OCV curve of the battery between 30%-10% is nonlinear, especially in the range of SOC at 24%-26% with a significant slope change. Therefore, polynomial fitting of SOC to OCV between 30%-10% theoretical SOC is performed, and the adjusted R-square of polynomial fitting is 0.996 5. Meanwhile the linear fitting of SOC to OCV between 26%-32% SOC is performed, and the adjusted R-square of linear fitting is 0.999 49. Both fitting equations are of desirable goodness-of-fit. The battery is charged to 100%SOC and then discharged to nearly 30%SOC in order to ensure the performance and the outgoing state of charge. The OCV of battery during standby period, the discharge capacity from 100% SOC to nearly 30% SOC and the total discharge capacity are recorded as OCV, C_y and C, respectively. On the basis of the relation between SOC, C_y, C and OCV, this study proposes two capacity prediction models based on the above mentioned fitting equations, then OCV and C_y are brought into the capacity prediction model to obtain the prediction capacity. The following conclusions are drawn from this study: the capacity prediction errors under the stable OCV after rest for 12 h were within ±1.5%; in the case of a short standby time, a correction factor of predicted capacity should be introduced to ensure the same level of prediction error; the prediction methods are feasible, and the prediction errors under two models are basically the same in the range of SOC selected.

Aiming at the problems of single extraction of health features(HFs) and low estimation accuracy in the process of state of health(SOH) estimation of lithium-ion batteries, a SOH estimation method of lithium battery based on charging stage data and grey wolf optimization (GWO) algorithm-bidirectional long short-term memory(BiLSTM) neural network is proposed. Firstly, five types of HFs are extracted from the data of battery charging stage. Then, kernel principal component analysis(KPCA) was used to obtain the key health factors of HFs. Finally, the GWO-BiLSTM model is used to dynamically model the mapping relationship between key health factors and SOH, and the SOH estimation of lithium battery is realized. The NASA battery aging data set is used for verification. The results show that the proposed method can accurately estimate the SOH of lithium battery, and the root mean square error is kept within 1%, which has high estimation accuracy and robustness.

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.

At present, the liquid cooling heat exchange technology of power battery is mature, and the liquid cooling plate heat exchange is a common liquid cooling heat exchange type, which directly affects the heat exchange performance of power battery. The development of liquid cooling plate heat exchange technology was analyzed, and based on its heat exchange principle, the research status of the liquid cooling plate heat exchange technology of power battery was analyzed from four aspects, including the structure type of liquid cooling plate, optimization of flow channel size, coolant medium and manufacturing technology of liquid cooling plate. It’s found that the new type of liquid cooling plate has high heat transfer performance, but its complex structure makes it difficult to manufacture. The optimization of flow channel size of liquid cooling plate can improve the heat exchange efficiency and save the system energy consumption. The ethylene glycol solution is a common coolant medium at present, and some high-performance new energy vehicles use nano-fluid coolant. The liquid cooling plate manufactured by stamping and brazing technology is widely used for new energy vehicles.

Nickel fluoride, as a new type of cathode material for thermal batteries, has the advantages of high voltage plateau, high theoretical specific capacity, and good thermal stability. However, the poor ionic conductivity characteristics inherent in NiF₂ cause its unsatisfactory actual discharge performance. Eutectic salts are common positive electrode additives, which can reduce the diffusion resistance of electrolyte ions on the surface of NiF₂ positive electrode materials by utilizing their high ion conductivity characteristics in the molten state, thereby improving electrochemical performance. In this paper, it is demonstrated that LiF-LiCl-LiBr eutectic salt additives can significantly enhance the discharge performance of NiF₂ cathode through microstructure analysis and electrical performance tests. By adjusting the addition amount of LiF-LiCl-LiBr eutectic salt, the stable output electrical performance of NiF₂ anode material under the condition of 500 mA/cm² was realized.

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.

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.