Multiphasic interfaces can effectively inhibit the complex structural phase transition in layered transition metal oxide cathode materials containing sodium,thereby increasing cycle stability. Nevertheless, the design and manipulation of the multiphasic interface are intrinsically linked to the synthesis and calcination process of layered oxides. The O3/P2 multiphasic interface of the O3/P2-Na _x Ni_1/3Co_1/3Mn_1/3O₂ multiphasic cathode material can be controlled, and its electrochemical sodium storage performance can be regulated by adjusting the cooling process. It is found that natural cooling promotes the return of sodium ions diffused to the surface of the material during the high-temperature calcination period back to the bulk phase, forming a stable O3/P2 phase interface. Rapid cooling process, such as liquid nitrogen quenching, will prevent sodium ions from returning to the bulk phase, reducing the capacity of the multiphasic material. It is also not beneficial to forming a stable O3/P2 phase interface, which reduces the cycling performance. According to electrochemical impedance and cyclic voltammetry tests, liquid nitrogen quenching would increase the interface impedance of O3/P2-Na _x Ni_1/3Co_1/3Mn_1/3O₂, limit the diffusion kinetics of sodium ions, and reduce the diffusion coefficient of sodium ions. We attempted to establish a sodium ion diffusion equilibrium mechanism to describe the Na⁺ diffusion behavior and explain the impact of the cooling process on the O3/P2 multiphasic interface and bulk phase sodium content. Reasonable regulation of the cooling process during the cathode calcination process of layered oxide is crucial for constructing a stable multiphasic structure, inhibiting structural phase transition, and improving the electrochemical stability of layered oxide materials.

Sodium-ion batteries (SIBs) are promising energy storage devices because of their low cost and high safety compared with traditional lithium-ion batteries (LIBs). The electrochemical performance of the electrode material determines the whole battery's function. As sodium ion's radius is larger than lithium ion's, the ion embedding/removal is relatively slow, and the electrode material is prone to structural damage after multiple cycles, resulting in capacity decay. Therefore, high energy density and long-life electrode materials are the breakthroughs to achieve high-performance SIBs. Meanwhile, the battery energy storage mechanism and electrode reaction dynamics still need to be further explored. Given the above problems, designing advanced cathode materials to achieve a good match with the existing positive electrodes is one of the urgent problems to be solved in developing high-performance SIBs to improve the energy density and cyclic life of the battery. The TiO₆ octahedrons were connected to each other by corners or edges to form tunnel- and layer-structured sodium titanates (NTO). This open structure made NTO promising anode materials for SIBs. In this work, we compared the electrochemical behavior difference of P- and S-doped NTO as anode materials for SIBs. We found that phosphorus-doped NTO (P-NTO) had excellent electrochemical performance compared with sulfur-doped NTO (S-NTO); when it was used as an electrode for SIBs, it exhibited outstanding long-term cycling stability and rate performance. When the current density was high, up to 2000 mA/g, the P-NTO delivered a reversible capacity of 111 mAh/g. Even after 1300 cycles (500 mA/g), the electrode retained a capacity of 150 mAh/g. These excellent performances are mainly attributed to the open structure of NTO, and doping P drastically boosted the electron movement within the nanosheets.

In this work, a pouch-type lithium-ion battery was fabricated using LiFePO₄ as the cathode. Moreover, Li/graphite obtained by calendering a lithium metal sheet onto the graphite surface was used as the anode material. Four pouch lithium-ion battery kinds were designed with different thicknesses of lithium metal sheet. The influences of different thicknesses of calendered lithium on cell capacity, first-cycle coulomb efficiency, rate discharge, high- and low-temperature discharge, storage, and cyclic life were investigated. The experimental results showed that compared with lithium metal sheets with 2.5 and 7.0 μm thicknesses, the graphite anodes lithiated with 4.0 and 5.0 μm lithium sheets showed better capacity and cyclic performance, and the capacity retention rate was greater than 100% after 600 cycles. Among them, the lithium sheet thickness of 2.5 μm was too thin, leading to a low coulombic efficiency; the lithium sheet thickness of 7.0 μm was too thick, and the anode had obvious lithium precipitation, and the capacity faded too quickly. Based on this work, the degree of lithium replenishment of anode prelithiation (DLRP) and its theoretical calculation method are proposed to evaluate the optimal prelithiation range of calendering pre-lithiation method. This study will help promote the application of prelithiated graphite anodes and provide an experimental basis for developing high-specific energy lithium-ion batteries.

Lithium metal is an ideal anode material for lithium batteries for its high theoretical specific capacity and low electrochemical potential. However, the commercial application of lithium metal anodes is limited due to problems such as dendrite growth and volume expansion. Therefore, it is particularly important to design a rational three-dimensional framework for the cycling stability of lithium metal anodes.In this work, porous Copper-Indium/Bismuth (Cu-In/Bi) alloy frameworks containing lithiophilic sites were prepared by vapor phase dealloying based on the difference in saturated vapor pressure between various metals and Kirkendall's effect. Then, it was followed by the fabrication of composite lithium metal anodes (3D Cu-InLi-Li and 3D Cu-LiBi-Li) with pre-stored lithium for high-rate lithium-metal batteries by the molten lithium infusion. The samples were characterized by X-ray Diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy(EDS), and the effects of indium and bismuth alloys as lithiophilic sites on the electrochemical performance of the lithium metal anode were researched. The experimental results showed that the porous copper electrodes had a low nucleation overpotential and exhibited excellent cycling stability. Paired with the LiFePO₄ cathode, after 1000 cycling at 10 ℃, the reversible specific capacities of the composite lithium metal anode were 65.7 mAh/g (3D Cu-LiBi-Li) and 61.9 mAh/g (3D Cu-InLi-Li), respectively, significantly higher than that of the commercial lithium foil (55.7 mAh/g). Cycling tests at 10 ℃ showed that indium and bismuth alloys improved the cycling stability oflithium metal anodes.The present work has high application value in preparing lithium metal anode by vapor phase dealloying and molten lithium infusion.

The graphene sheets were anchored into three-dimensional porous foam materials with the in situ polymerization of phenolic resin, and their structures were optimized. Then, after the carbonization and doping tin dioxide, their lithium storage properties were studied. The morphology and crystal structure were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influence of different phenolic resin dosages on the morphology of three-dimensional graphene foam and tin dioxide-doped samples was studied. The results showed that when 0.1 g resorcinol and 0.2 g glutaraldehyde were used, the three-dimensional graphene foam with the best morphology could be obtained with high specific capacity and cyclic stability after carbonization. After doping tin dioxide, the charge-discharge specific capacity was further improved, and the charge-discharge specific capacity reached 360 mAh/g over 100 cycles.

In this work, the graphene/Si/SiO _x nanocomposites (G//Si/SiO _x ) nanocomposites were synthesized. The synthesis process was done via a facile in situ sol-gel reaction of triethoxysilanein and graphene oxide suspension and a subsequent thermal reduction reaction under H₂/Ar atmospheres. The Si/SiO _x nanospheres with a 100-200 nm size were randomly distributed between two-dimensional graphene sheets in G/Si/SiO _x nanocomposites, in which crystalline Si nanodots with an approximate size of 20 nm were integrated into the amorphous SiO _x matrix. The unique G/Si/SiO _x nanostructure could provide a synergistic effect for electron transport within the electrode, accommodating the Si nanocrystals' volume variation during cycling and leading to excellent electrochemical performance. Benefiting from the unique structural features, the resulting G/Si/SiO _x electrode delivered exceptional rate performance and a high reversible specific capacity of 722.45 mAh/g at a current density of 200 mA/g, which remained at 853.76 mAh/g after 300 cycles.

Lithium-sulphur batteries are receiving increasing attention in research into electrochemical energy storage technologies due to their higher theoretical energy density. However, long-chain polysulfides tend to dissolve into the electrolyte during charge and discharge, causing a "shuttle effect" that can impact the cycling stability of the sulfur electrodes and lithium-sulfur batteries. Based on first-principles calculations, this research investigated a two-dimensional boron antimony (BSb) monolayer to suppress the shuttle effect as an anchoring material for lithium-sulfur batteries. The adsorption process of Li₂S _n on BSb monolayer was systematically investigated by calculating the adsorption energy, physical and chemical adsorption, differential charge density, density of states (DOS), diffusion barrier, and Gibbs free energy of polysulfide on BSb monolayer. As the lithiation process proceeded, the adsorption energy of Li₂S _n molecules increased from 1.64 to 3.44 eV, effectively inhibiting the dissolution of polysulfides in the electrolyte. Chemisorption prevails at the early stage of the lithiation process, and chemical bonds can be formed at the Li₂S₆ stage, which ensures that higher-order Li₂S _n can be effectively adsorbed and suppress the shuttle effect. The calculation of the density of states showed that the band gap of the BSb monolayer is reduced from 0.51 to 0.24 eV after adsorption, effectively improving the conductivity. The optimal migration paths were obtained using CI-NEB method calculations. The good adsorption properties and electrical conductivity of BSb monolayers indicate their promise as anchoring materials for lithium-sulfur battery cathodes.

A graphite anode electrode material (SG/C) suitable for lithium-ion batteries was prepared using spheroidized tailings (spheroidized micropowder) of natural flake graphite as raw materials. They were purified, mixed with asphalt, isostatically pressed, carbonized, crushed, and underwent screening treatment. The effects of asphalt addition, carbonization heating rate, and carbonization temperature on the physicochemical and electrochemical properties of SG/C materials were studied using characterization methods such as field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), nitrogen adsorption isotherms, laser particle size analyzer, X-ray fluorescence spectrometer (XRF), and electrochemical methods. The results showed that under the optimized treatment conditions of 10% asphalt addition, 2 ℃/min carbonization heating rate, and 1000 ℃ carbonization temperature, the obtained SG/C-V2-1000 material exhibited the optimal electrochemical performance. Its first reversible specific capacity at 0.1 C magnification was 352.4 mAh/g, and its first Coulombic efficiency was 93.12%. The capacity retention rate after 400 cycles at a 0.2 C magnification was 79%, and after 200 cycles at a 0.5 C magnification, the capacity retention rate was 85%. This study provides the experimental basis for transforming spheroidized micropowders of natural flake graphite into high-value materials.

Hydrated salt thermo-chemisorption heat storage has attracted immense attention due to its low heat storage temperature, high energy storage density, long-term nondestructive storage, and clean and pollution-free characteristics. This study obtained hydrophilic modified expanded graphite (MEG) by modifying expanded graphite. And a composite heat storage material MgSO₄-LiCl@MEG was prepared by mixing MgSO₄ with LiCl using a mixed ball milling method. The optimal ratio of mixed salt was 9∶1, and four different ratios of MEG were used to prepare the composite heat storage materials. The water absorption rate of the composite was found to be higher than the theoretical value under the same salt content, indicating that MEG was added to effectively alleviate the caking of MgSO₄ and the solution of LiCl while improving the adsorption capacity. The desorption process could be completed within 120 min.The linear driven force (LDF) model was used to fit the adsorption kinetic constants of the composite, which were about 0.005 s^-1. The equilibrium water absorption of the composite increased with the increase inhumidity and decreased with the increase intemperature. The composite was characterized using scanning electron microscopy(SEM) and X-ray diffraction(XRD), showing that the mixed salt was physically bonded and dispersed uniformly in the flake pores of MEG. MEG10 showed the best performance of heat storage, where the heat storage density was 957 kJ/kg, the peak heat storage temperature was 115.2 ℃, the water absorption rate was 0.925 g/g, and the thermal conductivity was 2.07 W/(m·K), which was 16.97 times that of MgSO₄. After 40 cycles of testing, the heat storage density of MEG10 was only reduced by 31.2%, and the adsorption and desorption rates were reduced by 15.1% and 19.6%, respectively, indicating excellent thermal stability and adsorption and desorption performance. The mixed ball milling method significantly increased the salt content of the composite and served as a good reference for a long period and high-density heat storage technology.

This paper explores the effects of phase change temperature (16—30 ℃), the installation location of phase change materials(PCMs), and phase change ventilation on the energy consumption of 5G base stations from the perspective of optimizing the base station cabinet. This is done byfocusing on the problems of poor heat dissipation performance, high energy consumption, high overheating risk, and low cooling efficiency of 5G communication base stations. In Changsha, 20 phase change cabinet models integrated by different phase change temperatures and installation positions of PCMs and two ventilated cabinetmodels were designed. EnergyPlus software was used to simulate energy consumption under different models. The results showedthat the annual power consumption of the traditional base station was 3469.92 kWh. The temperature of the traditional base station cabinet on a typical day in summer showed a downward trend from the outer wall to the inner wall, and vice versa in winter. A traditional base station was in a heat-release state for 72.75% of the year. In designing the base station cabinet, more attention should be paied to the design of heat dissipation capacity in winter and the transition season, considering the optimization of summer thermal insulation performance. When the base station is added with PCMs, the outer arrangement is better than the inner arrangement. When the phase change temperature is 25 ℃ and the outside of the PCMs are arranged, the base station has the best energy-saving effect. The base station's annual power consumption can be reduced by 124.75 kWh, and its monthly energy saving rate in January is the largest, reaching 16.87%. On this basis, the base station adds ventilation, and the annual energy consumption of the base station is reduced from 3469.92 kWh to 2316.87 kWh, and the annual energy saving rate reaches 33.22%. The monthly energy-saving rate of the base station from January to April and November to December is more than 50%. Compared with the ventilation base station without PCMs, the energy-saving rate of ventilation with PCMs is the largest in December, reaching 17.78%.

With the popularity of smart electronics and electric vehicles, there is an increasingly urgent need for high-efficiency energy storage devices. Zinc-ion capacitors can provide ideal energy and power density by integrating the energy storage mechanisms of supercapacitors and zinc-ion batteries. So, they have become one of the most promising electrochemical energy storage systems. Compared with Li-ion batteries, ZICs have the advantages of low cost, high safety, and high theoretical capacity. However, their development is still in the infant stage, and poor capacity and decay seriously prevent industrialization. Therefore, at present, the exploration of electrode materials and energy storage mechanisms are still hot spots. The cathode material is one of the core components of devices, and its microstructure and properties play a crucial role in electrochemical performance. This paper describes the current research advances inporous carbon materials, structural carbon materials, transition metal oxides, and transition metal carbide/nitride as cathode materials. The preparation method and structural design of materials are introduced. Moreover, the energy storage mechanisms and electrochemical behaviors are emphasized, and the causes of performance degradation are discussed. Finally, the current challenges and future development of cathode materials are pointed out.

In light of the global carbon-neutral strategy, major economies worldwide have successfully put forward hydrogen energy development plans and targets, raising the development of hydrogen energy to a strategic level. The green and low-carbon hydrogen production by water electrolysis from renewable energy sources has gained unprecedented global consensus. The novel hydrogen production technology by anion exchange membrane water electrolysis (AEMWE) is developed based on the anion exchange membrane (AEM), combining a low-cost material system and flexible dynamic response characteristics, which holds great potential in large-scale application in the future.Futhermore, AEMWE hydrogen production technology has received widespread attention both in domestic and overseas in recent years and is close to commercial application. This paper focuses on the key materials of AEMWE hydrogen production technology, AEM, introduces the structural characteristics and physicochemical properties of the representative commercial membrane materials, and discusses the progress of the membrane electrode assembly (MEA) preparation process based on AEM. This paper also highlights the performance of various commercial AEMs in the hydrogen production process by water electrolysis, analyzes the influence factor on the MEA performance in water electrolysis, and evaluates the potential in the application according to the long-time stability performance. Finally, from the industrialization perspective, the article summarizes the technical difficulties for the key AEM materials as well as possible directions in the hydrogen production field by electrolysis, and expects to provide references for developing AEMWE hydrogen production technology.

The Carnot battery system is a large-scale physical energy storage system that stores excess power in the form of heat energy and releases it outward through the power cycle when needed. It is free from geographical environment limitations, coMPact, and efficient, and has broad prospects in peak shaving, valley filling, and long-term energy storage. In this paper, a 10 MWh-class Carnot battery system was designed based on positive/reverse Brayton cycle and phase change heat storage technology.A numerical modelwas establishedbased on Python 3.8, and the influences of pressure ratio, isentropic efficiency, working fluid Reynolds number, medium length to diameter ratio, and other parameters on the system performance were explored.The results showed that the round-trip efficiency of the system could reach 0.6 when operating under the conditions of a compression ratio of 10 and isentropic efficiency of 0.9, and the energy storage and power density reached 378.44 kWh/m³ and 203.58 kW/m³, respectively. The energy storage process of the two tanks was experimentally studied under different operating parameters. It was verified that the greater the working fluid pressure at the entrance and the greater the difference between working and room temperatures, the higher the system's energy storage and power density.

The adiabatic compressed air energy storage (A-CAES) system can realize the triple cooling, heating, and electricity supply. If the designed A-CAES system can supply matched cooling and replace the user's refrigeration equipment in the residential area community, the deducted investment of air conditioning equipment can be used to offset part of the energy storage system investment. Therefore, this shortens the static payback period of the energy storage system. In addition, off-peak power consumption can reduce the consumption of peak power resources by large-scale cooling equipment in the summer. In this research, an adiabatic compressed air energy storage system was constructed with a 5000 m³ tank volume and a 4.6—10.0 MPa tank storage pressure range. The system's cooling capacity was supplied to the user in the form of cold air produced by the ejector. The charging and discharging periods were simulated to analyze the energy output characteristics. The system configuration and operating parameters were analyzed and determined to maximize the cooling capacity in the cooling season and the electricity generation in the non-cooling season. The research results showed that the maximum cooling capacity of the system in the cooling season was 36.96 GJ, supplying 190 households. Compared with the compressed air energy storage trigeneration system to maximize economic benefits, the cooling capacity was increased by 287.76%. Regulating the preheating hot water flow could change the energy output ratio of the system to make the system match the changing energy needs of users. Under the maximum cooling condition, the recovery cycle of the system was 12.39 years. The system constructed in this paper aims to provide a new idea for applying an adiabatic compressed air energy storage system in refrigeration and a new method for large-scale cooling in summer.

Renewable heat-storge generation plant is a new type of generation system that combines renewable generation and thermalstorage to optimize the generation of the plant. It has the advantages of controllability, high efficiency, and clean generation. When the power spot market widely takes place in China's power industry, maximizing the generation revenue of renewable plants in the power market with varying generation prices becomes the most critical task for the generation company. This paper proposes capacity optimization of the thermal storage system for the renewable-thermal-storage generation plant. An optimization generation model of renewable-thermal-storage generation plants is established. Maximizing the plant'srevenue is the objective function of the model. The model considers a variable locational marginal price and renewable accommodation capability at the plant node of the transmission network. Charging and discharging schedules of thermalstorage are optimized as the variables to simulate the optimal generation in the power market with consideration of renewable generation profile, parabolic troughs characteristics, the heat-storage capacity, and their coupling behavior. Based on the optimization generation model, a two-stage evaluation model is designed to optimize the capacity of thermal storage system using the internal return rate as the economic benefit index. Finally, the case study shows that the proposed optimization method can find the optimal thermal storage capacity for the actual planning of the renewable project. In comparison with the conventional economic evaluation method, a method is innovatively realized in the paper for the optimization model and the planning method for the heat storage system. Renewable generation plants will most likely operate in the power market with varying market prices. Therefore, the method can provide an objective and accurate optimal plan of heat storage in a power market for generation companies and energy storage investors and ensure the investment return and reduce financial risk.

This study investigates the mutual primary frequency modulation between flywheel energy storage and thermal power systems. The frequency modulation model for a thermal power unit with a flywheel energy storage system is established, and the model is verified using real-world frequency modulation operational data. The study proposes that during operations with small frequency differences, only the flywheel can perform adaptive virtual droop control, which allows the flywheel to track the theoretical frequency modulation while maintaining the state of charge of the flywheel within a reasonable range. Furthermore, under conditions involving long duration or frequent frequency modulation in the same direction with large or small frequency differences, the thermal power unit can handle a large amount of basic regulation, while the flywheel is responsible for managing minor fluctuation. Additionally, the flywheel system can provide feedback and adjustments to facilitate fast self-recovery.

The dual-mode railway line realizes the crossline operation and interconnection between the 25 kV AC power supply system of the urban (suburban) railway and the 1500 V DC power supply system of the urban metro, which is an essential means to help the efficient and energy-saving operation of rail transit. However, the mode barriers between the dual-mode traction power supply systems restrict the efficient utilization of the system's energy flow, resulting in a large number of train renewable energy that is difficult to fully utilize; therefore, the electricity cost continues to increase. This paper presents a topology of the railway power conditioner (RPC) based on hybrid energy storage, taking the lowest electric cost of a dual-mode traction power supply system as the optimization objective. In addition, power balance, converter capacity, the capacity of the energy storage device, and state of charge were considered the constraint condition. With the charging and discharging strategy of the hybrid energy storage device and the power flow control method of the RPC port as decision variables, the energy-efficient regulation and control between the AC system suburban railway and the DC system subway was realized. The optimization results showed that compared with the existing dual-mode traction power supply system, the proposed scheme could reduce the power consumption and maximum power demand of the traction substation, and the total cost-saving rate was 22.64%, verifying the effectiveness of the proposed coordinated operation method.

The aluminum-air battery and lithium-ion battery are formed into a hybrid power system, and the advantages and disadvantages of different topologies are analyzed to determine the topology of the hybrid power system. The principle of the aluminum-air battery hybrid power system was designed, the selection parameters of the key components of the system were determined, and the test platform of the hybrid power system was made. A rule-based control energy management strategy was proposed to improve the efficiency and lifetime of aluminum-air batteries. The strategy primarily considers the state of charge (SOC) of lithium-ion battery and load power variation so that the aluminum-air battery discharges at constant power in the high-power range and the Li-ion battery operates at variable power. The effectiveness of the strategy is verified through experimental testing.

The advancement of UHS (underground hydrogen storage) technology offers a viable solution to the volatility and intermittent nature of renewable energy. In increasing hydrogen production, the UHS must inject cushion gas to increase formation pressure and inhibit formation water flow. Since studies on cushion gas in the aquifer are limited and qualitative, the mechanism model of the hydrogen storage reservoir is established using a numerical simulation method that considers the effects of cushion gas injection types, different combinations, injection volumes, and injection rates on hydrogen recovery. The results showed that the impact of cushion gas injection on hydrogen recovery in the first injection-production cycle was more obvious, and the methane scheme increased the hydrogen recovery by 18.41%. Carbon dioxide as a cushion gas may have a poor effect because of the methanation reaction. The hydrogen recovery decreases with the increase in molecular weight of cushion gas and increases with the increase in injection amount of cushion gas. Moreover, the injection of cushion gas can increase formation pressure and inhibit formation water flow, reducing the influence of gravity segregation and increasing hydrogen recovery. In the early stage of hydrogen storage, the reasonable injection of cushion gas is crucial for the operation of hydrogen storage.

The thermal management system of batteries is of great significance to the safe and efficient operation of lithium batteries. Compared with traditional thermal management technology, immersion cooling technology has obvious advantages in controlling temperature and energy efficiency. With the rapid development of electric vehicles and energy storage power stations, research on immersion cooling systems has gained increasing attention. This paper first systematically summarizes the five commonly used dielectric fluids, including electronic fluorinated fluids, hydrocarbons, esters, silicone oils, and water-based fluids, from thermal conductivity, viscosity, density, safety, environmental protection, and economy perspectives. Then, according to the battery system's operating temperature characteristics, the research progress of immersion cooling in low-temperature preheating, room temperature cooling, and thermal runaway suppression is reviewed in detail. There is still a lack of research on low-temperature preheating. Ambient temperature cooling can be achieved through single-phase liquid cooling or gas-liquid phase change cooling. Dielectric fluids with high flash points may be crucial in suppressing thermal runaway during the battery system failure. Finally, the current progress of this field is introduced, and the future development direction of dielectric fluids for lithium-ion battery immersion systems is proposed. Among them, electronic fluorinated fluids and synthetic hydrocarbons are relatively mature, esters and silicone oils are less studied, and water-based fluids urgently need to solve the electrical insulation problem. This paper can provide a reference for designing an immersion cooling system for electrochemical energy storage systems.

In order to improve the practicability of the electrochemical model and its applicability at complex temperature environments and solve the problem of difficulty in quickly and accurately estimating the internal state of lithium-ion batteries, a state-of-charge estimation method based on an improved electrochemical model is designed. First, the order reduction of the solid-liquid phase equation of the electrochemical model is solved using the finite difference method and Galerkin method to explain the real-time state of lithium-ion concentration in the battery. Simultaneously, the equivalent circuit model is integrated further, and two RC network structures are used to characterize the internal polarization process of the battery. The temperature-dependent characteristics are included to form a low-order ordinary differential system suitable for the state of charge estimation, realizing effective simplification and order reduction of the electrochemical model and saving the calculation cost. Then, to address the model uncertainty caused by model simplification and reduce noise interference, a square root volume Kalman filter was introduced to design a lithium battery state of charge estimation algorithm at full operating temperature. The results showed that the proposed state of charge estimation method based on the improved electrochemical model could accurately estimate the state of charge under different temperatures and complex working conditions, with a maximum error of less than 1.6% under diverse temperature settings.

Lithium-ion batteries are commonly used for their high energy density and long service life. This paper suggests a fault detection method for actual battery pack operation data to more accurately detect faulty batteries with safety hazards in the battery pack. First, considering the differences in battery pack consistency caused by faulty cells, the local outlier detection algorithm is used with sliding windows to diagnose faulty cells more accurately, while detecting the inconsistency of battery cells and capturing the evolutionary characteristics of cell inconsistencies. Cells only with inconsistencies and faulty cells with hidden dangers are distinguished based on evolution; meanwhile, the inconsistency degree of cells is graded. Second, the fault types of detected cells are diagnosed by an improved standard deviation algorithm. Features containing fault type information are extracted as input, and a malfunction coefficient is introduced to realize the amplification of fault features, distinguishing different fault types by combining judgment criteria and thresholds for different faults. Early internal short circuits can be diagnosed effectively. Finally, the proposed method is verified through real operating data of the battery pack. The analytical findings demonstrate the effectiveness and reliability of the algorithm proposed in this study.

The electric vehicle is the inevitable development tendency for the vehicle industry. In addition, lithium-ion batteries act as the energy storage unit of vehicles, which is worthy of being investigated carefully since its life span is related to the accurate estimation of parameters. Unfortunately, the precise estimation of lithium-ion battery parameters, such as state of charge (SOC), state of health (SOH), and so on, is so tough. Therefore, multiple factors will strongly influence the accuracy of conventional estimation methods, especially for estimating non-stable SOH degradation caused by relaxation effects when using lithium-ion batteries. Hence, conducting research on SOH with a new method is significant. In this paper, the research status of common estimation methods for lithium-ion batteries are reviewed first, and the corresponding advantages and disadvantages are analyzed subsequently. Then, the variational mode decomposition (VMD) theory is introduced, including constructing the variational problem, reconstructing the unconstrained variational problem, and multiple iterations. Subsequently, the Transformer model and recurrent neural network (RNN) are brought in, which are useful for disposing of the time-order information. Finally, the particle swarm optimization (PSO) algorithm is described, which is helpful in completing the optimization of neural network super parameters. According to the content mentioned above, a joint method may be proposed based on VMD and PSO for transformer neural networks and gate recurrent units (GRU), improving estimation accuracy. First, VMD technology is used to decompose the capacity information of lithium-ion batteries. The central frequency method is used to determine the decomposition state, which serves as a basis for valid interpretation of the original data information to avoid unreasonable decomposition affecting the prediction ability. Second, the particle swarm optimization algorithm is used to optimize the hyperparameters of the transformed neural network and the gated recurrent unit structure after adjustment. The transformed neural network uses linear layers instead of decoders for better application with time-series data. It retains the encoder to capture global features and internal correlations of the data, thereby improving the prediction accuracy of individual Transformers and their joint models. Finally, the Transformer and GRU are used to predict the main trend and the high-frequency subsequences, respectively. Once the results are merged, the accurate estimation of lithium batteries is accomplished. Simultaneously, the NASA database verifies the model's reliability, and models of multi-layer perception (MLP), RNN, and Gaussian function-GRU are compared with the model proposed in this study. Consequently, the results of predicting accuracy and fitting degree of regeneration phenomenon are better than those of single or joint models, and MAE and RMSE are less than 0.62% and 1.19%, respectively. In addition, the determination coefficient is bigger than 87.08%, indicating the validity of the combined Transformer-GRU model.

This study takes a large-capacity power station of lithium iron phosphate battery energy storage as the research object, based on the daily operation data of battery packs in the engineering scene of energy storage systems. First, the key parameters characterizing the voltage and temperature consistency of Li-ion batteries were analyzed according to the operating data of the battery. Second, the evaluation features that can effectively reflect the battery pack consistency were extracted. Finally, based on such characteristics, the consistency analysis of the energy storage power station was divided into two levels, and the consistency analysis algorithm was proposed for large-scale battery packs in the station. Furthermore, a screening algorithm was proposed for abnormal cells in battery packs based on density-based spatial clustering of applications with noise (DBSCAN) clustering. The results showed that the proposed algorithm could efficiently obtain the key electrical characteristics related to the battery pack consistency in the operation data of the energy storage power station. Moreover, it could accurately judge the battery pack consistency in the energy storage system and locate the single battery that may fail. This study is helpful in judging the consistent state of large-scale battery packs in engineering scenarios. It can also timely and accurately screen out abnormal single batteries to ensure the battery packs' safety in energy storage power stations.

Energy storage has attracted considerable attention as a key technology enabling the development of smart grids and energy transformation, with battery energy storage represented by lithium-ion batteries becoming one of the preferred storage carriers for large-scale energy storage. However, with the gradual increase in the scale of battery energy storage applications, new challenges and risks in the quality and safety of energy storage systems have emerged. The battery energy storage system is not yet mature as a complete electrical equipment product, and there is uncertainty in the overall safety and quality status of energy storage power stations, resulting in low utilization rates of many existing energy storage power stations. Due to the immaturity and continuous iterative development process of the entire equipment product, it is particularly important to conduct a comprehensive performance evaluation around the core component of lithium-ion batteries for energy storage to improve the application level of lithium-ion battery energy storage power stations at the current stage, guided by safe and high-quality applications. This research reviews the latest progress of domestic standards related to energy storage of lithium-ion batteries. It provides a detailed analysis of the core standard for lithium-ion battery energy storage and its role in industry development. Based on the evaluation of battery energy storage characteristics and research accumulation of testing technology, a comprehensive solution has been proposed for the full process testing and evaluation of battery energy storage, including testing type, evaluation level, sampling arrival, testing grid connection, and operation assessment testing. It is demonstrated through detailed analysis of each link that the scheme can achieve closed-loop management of the entire chain of energy storage equipment on the grid side, power supply side, and user side involved in grid operation, which is of great significance for enhancing the standardization level of the battery energy storage equipment before the operation, improving the operation reliability of the energy storage power station, and reducing the safety risks of the energy storage power station.

The environmental adaptability of energy storage equipment is severely hampered by high altitude and harsh natural circumstances. Lithium battery packs, as the core of energy storage equipment,require stringent thermal management due to high-temperature rise and temperature differences caused by large amounts of heat generation during operation. It is obvious that changes in altitude directly influence the thermal characteristics of the lithium battery pack. In evaluating the thermal characteristics of the energy storage lithium-ion battery under different altitude conditions by adopting a forced air cooling system, this research elucidated the specific effects of altitude on the battery system parameters, investigated the influence of altitude (0—4000 m) on the temperature characteristics of the battery, and then proposed an optimum scheme for the heat-dissipating structures at high altitude condition. The results showed that a change in altitude influences the thermal characteristics of the forced air cooling system by altering air parameters and fan characteristics. The temperature rise and difference of cells increase in varying degrees with altitude, and the rate of temperature increaseis relatively high after 1000 m. Under high altitude conditions, optimization of increasing the inlet area and fan speed decreases the temperature rise and difference for the system battery. This researchprovides detailed temperature regular and optimization references for future engineering applications of energy storage battery systems under high altitude conditions.

An ultra-thin homogeneous temperature plate was proposed as the target heat dissipation structure to improve the heat dissipation performance of a polymer electrolyte membrane fuel cell reactor. The calculation model of a hydrogen fuel cell reactor based on the uniform temperature plate was established using the theoretical calculation and experimental verification methods and explored the influence of the heat transfer coefficient of the evaporation section of the uniform temperature plate and the arrangement angle on the heat dissipation performance of the target battery reactor. The results showed that the average temperature and the temperature uniformity index of the target cell stack decrease with the increase of the convective heat transfer coefficient in the condensation section of the temperature homogenizer. The average temperature and temperature uniformity of the battery stack are better than those of the anti-gravity arrangement at gravity and horizontal arrangement angles. With an increase in load, the maximum average temperature of the target battery stack should not exceed 341.15 K, the temperature uniformity index must be less than 1.1, and the maximum temperature difference must be 4.1 K. The ultra-thin temperature equalizing plate can effectively dissipate heat from the target battery stack and has excellent temperature distribution.

Aqueous organic flow batteries have attracted more and more attention from researchers in recent years. This is due to their potential advantages, such as low cost and adjustable active molecular structure and properties. However, aqueous organic flow batteries face a wide variety of active molecules, unclear electrochemical reaction mechanisms, poor stability, and many side reactions of the molecules. In-situ characterization techniques, especially in-situ spectroscopy techniques, are essential for analyzing the electrochemical reaction processes and mechanisms of organic active molecules and optimizing the battery's internal structure. This paper reviews the research progress of a series of in-situ spectroscopy characterization techniques in aqueous organic flow batteries in recent years, focusing on the role of in-situ nuclear magnetic resonance spectroscopy in revealing the structural evolution of molecules during electrochemical reactions. The in-situ infrared spectroscopy characterizes the intermolecular hydrogen bonding between molecules and water, and the molecular structure changes during charging and discharging. The periodic changes of molecular signals in the in-situ ultraviolet spectroscopy can determine the stability of molecular electrochemical reactions, and in-situ electron paramagnetic resonance spectroscopy is used to calculate the free radical concentrations and reaction rate constants. In addition, combining several in-situ characterization methods is expected to achieve functional complementarity to gain a more comprehensive understanding of the battery's electrochemical reaction mechanism, the battery's operating state, and the reaction process of the active material on the electrode surface. Finally, we hope that the in-situ spectroscopy characterization techniques introduced in this article can provide valuable insights for researching aqueous organic flow batteries and further promote the development and application of battery technology.

The macroscopic-scale numerical simulation method can simulate solid oxide fuel cells (SOFCs) by coupling multiple physical fields. It has advantages in studying the internal mechanism and external output performance of SOFCs, providing a basis for the optimization design of cells. The gas flow uniformity inside SOFCs directly affects the battery's efficiency, and the thermal field distribution will affect the power generation performance and long-term stability of the battery. This paper summarizes the research progress of the influence of the internal flow channel and external manifold of SOFCs on the flow field, optimization of the traditional flow channel, and design of a new flow channel, and macroscopic-scale numerical simulation in heat transport and thermal stability. Furthermore, the research progress of macroscopic-scale numerical simulation in analyzing fuel efficiency, coupled multiscale model, and designing SOFC components and new structures are reviewed. The application of macroscopic numerical simulation methods in studying SOFCs is summarized and prospected. It is considered necessary to unify the evaluation criteria of SOFC structure design for quantitative comparison.

This bimonthly review paper highlights a comprehensive overview of the latest research on lithium batteries. A total of 4463 online studies from June 1, 2023, to July 31, 2023, were examined through the Web of Science database, and 100 studies were selected for highlighting in this review. The selected studies cover various aspects of lithium batteries, focusing on cathode materials including Li-rich oxides, LiNiO₂, LiCoO₂, and LiNi_0.5Mn_1.5O₄. Investigations into the effects of doping, interface modifications and preparation of precursors on their electrochemical performances and structural evolution during prolonged cycling are discussed. The methods for improving the cycling performances of Si-based anode focus on the interface modification. Great efforts have been devoted to construction of artificial interface, and controlling the inhomogeneous plating of lithium metal anode. Studies on solid-state electrolytes focus on the structure design and performances in sulfide-based, chloride-based, and polymer-based solid-state electrolytes and their composites. In contrast, liquid electrolytes are improved through optimal solvent and lithium salt design for different battery applications and incorporating novel functional additives. For solid-state batteries, the design of composite cathode, inhibition of Li dendrite and side reactions, and preparation of electrolyte film are studied. The works for lithium-sulfur batteries are mainly focused on the activation of sulfur and to suppress the "shuttle effect". In addition, this review presents work related to dry electrode coating technology, and the characterization techniques for lithium deposition, silicon evolution and lithium-ion transport in the cathode. Theoretical simulations are directed to the stress and conductivity distribution of composite cathode and lithium deposition. This review provides valuable insights into the advancements in lithium batteries, contributing to the overall understanding and progress in the field.

The development of energy storage technologies is still in its early stages, and a series of policies have been formulated in China and abroad to support energy storage development. Compared to China, developed countries such as Europe, the United States, and Australia have more mature policies and business models related to energy storage. Furthermore, their energy storage projects have better economic efficiency. Mature market rules and good economic performance are more conducive to the healthy and sustainable development of the energy storage industry. Comparing energy storage policies and business models of China and foreign countries, and analyzing the energy storage development shortcomings in China, has essential reference significance for developing the energy storage industry in China. This article first introduces the relevant support policies in electricity prices, planning, financial and tax subsidies, market rules, etc., in Europe, the United States, and Australia, and analyzes the pre-meter and post-meter energy storage business models in major countries. Secondly, this article summarizes the relevant policies introduced by China in energy storage planning, participation in the electricity market, financial and tax subsidies, mandatory new energy storage, and electricity prices. Moreover, it analyzes the business models of new energy distribution and storage, user-side energy storage, controlling frequency of thermal energy storage, independent energy storage, and other scenarios. Finally, inspiration is drawn for China's energy storage policies and market mechanisms by comparing energy storage policies and business models of China and foreign countries. It is proposed that China should improve and optimize its energy storage policies by increasing financial and tax subsidies, reducing the forced energy storage allocation, accelerating the progress of energy storage contribution to the electricity spot market, and increasing the types of electricity market services in which energy storage can participate.