Anode materials are crucial components of Na-ion batteries, responsible for storing Na ions and influencing battery performance. Tin-based alloy anodes offer suitable potentials and high theoretical capacities but suffer from significant volume expansion during sodiation, which leads to particle pulverization, loss of electrical contact, unstable solid electrolyte interface (SEI) formation, and poor cycling stability. This review analyzes recent literature on tin-based alloy anodes in Na-ion batteries, including pure tin, tin-carbon composites, tin oxides, sulfides, selenides, and phosphides. Common causes of capacity degradation and corresponding modification strategies are elucidated. A comprehensive analysis indicates that strategies including nanostructuring the active material, controlling the phase transition process, designing the active material structure, modifying conductive carbon and binders, designing composite structures for inactive materials, optimizing the electrolyte, and employing high-loading tin foil anodes can effectively enhance specific capacity, areal loading, rate performance, and cycling stability. These strategies provide rational approaches for developing stable, high-rate, and high-energy-density tin-based alloy anodes for future Na-ion battery applications.

Lithium sulfide (Li₂S), as a critical precursor for synthesizing high-performance sulfide solid electrolytes, forming the foundation of the industrial development of sulfide-based all-solid-state batteries (ASSBs). Achieving a deep understanding of Li₂S's key physicochemical properties, alongside advancing high-quality, cost-effective, and scalable fabrication techniques, is strategically significant for the sulfide ASSB industry. This study elucidates the central role of Li₂S within the technological framework of ASSBs, emphasizing its core physicochemical parameters, key performance metrics, and their critical impact on industrial applications. Five promising synthesis methos are systematically reviewed from an industrial feasibility perspective, including direct sulfurization of metallic lithium, carbothermal reduction, hydrazine hydrate reduction, liquid-phase metathesis, and hydrogen sulfide neutralization. A multidimensional evaluation framework is constructed to compare these techniques across several dimensions, such as process characteristics, product performance, safety risks, and economic viability. This analysis identifies the key bottlenecks restricting the industrialization of Li₂S and proposes targeted strategies for optimization. Potential future directions in large-scale production technologies are also outlined. This study aims to serve as a valuable reference for the industrial production of Li₂S and its efficient integration into sulfide-based all-solid-state batteries, thereby facilitating technological advancements and cost reductions in sulfide solid electrolyte systems.

Zinc (Zn) powder has emerged as a promising anode material for aqueous Zn metal batteries (AZMBs), gaining significant attention for its low cost and high Zn utilization in practical applications. However, its spherical microstructure, which contributes to a high specific surface area and elevated electrochemical reactivity, makes Zn powder anodes prone to degradation mechanisms such as dendrite formation, hydrogen evolution, and corrosion. These side reactions severely compromise the overall electrochemical performance. This review systematically summarizes the latest research progress of Zn powder anodes in AZMBs, emphasizing modification strategies at both the micromodification and macrodesign levels. At the micromodification level, strategies such as Zn powder bulk design, composite Zn powder anode construction, and conductive networks are employed to reduce internal impedance, alleviate volume expansion during charge and discharge, and optimize Zn²⁺ deposition behavior. These measures significantly enhance rate performance and cycling stability. On the macrodesign front, advanced methods like 3D printing and electrospinning offer precise control over the spatial arrangement and structural layout of Zn powder materials. These strategies improve the organization and functionality of Zn powder anodes, leading to remarkable enhancements in cycling stability and coulombic efficiency. In addition, rheological design strategies present innovative solutions for suppressing side reactions by alleviating Zn²⁺ deposition stress. This review also outlines prospective development pathways for Zn powder anodes to achieve high-performance and practical applications. It emphasizes the critical importance of advanced characterization techniques and theoretical modeling in elucidating the fundamental failure mechanisms of Zn powder anodes. Furthermore, it stresses the importance of leveraging Zn powder's inherent advantages alongside multifaceted modification strategies to construct highly stable architectures. Finally, the review identifies addressing technological and economic challenges in scalable manufacturing as the core challenge for advancing the practical implementation of Zn powder anodes. These perspectives provide valuable scientific guidance and theoretical support for the ongoing development of high-performance Zn powder anodes in AZMBs.

Lithium-ion batteries are widely used energy storage devices owing to their high energy density and long cycle life. However, the formation of the solid electrolyte interface and irreversible side reactions during the initial cycling process consume active lithium, resulting in low initial coulombic efficiency and poor overall electrochemical performance. To address this issue, a lithium replenishment strategy is needed, with prelithiation technology being one of the most effective solutions. This study explores the initial capacity loss mechanism of lithium-ion batteries by examining the formation of the solid electrolyte interfacial film and irreversible reactions based on relevant literature. It then systematically classifies and summarizes various existing prelithiation strategies. For anode prelithiation technology, it introduces chemical prelithiation, anode lithium-rich additives, and electrochemical prelithiation strategies. For cathode prelithiation technology, it discusses the strategies of over-lithiation of cathode materials and anode prelithiation additives. In addition, this study highlights the challenges facing prelithiation technology and proposes improvements for various strategies. Finally, it explores the potential of prelithiation technology for large-scale practical applications, aiming to provide valuable insights for developing and applying advanced prelithiation technology in lithium-ion batteries.

Lithium metal anodes (LMAs) have attracted substantial attention for their extremely high specific capacity and lowest electrochemical equilibrium potential. However, their short lifespan and safety issues owing to lithium dendrite formation during repeated cycling hinder the practical application of lithium metal batteries (LMBs). The complex lithium metal-electrolyte interface plays a crucial role in regulating lithium deposition and enhancing the cycling stability of the battery. This review summarizes key advancements in pre-treatment strategies for constructing protective artificial solid-electrolyte interphase layers, categorized by the physical states of the reagents (solid, liquid, and gas) and their mechanisms for stabilizing LMAs. Finally, this review outlines future directions for pre-treatment technologies, emphasizing advanced strategies, application prospects, and mechanistic insights, while addressing current challenges, opportunities, and potential research directions toward high-energy-density LMBs.

Lithium iron phosphate (LFMP, LiFe _x Mn_1–x PO₄, where 0<x<1) has garnered significant attention as a cathode material because of its high safety and operating voltage in lithium-ion battery applications for electric vehicles and energy storage. However, poor conductivity and suboptimal cycle stability of LFMP materials remain critical bottlenecks to their commercial use. This paper delves into the root causes of LFMP performance degradation, which include the Jahn-Teller distortion effect of Mn, sluggish reaction kinetics, and disproportionation reactions in manganese-based cathode materials, and analyzes the evolution mechanism of gas and heat production under high temperature and pressure to reveal the failure mechanism. To enhance LFMP performance, this paper summarizes various strategies, such as ion doping combined with carbon coating, composite coating technology, and electrolyte modification. These approaches aim to improve the electronic conductivity and Li⁺ migration rate, stabilize the phase structure to suppress Mn dissolution caused by the Jahn-Teller effect, reduce interfacial stress, and enhance thermal stability and safety. Implementing these strategies has verified the failure mechanism analysis and outlined future development trends for high-performance lithium-ion battery LFMP cathode materials. Based on current research findings, attaining high specific capacity, stable cycle performance, excellent rate capability, and high safety may necessitate combining carbon coating, element doping, and electrolyte optimization. Furthermore, this paper reviews the specific impacts of various synthesis processes and Mn doping ratios on the structure and performance of LFMP materials in close conjunction with current industrial research advancements. The development of LFMP-based cathode materials exhibiting high energy density, long cycle life, and thermal stability for full-cell batteries is anticipated. This advancement will promote the widespread application of LFMP-based materials in high-performance lithium-ion batteries and lay a solid foundation for their commercialization.

Hydrogen energy is vital for achieving energy structural transformation and building a low-carbon society. Proton exchange membrane fuel cells are among the core devices for hydrogen energy conversion and utilization. Compared to industrial research on materials such as catalysts and proton exchange membranes, studies on carbon fiber paper, the base layer of the gas diffusion layer, have been underexplored. Domestic production of carbon fiber paper is considered the "last barrier" among core fuel cell materials. This study examines key bottlenecks in the industrial preparation of carbon fiber paper, beginning with an overview of mainstream manufacturing processes. The analysis highlights that the key technologies in wet-laying formation involve constructing a uniform and stable carbon fiber support framework and establishing a consistently integrated fiber-resin interface. Regarding industrialization, domestic efforts remain in the early stages and product validation phase. Compared to small-scale laboratory research, mass production presents increased engineering and technical challenges. Finally, this study summarizes recent domestic advancements in carbon fiber paper research and outlines future focus areas to promote sustainable industrialization of carbon fiber paper domestically.

Increasing the working voltage is an effective strategy to enhance the energy density of lithium-ion batteries. However, issues such as electrolyte oxidation, transition metal ion dissolution, and structural degradation of cathode materials pose significant challenges, severely limiting their practical application. Consequently, the development of electrolytes with superior electrochemical stability has become a key research focus. Nitrile compounds, owing to their high dielectric constant and excellent oxidative stability, are regarded as ideal candidates for optimizing electrolytes in high-voltage systems. This review examines the functional mechanisms and performance characteristics of nitrile compounds as solvents and additives. To overcome the incompatibility of nitrile solvents with graphite and lithium metal, four optimization strategies are presented: high-concentration electrolytes, weakly solvated electrolytes, fluorinated nitrile electrolytes, and eutectic electrolytes. The review explores the practical applications and commercialization challenges associated with each strategy, emphasizing that additives currently represent the most effective approach. Furthermore, novel nitrile additives modified with chemical groups containing silicon, boron, or sulfur are introduced, and the mechanisms and potential applications of these functional groups are analyzed. Finally, the review summarizes the opportunities and challenges in the development and application of nitrile compounds. It anticipates that process optimization and the development of new additives will enable the synthesis of multifunctional nitrile compounds with low viscosity, high purity, and enhanced interface stability, and discusses their potential applications in high-voltage electrolytes, particularly for lithium cobalt oxide battery systems.

Latent heat storage technology based on phase change materials (PCMs) has received extensive attention in recent years. Polyethylene glycol (PEG) is a non-toxic organic solid-liquid PCM with high latent heat. Compared to other organic PCMs, its excellent biocompatibility, adjustable phase change temperature, and tunable enthalpy make PEG highly versatile in thermal management, wearable devices, and other fields. However, its low thermal conductivity and leakage during solid-liquid phase transformation limit its practical applications. To address these problems, many methods have been developed to stabilize PEG. Besides commonly used physical methods such as blending, coating, and adsorption, the active hydroxyl groups at both ends of PEG enables its conversion into a solid-solid PCM through chemical modification. Herein, different techniques, including physical blending, microcapsule, fiber, porous material adsorption, and chemical modification, for preparing PEG-based form-stable composite PCMs are reviewed, and their properties are compared. Additionally, recent advances in PEG-based PCMs for the thermal management of electronic devices, photothermal conversion, building energy efficiency, and wearable devices are discussed. Finally, challenges such as low thermal conductivity and reduced enthalpy during composite processing are analyzed, and future research directions are outlined.

Solid-state electrolytes (SSEs) are crucial for next-generation lithium batteries, making the development of high-performance SSEs essential for achieving high safety and energy density. However, challenges related to lithium-ion transport and electrode-electrolyte interfaces in solid-state lithium batteries (SSLBs) have seriously hindered their development. Composite SSEs, formed by incorporating inorganic fillers into a polymer matrix, are considered the most promising option. Nanowires, with nanoscale diameter, high specific surface area, and excellent aspect ratio, enable continuous carrier transport, making them widely used in SSEs to promote lithium-ion transport and enhance electrode-electrolyte interfacial contact and stability, consequently improving the cycling performance and safety of SSLBs. Herein, wecomprehensively summarized recent progresses in nanowires for SSEs, detailing their role in regulating lithium-ion transport and electrode-electrolyte interfaces. Key mechanisms involve reducing the glass transition temperature and crystallinity of the polymer matrix, promoting the dissociation of lithium salts, restricting anion motion, attenuating the interactions between lithium ions and polymer chain segments, forming a new pathway for lithium-ion transport, enhancing electrode-electrolyte contact, and increasing the stability of electrode-electrolyte interfaces. Finally, existing challenges and prospects of nanowire-based SSLBs are discussed. This review aims to provide a comprehensive understanding of the mechanisms of nanowires regulating lithium-ion transport and interfacial stability, driving their further development in SSLBs.

The performance and safety of lithium-ion batteries are highly affected by temperature fluctuations. At low temperatures, battery capacity decreases significantly and charging efficiency drops, while high-temperature operations accelerate performance degradation and risk initiating thermal runaway. Composite phase change materials have emerged as an effective solution battery thermal management owing to their capability for efficient thermal storage and temperature regulation across a wide range of conditions. For cooling applications, composite phase change materials with high enthalpy, high thermal conductivity, and flexibility improve the temperature uniformity of battery packs by absorbing excess heat through phase transitions and distributing it evenly across the battery system. Under low-temperature conditions, conductive composite phase change materials enable rapid self-heating through the electrothermal conversion mechanism, effectively mitigating the performance challenges faced by batteries in cold environments. To mitigate the risk of thermal runaway, flame-retardant hydrated salt composite phase change materials effectively suppress heat spread by combining both phase change heat absorption and thermal decomposition heat absorption. This review discusses the use of composite phase change materials in battery cooling, heating, and thermal runaway protection. It also explores how the balance between heat storage capacity and thermal conductivity affects the efficiency of thermal management systems. Furthermore, recent advancements are discussed, including improvements in flexibility, flame-retardant modifications, and chemical-based thermal storage mechanisms. Despite progress, challenges remain in improving the stability, cost-efficiency, and scalability of these materials. Future research should prioritize the development of multifunctional composite designs, intelligent responsive technologies, and large-scale methods to advance the practical use of composite phase change materials in thermal management and thermal runaway protection of power batteries.

Compressed air energy storage is considered the most promising technology for large-scale energy storage, and the compressor, as a key component of the system, significantly influences overall performance. The compressor's intake filtration system is critical because its filter effectively prevents impurities-such as solid particles, liquid water, and oil pollution, from compromising safe and stable operation, an issue that has attracted widespread attention from scholars domestically and internationally. Although progress has been achieved in compressor intake filtration systems, literature reviews in this area remain relatively scarce. This article reviews research by domestic and international scholars on compressor intake filtration systems, categorizing studies according to filtration principles, including mechanical, adsorption, and electrostatic methods, and examines evaluation indicators and optimization approaches for filter performance. The following conclusions are drawn: compared with adsorption filters, mechanical and electrostatic filters are more widely used and offer advantages such as high filtration efficiency and low pressure drop; the evaluation indicators of the intake filtration system primarily include filtration efficiency, pressure drop, dust holding capacity, and moisture resistance; filter material, filter structure, and operating conditions interact to affect filtration performance; and the intake filtration system can be optimized by employing nanofiber composite filter materials with enhanced performance and by refining the filter element and channel structure.

The integration of informatization and industrialization is a key approach to advancing the cross-industry application of energy storage technology. The energy storage industry chain encompasses the vertical extension of production and manufacturing of energy storage components and the horizontal application across energy production, distribution, conversion, and storage. Integrating energy storage with digital technology enhances energy conservation, intelligence, and flexibility in industrial energy management. This study briefly introduces the development trends of energy storage technologies, including mechanical, electrochemical, thermal, and hydrogen storage, in digital innovation. It analyzes the temporal, spatial, and informational attributes of energy storage, highlighting the role of digital innovation in cross-industry coupling. A digital intelligence innovation map of the energy storage industry chain is developed, presenting two perspectives: the vertical extension focuses on manufacturing energy storage materials, components, devices, and systems, while the horizontal application perspective addresses the construction, investment, and operation of energy storage stations. From the horizontal application perspective, a roadmap for the coordinated development of energy storage and the energy internet is outlined. Characterized by one-dimensional centralized, two-dimensional cross-industry, and three-dimensional cross-internet applications, this study summarizes energy storage configuration paradigms for point, line, and plane applications and analyzes their characteristics in respective scenarios. Based on the "X + Y + energy storage" paradigm of the line scenario, a wind-solar-thermal-storage system supplemented by fuel energy storage is proposed. The combination of long-term thermal energy storage for solar thermal power generation applications and electric fuel energy storage for emerging heat engine applications—such as carbon-neutral fuel internal combustion engines, gas turbines, and fuel cells-enables multiscale temporal and spatial collaboration. This study summarizes the development path of energy storage technology in digital fusion and introduces a "wind-solar-thermal-mass-storage" system configuration, which substantially improves the stability of multienergy collaboration.

Li-rich manganese layered oxides exhibit high specific capacity and serve as an optimal cathode material for high-energy-density lithium batteries. However, during charging and discharging, the Li-rich manganese layered oxides cathode materials experience transition metal migration and irreversible oxygen reactions within the lattice. This results in low coulombic efficiency during the first cycle, severe voltage degradation, and poor cycling stability, collectively constraining industrial application. To address these issues, this paper employs surface coating to modify the materials. A MoS₂ coating was applied to the surface of the Li_1.2Ni_0.167Co_0.167Mn_0.666O₂ (LLO) material, inducing a transformation in the subsurface structure. The findings demonstrate that the MoS₂ coating layer shields the material from direct exposure to the electrolyte and effectively inhibits interfacial side reactions. The three-dimensional structure of the spinel phase facilitates lithium-ion diffusion. The modified materials exhibit initial coulombic efficiencies exceeding 88% at a current density of 0.1C. The cycling stability of LLO@MS1 (mass fraction 1% MS₂ coating) was markedly enhanced relative to that of the unmodified materials when subjected to a current density of 1.0C. The specific discharge capacities reached 160.0 mAh/g and 129.0 mAh/g at 5.0C and 10.0C, respectively, indicating that the modification strategy enhanced overall electrochemical performance.

LiNi_0.5Mn_1.5O₄ (LNMO) is a cathode material known for its high operating voltage (4.7 V), high energy density (650 Wh/kg), and low cost. However, owing to factors such as electrolyte decomposition, Jahn-Teller effect, and Mn dissolution, LNMO cathode materials usually demonstrate rapid capacity fading and poor rate capability. To improve their electrochemical performance, we prepared Mg-Cr co-doped LMMO materials via the hydrothermal method and studied the influence of Mg-Cr co-doping content on the electrochemical performance of the LNMO cathode. Our experimental results show that the optimal electrochemical performance is achieved when the doping content of Mg and Cr is 2% each. The Mg-Cr co-doped LMMO cathode exhibits a discharge capacity of 137.3 mAh/g at 0.1C rate and a capacity retention of 85.74% after 200 cycles at 1C rate, markedly outperforming the original LNMO cathode (116.5 mAh/g and 51.82%, respectively). In addition, it delivers capacities of 121.8 mAh/g at 0.5C and 94.3 mAh/g at 5C. Mechanistic analysis shows that Mg-Cr co-doping promotes the formation of a disordered Fd\overline{\mathrm{3}}m phase, enhancing the electronic conductivity of LMMO material and reducing the electrochemical polarization and charge transfer resistance of the cathode. This study presents a simple method to improving the electrochemical performance of LNMO cathode and offers valuable insights for designing high-performance lithium-ion battery cathode materials.

Hard carbon prepared from biomass-based precursors offers many advantages as anodes for sodium ion batteries (SIB), such as low cost and sustainability. In this paper, hard carbon was prepared by carbonizing typical fast-growing wood (balsa wood) at various high temperatures and then used as anodes for SIB. The morphology and structural characteristics of the obtained materials were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, specific surface area analysis, and pore size distribution (PSD) measurements. The electrochemical performance of the materials was evaluated by galvanostatic charge-discharge testing, cyclic voltammetry (CV), the galvanostatic intermittent titration technique (GITT), and electrical impedance spectroscopy (EIS). The results showed that the balsa wood-based hard carbon mainly consisted of a fibrous and layered structure, with the interlayer distance decreasing and structural defects increasing as the carbonization temperature increased. Among the samples, the hard carbon prepared at 1100 ℃ exhibited the largest specific surface area (38.8 m²/g) and demonstrated excellent performance in terms of initial Coulombic efficiency, rate capability, and cycling stability. Further studies indicated that the high ionic diffusion rate, low charge transfer resistance, and reduced diffusion-controlled process enabled the materials carbonized at 900 ℃ and 1100 ℃ to perform better at a high current density (5 A/g).

This study addresses the severe volume expansion and poor conductivity issues of silicon-based anode materials during the charge-discharge process in lithium-ion batteries. To improve structural stability and electrochemical performance, a Si@Void@C composite material with a hollow structure was designed. In this study, Sb₂S₃ was used as a hard template and nano-sized Si/Sb₂S₃ particles were prepared via mechanical ball milling. Subsequently, resorcinol-formaldehyde was used as the carbon source, and a hollow structure with internal voids was constructed using the carbothermal reduction method. During this process, the carbon shell coating the silicon nanoparticles prevented direct contact between silicon and the electrolyte while considerably enhancing the material's conductivity. Additionally, the voids between the silicon nanoparticles and the carbon shell buffered the mechanical stress caused by volume changes during charge-discharge cycles, further improving cycle stability. As an anode material for lithium-ion batteries, the Si@Void@C composite exhibited excellent electrochemical performance, achieving an initial discharge capacity of 1691 mAh/g at a current density of 0.5 A/g. Even after 500 cycles, it maintained a high reversible capacity of 735.9 mAh/g, demonstrating exceptional cycling stability and capacity retention.

Li-rich manganese-based cathode material has a higher capacity (>250 mAh/g) than common commercial cathode materials, but it is plagued by severe voltage decay, surface phase transitions, and lattice oxygen evolution during cycling. To address these issues, this paper designs a Cr/Mo co-doped Li_1.2Ni_0.167Co_0.167Mn_0.666O₂ (LLO) cathode material using a high-temperature solid-state method. The results show that stability and electrochemical performance are improved after this modification. On one hand, the large ionic radius of Mo⁶⁺ increases lattice spacing, while Cr doping stabilizes the layered structure. Conversely, the higher bond energies of Cr—O and Mo—O effectively mitigate structural distortion, resulting in reduced transition metal migration and oxygen release. Moreover, abundant surface oxygen vacancies lower irreversible oxygen redox. Electrochemical measurements display that the cycle performance and rate capability of LLO-CM1 are enhanced. In particular, LLO-CM1 delivers an initial discharge specific capacity of 272.7 mAh/g and maintains 177.7 mAh/g after 200 cycles in the voltage range of 2—4.8 V at 1 C, corresponding to a capacity retention of 84.0%, while an average discharge specific capacity of 102.0 mAh/g is delivered even at 10 C. The co-doped strategy sheds light on designing Li-rich manganese-based cathode materials.

The oxygen reduction reaction (ORR) exhibits sluggish kinetics, leading to substantial platinum (Pt) consumption at the cathodes of proton exchange membrane fuel cells (PEMFCs). However, the scarcity of Pt, along with the high cost, low ORR activity, and poor stability of commercial Pt/C catalysts, severely restricts the large-scale application of PEMFCs. Therefore, the development of efficient and practical catalysts with excellent activity, high stability, and reduced Pt usage is critical. Herein, a rapid microwave reduction method was developed to synthesize carbon-supported platinum-copper alloy nanoparticle (PtCu/C) catalysts. Transmission electron microscopy reveals that PtCu nanoparticles are uniformly distributed on the surface of the carbon support with an average particle size of 2.7 nm. Pt and Cu are evenly distributed within the nanoparticles, forming a Pt-rich surface structure with a thickness of two atomic layers. X-ray diffraction confirms the formation of PtCu alloy. X-ray photoelectron spectroscopy indicates electron transfer from Cu to Pt, facilitating electronic interactions. Furthermore, the effects of the Pt∶Cu molar ratio in the precursor mixture, along with the temperature, time, and power of the microwave reaction, on the catalytic activity are systematically investigated. Electrochemical test results suggest that the optimal PtCu/C catalyst exhibits mass and area activities of 0.280 A/mg and 0.346 mA/cm² at 0.9 V (vs. RHE), respectively, outperforming commercial Pt/C catalyst (0.15 A/mg and 0.213 mA/cm²). Additionally, the PtCu/C catalyst shows enhanced electrochemical stability. The improved activity and stability of the PtCu/C catalyst are mainly attributed to the small PtCu nanoparticle size, alloying effects, and Pt-rich surface structure.

The gravity energy storage system (GESS) has attracted extensive attention owing to its long-term operation, large capacity, zero self-discharge rate, and high safety. The energy efficiency level is a critical factor affecting the large-scale application of GESS. Firstly, for the vertical GESS based on belt drive, the sliding friction of the moving/fixed pulley relative to the bearing surface in the mechanical link, the ball bearing friction in the traction system, the elastic sliding friction of the drive belt relative to the pulley, and the copper loss, iron loss, wind friction, and stray loss of the motor in the electrical link are analyzed, and the theoretical calculation method for the efficiency and loss of each link of the system is derived. Secondly, a numerical example is provided for the proposed calculation method. The results show that the efficiency of the mechanical link decreases slightly as the mass block increases; the charging efficiency of the system initially increases and then decreases with increasing mass block; the discharging efficiency increases with the mass block; and under discharging conditions, the proportion of mechanical loss in the system is significantly higher than under charging conditions. Finally, a 1.1 kW prototype is built to verify the calculation results. The experimental results show that when the mass block is 127.35 kg, the measured motor loss proportions in charging and discharging states are 82.77% and 72.42%, respectively, which are close to the theoretical values of 80.56% and 72.96% obtained from the numerical example. The theoretical variation curve of the system's charging and discharging efficiencies with respect to the mass block exhibits the same trend as the measured curve, which verifies the correctness and practicability of the proposed energy efficiency analysis method.

To address the reduction in performance and lifespan of a battery pack caused by inconsistencies in the state of charge of individual cells, this paper proposes a double-layer active balancing control method for a lithium-ion battery pack based on intelligent PID control. The method employs a double-layer equalization topology, using a Buck-Boost circuit with good scalability within groups and a flyback transformer with high equalization efficiency between groups. A PID controller optimized by a Bayesian algorithm controls the output variable duty cycle and regulates the balancing current to achieve both intra-pack and inter-group balancing. Simulation results show that, compared with traditional equalization based on a Buck-Boost circuit, the equalization time in static and charging modes is reduced by 503 s and 515 s, respectively; equalization efficiency is increased by 65.7% and 66.5%, respectively; and energy transfer efficiency in static mode is improved by 4.4%. Experimental results indicate that when the equalization current is less than 1.5 A, the proposed method achieves equalization in 1110 seconds, a reduction of 616 seconds compared with the fuzzy PID algorithm, thereby demonstrating its superiority.

A novel integrated system based on underwater compressed air energy storage (UCAES) has been proposed to address the challenges of energy storage for offshore renewable energy and the scarcity of electricity, freshwater, ice, and thermal resources in remote marine areas. This system is designed to provide comprehensive solutions for producing electricity, freshwater, ice, cooling, and heating. Thermodynamic models were established to analyze the energy storage and release processes alongside the performance of the polygeneration system. Key findings include: Constant-pressure underwater energy storage offers significantly higher energy storage density and energy recovery efficiency compared to constant-volume storage methods. The integrated system can simultaneously produce electricity, freshwater, hot water, ice, and cooling through compressed air energy storage with interstage compression heat and expansion refrigeration. The interstage compression heat not only preheats the air entering the expander but also powers multieffect distillation desalination devices, enabling the production of 51.45 tons of freshwater per day while also supplying hot water above 60°C, using a 10000 m³ underwater air storage tank at a depth of 500 m. Intermediate-stage expanded air extraction supports ice production and refrigeration, with a daily ice output of 30.72 tons when extracting 50% of air flow rate (equivalent to 30.4 kg/s). The UCAES system effectively resolves the intermittency challenges of offshore wind and solar power, enabling the large-scale development of marine renewable energy. This technology supports the establishment of offshore energy stations that can provide comprehensive energy services for remote islands, fishing vessels, merchant ships, and floating platforms, thereby promoting high-quality growth of the marine economy.

In tower-type solar thermal energy storage and power generation systems, absorber tubes operate under extreme conditions, including high temperatures, intense radiation, and molten salt fluid erosion. Over time, these conditions result in the formation of complex heterogeneous salt films on the inner tube walls. The salt film, combined with the coating and the tube substrate, creates a multi-layered heterogeneous structure that significantly affects the propagation characteristics and echo signals of ultrasonic guided waves. Consequently, defect detection and analysis are rendered complicated. Thus, this study systematically investigates the formation mechanisms and influencing factors of heterogeneous salt films, characterizing their distribution and scale properties. Further, a novel simulation method for salt film surfaces, based on stochastic processes and time series models, is proposed. Employing the finite element software COMSOL, a multi-layered heterogeneous model incorporating the tube substrate, coating, and salt film is developed to simulate the effects of salt films under varying roughness levels on ultrasonic guided wave signal characteristics and propagation behavior. The presence of salt films is found to significantly attenuate echo signal amplitude, reduce wave propagation velocity, and induce mode conversion in ultrasonic guided waves. Moreover, with increase in the salt film roughness, the echo energy exhibits a non-linear growth trend, and the complexity of mode-converted waveforms intensifies. Thus, the results highlight the importance of this study in terms of bridging a critical gap in the simulation of acoustic fields in multi-layered heterogeneous pipelines, thereby providing a theoretical foundation for ultrasonic guided wave-based defect detection in absorber tubes. Furthermore, this study offers robust technical support for the safety assessment and maintenance of tower-type solar thermal systems.

The vanadium flow battery (VFB) is considered a promising energy storage technology for large-scale commercial applications due to its easy scalability, environmental friendliness, and high safety. However, capacity fade during long-term cycling limits its widespread use in energy storage. This study analyzed changes in the electrochemical characteristics of the VFB before and after cycling and, based on potassium permanganate titration results, identified electrolyte imbalance and electrode degradation — which led to a reduction in anode active material and increased polarization — as the main factors contributing to capacity fade. Furthermore, the specific discharge capacity of the electrolyte was restored to 92.7% of its initial value using oxalic acid reduction, and battery polarization was alleviated by swapping the anode and cathode, confirming that electrode exchange effectively restores and stabilizes the electrodes' electrochemical activity. Finally, the oxalic acid residue problem was resolved using a constant-voltage charging method, and a process route for oxalic acid recovery was established, successfully restoring the average oxidation state of the spent electrolyte from 3.580 to 3.508. This research comprehensively analyzed the underlying causes of VFB capacity fade, providing significant guidance for electrolyte recovery, and proposed a simple, effective technical solution for the residue issue during the oxalic acid recovery process, thereby offering new possibilities for the recovery and reuse of the electrolyte.

Conductive agents are crucial components of lithium-ion batteries, directly affecting internal resistance, rate capability, capacity, and cycle stability. To investigate the impact of different types and proportions of conductive agents on the electrochemical performance of ternary lithium-ion batteries, this study utilized three conductive agents (Super P, L-MWCNTs, and S-MWCNTs) with NCM622 as the cathode active material. Three types of button cells were prepared with a mass ratio of cathode active material to conductive agent to binder set at 8∶1∶1. Electrochemical tests, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge-discharge tests, were conducted to assess the effects of various conductive agents on the electrochemical performance of ternary lithium-ion batteries, with the aim of optimizing conductive agent selection. Based on the results, S-MWCNTs, which exhibited the best electrochemical performance, were further employed to explore the impact of varying conductive agent proportions on battery performance, thereby optimizing the balance between conductive agent content and electrode mass-specific capacity. The results indicated that batteries using S-MWCNTs demonstrated lower impedance, higher discharge specific capacity, and superior rate performance and cycle stability. Furthermore, cells with varying S-MWCNT proportions showed significant performance differences, particularly evident during high-rate charge-discharge cycles. This study highlights the importance of selecting and optimizing conductive agents to enhance battery performance, providing a reference for future optimization of conductive agent content in ternary lithium-ion batteries.

Thermochemical heat storage technology, known for its high heat storage density, low heat loss, and long storage duration, has become a research focus in heat storage. However, limited research exists on multiphysics coupling during thermochemical heat storage, and traditional fixed-bed reactors exhibit poor heat and mass transfer performance, leading to low reaction rates. This study establishes a multiphysics coupling model for the thermochemical heat storage process of CaCO₃ decomposition based on equations such as energy conservation, mass conservation, momentum conservation, and chemical reaction kinetics. A two-dimensional unsteady-state numerical simulation was conducted to analyze the energy conversion mechanism of CaCO₃ decomposition in fixed-bed reactors. The study examined the temporal evolution of indicators such as temperature, conversion rate, and reaction rate during the heat storage process and discussed the impact of reaction conditions, including porosity, inlet gas flow rate, and solid reactant thermal conductivity, on the heat storage process. Simulation results indicated that increasing porosity, inlet gas flow rate, and solid reactant thermal conductivity enhanced the reaction rate of the CaCO₃ decomposition process. By incorporating a permeable high-thermal-conductivity porous channel into the reactor, a synergistic improvement in heat and mass transfer characteristics was achieved, reducing the reactor's heat storage time by 45.09% and pressure drop from 87735 to 10 Pa. These findings provide crucial parameters and guidance for designing and optimizing high-power-density thermochemical heat storage reactors.

Addressing the inadequacies in existing benefit assessment methods throughout the full life cycle of shared energy storage, this paper proposes an evaluation approach that combines the Criteria Importance Through Intercriteria Correlation (CRITIC) method with the Analytic Network Process (ANP) to enhance the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS). First, a comprehensive evaluation system is established using economic, environmental, market, and social benefits as fundamental indicators, in accordance with the operational mode of shared energy storage in China. Next, experts are invited to assign scores using the ANP to derive subjective weights, while the CRITIC method calculates data correlations to determine objective weights. Then, a combined weighting method integrates the weights from the ANP and CRITIC methods equally, ensuring that more important factors exert greater influence in decision making and further enhancing data utilization. Finally, to overcome the limitation of traditional TOPSIS in providing results in a single form, the calculation of relative closeness to the ideal solution is refined by incorporating target scenarios that more intuitively reflect the development trend of shared energy storage and facilitate both horizontal and vertical evaluation comparisons among various scenarios. A pilot project of shared energy storage is employed as a case study, yielding the overall development trend of the project and the rankings of typical years. In the vertical evaluation, the closeness degrees to the expected targets for environmental and market benefits in the 15th typical year are 1.013 and 1.011, respectively, exceeding the expected targets, and in the horizontal ranking, the 15th typical year ranks first. The evaluation results validate that the proposed assessment method can accurately assess the development trend of shared energy storage and provide essential guidance for its construction.

Aiming at the complex control problem wherein a hybrid flywheel array composed of an inertia flywheel and a high-speed flywheel participates in grid inertia response and primary frequency modulation, this paper first introduces the concepts of magnetic suspension inertia flywheel and high-speed flywheel energy storage, as well as the architecture and working mechanism of the inertia flywheel array and high-speed flywheel array that participate in grid inertia response and primary frequency modulation. Secondly, the mathematical and control models of the flywheel energy storage system are established, and two control strategies are proposed: one is a collaborative control strategy based on inertia control and sag control, involving the inertia flywheel and high-speed flywheel array in grid inertia response and primary frequency modulation; the other is a control strategy based on inertia response and primary frequency modulation, respectively. Through simulation, the frequency modulation effects of the two control strategies are compared in terms of frequency change, frequency change rate and recovery time. The simulation results verify the correctness and feasibility of the two strategies, and they exhibit different advantages in the inertia response and primary frequency modulation stages.

In recent years, numerous exemplary solar thermal power stations have been established nationwide. Integrating these stations with efficient thermal energy storage systems is crucial for improving their power generation efficiency and reducing operational costs. This study investigates the operation of thermal energy storage systems by developing a dynamic model of a two-tank indirect thermal energy storage system. Mathematical models for the salt storage tank, oil/salt heat exchanger, and molten salt pump have been constructed, along with a PI control module to automatically control the speed of the molten salt pump. The STAR-90 simulation platform simulates the dynamic charging and discharging processes under typical daily conditions at the CGN Delingha 50 MW trough solar thermal power stations during the vernal and autumnal equinoxes. The results indicate that the performance curve of the molten salt pump model closely matches the actual manufacturer data. Compared to the original thermal energy storage system model, this new model more accurately captures molten salt flow fluctuations resulting from variations in input heat transfer oil temperature and flow rate. During heat storage, fluctuations in the hot oil inlet temperature at the oil/salt heat exchanger considerably influence the cold molten salt flow. The speed of the molten salt pump exhibits a strong nonlinear correlation with the flow rate, while the power consumption of the pump is linearly related to its speed. Under vernal equinox conditions, the average mass flow rate of molten salt is about 800 t/h, with an average pump speed of 154 r/min and a power consumption of 87 kW. During the autumnal equinox, the average mass flow rate increases to 1400 t/h about, with an average pump speed of 265 r/min and power consumption of 115 kW. When the turbine operates at a power output of 28 MW during heat discharge, the flow of hot molten salt is maintained at 2411 t/h owing to the stable flow and temperature of the cold heat transfer oil in the oil/salt heat exchanger. In this situation, the speed and total power consumption of the molten salt pump reach 855 r/min and 205 kW, respectively. The research provides valuable theoretical insights and practical references for optimizing the design and operation of thermal energy storage systems in solar thermal power stations.

This study addresses cost differences in frequency regulation among energy storage stations and inefficiencies related to state‐of‐charge (SOC) balance within energy storage cell groups. To address these issues, a two‐layer optimization strategy is proposed. The upper layer minimizes frequency regulation costs by considering SOC, state‐of‐health (SOH), internal losses, and aging costs, while the lower layer employs a multi‐objective optimization to minimize charging/discharging losses and SOC deviation within energy storage cell groups. Simulation results show that the proposed strategy reduces frequency regulation costs and losses compared with traditional methods, while maintaining SOC balance and preventing unilateral charging/discharging, thereby enhancing the economic efficiency of frequency regulation and contributing to the extended service life of energy storage units.

To address the challenges of insufficient estimation accuracy and inaccurate degradation modeling of lithium-ion battery state of health (SOH), this study proposes a lithium-ion battery SOH estimation method based on a convolutional neural network-local attention-bidirectional long short-term memory (CNN-LA-BiLSTM) model. First, the charging time, current, voltage, capacity, and temperature of the lithium-ion battery are measured during the charging phase. The lithium-ion battery undergoes incremental capacity (IC) analysis, and the IC curve area is extracted as an electrical characteristic of the lithium-ion battery. The temperature integral during charging the lithium-ion battery is calculated as a temperature characteristic. These features are combined into a joint IC area-temperature metric for SOH estimation of lithium-ion batteries. Then, the CNN-LA-BiLSTM model is constructed, incorporating LA to optimize the weights and biases of the CNN, while Huber loss function is used to optimize model parameters for enhanced SOH estimation accuracy. Results show that the proposed method effectively estimates the SOH of the battery, achieving a mean absolute percentage error of 0.5794%, root mean square difference of 0.0099, and a coefficient of determination of 0.9961. Compared with traditional methods, the proposed method shows better performance in battery SOH estimation.

The turbine expander is a key component in a carbon dioxide (CO₂) energy storage system. Optimizing the structural parameters of the turbine impeller improves overall expander performance. This study investigates a centripetal turbine in a hundred‐kilowatt-class CO₂ energy storage system. Initially, the main structural parameters of the CO₂ turbine are defined through aerodynamic design. A subsequent flow field simulation using Numeca software evaluates the effects of impeller blade number, inlet angle, and outlet angle on flow characteristics. In addition, leakage flow and losses in the impeller top clearance are examined. Finally, turbine performance under unsteady flow conditions is assessed. The results demonstrate that increasing the impeller blade number causes the percentage of the low Mach number region in the impeller channel to decrease and then increase. Both the impeller inlet and outlet angles significantly affect the flow separation region and vortex distribution. After optimization, the turbine's isentropic efficiency reaches 83.65%, an increase of 0.75% relative to the initial design. Furthermore, the isentropic efficiency decreases approximately linearly with greater impeller top clearance, and nozzle wake flow induces unsteady conditions, reducing efficiency by 0.57% compared to steady flow.

Frequent charge-discharge cycles reduce the service life of energy storage power stations, and the transmission power of energy storage units connected to the power conversion system (PCS) may become too low, violating national energy management grid connection standards. To address this issue, this study proposes a frequency-modulation power optimization method for energy storage power stations that considers the transition state of charge-discharge and power constraints. This method divides the unit group into charging and discharging groups to meet their respective requirements. While ensuring that the alternating current (AC) power of the corresponding PCS does not fall below a set lower limit during energy storage unit output, each unit in the charging and discharging groups is dynamically updated based on the automatic generation control (AGC) instruction. This reduces the number of charge-discharge state transitions. Compared with traditional allocation strategies, the proposed strategy lowers frequency modulation costs and charge-discharge conversion frequency and ensures compliance with national grid connection standards by preventing the corresponding PCS AC side power from exceeding its limit during energy storage unit operation.

Rapid and reliable identification of unintentional islanding is crucial for grid-forming energy storage inverters to achieve smooth transitions between grid-connected and islanding operation modes. Current islanding detection methods often fail under perfectly matched loading conditions and struggle with threshold selection. To address this, this study proposes a hybrid islanding detection method based on the V-I Lissajous pattern and impedance. This method utilizes the area and minor axis of voltage-current Lissajous plots to capture the characteristics of voltage and current. When the detected islanding detection indicators fail to meet the threshold, disturbances are injected to identify impedance. The combined Lissajous pattern-impedance identification enables the detection of minor changes in voltage and current under perfectly matched load and converter power while effectively distinguishing islanding conditions from non-islanding faults. To overcome the challenge of threshold selection for islanding detection, which is highly correlated with grid parameters, this method employs relative indicators and uses the Otsu method to determine a threshold for passive detection indicators. The proposed method is verified through MATLAB/Simulink simulation and hardware-in-the-loop experiments. The experimental results show that even with perfectly matched load power with the converter and a quality factor of 2.5, the proposed method effectively and reliably detects islanding phenomena.

This bimonthly review provides a comprehensive overview of recent research on lithium batteries. A total of 5413 online papers published between December 1, 2024 and January 31, 2025 were examined using the Web of Science database. Using the BERTopic model, the abstract texts were analyzed, and a research topic map for lithium battery studies was generated. From these, 100 papers were selected for in-depth discussion. The selected studies covered various aspects of lithium batteries. Research on cathode materials, including Ni-rich layered oxides and LiNi_0.5Mn_1.5O₄, focuses on improvements through doping, surface coating, and microstructural modifications. The cycling performances of Si-based anodes were enhanced through structural design. Considerable efforts have been devoted to interfacial and bulk structure design for lithium metal anodes. Studies on solid-state electrolytes examined structural design and performance in polymer, sulfide, and halide electrolytes as well as their composite forms. In contrast, liquid electrolytes were improved through optimized solvent and lithium salt designs for different battery applications and the incorporation of novel functional additives. For solid-state batteries, studies have explored cathode modification, surface coating, and synthesis methods as well as interface construction and three-dimensional structural design for lithium metal anodes. Interface modifications of current collectors for anode-free batteries have also been widely investigated. In lithium-sulfur batteries, the structural design of the cathode and liquid electrolyte contributes to extended cycle life. In addition, lithium-sulfur and lithium-oxygen batteries have garnered considerable attention. Other studies have investigated ion transport and degradation mechanisms in electrodes, lithium deposition morphology, and solid electrolyte interphase evolution. Research has also addressed thermal runaway analysis in full batteries, theoretical simulations of solvent effects on the cathode electrolyte interphase, and optimization of manufacturing processes.