Room-temperature sodium-sulfur batteries (RT NA-S) consist of sulfur (S) and sodium (Na) as positive and negative electrode materials, respectively. Using S and Na elements as battery components is advantageous due to their low cost, abundance, and high energy density. Consequently, RT Na-S batteries have the potential as rechargeable batteries operating at room temperature. However, several problems, such as low coulomb efficiency and poor cycle stability, hinder the practical application and further development of RT Na-S batteries. In addition, the electrochemical performance of the Na-S battery is affected by various factors, including the structure of the S cathode, diaphragm, and electrolyte. Additionally, researchers must address the crucial issues of the shuttle effect of polysulfides and the slow kinetics of the multi-step reaction. This study summarizes recent research on RT Na-S batteries. It provides an overview of their current development status from the perspectives of nanostructure design, diaphragm design, and electrolyte design in the S cathode. The study begins by discussing the redox mechanism of S in the electrolyte. Furthermore, the study lists challenges of RT Na-S batteries during their current development stage. The results show that most strategies for improving the sodium polysulfide (NaPSs) conversion rate focus on inhibiting the shuttle effect and promoting slow kinetics. The main challenges facing RT Na-S batteries at present are related to the nature of the S-positive electrode, the electrolyte, the considerable volume change, and the shuttle effect caused by polysulfide intermediates. This study aims to provide new routes for the further development and commercialization of RT Na-S batteries.

Sodium ion batteries (SIBs) are often used as substitutes for lithium ion batteries due to their abundant resources and low prices. However, due to the relatively large atomic radius of sodium and the relatively slow kinetic performance, the commercialization of sodium ion batteries has been limited. Based on the latest research, this article systematically summarizes the application of magnetic metal elements in Prussian blue, layered transition metal oxides, and polyanions in the cathode materials of sodium ion batteries, and improves electrochemical performance and cycle stability by doping magnetic elements. In practical applications, Prussian blues generally have shortcomings such as low capacity utilization, low efficiency, poor magnification, and unstable circulation. However, doping with magnetic metal elements reduces the diffusion resistance of Na⁺ ions through SEI films, accelerates the ion diffusion process, and increases active sites. Layered transition metal oxide and polyanion cathode materials utilize magnetic metal elements to enhance the electrochemical performance of sodium ion batteries. Compared to lithium ion battery anode materials, a new type of sodium ion battery anode material containing magnetic elements was designed to achieve rapid sodium storage. Magnetic metal elements were loaded into carbon based materials to accelerate the diffusion of Na⁺ ions. This article analyzes, summarizes, and summarizes the latest developments.

Potassium-ion batteries (PIBs) have become an ideal new energy storage system to replace lithium-ion batteries (LIBs) due to their abundant potassium resources, low cost, environmental friendliness and high energy density. Although the research of PIBs in the field of anode has made significant progress in recent years, the research on cathode materials is slow, and its design and application are faced with problems such as low reversible specific capacity, poor cycle stability, and unsatisfactory energy density. Therefore, the discovery and design of cathode materials is critical to building potassium-ion (K⁺) batteries for practical applications. Due to the successful application of polyanionic materials in LIBs and sodium-ion batteries (NIBs), in recent years, people have also focused on polyanionic materials focusing on PIBs. Polyanionic materials have the advantages of high redox potential, produces a favorable induction effect, high security, thermal stability and structural stability well, and can achieve relatively stable capacity storage, but their low reversible capacity and poor conductivity need to be solved. This review reviews and discusses the research of polyanionic cathode materials for potassium-ion batteries, with the purpose of exploring the development design potential and research space of polyanionic cathode materials, focuses on the development status of phosphate, fluorophosphate, pyrophosphate and sulfate materials, summarizes the main concepts of the current polyanionic cathode material design, and puts forward some suggestions and prospects for the modification of polyanionic cathode materials.

Rapid exploitation of renewable energy sources to replace conventional fossil fuels drives the development of electrical energy storage systems. With the increasing demand for grid-scale energy storage systems, potassium-ion batteries (PIBs) have emerged as a promising alternative to commercial lithium-ion batteries owing to their low cost, natural abundance of potassium resources, low standard reduction potential of potassium, and fascinating transport kinetics of the K⁺ ions in the electrolyte. Owing to the high abundance of potassium and their low cost, PIBs have considerable advantages in secondary battery energy storage systems. The main challenge in the commercialization of PIBs is finding suitable cathode materials with fast transport kinetics and stable framework structures to intercalate/de-intercalate large-size K⁺ ions. Transition metal layered oxides have excellent potential and have been extensively investigated as cathode materials for PIBs because of their stable skeleton structure, simple synthetic chemistry, and low cost. In this paper, the effects of the potassium content and synthesis temperature on the crystal structure of transition metal layered oxides are introduced and the structural evolution and capacity loss mechanisms of various crystal structures during potassium removal are explained. Furthermore, modification methods for Mn-based transition metal layered oxides with different crystal structures are proposed to improve their electrochemical properties. Finally, the main research directions for novel transition metal layered oxide cathodes are discussed to provide guidelines for the development of advanced PIBs.

Sodium metal anode is considered as the superior anode material due to its high specific capacity, low redox potential, and abundant resources. However, the problems of unstable solid electrolyte interface (SEI) and sodium dendritic growth have seriously hindered its practical application. It is thus essential to adopt appropriate strategies to achieve stable and efficient use of sodium metal anode. Generally, the construction of an artificial interface layer on the surface of the sodium metal anode can not only effectively achieve uniform sodium deposition, but also effectively mitigate the volume change and sodium dendrite growth during the electrochemical process. Therefore, this review focuses on the research progress on sodium metal anode modified by artificial interface layer. Firstly, the basic properties of spontaneously formed SEI films are discussed. Generally, they suffer from poor stability, poor toughness and low mechanical strength. To address these issues, the construction of inorganic, organic and inorganic-organic artificial interfacial layers to protect sodium metal anodes for dendrite-free sodium deposition/exfoliation is proposed. Sodium-contained inorganic materials usually have the advantages of high shear modulus, corrosion resistance, structural stability, and high ionic conductivity, but are brittle; organic materials usually have structural designability, functional group diversity, and high mechanical toughness, but are poorly stable; the inorganic-organic composite protective film combines the advantages of the above two and can build an artificial interface layer with excellent comprehensive performance. The implementation methods and modification effects of these three artificial interface films are elaborated in this paper. Finally, it is suggested to continuously optimize the artificial interfacial films as well as to use advanced characterization techniques, theoretical calculations and simulations to study the mechanisms of interfacial stability in depth.

As an important component of alkali metal ion batteries, the anode has a huge impact on the performance of the batteries. Traditional anode such as graphene are difficult to meet the future demand for energy storage due to their low specific capacity. Therefore, it is crucial to find anode materials with high specific capacity, excellent cycling performance and stability performance. Quantum dots are widely used for compositing with anode due to their fine size and huge specific surface areas. This anode composite with quantum dot structure shows excellent electrochemical performance in alkali metal ion batteries. However, there is a lack of review and outlook on the research of quantum dots and their composites for the anode of alkali metal ion batteries. In this paper, six aspects of quantum dots, namely, metal oxide quantum dots, metal sulfide quantum dots, metal nitride quantum dots, carbon quantum dots, monolithic quantum dots and other types of quantum dots for alkali metal ion batteries are reviewed. They are focused on the mechanism of action and electrochemical properties of various types of quantum dots for composite materials. Quantum dot composite anode materials can effectively shorten the diffusion path of alkali metal ions, provide more active sites and have higher cycle stability, and are expected to become the most promising anode materials for alkali metal ion batteries. Besides, this paper analyze the problems of quantum dot anode composites, and also make an outlook on the future development of quantum dots and their composites in the field of batteries: ① Optimize quantum dots synthesis path; ② Clarify the mechanism of action of quantum dots; ③ Reduce side effect; ④ Select more suitable host materials.

Owing to the abundant resources, low cost, environmental friendliness and high energy density, Potassium ion batteries (PIBs) become an ideal novel energy storage system to replace the lithium ion batteries (LIBs). Although remarkable progress has been made in the research of PIBs in the field of electrodes in recent years, the research of electrolytes for potassium ion batteries is still in its infancy, and its design and application face many challenges, such as serious side reactions between electrolytes and electrodes, unstable solid-liquid interfaces and low Coulombic efficiency. Therefore, the development of an excellent electrolyte is the key to realize industrial application of PIBs. Herein, we review the characteristics and research progress of PIBs electrolytes in recent years. Firstly, we focus on the development status and prospect of four mainstream electrolytes, such as organic electrolyte, aqueous electrolyte, ionic liquid electrolyte and solid electrolyte. Ester-based electrolyte and ether-based electrolyte in organic electrolyte are emphatically introduced. The key problems faced by PIBs electrolyte at present are summarized, including poor safety (organic electrolyte), narrow potential window (aqueous electrolyte), low ionic conductivity (solid electrolyte) and high cost (ionic liquid electrolyte). And discuss the modification design and solutions of new electrolytes. The review purposes to expound the importance of electrolytes in PIBs, explores the application potential of current and emerging PIBs electrolytes, and puts forward some suggestions and prospects for the future development of electrolytes.

The effective extraction and functionalization of cell wall materials are essential for the high-value usage of waste biomass. Nanocellulose, as the skeleton of cell wall material, has been widely used in constructing multifunctional composites, such as aerogel, self-healing hydrogels, photonic CNC films, and photosensitive fabrics due to its unique nanostructure. This review focuses on the chemical structure and preparation method of cellulose and the rational design of multifunctional materials for energy storage. The first section of this review briefly describes cellulose chemistry and the advantages of cellulose in multifunctional composites. Furthermore, it discusses the extraction methods' evolution, advantages, and disadvantages, considering experimental conditions, eco-friendliness, economy, yield, and fiber quality. The second section of the review provides detailed information on the micro/nanostructure, chemistry, and mechanical properties of nanocellulose-based fibers, films, aerogels, and their applications in sunlight reflection and adsorption, infrared emission, and water adsorption and transportation in thermal management devices such as building coolers and solar-driven water harvesters. Additionally, it explores the applications of nanocellulose in flexible electrodes, lithophilic separators, carbon-based current collectors, and other emerging materials. Finally, this review concludes with an outlook on using unique biomass structures, separation and conversion of components, and design of composites. This outlook emphasizes the potential for further research and development of nanocellulose-based materials and their potential impact on energy storage.

In this study, pitch-based carbon microspheres were successfully obtained by using a coordinated emulsification and oxidation method with coal tar pitch as the precursor and assisted by surfactant and dispersion medium without a template. The influence of emulsification temperature on the morphology of microspheres was explored, and the optimal temperature was determined to be 280 ℃. The prepared pitch-based carbon microspheres present excellent electrochemical performance with an initial discharge capacity of 310 mAh/g at 0.05 A/g and 102 mAh/g at 2 A/g. Their long-term cyclability was at 108 mAh/g after 1000 cycles at 1 A/g.The excellent potassium storage performance was because the cross-linking structure formed by low-temperature pre-oxidation can realize the structural evolution from order to disorder. In addition, the introduced oxygen-containing groups promoted crosslinking of precursor molecules at the spatial level, ensuring structural stability during electrochemical de-/intercalation. Nevertheless, they produced abundant vacancies and defects, thereby increasing potassium storage sites.

Recycling valuable metals from used ternary lithium batteries can reduce environmental pollution and alleviate problems such as resource scarcity. Herein, an advanced and simple front-end lithium extraction process provides positive and negative mixing powder from dismantling used lithium-ion batteries using a tube furnace. The tube furnace is maintained at a certain pressure and continuously fed with carbon dioxide to roast at 750 ℃ for 1 h. Then a certain amount of water is added to the roasted powder to make a slurry, continuously passing carbon dioxide gas after solid-liquid separation to obtain a lithium bicarbonate solution. Then the solution is heated and decomposed to obtain 99.5% purity of battery-grade lithium carbonate. The overall lithium leaching rate and the recovery rate can reach 99.05% and 99%, respectively, which is one of the most advanced recovery technologies and can effectively solve the problems of difficult lithium recovery, high recovery cost, and poor economic efficiency.

Flow batteries, which are represented by vanadium batteries, are expected to drive a battery technology breakthrough for large-scale energy storage applications owing to their long cycle life, high energy efficiency, and independent regulation of power and energy. Vanadium, which is the core element of vanadium battery electrolytes, is relatively scarce and expensive, restricting the start-up and development of the vanadium battery industry. Therefore, it is imperative to explore various vanadium resources. The majority of vanadium is produced by smelting vanadium-titanium magnetite slag. The efficient extraction of vanadium from steel slag has become the key measure for the sustainable development of the vanadium industry in our country. Herein, vanadium steel slag was used as the raw material and roasted at 1000 ℃ and an 8% calcium ratio for 3 h. Finally, the roasted slag was used as the raw material for leaching. The effects of the leaching temperature, liquid-solid ratio, leaching time, and sulfuric acid concentration on vanadium leaching were investigated by carrying out a single factor test. The leaching rates of vanadium under different conditions were calculated using the potassium permanganate-ammonium ferric sulfate titration method, and the optimal leaching parameters were determined. The results revealed that when the leaching temperature was 90 ℃, the liquid-solid ratio was 10∶1, the leaching time was 60 min, and the sulfuric acid concentration was 35%, the vanadium leaching effect was optimal, and a leaching rate of up to 80.25% was achieved. This study provides a new pathway for alleviating the vanadium resource gap, reducing the production cost of the vanadium battery industry, and accelerating the development of electrochemical energy storage devices in the country.

Iron oxide is an anode material for sodium-ion batteries and has a high theoretical specific capacity; however, it undergoes large volume expansion during cycling and exhibits considerable capacity decay. The in situ construction of nanostructured metal oxides on flexible carbon-based materials can be an effective means to mitigate their volume expansion. Herein, porous carbon nanofibers (CNFs) were grown in situ on copper foam via chemical vapor deposition as a flexible conductive substrate. Furthermore, three-dimensional multistage integrated Fe₃O₄/CNF (3D Fe₃O₄/CNF) electrodes were prepared using a simple combination of salt solution impregnation and annealing and were used as the negative electrodes in sodium-ion batteries. The compositions and morphologies of the electrodes were analyzed using X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning electron microscopy. The electrochemical properties of the electrodes were characterized using constant current charge/discharge, cyclic voltammetry, and electrochemical impedance spectroscopy analyses. The results showed that Fe₃O₄ nanorods with a diameter of approximately 50—100 nm were uniformly dispersed on porous CNFs to construct a highly porous 3D multilevel structure. At a current density of 0.1 A/g, the integrated 3D Fe₃O₄/CNF electrode achieved a specific capacity of 893.4 mAh/g after 100 cycles, which is higher than CNF electrodes. Additionally, the integrated electrode exhibited faster sodium ion diffusion kinetics and better electrochemical reversibility than CNF electrodes. This study provides an idea and experimental basis for the study of metal oxide/carbon-based composite electrodes.

Transition metal oxides (TMOs) with high theoretical specific capacitance have attracted considerable attention in the field of supercapacitors; however, their high-rate and long-term applications are still challenging. In this work, a series of ternary NiCuMn-based electrodes (MPO-NiCuMn) with high-electrical conductivity and porous structure was prepared by combining dealloying and self-combustion methods and using the sandwich-like NiCuMn/Ni/NiCuMn as the mother alloy. Then, the effect of Cu doping on the electrochemical properties was investigated. The results show that the Ni-supported nanoporous alloy layers were formed by the one-step dealloying process. Because of the high-specific surface energy of the NP-NiCuMn precursor, the alloy can self-combust in an open system by partial self-sacrifice. By this one-step combustion method, the final electrodes could simultaneously enhance the electrical conductivity and promote the mass loading of TMOs. The electrochemical performance shows that the MPO-Ni₁₅Cu₁₅Mn₇₀ electrode with 15% Cu dopant has a maximum areal capacitance of 12.2 F/cm² at a high current density of 50 mA/cm², much higher than that of MPO-Ni₂₀Cu₁₀Mn₇₀ (5.6 F/cm²) and MPO-Ni₁₀Cu₂₀Mn₇₀ (7.7 F/cm²) electrodes. The assembled symmetric supercapacitor demonstrates outstanding cyclic stability with a capacitance retention of 95.7% after 8000 cycles at a current density of 50 mA/cm², as well as a high-rate performance. It also shows a high energy density of 241 mWh/cm² at a power density of 4.2 mW/cm². This study verified that doping using appropriate amounts of Cu can play a major synergistic role in effectively improving the energy storage performance of supercapacitors.

All-solid-state lithium-ion batteries constructed with solid-state electrolytes have extremely high safety and reliability and are currently a research hotspot. Composite solid-state electrolytes not only improve the mechanical properties and low ionic conductivity of polymer electrolytes but can also solve the issue of interfacial contact with inorganic solid-state electrolytes. Herein, Li₇La₃Zr₂2O₁₂ powder doped with Al and_{Mo was prepared using the sol-gel method. Furthermore, PEO compounds with different proportions of the Li6.65Al0.05La3Zr1.9Mo0.1O12 powder were prepared using the solution casting method, and their performances in solid-state batteries were investigated. The Li6.65Al0.05La3Zr1.9Mo0.1O12 powder and its composite solid-state electrolytes were characterized using various analytical methods, such as X-ray diffraction, scanning electron microscopy, and differential thermal analysis. The performance of the composite solid-state electrolytes in all-solid-state batteries was evaluated using an electrochemical workstation and a battery charging and discharging test system. Compared with pure PEO electrolyte, the 15%-Li6.65Al0.05La3Zr1.9Mo0.1O12 composite electrolyte exhibited an electrochemical window of up to 4.79 V and a stable circulation at 0.2 mA/cm² and 0.1 C ratio for about 500 h. Furthermore, it exhibited a capacity retention of 89.9% after 100 cycles.}

Developing high-performance sodium-ion battery anode materials is imminent. Transition metal sulfides have the advantages of high sodium storage capacity and good redox reaction reversibility but rapid capacity decay during charging and discharging exists. Improving the electrochemical performance of electrodes by optimizing the electrolyte is a more convenient, environmentally friendly, and effective strategy than modifying electrode materials. This study investigates CoS₂/NC as anode materials for sodium-ion batteries and their electrochemical and reaction kinetic differences between two electrolytes: ethylene glycol dimethyl ether (DME) and ethylene carbonate/diethyl carbonate (EC/DEC). The results show that the DME electrolyte, which has few side reactions with the intermediate Na₂S₆, exhibits excellent multiplicative and cycling performance. The higher stability of Na₂S₆ in DME electrolytes was demonstrated using UV spectroscopy. The electron transport and ion diffusion rates of the electrode materials were analyzed using electrochemical impedance spectroscopy and cyclic voltammetry tests at different sweep rates. The results demonstrated that the side reactions of CoS₂/NC with the electrolyte arise from the reaction of the intermediate sodium polysulfide with the electrolyte. Furthermore, the difference in the stability of the intermediate in the electrolyte is one of the main reasons affecting the electrochemical performance of CoS₂/NC. This study investigates the differences in electrochemical performance owing to the stability of sodium polysulfide in two typical electrolytes, adding new insights into the interactions between TMS anodes and electrolytes.

Microgrid systems with distributed photovoltaic and other new energy sources are becoming widely used to supplement large power grids. However, with the increasing proportion of new energy in microgrid systems, the fluctuation in their output directly affects the overall stability of the microgrid systems. Flywheel is a powerful energy storage system that can adapt to short-term high-frequency charging and discharging and has better environmental adaptability and lesser pollution throughout the life cycle than the supercapacitor system. The combination of the flywheel and battery energy storage systems can smooth the fluctuations in the distributed new energy output and improve the stability of the microgrid system. However, the operating characteristics of flywheel and battery energy storage are quite different, and the control is difficult; thus, it is currently less used in microgrid systems. Herein, an AC and DC hybrid microgrid operation topology with distributed photovoltaic and battery-flywheel electromechanical hybrid energy storage system access is designed. Based on this, a coordinated control strategy of a microgrid system based on battery-flywheel electromechanical hybrid energy storage system is proposed. The control strategy divides the hybrid energy storage system into different states according to the remaining capacity of the flywheel and battery. It takes the output-rated power of different energy storage systems and the fluctuations in distributed new energy power simultaneously and adjusts the charging and discharging currents of the flywheel and battery to reduce the power fluctuations in the microgrid caused by new energy access. Herein, a microgrid system is built based on MATLAB/Simulink, and the simulation results verify the effectiveness of the proposed microgrid-coordinated control strategy.

Research progress on energy storage technologies of China in 2022 is reviewed in this paper. By reviewing and analyzing three aspects in terms of fundamental study, technical research, integration and demonstration, the progress on China's energy storage technologies in 2022 is summarized including hydro pumped energy storage, compressed air energy storage, flywheel, lithium-ion battery, lead battery, flow battery, sodium-ion battery, supercapacitor, new technologies, integration technology, firecontrol technology etc. It is found that important achievements in energy storage technologies have been obtained during 2022, and China is now the most active country in the world in energy storage fields on all the three aspects of fundamental study, technical research, integration and application.

This bimonthly review paper provides a comprehensive overview of recent research and developments in the field of lithium batteries. Our search of the Web of Science yielded 3714 papers from February 1, 2023 to March 31, 2023, from which we selected 100 for highlighting. One noteworthy area of investigation is the use of high-nickel ternary layered oxides and LiNiO₂ as cathode materials, with extensive investigations of how doping and interface modifications affect their electrochemical performances, as well as monitoring of surface and bulk evolution of structures during prolonged cycling. For anode materials, researchers focus mainly on silicon-based composite materials optimizing electrode structures to mitigate the effects of volume changes, while also emphasizing the importance of functional binders and interface modification. Efforts have also been devoted to designing the three-dimensional electrode structures, modifying the interface, and mitigating inhomogeneity plating of lithium metal anodes. Research on solid-state electrolytes is mainly focused on designing and optimizing their structure and performance, particularly in sulfide-, oxide-, chloride-, and polymer-based solid-state electrolytes and their composites. Liquid electrolytes similarly benefit from the use of optimized solvents, lithium salts, and functional additives for different battery applications. For solid-state batteries, the studies are mainly focused on the suitability of layered oxide cathode materials with sulfide based- and chloride based-solid-state electrolytes. Additionally, researchers are investigating composite sulfur cathodes with a high ion/electron conductive matrix and functional binders to suppress the “shuttle effect” and activate sulfur in Li-S batteries. Other relevant works are also presented to the dry electrode coating technology. There are a few papers for the characterization techniques of lithium-ion transport in the cathode and lithium deposition. Ultimately, theoretical calculations are carried out to better understand the stability of solid electrolytes and the interface between the solid-state electrolyte and Li.

Neutral aqueous organic redox flow batteries (AORFB) are a promising electrochemical energy storage technology owing to their low cost, easy performance regulation, and high operational safety. The technology uses water-soluble electromechanical active materials as electrolytes to store and release energy through their reversible oxidation-reduction process under neutral conditions. Their excellent properties make them highly suitable for large-scale grid connection and intelligent distribution in the renewable energy sector. Drawing on current research on neutral AORFBs, this comprehensive review summarizes the development status, main challenges, and future development direction of positive electrolytes based on ferrocene derivatives and TEMPO derivatives. The modification strategies of ferrocene derivatives and TEMPO derivatives and the development prospects as cathode electrolytes for AORFB are comprehensively summarized and compared. By contrast, TEMPO derivatives have several advantages, such as high redox electrode potential, solubility, battery capacity compared to ferrocene derivatives, and are thus considered to be more promising in practical applications. However, their structural stability is still deemed insufficient for long-term operation. To this end, various modification strategies have been proposed, including the introduction of steric hindrance and electrostatic repulsion, both of which have demonstrated to be and effective. This paper presents a summary and analysis of the degradation mechanism of TEMPO derivatives, which highlights that the breakdown of nitrogen-oxygen bonds owing to proton attack is the primary cause of degradation. The authors suggest the incorporation of importing of protecting groups on the TEMPO main-ring as a potential approach to further improve the long-term structural stability.

Aqueous zinc metal batteries (AZMBs) are gaining popularity in large-scale energy storage owing to their low cost and high safety. However, the unstable nature of the zinc metal in conventional aqueous electrolytes leads to the occurrence of zinc dendrite and side reactions such as hydrogen evolution and corrosion tend to occur at the interface, ultimately resulting in a shorter cycling life of AZMBs. To effectively regulate the chemical properties and reaction processes at the zinc anode interface and improve interfacial stability, electrolyte additive are used that can greatly extend the cycling life of AZMBs. Therefore, it is highly necessary to summarize the relevant research on electrolyte additives stabilizing the zinc anode, and propose new solutions to the key issues currently present. This paper provides examines the literature on the challenges faced and mechanisms of zinc anode, emphasizing the regulation mechanisms of electrolyte additives, including the design of an electrostatic shielding layer, water-poor double electric layer, in situ solid electrolyte interface layer and regulation of the zinc-ion solvation shell. In addition, different types of additives were classified and discussed, including cationic, anionic, organic small molecule, organic polymer, and others, and their respective regulation mechanisms and effects on electrochemical performance were analyzed. Ultimately, the study proposes new prospects for the development of electrolyte additive strategies to stabilize zinc negative electrodes.

Li-rich Mn-based cathode has the advantages of high specific capacity and low cost, which is expected to be the cathode material for the next generation of high-energy density Li-metal batteries. However, in practical applications, its charging cutoff voltage is 4.8 V versus Li, leading to the failure of electrolyte oxygenation decompositions, thereby deteriorating the interface between the cathode and electrolyte, making stable battery cycling challenging. A novel high-voltage electrolyte based on LiPF₆ is developed, in which 1, 1, 2, 2-tetrafluoroethyl-2, 2, 3, 3-tetrafluoropropylether (TTE) is used as a solvent to promote coordination. The experimental and characterization results show that many Li anions participate in the solvated structure of Li⁺ coordination after introducing appropriate TTE in the electrolyte, which can form a 5-nm-thick fluorine-rich cathode electrolyte interphase (CEI) on the surface of the cathode, stabilizing its interface and inhibiting the degradation of the cathode layer structure. The Li-rich Mn-based cathode Li-metal battery with the new electrolyte has an 83.9% capacity retention rate after 400 cycles with an average efficiency of 99.8% (0.5 C). The 1.25-Ah Li-rich Mn-based cathode Li-metal battery pouch cell can provide 370 Wh/kg mass-energy density at 0.04 C and still has an 80% capacity retention rate after 45 cycles at 0.08 C, showing a good application prospect. This study is helpful to promote the application of Li-rich Mn-based cathode and provide an experimental basis for the research and development of high energy density Li-metal batteries.

Lithium-ion batteries (LIBs) have been widely applied as common energy storage devices owing to their high energy and power densities, low cost, environmental friendliness, etc. The demand for developing nongraphite-based anode materials to improve battery performance is increasingly urgent. CuMoO₄ is a potential anodic material owing to its high theoretical specific capacity and low reduction potential. To address the problems of poor electrical conductivity and irreversible structural pulverization when CuMoO₄ is used as an anodic material, micro-nanostructured C/TiO₂/CuMoO₄ fibrous composite was fabricated using natural cotton fibers as the structural scaffold and C source, showing excellent electrochemical performance. The cotton fibers were first pretreated with H₂SO₄ and NaOH to increase the specific surface area, and thereafter, ultrathin TiO₂ layers were deposited on the fiber surfaces using a sol-gel method. The CuMoO₄ layers were further deposited via the layer-by-layer (LbL) self-assembly technique. The micro-nanostructure C/TiO₂/CuMoO₄ fibrous composite was obtained via calcination at 500 ℃ in an Ar atmosphere for 6 h. When applied as an anodic material for LIBs, the composite with 22.8% CuMoO₄ delivered initial discharge and charge capacities of 1212 mAh/g and 675 mAh/g, respectively, with a coulomb efficiency of 55.7%; after 200 charge-discharge cycles at 100 mA/g, the specific capacity was 403 mAh/g with a capacity retention of 59.7%, showing good cycle and rate performances. The conductivity and structural stability of the composite are improved owing to its micro-nanostructure, enhancing electrochemical performances.

Lithium lanthanum zirconate (Li₇La₃Zr₂O₁₂, LLZO) solid-state electrolytes were synthesized using the chemical coprecipitation method. The effects of the operation parameters of the sintering process, ball milling, Al doping, and compression force on the grain boundary, phase, densification, and final Li⁺ ion conductivity were evaluated using various characterization techniques, e.g., scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS) analyses. Wet ball milling using isopropanol as a grinding aid or hot-pressed sintering is beneficial for improving the density of LLZO pellets. However, the Li⁺ ion conductivities at room temperature of the samples is low due to their poor structures. The cubic phase structure (c-LLZO) was synthesized via dry ball milling and pressure less sintering, and the crystal structures became pure as the sintering temperature increased. To solve the subsequent problem of the grain coarsening, a two-step sintering was proposed instead of one-step sintering to synthesize LLZO electrolytes with small particle sizes and high relative density. At the same time, the effect of Al doping in stabilizing the cubic structure was also enhanced using the two-step sintering. Finally, the as-prepared Al-doped LLZO solid-state electrolyte obtained via dry ball milling, cold pressing at 750 MPa, and two-step sintering of 1100 ℃ for 6 h and 1200 ℃ for 20 h exhibited the highest ionic conductivity (1.52×10^-4 S/cm), mainly owing to its cubic garnet structure and the highest relative density. This research will shed light on preparing and applying LLZO-related ceramic materials, providing a solid basis and guidance for developing solid-state battery technology.

As a key cathode material for future high-specific capacity lithium-ion batteries, nickel-rich cathode materials have advantages of high capacity, strong stability, low cost, and environmental friendliness. Meanwhile, increasing the elemental Ni content in the materials contributes to high reversible capacity and further enhances the specific energy of the battery. However, increased nickel content in the material suffers many problems, such as increased cation mixing, which increase surface-interface side reactions, decrease thermal stability, crack crystals, and spread rapidly, as well as considerably elevate residual lithium compounds on both surface and interior of the cathode. Owing to these negative impacts, high-nickel cathode materials often suffer failure and safety problems while charging-discharging, hindering their practical applications. Based on the above considerations, we comprehensively compared and analyzed the modification methods used to stabilize and enhance the high-nickel cathode materials for Li-ion batteries in recent years. As a result, we concluded that small-scale refined structure modifications should be conducted based on the original modification strategy for developing high-nickel positive electrodes of lithium-ion batteries. Besides, the microstructure of the nickel-rich positive electrode materials should be optimized depending on their applications to improve their performance.

The power system distribution station area is the critical unit of electric energy distribution. Its core component, the energy storage battery pack, comprises many cells. Given the inevitable consistency difference of each cell in the energy storage battery pack, an adaptive group equalization control method for an energy storage battery pack is proposed based on K-means clustering. First, an equalization topology is introduced to transfer equalization energy between cells or battery modules containing any number of cells. Second, the idea of group equalization is introduced, and the adjacent cells that need to be charged and discharged are clustered into groups using the K-means clustering algorithm to realize a balanced energy transfer between battery groups containing a different number of adjacent cells. Finally, simulation experiments verify the proposed cluster group equalization control. Compared with the range-based cell-to-cell equalization control, cluster group equalization control improves the equalization speed by 34.8%, 19.8%, and 17.6%, respectively, under the initial SOC distribution conditions: high in the middle, low on both sides; high on both sides, low in the middle; and balanced distribution. Herein, the idea of cluster equalization for an energy storage battery pack composed of a large number of cells is proposed, which is conducive to the equalization speed of the energy storage battery pack, thereby improving its energy utilization rate and cycle life and promoting the application of the energy storage battery pack.

Among power batteries, large-capacity NCM lithium-ion batteries have a large output and a high risk of thermal runaway. The research on using water mist to suppress thermal runaway fire has attracted wide attention. Herein, a 150 Ah large-capacity NCM lithium-ion battery is used with a 10-MPa water mist to adopt continuous and intermittent spray strategies for the thermal runaway fire suppression experiment. The influence of parameters on the thermal runaway behavior, such as different release times, a period of pulse, duty cycle, temperature, heat production rate, and other experimental results, were compared and analyzed. The results show that, compared with ordinary capacity batteries, the thermal runaway of large-capacity NCM lithium-ion batteries repeatedly occurs with intense combustion behavior, considerably increasing the temperature. However, water mist has an apparent fire suppression effect on the large-capacity NCM lithium-ion batteries. The longer the release time, the better the fire suppression and cooling effect. However, the continuous spray strategy still has a reignition phenomenon, and with the increase in release time, the increase of cooling efficiency gradually slows down. For large-capacity NCM lithium-ion batteries, the thermal runaway fire suppression ability of the intermittent spray strategy is better than that of the continuous spray strategy, which can quickly extinguish open flame without reignition and effectively reduce the heat production rate and the maximum temperature of the battery surface. Under the studied conditions, when the duty cycle is 0.3, the optimal cooling effect for the pulse water mist is at a water consumption of 10 L in a period of 10 s. Compared with the continuous spray under the same water consumption, the heat generation rate decreased by 28%, and the maximum temperature of the battery surface dropped by 176 ℃. This study can provide a reference for the design of fire-extinguishing facilities of large-capacity NCM power battery systems.

The proposal of carbon peaking and carbon neutrality goals has accelerated China's low-carbon energy transformation, leading to the rigorous promotion of the new energy vehicle industry. The power battery, as the core component of these vehicles, is about to face a massive retirement wave in the replacement process. However, the cascade utilization of power batteries could alleviate recycling pressure and environmental pollution while maximizing the full life cycle of the battery, which is crucial for low-carbon emissions, energy savings, and environmental protection. To further improve the green and sustainable development system of cascade utilization, this paper analyzes the current policies, standards, and application scenarios of echelon utilization. The study discusses the battery recycling mode, aging principle, detection, screening, capacity configuration, control principle, battery management system, and other technologies from the aspects of battery recycling and cascade utilization of the energy storage system. Ultimately, the paper presents the problems and challenges faced by the cascade utilization of decommissioned power batteries, and constructive suggestions are made for the breakthrough of industrial technology and the formation of an industrial system. This research could help the industrial layout of cascade utilization.

With the advancement of energy transition in China, using power batteries is rising yearly. The problem of battery safety has gradually come to the fore. In the battery management system (BMS), the equivalent circuit model (ECM) is the core of its work to ensure safe and stable operation. The current battery model in the BMS is mainly linear, which is limited by the computational volume and the computing power of the chip, which cannot reasonably and practically express the nonlinear characteristics of the battery under extreme operating conditions, such as high power. To address this problem, herein, from the perspective of available power, pulse discharge experiments are conducted on the battery at different multipliers to analyze the nonlinear characteristics of the internal resistance of the battery, improve the equivalent circuit model of the battery, and establish the variation of impedance with current under high multiplier conditions. The error of the improved impedance model is 1.74%, considerably smaller than the 8% of the old model. The results show an improved accuracy compared with the traditional equivalent circuit model, and the calculated computational volume is smaller than that of the P2D model, which is expected to be used in the online simulation calculation of the battery model in BMS to avoid over-power discharge of power batteries and improve the safety of battery use.

Large-scale energy storage applications require high safety measurements for lithium-ion batteries. Thus, the safety detection technology of lithium-ion batteries for energy storage should be fully explored to improve the safety performance of batteries. As the first national standard for energy storage batteries in China, GB/T 36276—2018 “Lithium ion battery for electrical energy storage" estimates whether the specified safety test provisions are scientific and reasonable and whether the test methods are feasible and need to be verified. First, based on the safety accident promotion factors of lithium batteries, this study decomposes the necessary fire factors via the fire accident tree principle. Then the Boolean algebraic algorithm is used to simulate and scientifically propose the safety detection items of energy storage batteries. The results are compared and analyzed with the national standard GB/T 36276—2018, which verifies the scientific rationality of the current national standard terms. Finally, based on the test platform, 14 safety testing experiments are performed on lithium-ion batteries for energy storage in different systems, such as lithium ternary, lithium titanate, lithium iron phosphate, and lithium manganate, to verify the proposed test items. The operability and feasibility of the safety test clauses in the national standard GB/T 36276—2018 have been verified for the first time at home and abroad, providing basis and data support for revising the new version of the national standard GB/T 36276.

Accurate estimating the state of health (SOH) of electric vehicle batteries is crucial for their safe and efficient operation. One approach to achieve high-precision SOH estimation is by extracting health characteristics from electrochemical impedance spectroscopy (EIS). However, collecting online EIS data requires high-tech on-board equipment, posing a challenge to the efficacy of this technique. In addition, SOH estimation based on single frequency impedance leads to low accuracy. To address these issues, a new SOH estimation method has been proposed in this study that combines the frequency impedance characteristics. The method involves forming a combination of frequency impedance characteristics by merging the imaginary impedance part in the first 120 cycles at 10 Hz with that in the last 320 cycles at 7.94 Hz after analyzing the experimental data. The method then involved training a long short term memory neural network model with test data from B1 and B2 cells to estimate battery SOH, based on the selected combination frequency impedance characteristics. Subsequently, this model was validated with data from B3 and B4 cells. Results estimate that SOH estimation model based on the combination of frequency impedance features yields a root mean square error of 0.3% at least. This figure is at least 23.9% lower than that achieved with the single frequency impedance model. Therefore, the SOH estimation method not only facilitates performing impedance measurements, but it also promises high estimation accuracy. Additionally, it can be applied to online SOH estimation.

As a technology that can adjust energy, time, and space, batteries are one of the best ways to optimize energy applications and improve the comprehensive efficiency of energy use. With the increasing demand for energy storage and the wide application of large-scale energy storage systems, batteries with high-energy density and long-cycle life have become a current research focus. However, with the improved battery performance, its safety has become increasingly a concern. Battery accidents are often closely related to the flammable and explosive properties of organic electrolytes, heat accumulation induced by high current charging and discharging, battery monomer structure, and the thermoelectric loop control technology of modules. Nondestructive characterization means are used to accurately analyze the battery performance evolution, such as thermal runaway and life attenuation. These techniques can considerably avoid external interference and conduct insitu detection and analysis of the battery under the real environment and operating conditions to express and monitor the battery service behavior clearly and accurately. Thus, critical information, such as the reaction principle and the health state of the battery, can be derived. Furthermore, preparing electrode materials and designing and grouping battery structures improve the safety and reliability of the battery. Herein, the recently reported battery nondestructive testing, monitoring, and characterization methods are reviewed, including sensor, magnetic resonance, X-ray, neutron scattering, ultrasonic detection, and Raman scattering. These methods help to describe their principles, application methods, and characteristics of information acquisition, making a comprehensive comparison of each characterization technology, especially the mutually supportive relationship of battery data. It provides methods and technical means to deeply explore the relationship between the internal microstructure evolution, electrical performance, and battery safety under different working conditions, which gradually improve the battery efficiency and support the establishment of battery accident warning and life warning mechanisms.

Under the background of "dual carbon", the importance of energy storage as a supporting technology to overcome the instability of clean energy, such as photovoltaic and wind power, is becoming increasingly apparent. Performing high-level basic talent research in energy storage is of great importance to China's independent and original innovations in energy storage. This study uses bibliometric methods and the global list of "highly cited scientists" to analyze the structural characteristics, distribution, and trends of high-level talents in energy storage.Furthermore, this study provides a reference and basis for relevant departments to formulate policies in the field of energy storage for the training and introducing talents, constructing high-level research highlands, and encouraging enterprises to participate in basic research.