Sodium?ion batteries have become one of the research hotspots in the field of energy storage because of their advantages of low cost and high safety. This paper tried to clarify the development history of the hard carbon anode of sodium?ion batteries and address the current disadvantages of sodium?ion batteries, such as low initial coulombic efficiency, poor stability, and insufficient high magnification performance. In addition, to explore the sodium?ion storage mechanism in hard carbon, this paper used CiteSpace to visually analyze the development process of sodium?ion batteries and reviewed the research progress of performance optimization strategies for hard carbon anode in terms of material design, structure regulation, and function design and interface optimization. Furthermore, the paper summarized and discussed the existing hard carbon sodium storage mechanisms and finally prospected the development direction of the hard carbon anode of sodium?ion batteries.

As carbon peak and carbon neutrality become a global consensus,electrochemical energy storage technologies and related industries have been developing rapidly.The demand for electrode materials is also increasing steadily.How to prepare high?performance anode materials with widely available and low?cost precursors has thus become a research hot spot both in China and abroad.Coal is the most promising precursor for anode materials because of its high carbon content,abundant reserves,and low price.In recent years,researchers have prepared various anode materials,such as amorphous carbon,graphite,carbon nanotubes, and graphene,from coal and studied their application in lithium?ion batteries in depth.This paper summarized the research progress of three typical coal?based carbon anode materials in lithium?ion batteries.Then, it reviewed their synthesis methods,optimization and modification,and electrochemical performance.Finally,the paper presented an outlook on the development and application of coal?based carbon anode materials.

As the society and economy move forward, energy and environmental problems have attracted extensive attention. Hydrogen energy is considered the ideal clean energy in the 21st century due to its high energy density, pollution?free attribute, abundant reserves, and wide application. As a clean production technology, hydrogen production by water electrolysis has developed vigorously under the goals of carbon peak and carbon neutrality. The key challenge lies in the development of high?performance electrocatalysts for the hydrogen evolution reaction (HER) to reduce the overpotential of water splitting. This paper reviewed the current mainstream hydrogen production technologies by water electrolysis in detail and analyzed the characteristics and advantages and disadvantages of each technology. Moreover,it summarized the research progress of HER catalysts and predicted the development directions of the hydrogen production technology by water electrolysis and its electrocatalysts.

Solid oxide electrolysis cell (SOEC) technology can realize the efficient and flexible conversion of electrical and thermal energy to chemical energy on the basis of solid electrolytes. It can be connected with renewable energy sources such as solar and wind power and tidal energy to utilize the excess electricity generated for efficient, clean, and large?scale production of hydrogen. When coupled with the CO₂ capture process, it enables the co?electrolysis of CO₂ and H₂O to produce syngas. In addition, it can be combined with large?scale industries to produce high?value?added chemicals such as ethylene, ammonia, and formaldehyde with low?value?added raw materials generated. SOEC technology can meet the needs of the future society for the large?scale renewable energy conversion and storage,which is of great significance for accelerating the substitution process of non?fossil energy worldwide and the realization of China's carbon peak and neutrality goals. This paper mainly discussed the electrode and electrolyte materials used in solid oxide electrolysis technology, the application scenarios and principles at the current stage, and the challenges faced. Moreover, it predicted the future development directions of the technology.

Sodium?ion batteries (SIBs) have the advantages of rich resources and low cost and supply risk.Therefore,they are regarded as a new generation of electrochemical energy storage devices with great potential.At present,vanadium pentoxide (V₂O₅) has gradually become a research hotspot of cathode materials for SIBs because of its high working voltage and theoretical capacity. However,the disadvantages of V₂O₅ cathode material,including low ion diffusion coefficient,low conductivity,and structural instability caused by repeated ion intercalation/deintercalation,have limited its application in SIBs.This paper analyzed the crystal structure and sodium storage mechanism of V₂O₅ and summarized the research progress of V₂O₅ cathode material in SIBs through modification methods such as morphology control,crystal structure modification,chemical pre?insertion,and composition with other materials.Finally,the paper prospected the development trend of V₂O₅ electrode material.

Electrochemical reduction of CO₂ to CO using renewable energy is one of the effective ways to achieve "carbon neutrality" and renewable energy storage.This review briefly described the advantages and basic principles of the electrochemical reduction of CO₂ and summarized the research progress of metal electrocatalysts for the electrochemical reduction of CO₂ to CO in aqueous solutions in recent years.Specifically,this study mainly introduced the recent research progress of mono?metal nanocatalysts,bimetallic catalysts,metal?organic complex catalysts,and mono?atom catalysts,which included their influences on the electrochemical reduction of CO₂ and relevant reaction mechanisms.The introduction was conducted from several perspectives,such as the preparation of nanoparticles as well as the regulation of their composition and structure,alloy construction,structural design of metal centers as well as their ligands and carriers,and the development of mono?atom catalysts. In addition, this study summarized the advantages and disadvantages of various catalysts and predicted the development trend of metal catalysts.

Asymmetric supercapacitors(ASCs) have the merits of rapid charge and discharge,high power density,and long?term cyclic stability.The properties of electrode materials determine the performance of ASCs.Cation substitution is an effective method to tune the structure and properties of electrode materials and optimize energy storage performance accordingly.This paper prepared MCo₂S₄(M=Co,Ni,or Cu) nanosheet arrays on the surface of a nickel foam substrate.For this purpose,it controlled the cationic components of the spinel sulfide and employed a hydrothermal method.Due to the differences in the radius and electronegativity of metal irons,the lattice structure of Co₃S₄ underwent strain when Ni²⁺ or Cu²⁺ ions were introduced into Co₃S₄ to obtain NiCo₂S₄ or CuCo₂S₄.The result was reinforced reactivity of the metal sites.The charge transfer and ion diffusion resistances of NiCo₂S₄ are respectively 48.6% and 28.7% lower than those of Co₃S₄,indicating favorable electrochemical properties achieved.The specific capacity of NiCo₂S₄ is 1 128.8 F/g under a current density of 1 A/g.The capacity retention is 59.8% under a current density of 10 A/g.The retention of the initial specific capacity is 60.2% after 8 000 cycles.

This paper used metals (Ni,Cu,Sn,In and Ti) after smelting,forging,grinding,and polishing as substrates of Zn anode for aqueous Zn?ion batteries.In addition,the paper adopted XRD,SEM,in?situ optical microscope,and electrochemical characterization techniques to analyze hydrogen evolution rate in different substrates,Zn deposition/dissolution behaviors,galvanic corrosion,and cycling performance in different substrates.The results show that Sn and In can not only inhibit the side reactions caused by the contact between Zn and substrates，but also have excellent Zn?philic properties. However, the morphology of Zn deposition on Sn substrate surfaces is greatly affected by Sn crystal planes.In contrast,In is more suitable for the substrate of the Zn anode.

The concentration of heavy metal Pb²⁺ is one of the important monitoring indicators in environmental management and control,and excessive Pb²⁺ in the environment will pose a severe threat both to human health and ecological stability.Herein,a polydopamine coating was successfully modified on the electrode surface by a simple in?situ electro?induced polymerization method,and the electrode was further applied to the electrochemical analysis for the detection of trace Pb²⁺ in water.The results show that Pb²⁺ are easily enriched on the electrode surface through chelation with abundant functional groups (-OH,-NH₂,etc.) in the polydopamine surface,and they are redissolved into the aqueous solution from the electrode surface by an anodic stripping voltammetry method.As a result,sensitive and specific electrochemical signals are developed.After analyzing the influences of experimental parameters such as electrolyte,pH value,and enrichment time on the intensity of the electrochemical signals,the study optimized the performance of the proposed method in detecting Pb²⁺ in water,with a detection limit of 32 nmol/L within a detection range of 50~800 nmol/L.Furthermore,the method was applied to detect the Pb²⁺ in actual water samples,with an average recovery rate of about 95%.This simple electrode modification strategy can provide new ideas for designing portable sensitivity sensors to detect and analyze trace heavy metal ions in the environment.