Traditional iron/manganese-based cathode materials for sodium-ion batteries have attracted extensive and in-depth research because of their low cost, high theoretical capacity, and high operating voltage advantages. However, iron-manganese-based layered oxides undergo irreversible phase transitions in their crystal structures during charging and discharging processes, leading to rapid capacity decay and reduced cycling stability, which hamper their large-scale application and development. To address this issue, this study employed anion F^- doping and a metal oxide CuO coating to prepare a P2/O3 hybrid-phase Na_0.85Ni_0.3Fe_0.2Mn_0.5O_1.95F_0.05@CuO iron/manganese-based cathode material and investigated the electrochemical performance of the material at different coating temperatures. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS) revealed a uniform coating of CuO on the material surface. An ex-situ X-ray diffraction (ex-situ XRD) analysis showed no irreversible phase transitions during charging and discharging processes, maintaining a well-preserved crystal structure. Na_0.85Ni_0.3Fe_0.2Mn_0.5O_1.95F_0.05 @CuO-800 exhibited an initial discharge capacity of 122.7 mAh/g at 2.0—4.2 V, with a capacity retention rate of 72.62% after 100 cycles. At high charging and discharging rates, current densities of 5 and 10 C, respectively, the discharge specific capacities remained at 75 and 60 mAh/g after 200 and 800 cycles, respectively, with a capacity retention rate of approxiamtely 82%. The strong TM—F bonds formed by F^-doping combined with the uniform dense CuO coating layer maintained the stability of the crystal structure, suppressed the irreversible O2 phase generation, reduced the occurrence of side reactions between electrode materials and the electrolyte, and prevented the peeling of the cathode material caused by the dissolution of transition metal ions. This study significantly improved the long-term cycling performance of the iron/manganese-based cathode material under high rates; thus, it provided a basis for the design of iron/manganese-based cathode materials with high rate capability and long cycling stability.

Lithium sulfur batteries with merits such as high theoretical specific capacity and energy density have become a great potential power cell for next-generation secondary battery systems. Sulfur cathodes still suffer some problems such as poor conductivity and sluggish redox kinetics of polysulfide conversion reactions, which trigger a serious shuttle effect, ultimately resulting in low sulfur utilization, poor power density, and bad cyclability, thus hindering a further development of lithium sulfur batteries. Heterostructure composites with abundant active sites and superior catalytic activity can effectively catalyze polysulfide conversion. However, catalytic mechanisms of a heterostructure interface on polysulfide conversion remain poorly understood. This study investigates the heterostructure interface and its effects on absorption, the reduction/oxidation of lithium polysulfide with in-situ synthesized sphere TiO₂/TiN composites as models to solve the above scientific question. The formation mechanisms of a built-in electric field and the effects of the heterostructure interface on electrochemical performances of lithium sulfur batteries are investigated through absorption experiments, XPS, UV-vis spectroscopy analysis, galvanostatic charge-discharge, and cyclic voltammetry tests. The results showed that a space charge region and built-in electric field were formed at the interface between TiO₂ and TiN with electrons flowing from TiN to TiO₂. The built-in electric field improved the anchor ability of lithium polysulfides species, rapidly facilitated the Li⁺ transport, and promoted the conversion reaction between lithium polysulfides and Li₂S. The step-increased current densities charge-discharge tests revealed that TiO₂/TiN heterojunction composite-based lithium sulfur batteries delivered a discharge capacity of 1070 mAh/g at 0.05C, while maintaining a capacity retention of 60.7% at 1C. Cyclic voltammetry tests at various temperatures indicated that the reaction activation energy of lithium polysulfide to Li₂S decreases to 2.73 kJ/mol. It provides a new idea for designing composite cathode materials for lithium sulfur batteries and accelerating a further development of lithium sulfur batteries.

Graphite is an important anode material for lithium-ion batteries (LIBs), but its shortcomings in conductivity, theoretical capacity, and rate performance limit its application in these systems. Surface coating is an effective strategy for optimizing the electrochemical properties of graphite in LIBs. Currently, surface coating is widely used for the modification of graphite by using pitch-based materials as coating precursors, which can reduce the specific surface area and polarization capacity loss. However, the strategy underlying anode modification must be optimized considering the applications of next-generation batteries. In this study, the in-situ surface coating modification of graphite is carried out by using an N-heterocyclic conductive polymer as a coating agent for a gradient coating. Upon investigating the coated graphite, it was found that the coating using the N-heterocyclic conductive polymer on the surface of graphite can effectively improve its specific capacity as the coating amount is increased (Gr: 352.3 mAh/g; N-heterocyclic-coated graphite: 359.7 mAh/g). Moreover, the fast charging performance of graphite was significantly enhanced after coating with the N-heterocyclic conductive polymer and optimizing the coating quantity (at 1.2 C/0.05 C, Gr: 39.22%; N-heterocyclic-coated graphite: 50.97%), achieving a significant breakthrough as commercial anodes considering the electrochemical performance of LIBs. The characterization and mechanism analyses indicate that the coating modification by the N-heterocyclic conductive polymer provides surface conductive network and additional lithium-ion adsorption sites for graphite. This greatly contributes to enhancing the specific capacity and fast charging performance of graphite, and it can be used as an effective method for the surface modification of next-generation anodes.

Secondary zinc batteries represent a low-cost, environmentally friendly, and highly safe energy storage technology. However, the insufficient compatibility of zinc-metal anodes with traditional aqueous electrolytes and the growth of zinc dendrites have long posed challenges to their energy density and operational lifespan. Developing solid-state secondary zinc batteries presents a practical pathway to address this bottleneck. However, the high-charge density of divalent zinc ions renders solid-state zinc-ion conduction in conventional ceramic and polymer electrolytes at room temperature exceedingly challenging. In this study, we leveraged zinc trifluoromethyl sulfonate [Zn(TFO)₂] with an intrinsic layered crystal structure as the primary ionic salt framework. We reshaped the coordination environment of zinc ions by incorporating succinonitrile (SN), a bidentate, weakly coordinating ligand recognized for its soft base properties. We designed a new class of crystalline coordination compounds for zinc-ion solid electrolytes [Zn(TFO)₂(SN) _n ]. The co-coordination structure of the cyano group (—CN) and the trifluoromethyl anion (TFO^-) significantly reduce the electrostatic constraint of the anion framework to zinc ions, leading to three orders of magnitude improvement in the room-temperature ion conductivity (from 1.1 × 10^-9 S/cm for Zn(TFO)₂ to approximately 1.8 × 10^-6 S/cm). This solid electrolyte can support long-term zinc-plating/stripping cycles with low polarization voltages (0.08 V, 0.05 mA/cm²) and the reversible charging and discharging of a solid zinc-air battery at room temperature.

In this work, a flame-retardant gel polymer electrolyte was prepared using an in situ polymerization process. We introduced 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE) into an electrolyte system to improve the flame retardancy of the electrolyte. HFE can also inhibit the shuttle effect in lithium-sulfur batteries by adjusting the solubility of polysulfides. By comparing the flame retardancy and electrochemical performance tests of electrolytes without HFE (HFE-0) and electrolytes with different HFE contents, it was found that when the volume ratio of DOL, DME, and HFE was 1∶0.5∶0.5 (HFE-0.5), respectively, the gel polymer electrolyte demonstrated the best flame retardancy and electrochemical performance. Scanning electron microscopy (SEM) and electrochemical tests were performed to analyze and compare the electrochemical properties and lithium anode surface morphologies of lithium-sulfur and lithium-iron-phosphate batteries using HFE-0 and HFE-0.5 electrolytes after cycling. The results show that the lithium-sulfur battery with the HFE-0.5 electrolyte can maintain a specific discharge capacity of 706 mAh/g after 100 cycles with an 84.5% capacity retention rate at 0.1 C, and the cycling performance is significantly better than that of the electrolyte without HFE. In addition, the specific discharge capacity of the lithium-iron-phosphate battery with the HFE-0.5 electrolyte reached 117.2 mAh/g after 110 cycles at 0.2 C, indicating that the prepared gel polymer electrolyte can also be applied in these batteries. The designed flame-retardant gel polymer electrolytes with good electrochemical performances are useful for promoting the development and application of lithium-sulfur batteries.

As a typical conversion reaction-type anode material for sodium-ion batteries (SIBs), FeS₂, which possesses the merits of nontoxic, low-cost, and high theoretical specific capacity, has become a potential anode material for SIBs. However, owing to the large atomic radius and mass of Na⁺, the Na storage process of FeS₂ features sluggish kinetics, which hinders its practical applications. In this study, we synthesize FeS₂ with different morphologies through a solvothermal method. The morphology can be easily controlled by changing the molar ratio of Fe and S in the precursor. Characterization results reveal that as-obtained FeS₂ with different molar ratios of Fe and S presents an irregular spherical particle and a mixture of an irregular spherical particle and regular cubes. Furthermore, the Na storage performances of as-obtained samples were systematically investigated. FeS₂ with a regular cubic morphology reveals a superior Na storage performance. A reversible discharge specific capacity of 354.5 mAh/g can be maintained at a current density of 0.1 A/g. Long-term cyclic tests reveal that after 500 cycles, a discharge specific capacity of 246.3 mAh/g can be obtained, which is 1.2 times higher than that of the control sample. A Na storage mechanism analysis indicates that FeS₂ with a regular cube morphology presents a capacitive-dominated Na storage process, which promotes an enhanced rate capability and fast Na⁺ diffusion coefficient. This study can provide theoretical reference for fabricating high-performance anode materials for SIBs.

In this study, three systems of cathode electrodes were prepared using high-nickel, ternary-single-crystal and polycrystalline particles. The negative electrode employed high-first-efficiency and low-expansion silicon-oxide particles. Individual cells were fabricated through the stacking and injection of pouch-cell components. Three distinct formation processes were used to activate individual cells: high-temperature exposure, pressurization, and stepwise current formation. The fabricated cells demonstrated an impressive capacity retention rate of 95.3% after 500 cycles. The individual cells demonstrated excellent electrochemical performance with a discharge capacity of 23 Ah and an energy density of 269 Wh/kg at 2 C. Following 1000 cycles at 1 C and 2 C, the capacity retention rate reached 88.3%. After storage in a high-temperature chamber for 7 days, the cells exhibited a capacity retention rate of 95.7% with a capacity recovery rate of 97.4%. The fabricated batteries also exhibited outstanding rate capabilities, with a discharge capacity ratio of 83.3% at 10 C using a 1 C discharge capacity as the reference. According to national standards, the cell also successfully passed rigorous heating and external short-circuit safety requirement evaluations. Furthermore, by selecting six individual cells with high consistency and assembling them in series, a unmanned aerial vehicle (UAV) battery pack was successfully developed. The dimensions of the battery pack were 81 mm×183 mm×71 mm, weighing 1902 g with an energy density of 240 Wh/kg at 2 C. This design ensures reliable power supply for UAVs under various working conditions.

Silicon, which has high specific capacity and low voltage characteristics, is considered one of the most promising anode materials for lithium-ion batteries. However, the significant volume expansion of silicon electrodes during lithiation/delithiation processes, along with the associated material fracturing and pulverization processes, limits its rate performance and cycling stability. Existing studies have demonstrated that applying external loads to silicon electrodes during cycling can effectively enhance the cycling performance of silicon-based batteries. This study proposes a macroscopic control method by applying external mechanical loads to enhance the capacity retention of silicon-electrode lithium-ion batteries. We employed a custom-designed, in situ loading device connected with a battery cycling tester and CR2032 button cells as the experimental objects, and the effectiveness of this method was evaluated using cycling tests. The experimental results demonstrate that applying a 0.2 MPa axial external load on the surface of the CR2032 cells effectively suppress the expansion of the silicon electrodes during the charge-discharge processes and regulates the internal state of the battery. After 50 charge-discharge cycles, the capacity retention rate increases from 59% without external loads to 70%. Additionally, considering the different stress states of the silicon electrode active material particles during the lithiation and delithiation processes, we propose a novel control method by applying a 0.1 MPa external load during the lithiation stage and a 0.2 MPa load during the delithiation stage in the cycling process. The experimental results demonstrate that this method can further improve the cycling performance of silicon-based lithium-ion batteries. Moreover, the scanning electron microscopy imaging results of the electrode surface also support this conclusion. The method of applying external mechanical loads used in this study provides important insights for improving the performance of silicon-based electrodes in lithium-ion batteries from a macroscopic perspective.

With the introduction of the "Dual Carbon Goal," lithium batteries have taken on an unprecedented role in carbon reduction. The calendering process plays a vital role in shaping lithium battery electrodes, thus impacting their microstructure and mechanical properties, which significantly determine the overall battery performance. This study employs the discrete element method to investigate the impact of the calendering process on the microstructure and mechanical properties of lithium battery electrodes. The results show that as the calendering uniformity increases, the electrode porosity initially decreases linearly, and then it gradual decreases, deviating from a strictly linear pattern. The electrode density linearly increases, and calendering enhances the coordination between electrode particles. Furthermore, the internal stress in the lithium battery electrode increases exponentially during calendering, with the z-direction stress increasing faster than in the x- and y-directions.

During the operation of PEMFC for vehicles,the humidity inside a fuel cell stack is affected by the water generated by the reaction and the airflow. The working conditions of vehicles frequently change, resulting in frequent changes in humidity. Frequent humidity changes lead to a decrease in the system lifespan; therefore, the process of dynamic changes must be studied. A simulation model of a fuel cell cogeneration system was designed using MATLAB/Simulink, including stacking, and air, hydrogen, and cooling systems. Humidifiers use exhaust gas to humidify the air. The air compressor and exhaust valve control the parameters of an air system. This study also considers the speed and path change of the air compressor and relative time of three parameters (air compressor, tailgate valve, and current). In the condition setting, changing the current after the intake flow rate and pressure were completely changed to the target value helps to reduce the voltage overshoot, but it causes significant fluctuations in humidity, which adversely affects the system lifespan. Considering the reduction in the voltage overshoot and humidity fluctuations, during the dynamic change process, the speed change of the air compressor occurs before the current change, and the opening of the tailgate valve occurs slightly before the current change.

The motor is the fundamental component of the flywheel energy storage system that realizes electric-kinetic energy conversion. Its design characteristics of small size, large power, and medium vacuum operation environment lead to prominent temperature increases. The structural design of the water channel is crucial for enhancing heat dissipation. Starting from two aspects of flow characteristics and cooling efficiency, this paper compares the influence of the spiral channel, circumferential channel, and axial channel inlet and outlet pressure differences, heat transfer area, heat transfer coefficient, and other factors on heat dissipation. It considers all factors to determine the channel form of the motor as a circumferential channel. The heat dissipation of the motor and its components is crucial for the safe operation of the flywheel energy storage system. This is a critical scientific and technical problem that needs to be addressed in the development of the flywheel energy storage technology. Accurately calculating the rise in temperature is crucial to solving this problem, which is of great significance to the research on the thermal management of flywheel energy storage systems. In this paper, the finite element thermal simulation of a 40 kW flywheel energy storage system is performed, focusing on model simplification, key component equivalence, loss distribution, and other aspects. The temperature field simulation calculation of the motor is performed considering the heat conduction, convection, and radiation in the heat transfer process, the multi-physical coupling of the fluid and temperature fields, the initial water flow rate of 25 L/min, and the temperature of 18 ℃. Finally, the calculation results are compared with the test results, and the error is within 3%, verifying the accuracy and reliability of the simulation calculation. The calculation method is a reliable reference for designing flywheel energy storage motors in the future.

The integration and miniaturization of electronic components have aggravated the heat flux problem of chips. The passive cooling technology based on phase-change materials (PCMs) can no longer meet the requirements of high-power electronic devices with power fluctuations. This paper proposes a novel mini-channel phase-change heat sink structure for air-cooled heat dissipation by combining phase-change technology with active cooling technology. The structure improves the poor thermal conductivity of PCMs and resolves the leakage problem after PCM melting. The effects of different heat fluxes and air velocities on its thermal control performance are experimentally evaluated. The heat storage and release characteristics of hybrid heat sinks are summarized, and the thermal control performance is compared with that of unfilled PCM heat sinks. In the experiment, the heat flux is 1.81—3.47 W/cm² and the airspeed is 0—4 m/s. The result shows that an increase in heat flux and a decrease in air velocity shorten the temperature control time. The 2 m/s air velocity is sufficient to meet the heat dissipation demand with a heat flux of less than 2.91 W/cm². The 4 m/s air velocity can maintain the heat sink substrate temperature at 70 ℃ with a 3.47 W/cm² heat flux. Unlike the unfilled PCM heat sink, the heat sink proposed in this study can extend the temperature control time and reduce the steady-state temperature. Furthermore, opening the fan can effectively shorten the cooling time of the heat sink, which is crucial for the application of electronic devices that work intermittently. This study's results can provide a reference for the practical application of mini-channel phase-change heat sinks.

This paper examines the effects of different mass flow rates [G = 200—400 kg/(m²·s)], heat fluxes (q = 200—400 kW/m²), and system pressures (P = 5—7 MPa) on the flow and heat transfer characteristics of supercritical nitrogen in a vertical corrugated channel. The local heat transfer distribution characteristics and periodic average convective heat transfer coefficients are analyzed. The primary reasons for the differences between the vertical flow directions are analyzed using the field synergy principle and the buoyancy effect. The results show that the local heat transfer coefficient is unevenly distributed and fluctuates in the period. The periodic mean heat transfer coefficient better reflects the overall flow heat transfer characteristics of supercritical nitrogen in the flow channel. Increasing the mass flow rate can significantly enhance the heat transfer and weaken the influence of the flow direction on the heat transfer coefficient. Increasing the heat flux decreases the heat transfer coefficient in the flow channel and strengthens the influence of the flow direction on the heat transfer coefficient. When the system pressure is close to critical, the peak value of the heat transfer coefficient in the flow channel increases, and the differences in the heat transfer coefficients in different flow directions are slightly affected by the system pressure. The difference in the convective heat transfer coefficient in different flow directions in a corrugated channel is primarily caused by the buoyancy and field synergy effects.

A refrigerant hydrate cold storage is a new type of cold storage technology that reduces the peak valley difference in the power grid and improves the economic efficiency of air conditioning. A hydrate cold storage has a large latent heat of phase change and an appropriate phase change temperature, which can effectively overcome the shortcomings of traditional cold storage media. However, refrigerant hydrates have certain disadvantages such as long induction time and randomness. To promote the formation of the HCFC-141b refrigerant hydrate and improve the hydrate cold storage capacity, acid ether, nonionic surfactant polyoxyethylene stearate (SG-10), is selected as an additive to investigate its effect on HCFC-141b hydrate formation and the cold storage capacity. SG-10 can effectively promote hydrate formation, and the amount added determines its promotion effect. Experimental studies were conducted on the effects of four different mass concentrations of SG-10 on hydrate formation. Within this concentration range, SG-10 can further promote the dispersion of HCFC-141b in water, increase the contact area between the reactants, and accelerate hydrate formation. When the concentration is 2%, the stability of hydrate formation is good and the amount of hydrate formation increases and grows densely, making it the optimal addition amount for this system. Furthermore, the induction time for hydrate formation is the shortest (209 min), the cold storage capacity is the largest (approximately 212.7 kJ/kg), and the hydrate growth rate is the fastest [4.09 kJ/(kg·min)]. When the mass fraction of surfactant SG-10 increases to a certain value, it spontaneously associates to form micelles, which provide nucleation sites for hydrate formation. Introducing SG-10 in a solution to form micelle is an effective way of promoting hydrate formation.

Latent heat thermal energy storage technology based on hydrated salt phase-change materials (PSMs) characterized by high energy storage density and low cost, holds significant promise for widespread application in clean heating. In this study, we designed and constructed a packed-bed phase-change thermal storage system using sodium acetate trihydrate as the thermal storage material and cylindrical PSM encapsulation units as the fundamental building blocks. Through experimental investigations of the operational characteristics of the packed-bed thermal storage system, we explored the impact of the flow rate and thermal storage temperature on the charging/discharging duration, outlet temperature, thermal storage efficiency, and energy storage density of the system. The experimental results indicate that elevating the thermal storage temperature and increasing the flow rate can reduce the charging duration, enhance the thermal storage efficiency, and increase the energy storage density. The thermal efficiency of the storage system can reach 94.73%, and the energy storage density can achieve 71.77 kWh/m³.

Existing phase transition models artificially set the phase fraction to be linearly related to the temperature interval, failing to consider the influence of the temperature change rate on the phase transition process and resulting in a low prediction accuracy. In this study, to investigate the two-phase transformation law under the joint effect of temperature and the temperature change rate, a theoretical analysis of the phase change process is conducted and a solidification-melting kinetic model is established through the reversible reaction between the PCM components in the solid and liquid phases using the phase fraction as the key parameter. The Avrami equation was set as the reaction function in the model, and the Arrhenius equation was used as the rate function. Fatty acid phase change materials commonly used in the construction field (i.e., n-decanoic acid, lauric acid, and octanoic acid) were selected as experimental materials, and the Avrami equation was fitted and verified via isothermal crystallization experiments using the T-history method. After verifying that the Avrami equation shows a high degree of consistency and reliability with the data obtained from isothermal crystallization experiments, the thermodynamic characteristics of the phase-change materials at different temperatures and rates of temperature change were evaluated using non-isothermal experiments. The key kinetic parameters in the model were investigated and obtained in conjunction with the kinetic thermal analysis method. The results show that the activation energy and constant factor change via the same trend and exhibit a complementary relationship. Moreover, the activation energy and constant factor differ between different phase-change materials, and these changes vary depending on the phase transition process. The number of reaction levels decreases with increasing temperature change rate, and the number of reaction levels during the solidification process is generally larger than that during the melting process.

Sodium-ion batteries have attracted widespread attention due to their capacity and cost advantages. Carbon-based materials, represented by hard carbon, are currently the most used anode materials, but their limited theoretical capacity restrains the improvement in energy density for sodium-ion batteries. Antimony and bismuth are capable of reversibly alloying with Na⁺ and are highly promising anode materials owing to their high theoretical capacity, stability, and conductivity. However, due to the volume difference between different alloy phases, antimony and bismuth exhibit large volume expansion during sodiation/desodiation, which causes problems such as poor structural stability, destruction of the solid electrode interface (SEI), and continuous consumption of the electrolyte, limiting the industrial applications of these systems. This review summarizes the sodium storage mechanism, modification strategies, and methods for obtaining antimony- and bismuth-based metallic anode materials. At present, the modification strategies for antimony- and bismuth-based metallic anode materials mainly include fabricating nanostructures and composite materials. By building nanostructures, the particle size can be reduced, the particle morphology can be adjusted, and the strain can be reduced due to nano-effects. When using composite materials, alloy-based anodes can be can be combined with carbon-based and other materials to buffer volume changes using special structures such as core-shell systems. In addition, this review considers antimony bismuth alloy as an example to discuss binary alloy anodes. Finally, future research considerations such as the design of composite materials, development of large-scale manufacturing methods, and research on interfacial characteristics are proposed.

Lithium-ion capacitors represent novel power storage devices amalgamating the features of both lithium-ion batteries and supercapacitors. However, the sluggish dynamics of the lithium-ion capacitor's battery-type negative electrode, compared to the capacitor-type positive electrode, lead to a diminished power density and compromised cycle stability. Notably, porous carbon-based materials derived from metal-organic frameworks (MOFs) have emerged as a focal point in electrochemical energy storage research owing to their expansive specific surface area, porous structure, and exceptional chemical stability. This study analyzes the challenges associated with electrode materials of lithium-ion capacitors and elucidates the energy storage mechanism of lithium-ion capacitors. Subsequently, the influence of carbonization temperature and heat treatment time on the physicochemical properties of MOF-derived porous carbon-based materials is examined. Moreover, diverse products generated through the carbonization process are discussed. Furthermore, the advancements in utilizing MOF-derived porous carbon-based materials in lithium-ion capacitors are reviewed. Finally, the crucial role of composite or doping modifications with other carbon materials in improving the power and energy densities for anode materials of lithium-ion capacitors is emphasized.

In urban rail transit, trains frequently start and brake, resulting in high braking energy and large voltage fluctuations. Some lines experience serious problems with rail potential. The wheel energy storage device has high power, fast response speed, and long service life. It can collect and use regenerative braking energy on the DC side, with a good energy-saving effect and stable grid voltage fluctuations. Because of the connection of the flywheel energy storage device, it can achieve multi-point reflux and shorten the current reflux path, thus improving the potential of the steel rail. This article explains the capacity configuration method of flywheel energy storage devices for existing and new lines, considering factors such as space limitations in traction stations, the average peak power of energy storage devices, and energy-saving effects, and provides capacity configuration explanations for actual cases. To flexibly respond to the complex working conditions of subway lines with the control strategy of flywheel energy storage devices, five working modes are set up: energy conservation, voltage stabilization, grid voltage support, rail potential management, and emergency power supply. The application case of the flywheel energy storage device in engineering has verified that the flywheel energy storage device has a good voltage stabilization effect, with an average energy saving rate of 11.36%—17.28% and a full power response frequency of 31 times/h. Furthermore, the experimental verification shows that the flywheel energy storage device has an emergency power supply function.

To overcome the low thermal conductivity of PCM, a heat transfer enhancement approach involving metal foam combined with metal fins is introduced for tube-shell latent-energy storage units (LESUs). The metal foam is partially filled in the LESU to further accelerate the heat transfer process during energy storage. Various configurations of the metal foam are examined in this study. Based on the enthalpy-porosity method, the enhanced melting process of PCM using metal fins and foam in a LESU is numerically investigated. The dynamic melting process, temperature response, dimensionless heat storage capacity, and economical efficiency of the LESU with different configurations of metal foam are compared. The results show that metal foam is highly effective in enhancing the energy storage process in PCM systems as the melting time of PCM can be reduced by up to 85%. The filling position of the foam metal also plays a crucial role in the performance enhancement of this system. It is found that the optimal configuration of the metal foam is achieved by filling it between the tip of the fin, which is directed away from the heat transfer fluid, and the shell of the LESU. The thermal energy storage capacity per unit time in the LESU with an optimal metal-foam configuration 6.5-times that of an LESU without metal foam. Based on the optimal LESU, the variation of the liquid fraction of PCM under different heating temperatures are calculated and nondimensionalized. A fitting formula for predicting the melting process of PCM based on the Fourier number (Fo) and Stefan number (Ste) is proposed. This work furthers the development of solid-liquid phase-change thermal storage technology and provides guidance for the design of solar photovoltaic LESUs for application in plant factories.

Photovoltaic power generation has certain volatility and uncertainty, weather, seasons and other factors will lead to changes in photovoltaic power, the energy storage system needs to track, forecast and adjust in real time to maintain the balance of supply and demand, but volatility and uncertainty increase the complexity of control. Therefore, a new adaptive coordinated control method for distributed energy storage capacity is proposed. Calculate the reactive power loss of energy storage after a high proportion of photovoltaic energy is added, and set power constraints to ensure power stability. Based on this, the optimal voltage condition, the lowest access load and net power, and the optimal power adjustable range at the high proportion photovoltaic access point are taken as the regulatory goals, and the adaptive coordinated control of distributed energy storage capacity of high proportion photovoltaic access is realized. Experimental data prove that the proposed method has significant advantages in terms of control effect, and can realize efficient distributed energy storage control and ensure efficient photovoltaic output.

Peak shaving is an important operating condition for battery energy storage power stations, and battery cooling is crucial for the safe operation of batteries. This study investigated the liquid cooling technology of lithium iron phosphate battery packs under peak shaving conditions. First, the heat generation and liquid cooling of the lithium iron phosphate battery pack under actual peak shaving conditions were studied, and heat generation and liquid cooling models of the lithium iron phosphate battery pack under peak shaving conditions were established. Second, the liquid cooling model of the lithium iron phosphate battery pack under peak shaving conditions was optimized through a finite element simulation analysis. Finally, the liquid cooling was optimized by adjusting the flow direction of the cooling liquid and adjusting the flow rate. The simulation and experimental results showed that a reasonable setting of different cooling-pipe coolant flow directions can effectively improve the uniformity of liquid cooling heat dissipation. By comparing the simulated temperature cloud map and innovatively adopting the difference between the maximum and average temperatures, the superiority and inferiority of the uniformity of different schemes can be reflected. Although increasing the flow rate helped to cool down, when the liquid cooling rate reached or exceeded 2.0, the increase in the cooling effect was limited, but the energy consumption increased significantly. Through simulation results, the optimal flow rate range was proposed to be between 1.5 and 2.0. The proposed solutions have been experimentally validated and applied in for battery cooling in energy storage power stations.

Under the background of dual carbon, the comprehensive consideration of energy storage system capacity allocation method and operation strategy can help to improve the rate of wind and solar renewable energy consumption and guarantee the economic and safe operation of the system. In the planning stage of the energy storage system, this paper proposes an optimization configuration strategy for the energy storage system that takes into account operating costs for different wind-landscape collaborative consumption scenarios. Firstly, an objective function is established to minimize operating costs, including wind and light abandonment, as well as energy storage investment costs. Secondly, all system constraints are considered. Finally, the energy storage capacity is planned for different scenarios to reduce wind and solar abandonment and increase renewable energy absorption. During the energy storage system's operation stage, a double-layer operation strategy is proposed to address the poor state of charge (SOC) balance and implementation difficulties. In the upper layer, the optimal battery subsystem for charging and discharging is selected based on the SOC and charging/discharging capacity of the energy storage battery subsystem. In the lower layer, power is optimized with the goal of achieving SOC balance for the battery unit. Based on the AOE control configuration, the strategy is implemented by creating a configuration file using Excel. It has the advantages of low difficulty of use, simple writing, intuitive control process, high calculation and operation efficiency, which is of great significance for slowing down the aging of the battery, reducing the difficulty of realizing the operation strategy of the user, and effectively consuming the wind-scenery renewable energy.

For the thermal management system of a power battery using direct refrigerant cooling, the refrigerant flows and boils in the pipeline, and the pipeline is too long, resulting in superheated segments in the flow paths of the cold plate. These superheated segments cause the temperature difference between the battery packs and the poor temperature uniformity on the vertical side of the battery. In this paper, two cold plates with parallel serpentine flow path structures placed at the bottom of the battery pack were designed for a battery pack containing 48 square cells to improve the poor temperature uniformity caused by the single serpentine flow path. This paper compares the average temperature and temperature uniformity within the flow paths of three direct-cooled plates at the end of the discharge rate of 1C of a battery pack at an initial temperature of 30 ℃. The maximum temperature and the temperature difference of the battery packs under these three flow path structures are compared. The temperature uniformity of the battery packs with the three flow path structures is analyzed horizontally and vertically. Adding a small surrounded cold plate in the upper layer of the battery pack should optimize the temperature difference vertically. The results show that the bottom cold plate can control the maximum temperature of the battery pack below 40 ℃ and ensure horizontal temperature uniformity. However, the temperature difference in the vertical direction of the battery pack is too large. By adding a small cold plate on the top layer, the temperature difference in the vertical direction of the battery pack can be maintained below 5 ℃ throughout the entire charging and discharging process, thereby fulfilling the temperature control requirements.

New energy generation technology is gradually being promoted and applied in domestic and foreign markets with its low cost, low pollution, and low dependence. The energy storage system plays a role in transforming the form of electricity in new energy systems, affecting the efficiency and quality of power generation systems. However, in practical applications, there are difficulties such as low power density, imperfect mechanisms, and poor operating conditions. It is necessary to conduct research on the application scenarios, characteristics, and optimization profits of battery energy storage technology in new energy generation systems. This article reviews the latest battery energy storage technology at home and abroad, analyzes its technical characteristics and matching scenarios, and proposes optimization application strategies for it in new energy generation from a macro perspective, aiming to form a new energy power pattern that emphasizes both efficiency and safety, and considers green and efficient aspects.

The new energy microgrid provides an effective means to achieve self-sufficient and independent power supplies for military facilities. It also enables the sustainable and uninterrupted power supply for equipment and combat missions, which is a future development trend for military energy systems. The centralized power generation mode can be transformed into a local, flexible, and reliable sustainable power or energy storage system as the new energy microgrid can help alleviate power shortages in daily life and improve production in battlefield or territorial areas, thereby improving the overall energy utilization efficiency of these areas and reducing logistical pressure regarding power supply. The power generation mode of the new energy microgrid has been widely adopted in the field of military energy as it is unrestricted by time and space. The application of this system is rapidly improving through the accumulation of experience and technological advancements, which significantly influence strategic decision-making processes, combat deployment, and equipment effectiveness. However, unlike new energy microgrids for civil applications that operate in normal environments and working conditions, the operation and maintenance of new energy microgrids for military applications encounter a several challenges as they must often be used in extreme environments, complex working conditions, and under high-intensity damage. Therefore, training must be conducted to ensure the efficient operation and maintenance of these systems, and coping strategies for rapid responses and efficient disposal must be determined. Furthermore, the quality of relevant components and ancillary facilities during the construction process must be improved considering the conditions in which new energy microgrids might encounter during military applications, including grid graphite/carbon-fiber bombs, impact damage from explosive waves, electromagnetic pulse interference, grid viruses, drone intrusions, and other artificial interventions that may disrupt the balance of the grid. By improving the adaptability of microgrids to battlefield environments and other complex working conditions, the security, efficiency, and sustainability of these systems may be ensured while supplying energy to the battlefield. This paper provides a systematic review of the latest research on the operation, maintenance, and fault disposal analysis of solar energy, wind energy, and other new energy microgrid systems for military applications. Additionally, directions for the future development and construction of new energy microgrids oriented towards battlefield applications are proposed.

The noise voiceprint situation can extract a large amount of mechanical status information of energy storage transformers. The method based on voiceprint features and vibration signal shaping analysis is a more advanced means in transformer mechanical status detection. This article summarizes the operation and maintenance detection techniques of energy storage transformers based on voiceprint characteristics, combined with practical situations. Firstly, the research and development status of commonly used high-quality voiceprint vibration detection technologies at home and abroad were analyzed through examples. Then, the vibration model of energy storage transformers was divided from three aspects: winding vibration principle, iron core vibration principle, and iron core vibration under DC bias magnetization. Finally, various transformer feature diagnosis methods were summarized to achieve transformer problem detection.

Gravity energy storage has the advantages of high security, low cost, long life, no decay of stored energy, short construction cycle, and environmental friendliness, and it has broad application prospects in long-time large-capacity energy storage. However, the inherent power discrete and time lag characteristics of gravity energy storage lead to its poor performance when used in grid auxiliary services such as automatic generation control (AGC). To address this problem, this study proposes a hybrid energy storage optimization operation method to enhance the performance of ramp-type gravity energy storage AGC. First, the effects of power discrete and time lag characteristics of a ramped gravity energy storage on the tracking accuracy and speed of AGC commands are analyzed. Consequently, the configuration of the battery energy storage for gravity energy storage is proposed to construct a hybrid energy storage system and realize continuous and fast regulation of output power. The power optimization model of the hybrid energy storage system was established by considering the depreciation cost of the battery and the cost of the AGC deviation power penalty and by combining the safe operation requirements of gravity energy storage and the operation constraints of the battery energy storage. According to the operating characteristics of the hybrid energy storage system, a process framework for the optimization operation method was proposed, and a genetic algorithm for minimizing the AGC response cost was designed. The simulation results show that the optimized operation method proposed in this paper can significantly reduce the AGC response cost, thus solving the problem of poor AGC performance in ramped gravity energy storage systems.

Against the backdrop of promoting the "dual carbon" goals (carbon peak and carbon neutrality) globally, energy storage technology in the power system has become a key technology to support the transformation of clean energy and the safe and stable operation of the power grid. This article reviews the application and research progress of energy storage technology in power systems under the dual carbon background. Firstly, the article analyzes and summarizes the current domestic and foreign energy storage technologies under the dual carbon goal, including technical themes, energy storage demand, and clarifies the important impact of energy storage planning in power systems on the dual carbon goal; Then, the research reviewed the application and future development trends of energy storage technology in the power system. Finally, the current advanced hydrogen energy storage technology was explored, in order to provide certain ideas and references for the research of energy storage technology in the national power system.

Pumped storage power stations and new energy storage are essential technologies for peaking carbon emissions and achieving carbon neutrality, supporting the development of new energy power networks. Compressed air energy storage (CAES) uses compressed air to store energy and generate electricity. It is currently the most significant physical energy-storage method apart from pumped storage power stations. Hard rock shallow-buried CAESs, with flexible site selection in artificial air-storage caverns, have the potential for large-scale and commercial development. Considering the situation and requirements for developing and constructing large and medium-sized CAESs in China, combined with relevant research and practical experience, the basic design concept for the overall, local, cycling, and sealing stability of shallow-buried artificial air-storage caverns under hard rock conditions is proposed. The requirements for site selection and geological exploration requirements, burial-depth design, storage cavern layout, structural design, and sealing system design method are summarized. This study would provide reference and guidance for designing shallow-buried artificial air-storage caverns in compressed air energy-storage power stations.

As a device that can support efficient energy conversion and storage, energy storage equipment plays an increasingly prominent role in the field of power Internet of Things. In order to expand the application field of energy storage equipment, the effect of energy storage equipment in the field of power Internet of Things is studied. The main types and technical principles of energy storage equipment are analyzed, and it is pointed out that electrochemical energy storage equipment has great advantages in energy storage efficiency and safety. On this basis, the effect of energy storage equipment is analyzed from three aspects: improving power supply stability, optimizing energy utilization efficiency and improving power quality.

With the expansion of the scale of electrochemical energy storage power stations, how to improve the efficiency of system fault detection and diagnosis to achieve early prevention and treatment of faults has become a hot spot at home and abroad. Starting from the common faults of electrochemical energy storage power station, the variables and influencing factors of system faults are found, and then the detection indicators of system faults are determined. Then, according to the different types and regions of faults, appropriate detection and diagnosis methods are selected to minimize the harm caused by system faults and support the safe operation of electrochemical energy storage power stations.

Reviewing methods for predicting the lithium-ion battery state of health(SOH), we propose a battery SOH prediction method, which uses Transformer network based on Kalman Filter. Firstly, the battery data is preprocessed by adding Gaussian noise and auto-encoder reconstrution to remove the original noise from the data and strengthen the data features. Secondly, the battery data is extracted using the proposed (Kalman Filter-Transformer, KF-Transformer) model to extract the features of battery SOH changes, so that the Transformer network can better capture the nonlinear changes of battery SOH. Finally, the mapping from the features to the prediction of battery SOH is accomplished through the linear layer to obtain the prediction results of lithium-ion battery SOH. In this paper, three datasets (NASA, CALCE CS2 and CALCE CX2) are used for training and testing, and the two datasets use different temperatures and different batteries. The R² value of the predicted result in this paper is 0.987 and the mean absolute percentage error (MAPE) value is 1.8%, which is better than Multilayer Perceptron (MLP), Recurrent Neural Network (RNN), Long Short-Term Memory (LSTM), Gated Recurrent Unit (GRU). These results demonstrate the accuracy and stability of the proposed method for SOH prediction.

Fires and explosions of energy storage systems caused by the thermal runaway (TR) of lithium-ion batteries restricts the their use in the industry. A 280 Ah lithium-ion battery and 1P48S battery module were used as research objects to investigate the propagation behavior of the TR and the explosion risk of large batteries and battery modules used for energy storage in real-life scenarios. Moreover, experimental studies were conducted on the heat and gas production characteristics of battery cells, as well as the TR propagation characteristics of the module under the condition of thermal abuse. Based on the gas production results, the explosion risk in two typical energy storage application scenarios caused by TR propagation within the module was analyzed. The results show that the maximum temperature of the cell caused by the TR was 380.1 ℃, the total gas volume during TR was 156.8 L, and the explosion limit of the mixed gas was 6.9%—35.5%. The heat insulation plate installed inside the module effectively inhibited the TR propagation, six battery cells without heat insulation plates experienced TR, the highest surface temperature of battery cells exceeded 1200 ℃, and the TR propagation speed was in the range 0.162—0.233 mm/s, meanwhile the upper surface temperature of the module box reached 281.3 ℃. Six cells that experience TR in the module will lead to a high explosion risk in a container-type energy storage system; thus, the TR propagation should be controlled within two cells, but the process from venting to the TR of one cell in the module will lead to a high explosion risk in the energy storage cabin for commercial and industrial use. This research can provide a guide for the safe design of battery modules and explosion-proof design of an energy storage system.

To solve the low internal parameter identification accuracy and large charge state estimation error caused by complex working environments and the aging of lithium-ion power batteries, this study proposed a combined algorithm of a multi-innovation least squares method and square root cubature Kalman filter to estimate the charge state of lithium-ion batteries, and realized the state estimation of power batteries under multitemperature conditions during the its lifetime. First, to solve the low utilization rate of historical data by the traditional least squares method, the multi-innovation theory was incorporated into the least squares method, a first-order RC equivalent circuit was used to establish the battery model, and the internal parameters of the battery were identified by the multi-innovation least squares method. Subsequently, the SOC was estimated by the square root cubature Kalman filter. Finally, the effectiveness of the proposed algorithm was verified by comparing the experimental data of the multitemperature battery with that obtained using the extended Kalman filter and cubature Kalman filter algorithms. The experimental results showed that the proposed algorithm could accurately reflect the internal parameters of the power battery and estimate the SOC of the battery under the condition of the multitemperature lifetime. The average absolute voltage error was less than 40 mV, and the SOC estimation error was controlled within 2%.

The widespread application of lithium-ion batteries in new energy vehicles and energy storage presents challenges in accurately estimating their internal states, particularly the temperature within the battery core, which is crucial for thermal runaway prediction. This paper reviews classical sensor-less methods for battery temperature detection and introduces a temperature estimation approach based on electrochemical impedance spectroscopy (EIS). Moreover, this study investigates the influence of internal battery parameters on temperature estimation using EIS and analyzes the relationship between impedance magnitude, phase angle, and temperature for high-capacity ternary lithium-ion power batteries at different frequencies. A model for the online temperature estimation of lithium-ion batteries based on EIS is proposed, which achieves an accurate estimation of the internal battery temperature by analyzing the relationship between the magnitude of the impedance, phase angle, and temperature at different frequencies. The study indicates that a frequency point of 10 Hz is suitable for estimating temperature using impedance magnitude information, while a frequency point of 17.5 Hz is suitable for estimating temperature using impedance phase angle information. Within the range of -20 ℃ to 45 ℃, the maximum temperature estimation errors obtained when using the impedance magnitude and impedance phase angle are 3.79 ℃ and 2.69 ℃, respectively. Validation results demonstrate that the use of the impedance spectrum magnitude and phase angle information effectively estimates the true internal temperature of the battery. This study helps to improve the acquisition function of automotive BMS, which can be used to improve the management strategy of battery thermal management and thermal runaway.

With the rapid development of electric energy storage technology, the requirements for the operation safety and performance stability of energy storage equipment are increasing day by day. Voiceprint recognition, as a non-contact monitoring method, has shown great potential in the fault diagnosis of power storage equipment. This article delves into the research progress of data-driven applications in voiceprint recognition and monitoring diagnosis of power energy storage equipment. The article first analyzes the research progress of data-driven technology and common technology categories in the market; Then, based on data-driven analysis, the development of voiceprint recognition monitoring technology for energy storage equipment was analyzed. This includes techniques for collecting voiceprint samples from power energy storage equipment and processing voiceprint signals from power energy storage equipment. By relying on the final processed data, a recognition and diagnosis model can be established to achieve fault diagnosis.