This bimonthly review paper highlights 100 recent published papers on lithium batteries. We searched the Web of Science and found 6213 papers online from Dec. 1, 2023 to Jan. 31, 2024. 100 of them were selected to be highlighted. The selected papers of cathode materials focus on high-nickel ternary layered oxides and Li-rich oxides, and the effects of doping, interface modifications and structural evolution with prolonged cycling are investigated. For anode materials, silicon-based composite materials are improved by surface modification and optimized electrode structure to mitigate the effects of volume changes. Efforts have also been devoted to designing artificial interface and controlling the inhomogeneous plating of lithium metal anode. The relation of structure design and performances of chloride-based, sulfide-based and polymer-based solid-state electrolytes has been extensively studied. Different combination of solvents, lithium salts, and functional additives are used for liquid electrolytes to meet the requirements for battery applications. For solid-state batteries, the modification and surface coating of the cathode, the design of composite cathode, the interface to anode/electrolyte interface and 3D anode have been widely investigated. Studies on lithium-sulfur batteries are mainly focused on the structural design of the cathode and the development of functional coating and electrolytes, and solid state lithium-sulfur battery has also drawn large attentions. New binders and the dry electrode coating technology are developed for Li-ion batteries. There are a few papers for the characterization techniques of structural phase transition of the cathode materials and the interfacial evolution of lithium deposition, while theoretical papers are mainly related to the study of interfacial ion transport and the optimization of electrode structure.

The LiCoO₂ is a commercially successful lithium-ion battery cathode material; however, its actual capacity falls short of its theoretical capacity (274 mAh/g). Increasing the charging cutoff voltage can boost discharge capacity; however, the instability of LiCoO₂ under high voltage compromises its cycle life. This study aims to introduce an in situ co-doping strategy with Al-Y-Zr to enhance the cycling performance of LiCoO₂ at 4.53 V. The LiCo_(1-a-b-c-d)Al _a Zr _b Y _c Mg _d O₂ cathode material was synthesized using a high-temperature solid-phase method by mixing Al-Y-Zr-doped Co₃O₄, Li₂CO₃, and MgO in a specific stoichiometric ratio. The impact of in situ co-doping on high-voltage LiCoO₂'s cycling performance was investigated. X-ray diffraction revealed a hexagonal layered crystal structure before and after doping, whereas scanning electron microscopy confirmed the regulation of crystal particle size by the doping elements. Electrochemical impedance spectroscopy demonstrated that the co-doping of Al-Y and Al-Y-Zr effectively inhibits growth of R_ct value during cycle testing. Test results from coin and pouch cells showed that in situ co-doping substantially improves the cycling performance, with the latter displaying substantial pronounced enhancement. This study contributes to advancing the application of high-voltage lithium cobalt oxide cathodes. In addition, it provides an experimental foundation for research and development in high-specific-energy lithium-ion battery technology.

Metallized plastic current collectors (MPCCs) have attracted considerable attention from industrial researchers as MPCCs can considerably increase the energy density of batteries by reducing the thickness and weight of devices. Furthermore, polymer properties, such as insulation, heat shrinkage, and melting considerably increase battery safety. Understanding the properties and preparation methods of polymer substrates and MPCCs is crucial for the development of high-quality MPCCs and the promotion of the development of high energy density and high-safety batteries. Therefore, this review focused on the properties of commonly used and potential polymers and clarified the advantages of high-quality polyethylene terephthalate (PET)-and polypropylene (PP)-based MPCCs applied to lithium-ion batteries as well as their fabrication and operational challenges, including the dissolution reaction of PET, low adhesion between PP, and metal layers. We have proposed measures to overcome these drawbacks. This paper summarizes the principles, advantages, disadvantages, and strategies (magnetron sputtering, evaporation, chemical deposition and electrochemical deposition, etc.) for depositing metal layers on polymer surfaces to improve the homogeneity, consistency, and electrical conductivity of the metal layers on polymer surfaces. Finally, to improve MPCC availability in batteries, the directions of developing MPCC, including improving the metal-polymer interfacial bonding, safety, and conductivity of batteries, as well as functionalizing and refining MPCC elaborated.

Because of its high energy density and long cycle life, Li-ion battery is widely used in electronic products and electric vehicles. However, the formation of a solid electrolyte interface (SEI) film on the anode surface during the first charge and discharge of Li-ion battery permanently consumes the active lithium in the cathode material, which results in irreversible capacity loss, and further reduces the first coulomb efficiency. The results show that prelithiation technology can effectively improve the first coulomb efficiency of the battery. Among the many prelithiation technologies, the cathode prelithiation additive has the advantages of simple process, low cost and high safety, so it has a wide application prospect. In view of this, this review describes three classes of cathode prelithiation additives: Starting from the basic working principles of ternary lithium-rich compounds, binary lithium compounds and nano composite materials based on reverse conversion reaction and the key scientific problems restricting the development of the same, the research progress and the problems to be urgently solved in the aspects of the property optimization of cathode prelithiation additive materials and energy storage mechanism research in recent years are emphatically summarized. The importance of lithium supplement additive in compensating the first capacity loss is pointed out, and the development of this method is prospected. On the basis of summarizing the current research progress, the paper forecasts the future research ideas and development direction of the cathode prelithiation additive, and puts forward the further research on the synthetic conditions and modification strategies of the prelithiation additive. improving the environmental stability of the lithium supplement additive on the premise of not sacrificing the capacity or developing a novel electrolyte additive to solve the effect of residue or gas generation on the long cycle performance of the battery when the cathode prelithiation additive is first cycled. These strategies are expected to further promote the development of power ion batteries.

Cathode materials are vital for lithium-ion batteries (LIBs) because they determine their performance by directly affecting the energy density, cycle life, rate, and safety of these batteries. Olivine-type LiMnFePO₄ is a commercial LIB cathode material with good market prospects due to its high energy density, low cost, environmental compatibility, stability, and safety. However, the inherent shortcomings of LiMnFePO₄, such as low electronic and ionic conductivity, seriously hinder its large-scale commercial application in high-performance LIBs. Thus, improving the electron and ion conductivity of LiMnFePO₄ is an urgent problem to solve. This review comprehensively discusses the structural characteristics, synthesis methods, and the recent research progress in LiMnFePO₄ cathode materials. Improving the conductivity of LiMnFePO₄ cathode materials by surface coating, morphology control, and ion doping is discussed. Although these three modification methods can optimize the electron and ion transport path in the LiMnFePO₄ matrix, the problem of poor electronic and ionic conductivity is difficult to solve via a single method. To improve the comprehensive performance of LiMnFePO₄ cathode materials, this paper summarizes the current research progress and proposes future research directions for LiMnFePO₄. The modification strategy of combining carbon-doped heteroatom coating, control of the short b-axis morphology, and ion doping is considered an effective remedy for the poor electronic and ionic conductivity and can endow LiMnFePO₄ cathode materials with high capacity and high stability.

Hydrogen energy is expected to become the "ideal fuel" in the era of decarbonization; therefore, the discovery, development, and modification of high-performance hydrogen storage materials are critical to the development of solid-state hydrogen storage and hydrogen energy use. Magnesium hydride (MgH₂) has attracted significant attention as a solid hydrogen storage material because of its strong hydrogen storage capacity, abundant natural reserves, and environmental friendly characteristics. However, the high thermodynamic stability, slow kinetic performance, and inevitable agglomeration and coiling during magnesium-hydride cycling limit the large-scale production and practical application of magnesium-based solid hydrogen storage materials. In recent years, several studies have focused on the thermal and kinetic modification of Mg-based hydrogen storage materials, leading to numerous achievements. This review discusses the latest research on magnesium-based solid hydrogen storage materials and summarizes modification strategies, such as alloying, nanification, and introduction of catalysts. Considering the current problems, future development directions are proposed to provide reference and guidance for the research and development of high-performance magnesium-based hydrogen storage materials.

Sodium-ion batteries (SIBs) are considered one of the most promising technologies for large-scale energy storage because of their high abundance, uniform distribution, low cost, excellent low-temperature performance, and fast charging characteristics. The electrode material substantially influences the electrochemical performance of SIBs. Among the negative electrode materials, hard carbon (HC) is deemed the most suitable for SIBs owing to its low oxidation/reduction potential, appropriate specific capacity, environmental friendliness, simple manufacturing methods, and versatile applications. However, the practical application of HC in SIBs is hindered by insufficient initial Coulombic efficiency (ICE), resulting in excessive sodium consumption in the cathode of the whole cell. This limitation prompts a detailed exploration of key scientific issues contributing to the low ICE of hard carbon. This study systematically summarizes and analyzes the recent research progress to enhance the ICE of hard carbon-negative electrode materials for SIBs. Four methods are discussed: adjusting pyrolysis temperature, reducing defects, controlling pore structures, and catalytic control of carbon structure by metal atoms. This study aims to briefly introduce the three fundamental structures of hard carbon materials, namely, carbon interlayer spacing, defects, and pores, alongside the latest research advancements concerning the influence of these structures on sodium ion storage behavior. Furthermore, different HC-negative electrode materials' design concepts and commercialization progress are explored. Finally, this study analyzes and explores the development direction for SIB hard carbon-negative electrode materials.

Polyurethane type solid-solid phase change energy storage material can effectively improve the phase change energy storage capacity of asphalt, so as to reduce the temperature fluctuation while regulating the pavement temperature. Based on the above background, the influence of polyurethane-type solid-solid phase change energy storage materials on the temperature control effect of asphalt was studied. The classification standard of PCM was determined, and its energy storage principle and application were studied respectively. The characteristics of polyurethane solid-solid PCM were analyzed. On this basis, the boundary conditions of periodic heat storage were defined, and the energy variation rule of PCM was deduced according to the change form of cohesive energy density in the process of asphalt temperature regulation, so as to determine the influence of polyurethane type solid-solid PCM on the temperature regulation effect of asphalt.

Phase change energy storage materials have strong thermal storage and release capabilities and play an extremely important role in maritime logistics transportation. To ensure the smooth development of maritime logistics projects, research is conducted on the preparation and thermal properties of phase change energy storage materials. Starting from three different forms of energy storage, namely latent heat storage, thermochemical energy storage, and sensible heat storage, this paper analyzes the specific preparation methods of phase change energy storage materials, and based on this, further studies the thermal properties of phase change energy storage materials, and explores their application in maritime logistics.

Phase change energy storage materials are a new achievement in the development of modern energy storage professionals, playing an important role in multiple fields such as energy storage development, construction, and environmental protection. This article analyzes and summarizes the application of phase change energy storage materials in the field of energy-saving buildings, including the categories of conventional phase change energy storage materials, the modification and selection of phase change energy storage materials, and their typical applications in energy-saving building design. Research has shown that the compatibility between modern energy storage technology and the field of building environmental protection can effectively enhance the development perspective of related industries, with good market recognition and application prospects, and is worthy of deeper exploration and research.

Battery energy storage systems based on cascaded H bridges are prone to grounding faults between modules, and reducing such fault losses requires rapid and accurate determination of the fault location. The electrical characteristics of the fault are related not only to the location of the fault but also to the ground transition resistance. To rapidly and accurately locate the fault module under conditions of uncertain grounding transition resistance, we propose a fast fault diagnostic method based on the loss characteristic matrix. First, a zero-sequence equivalent circuit model is established, and then the zero-sequence current model is discretized. Finally, a fault diagnostic method is developed based on the loss characteristic matrix. In this method, the topological matrix describes the traversal information of the fault location and the transition resistance. The zero-sequence current is calculated based on the discretized model, and the difference between the calculated and measured results is recorded in the loss characteristic matrix. This study further confirms that the fault location has a unique optimal solution, and given an uncertain ground transition resistance, the deviation optimal solution still accurately locates the fault. Based on convergence, this paper also proposes an acceleration method based on optimization calculations. The experimental results show that the average position given by the proposed method errs by only 0.2 submodules, which means that the fault position is accurately determined when the grounding transition resistance is highly uncertain. In addition, the diagnostic speed was significantly improved.

Based on traditional virtual inertia and virtual sag control methods, and considering the characteristics of new energy output, we propose a new energy storage adaptive control strategy for primary frequency regulation using a reinforcement learning algorithm. Herein, reinforcement learning agent dynamically adjusts the output proportion of the energy storage participating in primary frequency regulation through the virtual inertia control method, responding to real-time fluctuations in system frequency and frequency difference change rate. Subsequently, energy storage primary frequency regulation adaptive controller calculates the output proportion of the virtual sag control method, thereby obtaining the total primary frequency regulation output command for the energy storage. Considering the inherent randomness of active power output in new energy stations, reinforcement learning agent learns from the output disturbances, which are influenced by wind speed disturbances through the wind turbine model in the new energy station. The proposed control strategy maximizes the distinct advantages of virtual inertia and virtual sag control methods before and after frequency regulation. It achieves an optimal combination of the two control methods, unlocking the full potential of energy storage in participating in primary frequency regulation. To validate the effectiveness of the proposed strategy, we constructed a regional power grid frequency response model in Matlab/Simulink. This model simulated extreme working conditions and actual operational scenarios of the new energy station. The simulation results confirm that the strategy can appropriately adjust the proportion of virtual inertial output and virtual sagging output during the frequency modulation process. This adjustment reduces the operation depth of battery energy storage, effectively mitigates frequency fluctuation caused by variations in new energy output to the power grid, and enhances overall frequency quality.

This study aims to examine the impact of temperature and humidity on the output performance of automotive fuel cells. To this end, we propose a temperature and relative humidity-current (TRH-C) model. This model accounts for three sources of water: electrochemical reaction, electroosmotic migration, and humidification and condensation. It reveals the pattern of current variations with temperature and humidity and provides a calculation formula for the electroosmotic migration coefficient characterized by water activity. To implement our model, we established a grid in COMSOL and introduced the TRH-C model, which was then calculated using the finite volume method. We then built a fuel cell test system and conducted experiments at operating temperatures of 60 ℃ and 70 ℃, and relative humidity of 50% and 100%. We compared the polarization curve obtained from the TRH-C model with the experimental data and analyzed the cloud map of current density and film water content distribution. Our findings suggest that the TRH-C model can accurately predict fuel cell performance. However, we observed that when the operating temperature is 60 ℃ and the relative humidity is 50%, the relative errors of voltage and power density (with a current density of 0.018 A/cm²) are the largest, at 3.674% and 3.696%, respectively. We also found that an increase in operating temperature results in a decrease in membrane water content, while an increase in relative humidity leads to an increase in membrane water content.

In this study, graphic user interface (GUI) features such as current distributions inside a stack, fluid resistance, heat loss of free convection in a steady state, stack compression load, and selection of fastening blots were studied. The proposed model allows researchers to conduct multidisciplinary calculations and preliminarily evaluate stack performance. The mesh current method was used to analyze the equivalent circuit diagram of a multiple sub-stack battery, and Kirchhoff's voltage law under the constant-current conditions was used to solve the corresponding mesh currents. This approach could be used to calculate the actual current passing through each cell, bypass currents in channels and accumulated bypass currents. The flow resistance of a battery was indirectly affected by flow channels, stack external pipelines, electrode parameters, and head pressure of a stack. An empirical correction was used to implement the Darcy friction coefficient of rectangular flow channels to mitigate the calculation error of a turbulent flow to lower than 10% and achieve accurate laminar flow. The pressure drop formula of the Darcy 3 K method was used to estimate the coefficient of fittings in a minor loss. The electrolyte flow-through distance, the electrode permeability and electrolyte viscosity were used to determine the flow resistance of an electrode. Because if considerable deviation from the formula for calculated permeability, this factor appraisal was altered by entering the actual measured value. The heat dissipation of a stack inside a container was considered as free convection with and without thermal insulation in the steady state. The required inputs consisted of stack geometric dimensions, thickness of the covered insulations, ambient temperature, and stack-inside temperature. An optimal cell model was depicted as a panel with embedded cover plates that was used to simulate the stack compression load. This force was used to eliminate panel warping to press seals into the sealing grooves to counteract the internal fluid pressure and material thermal expansion and subsequently complete bolt selection.

Although distributed photovoltaics (DPVs) are increasingly being integrated into power grids, the problems of daytime overvoltage and nighttime low voltage in the distribution the network persist, which affect network economy. To overcome this problem, a two-stage optimization operation strategy involving DPVs and energy storage systems (ESSs) was proposed. In the first stage of the strategy, the position and amount of charge and discharge of the ESSs were determined by calculating the voltage sensitivity of the node and the adjustable photovoltaic reactive power node. Next, the optimization operation model was established. The model minimizes the sum of dispatching cost of ESSs, power exchange cost, and network loss cost. The constraints of the study include the distribution network, node voltage, state of charge (SOC) of ESSs, and adjustable reactive power capacity of photovoltaic inverters. In this model, particle swarm optimization was used to devise the daily scheduling output strategy of DPVs and ESSs. Finally, the effectiveness of the proposed method was verified using a 31-node actual distribution network. The simulation results revealed that the proposed strategy can effectively solve the voltage violation problem through the cooperative dispatching of DPVs and ESSs. Thus, the operating cost of the distribution network can be optimized while ensuring voltage safety.

With the large-scale integration of new energy sources such as wind power and photovoltaic power generation, the requirements for power quality and voltage stability in distribution networks are becoming increasingly high. However, the integration of distributed power sources and energy storage devices into the power grid will have a certain impact on the distribution network. Reasonable utilization of energy storage devices is an effective means to improve the quality of power supply and reduce energy loss in the distribution network. In order to improve the operational efficiency and reliability of energy storage equipment, control strategies based on battery management systems, energy management systems, maximum power point tracking, predictive models, and energy recovery are particularly important. These strategies can ensure the normal operation of energy storage equipment, real-time monitoring, adjusting charging and discharging status, optimizing energy utilization, improving conversion efficiency, and achieving reliable energy supply. Due to the direct relationship between the normal operation of energy storage equipment in distribution networks and energy storage capacity, coordinating and optimizing the operation strategy and capacity of energy storage equipment in distribution networks is of great significance for promoting the development of energy storage science.

Limiting multiple energy conversions when recovering braking energy in hybrid electric vehicles is a new technical solution for the dynamic coupling of flywheel and powertrain systems. In these systems, the kinetic energy lost by a decelerating rear wheel can be stored in two forms: as electrochemical energy stored in the battery or as kinetic energy for the next acceleration. First, the energy-conversion characteristics of accelerating and decelerating vehicles are analyzed to deduce the conversion efficiency of electromagnetic couplers at mechanical and electrical ports under the rated state. Second, based on a system model established using Matlab and simulink, the power characteristics and energy characteristics of the system are discussed for a vehicle decelerating from an initial speed of 60 to 42 km/h. During deceleration, the output power of the electromagnetic coupler increases from 1.257 to 1.546 kW. The transmission power is about 1.14-1.41 times the rated power. In this process, 72.34% of the kinetic energy from the rear wheel can be directly stored in the flywheel, and 27.66% of the energy can be stored in the battery after being converted by the electric port of the electromagnetic coupler. Finally, we test the electromechanical composite energy storage system to verify the rationality of the system.

This study focused on air-cooling methods to address challenges associated with high temperature and consistent thermal distribution in battery packs with lithium-ion battery charging and discharging equipment. This study establishes a thermodynamic calculation model based on numerical heat transfer theory, which was validated through practical testing. By abstracting heat dissipation characteristics, two main factors influencing the thermal behavior of battery packs are identified. Various research schemes are devised to explore diverse tray ventilation structures and fan layouts. The study analyzes the effects of different tray vents, tray annular vents, fan locations, and fan quantities on the thermal characteristics of battery packs and the associated flow fields in lithium-ion battery charging and discharging equipment. Results demonstrate that rise in temperature during equipment discharge closely aligns with simulation data, affirming the accuracy of the thermodynamic model. While tray vents positively affect the thermal characteristics of the battery pack, their effect is somewhat limited. Notably, annular vents on the tray emerge as crucial contributors, enhancing turbulent kinetic energy and convective heat transfer on the battery surface. Optimal heat transfer is achieved when the fan directly faces the batteries, and the number of fans positively correlates with battery pack thermal characteristics. With six fans, the system meets the thermal performance requirements of the battery pack and improves overall energy consumption. The research results offer valuable insights for effectively managing the thermal characteristics of lithium-ion battery charging and discharging equipment.

Vigorously developing renewable energy and achieving a clean energy transformation are crucial for achieving carbon peak and neutrality. The demand for various energy storage technologies in power grid is increasing, with large-scale energy storage being a key technical approach for effectively addressing the challenges associated with connecting renewable energy to the grid. Pumped energy storage is a well-established, widely used, and high-capacity physical storage technology that serves as a benchmark in the field. Gravity energy storage has recently emerged as a widely recognized physical energy storage technology. It encompasses various types of technologies tailored to different application scenarios. This study aims to introduce slope gravity energy storage principles and structures, specifically focusing on installations based on mountain slopes and inclined mines. It meticulously classifies and elaborates on application scenarios and technical characteristics, encompassing technology types such as pumped energy storage based on mountain slopes, track-type gravity energy storage, and cable-type gravity energy storage. Subsequently, this study delves into a comprehensive review of the research progress and application of slope gravity energy storage across different categories. It provides an in-depth exploration of advantages and disadvantages associated with each technology type. Based on this analysis, we propose an enhanced slope gravity energy storage technology: slope cable rail gravity energy storage. This approach combines the strengths of slope track and slope suspension cable car gravity energy storage while addressing their drawbacks. Subsequently, this study summarizes current issues and outlines future slope gravity energy storage technology prospects.

Gravity energy storage technology, which relies on solid weights, is expected to become an important energy storage solution in the water-scarce areas of north and northwest China. Its independence from water, high efficiency, and flexible location make it ideally suited to meet the demand for energy storage technology in the large-scale renewable energy power grids. However, the nonfluidity and discontinuity of solid weights present challenges. The start/stop and load/unload processes involving these weights can impact both the mechanical transmission and power grid system, an important consideration in solid gravity energy storage. This paper introduces the research development and demonstration projects related to vertical gravity energy storage technology, based on vertical shafts and ground buildings, both domestically and internationally. It further explores the mechanical transmission technology of vertical lifting, horizontal transfer, automatic joint, generator/motor, and grid-connected control technology. Finally, this paper discusses the future development trends of vertical gravity energy storage technology. The research shows that although many technical schemes have been proposed for the vertical gravity energy storage system, there are still many problems to address. These include the rapid lifting and transfer, process control of start/stop and load/unload of heavy loads, grid-connected control, and energy efficiency improvement. As construction costs decrease, efficiency improves, and lifespan extends, the gravity energy storage system is expected to see commercially application in the future.

This article provides an overview of the application of smart energy computer technology in the field of wind and solar energy storage. A detailed analysis was conducted on the topology structure of the wind solar energy storage power generation model, including photovoltaic power generation model, wind power generation model, and wind solar energy storage model. Based on the model structure, this paper explores the application of smart energy and its core computer network technology in wind and solar energy storage, focusing on the perception layer and management layer architecture for the establishment of smart energy, and pointing out the specific components of each level. Finally, the future application prospects of smart energy technology in the energy storage industry were analyzed. It is certain that, relying on the idea of "Internet plus" and "Internet of Everything", smart energy, as an emerging soft power of energy storage system, will become more and more important and an important subject for the development of new energy and energy storage industry in the future.

Energy recycling technology in green buildings has important value in improving the quality of residents, increasing energy utilization efficiency, and maintaining ecological balance. This paper first analyzes the characteristics and design principles of green buildings. Secondly, specific analysis was conducted on technologies related to energy recycling, including renewable energy, water supply and drainage, and phase change materials. Through the comparison of various recycling technologies, the paper proposes that designers can flexibly choose recycling technologies based on the actual needs of buildings, and promote the long-term development of green buildings.

With the advancement of fuel cell stack technology for the development of higher power outputs, operational disparities among individual cells have become more apparent. Longevity of a cell subjected to prolonged poor operating conditions is markedly diminished compared to its counterparts, often becoming a decisive factor in determining the overall stack lifespan. Thus, to assess the effects of varied operational parameters on achieving uniform performance in high-power fuel cells, a comprehensive 110 kW, high-power fuel cell model was developed. This model encompasses a fluid network, fuel cell voltage, and fuel cell thermal resistance models. Subsequently, a steady-state test was executed to validate the fuel cell model, revealing that the error between simulation and test results remained within a 5% margin. Employing the model simulations, maximum deviation rate of voltage was utilized as the evaluation criterion to analyze the influence of three key operating parameters: operating current, cooling water flow rate, and cooling water inlet temperature on the voltage uniformity of the fuel cell. Thus, the simulation results indicate that the operating current exerts the most pronounced impact on the voltage uniformity of the fuel cell, followed by the cooling water inlet temperature, with the cooling water flow rate exhibiting the test influence. This study offers valuable insights for guiding the structural optimization design of high-power fuel cell engines and the formation of thermal management control strategies.

Life prediction for fuel cells is crucial to fuel cell health management, offering their operation and maintenance guidance. Advantages of a long short-term memory neural network (LSTM) and an unscented particle filter (UPF) algorithm are combined to enhance condition adaptability in life prediction and ensure accuracy. The proposed LSTM-UPF hybrid method is designed to predict fuel cell life under steady-state and quasidynamic conditions. Initially, experimental data used for model training is optimized and decomposed into high-frequency and low-frequency components using the discrete wavelet transform technique. The LSTM algorithm predicts these components, forecasting the long-term aging trend of fuel cells. Drift correction is then applied to refine the trend prediction results. The fuel cell's remaining useful life (RUL) is estimated using the UPF algorithm based on the long-term aging trend. Evaluation indexes, including prediction life end, life prediction error, confidence interval width, and RUL prediction error, are adopted to assess different life prediction methods. Comparative results demonstrate that the LSTM-UPF hybrid life prediction method yields RUL prediction errors of 4.1% and 3.4% for steady-state and quasidynamic conditions, respectively. Moreover, it exhibits more accurate RUL predictions, high-quality confidence intervals, and strong adaptability in both scenarios. This study enhances the accuracy and confidence level of fuel cell life predictions.

Research on the thermal runaway of lithium-ion batteries is crucial for enhancing battery thermal safety and reducing thermal incidents in new energy vehicles. This study focuses on thermal abuse and aging-induced thermal runaway issues in high-specific-energy 21700-type NCM811 lithium-ion batteries. Experimental research was conducted to explore the state of health (SOH) impacts on battery charging and discharging characteristics, and the mechanism underlying thermal runaway. The quantitative analysis covered battery aging characteristics and thermal runaway parameters, including triggering time, surface temperature, operating voltage, combustion characteristics, energy, TNT equivalent, and damage radius. The findings reveal that energy efficiency decreases with increasing aging cycles, and temperature rise during thermal runaway decreases with decreasing SOH. Notably, time required for thermal runaway triggering in aged batteries is substantially shorter. For example, a battery with 60% SOH triggered thermal runaway in 608 s, a 64.8% reduction compared to 100% SOH. Moreover, smaller SOH values correspond to weaker thermal runaway intensity and reduced mass loss after thermal runaway. During the thermal runaway process, peak temperature, released energy, TNT equivalent, and damage radius decrease with decreasing SOH. This indicates that thermal runaway damage in aged batteries is lower than in fresh batteries. The study results offer valuable insights for characterizing behavior, early warning systems, fire prevention, and control in the thermal runaway of full-lifecycle 21700 batteries.

We report the results of energy-storage experiments on a 52 Ah square Li-FePO₄ battery. A 400 W external heat source and 20.8—166.4 W (1—8 h rated discharge) discharge power were used to simulate the thermal conditions of the battery under working conditions. The battery surface temperature and voltage were measured during thermal runaway, and the key time points of thermal runaway were recorded to study how discharge power affects thermal-abuse-induced thermal runaway. The results show that discharge accelerates thermal runaway: the higher the discharge power, the earlier the thermal runaway starts. From nondischarge to 166.4 W constant discharge, the opening time of the safety valve is shortened by 23.4%, and the thermal-runaway-triggering time is shortened by 5.6%. At the same time, the release of energy in the four stages of discharge reduces the severity of the thermal runaway, and the three maximum thermal runaway temperatures and the maximum temperature increase during discharge are reduced by 9.0% and 53.3%, respectively, with respect to the nondischarge condition. In addition, discharge increases voltage fluctuations during thermal runaway. The time window for subsequent voltage drop shifts forward to the vicinity of the valve-opening time, which favors using voltage change as an early warning of thermal runaway. Overall, the discharge operation accelerates thermal runaway while reducing its severity. This paper thus provides a reference for the safe daily operation, and the design of a battery-management system for electrochemical energy-storage power plants.

The state of health (SOH) of lithium-ion battery batteries is a crucial parameter for battery management systems, playing a substantial role in ensuring reliable operation and extending battery lifespan. This study aims to introduce an estimation method based on convolutional Fastformer model to improve the accuracy of data-driven SOH estimation for lithium-ion batteries. Initially, voltage and current curves from various charging stages of the lithium-ion battery are extracted for each cycle. These curves are then transformed into statistical health features, providing insights into the battery's aging characteristics. The Pearson correlation coefficient is used to analyze the relationship between selected statistical features and capacity, facilitating the identification of highly correlated health features and the elimination of redundant ones. Based on the strengths of convolutional neural networks and the linear complexity of Fastformer neural network, our approach combines the feature extraction capability of the former with local information mining of health features. The Fastformer's multihead attention mechanism efficiently summarizes contextual information within lengthy sequences. Model training time is reduced by optimizing hyperparameters using an orthogonal experimental method. Finally, a publicly available dataset is used for comparative evaluations, pitting our approach against other models such as CNN, GRU, and RNN. The results validate the accuracy of the convolutional Fastformer model, with maximum mean absolute error and root mean square error at only 0.25% and 0.29%, respectively, and a relative error within 0.08%. These findings demonstrate the high accuracy and stability achieved by the proposed method for SOH estimation.

The combustion characteristics of an electric sports utility vehicle in a fire caused by thermal runaway of power battery was simulated. The ternary lithium battery was considered to be the ignition source. Furthermore, flame propagation during the combustion process was studied, and cockpit smoke analysis was conducted considering the influence of internal combustibles such as seats, door panel interior decoration, and tires on heat transfer. The results revealed that vehicle combustion caused by the battery pack can be categorized into three stages, namely heat diffusion in the battery pack, fuel combustion in the carriage, and full vehicle combustion. In the simulation, after approximately 35 s, visible flames appeared in the chassis and gradually spread over the vehicle. The speed of heat propagation from the chassis was greater than that of the backward spread. Furthermore, the fire process was accompanied by considerable smoke. The temperature of the vehicle was high at the bottom and two ends but low in the middle of the vehicle. The temperature of that of the car battery pack was the highest, followed by the front power cabin, and the temperature of the rear power cabin was the lowest. The peak heat release rate generated during the combustion process was 5100 kW, and the maximum temperature exceeded 800 ℃. Smoke analysis revealed that the smoke entered the cabin 15 s after the fire broke out and completely covered the crew cabin within 10 s, which threatened the safety of personnel. The combustion and fire characteristics and critical time nodes of electric SUV vehicles can help understand the thermal hazards of ternary lithium batteries and electric vehicles and can be used as a reference for designing personnel escape strategies and fire protection design.

Accurate prediction of the remaining useful life (RUL) of power batteries can avoid the risk of battery overuse, inform decision making on the secondary use of retired batteries, and improve the utilization rate of second-life batteries. We propose a method based on ensemble empirical mode decomposition (EEMD), gated recurrent units (GRUs), and temporal recurrent unit networks to reduce the dependence of RUL prediction accuracy on nonlinear features (this dependence is caused by noise and capacity recovery in the power battery RUL prediction task). GRU and temporal convolutional networks (TCNs) are integrated into the RUL prediction model for power batteries. First, the raw data are decomposed using EEMD, and the nonlinear features caused by noise and capacity rebound during power battery capacity decline are decomposed into high-frequency components. The main trends of the raw capacity data are decomposed into low-frequency components. Next, GRUs and TCNs are used to predict the high- and low-frequency components, respectively. Finally, the predictions are integrated using attention. The experimental results on the NASA dataset show that the prediction accuracy and the fitting of nonlinear features of the integrated model proposed in this paper are better than those of other single models and other models of the same type, with the maximum average absolute error and the maximum root-mean-square error within 0.52% and 0.74%, respectively, and the absolute error within one cycle period. These results prove that the proposed model produced more accurate predictions of the RUL than conventional models.

Enhancing natural convection inside a phase change material (PCM) improves the performance of latent heat storage (LHS) systems. To investigate the impact of eccentric arrangement in detail, a three-dimensional numerical model was established for the horizontal double-pipe LHS unit based on the enthalpy-void fraction method, and the melting process of the PCM in annular space was simulated using Fluent software. Analyses of the flow field, temperature, and liquid fraction contours during the melting process lead to the melting process being divided into three stages: the initial stage in which heat conduction predominates, followed by the concurrent action of natural convection and heat conduction, and the final stage in which heat conduction dominates again. The corresponding annular space of PCM can be divided into two regions, and a new evaluation parameter called the "eccentric area ratio" is proposed accordingly. The results showed that the optimal eccentric area ratio is approximately 16∶1 for the PCM stearic acid. The melting time decreases by 45.8% compared with that of the concentric structure, whereas the energy efficiency of the LHS unit decreases slightly. The optimal eccentric area ratio for other materials should be directly related to the ratio of the natural convection intensity to the heat conduction of the material. Combining the eccentric structure with fins further enhances heat transfer. The results show that the X-shaped fins perform best; the melting time decreases by 36.7%, 20.3%, and 7.1% compared with that of the smooth structure, helical fins, and cross-shaped fins, respectively.

Nanoparticles are typically added to molten salt to form nanofluids that enhance the thermophysical properties of heat storage materials. In this study, Fluent software was used to perform numerical simulations of the melting process of binary chloride salt (52NaCl-48CaCl₂, %) and its doped Mg nanofluids in a two-dimensional square cavity. Furthermore, the melting process of the molten salt in a square cavity and the influence of doping nanoparticles on the melting process of molten salt were analyzed. The results revealed that during the melting process of the molten salt and its nanofluids, heat transfer occurred in three stages, namely conduction, natural convection, and conduction. The addition of nanoparticles increased the heat transfer rate of molten salt and reduced the time of melting and phase change processes. The melting times of 1% and 2% Mg nanofluids were reduced by 11.34% and 19.92%, respectively. Furthermore, the solid-liquid transformation time 1% and 2% Mg nanofluids reduced by 33.3% and 43.0%, respectively.

The vanadium redox-flow battery (VRFB) offers the advantages of high security and long life, and has broad application prospects in the field of large-scale energy storage. High-precision battery models and accurate battery state-of-charge (SOC) estimation are important technical foundations for the practical application of VRFBs, and the main challenge that must be overcome for their large-scale application. This paper reviews the simulation model of VRFBs, the identification of model parameters, SOC monitoring with online estimation, and the factors specific to VRFB that affect SOC estimation. Two types of simulation models, an electrochemical model and an equivalent-circuit model, are introduced.The principles, advantages, and disadvantages of several equivalent-circuit models for VRFBs are analyzed and compared. This paper focuses on methods to monitor the SOC of VRFBs, including the ampere-time integration method, open-circuit voltage method, potential titration method, conductivity method, optical analysis method, and SOC online estimation method that are promising for engineering applications. The paper summarizes the techniques of offline and online identification of the model parameters of VRFBs and introduces the SOC online estimation method, which is based on the filtering and data-driven algorithms. To understand the specific factors that affect SOC estimation of VRFB, we focus on the transmembrane migration of vanadium ions, the negative electrode oxidation side reaction, the negative electrode hydrogen precipitation reaction, and temperature on parameter identification and SOC estimation. Finally, this paper summarizes the outlook for this technology and proposes possible research directions for modeling and SOC online estimation of VRFBs.

Hydrogen energy is crucial for achieving energy security and dual carbon goals, representing important directions of global new energy development. China's western region is rich in renewable energy sources, and green hydrogen production potential is large, but the energy consumption is mainly concentrated in the eastern region, resulting in a noticeable supply and demand mismatch. Research and development of "West-to-East hydrogen transmission" can effectively alleviate this resource mismatch in China and promote the development of a high-quality hydrogen industry. This study expounds on the necessity of implementing "West-to-East hydrogen transmission" and introduces various storage and transportation technology paths encompassing gaseous, liquid, chemical hydrogen storage medium, and solid and organic liquid. Comprehensive technical feasibility analysis and comparison are conducted across four aspects: technical characteristics, technical maturity, standard system, and market application. The proposed feasible technical paths to realize "West-to-East hydrogen transport" in the near, middle, and long term include chemical hydrogen storage mediums, liquid hydrogen, and pipeline hydrogen transport. Taking the transportation route from Jiuquan City in Gansu Province to Shanghai as an example, a supply chain model is constructed, including hydrogen production, medium storage, transportation, reduction, and distribution. Economic feasibility was analyzed and compared by calculating the comprehensive cost of the whole supply chain process. The comprehensive study shows that mature ammonia and methanol as storage and transportation media, respectively, are feasible in the near term. In the medium term, the development of a liquid hydrogen transport mode is advisable, while in the long term, constructing large-scale, long-distance hydrogen transport pipelines emerges as a viable strategy for realizing "West-to-East hydrogen transport" in China.

This study conducts a quantitative analysis on the technical and economic feasibility of pumped storage in typical provincial power grids using time-series simulations. Initially, we base our calculations on the future power planning data of a typical provincial power grid, examining the operational status of the power system for the entire years of 2025 and 2030. The results show that during certain periods of the year, the system experiences a tight power supply balance with a backup rate of less than 10%. This poses significant challenges to its adequacy and safety. Subsequently, we select two flexible regulation power sources, namely pumped storage and thermal power units, to compare and analyze the improvement of system power supply reliability and the economic quantification under the addition of these two new regulation power sources. Our findings suggest that, using the simulation results of the provincial power grid in 2030 as an example, configuring 12 million kilowatts of pumped storage and thermal power units can increase the annual standby rate of the provincial power grid system by more than 10%. This effectively addresses the issue of an insufficient system standby rate, thereby enhancing the system's supply guarantee capacity. Considering the environmental costs arising from changes in system carbon emissions, the annual comprehensive cost of improving the system's power supply level through pumped storage is lower than that of thermal power units at the same level. Additionally, it can positively influence the consumption level of new energy and reduce carbon emissions. Ultimately, we conduct a comparative analysis on the comprehensive economic benefits of pumped storage and lithium-ion battery storage in improving system power supply reliability. The results indicate that pumped storage has significant advantages in improving system power supply reliability and adequacy in terms of comprehensive economic benefits.

In the context of carbon-neutrality goals, constructing new energy systems is essential to guarantee China's energy security. As a core course in the undergraduate curriculum of energy storage, the course "Energy Storage and Integrated Energy Systems" has the essential characteristics of discipline intersection, knowledge-method integration, and technology coherence, which help to cultivate the energy-storage major. This paper uses this course as an example; it is based on the energy storage know-how of North China Electric Power University and the teaching experience garnered from two past classes. It focuses on the construction background, core features, framework content, characteristic highlights, and practical experience. It condenses the course features represented by the words "embedded, interactive, inquiry, digital, scenario, and iterative," and analyzes the objectives of the course and its capacity to transmit the core concepts of energy-storage science and engineering.

Energy storage is pivotal in promoting the development of clean and renewable energy sources, such as solar and wind energy. The establishment and personnel training of the energy storage science and engineering major provide solid support for the rapid development of the energy storage industry. This is crucial in achieving the "dual carbon" goals. Since Xi'an Jiaotong University launched the first undergraduate major in energy storage science and engineering in 2020, more than 60 universities have since followed suit. This rapid development trend clearly indicates that the establishment and personnel training of this major are experiencing a vigorous development stage. However, the energy storage science and engineering major encompasses knowledge systems from multiple disciplines such as power engineering, engineering thermophysics, electrical engineering, and materials science and engineering. This diversity brings certain difficulties to the major's establishment and personnel training. Despite several years of development, the professional establishment and personnel training model for this major are still under continuous exploration and improvement. Moreover, different universities have distinct curriculum systems and personnel training directions, each presenting its own characteristics. This article provides an overview of the curriculum system construction, personnel training direction setting, and energy storage teaching resources and platform construction in various universities offering the energy storage science and engineering major. It also consolidates experiences and ideas from different universities regarding personnel training in energy storage, providing a reference for others looking to establish and train personnel in this major.

Traditional liquid electrolytes fail to meet market demands in the rapidly advancing new energy vehicle industry. Solid electrolytes, boasting safety and energy density advantages, are the focus of future development. However, practical applications are hindered by inherent issues such as the poor interface performance of inorganic electrolytes and the low ion conductivity of polymer electrolyte materials. To address this, researchers have concentrated on composite solid electrolytes. These aim to combine the high ion conductivity and excellent mechanical properties of inorganic electrolytes with the flexibility of organic electrolytes that do not react with lithium metals. This study examines solid-state electrolyte trends for organic-inorganic composite lithium-ion batteries. It analyzes global and Chinese patent applications using Patsnap's database, comparing primary source countries and applicant status. The correlation between technical means and effects is also established. Patented technologies are analyzed across three dimensions: material composition (organic, inorganic, and additive), composite methods (physical blending, three-dimensional and multilayer composites), and specific preparation processes. The analysis indicates China's quantitative advantage in organic-inorganic composite solid-state electrolytes. However, applicants are dispersed, and technical protection mainly focuses on materials. Collaboration is recommended for comprehensive technical protection in upstream and downstream industries. Regarding technological direction, three-dimensional composite systems with a high inorganic phase content exhibit superior comprehensive performance. Moreover, from an industrialization perspective, polymer-filled inorganic particle systems may develop faster.

The technological innovation and process optimization of lithium and downstream power batteries have become an important force in improving the battery industry chain and accelerating the transformation and upgrading of the national economy. In the context of globalization, the battery industry is facing a stock cycle after capacity expansion. It integrates resource, production, product, and application ends, explores advantageous research and production modules, and strengthens the synergy effect of the industrial chain through deep cooperation. This article reviews the research results on the foundation and composite applications of the battery industry, grasps the international landscape of the industry, and proposes resource, technology, funding, and management cooperation based on vertical subdivision fields to build a good ecosystem for the symbiotic development of the battery industry chain.