碳材料作为过渡金属氧/硫族化物负极材料负载剂的研究进展

Advances of Carbon Materials as Loaders for Transition Metal Oxygen/Sulfide Anode Materials

在过去的几十年中,碳质材料和含碳复合材料因其具有高比表面积、良好的活性中心、可调的形貌以及优异的传质和扩散性能而引起了人们的极大关注。在储能领域,可充电锂离子电池(LIBs)和钠离子电池(SIBs)作为下一代大型储能系统,被广泛研究。然而,其能量密度、功率密度以及循环性,仍然是LIBs/SIBs面临的主要挑战,尤其是作为瓶颈的阳极,其中过渡金属氧化物/硫化物由于其固有的低的导电性和循环过程中大的体积膨胀,限制了它们商业化的应用。碳材料由于其导电性好,在循环过程中具有良好的循环性能,因此作为大部分负极材料的负载物,提高复合材料的导电性及循环性能。本文从锂/钠离子电池负极材料常用的过渡金属氧化物/硫化物/硒化物与碳复合的材料出发,系统地总结了锂/钠离子电池中载体碳的类型、复合材料的合成方法,并展望了碳负载负极材料所面临的挑战。

In the past few decades,great efforts have been made in exploring advanced active materials with improved electrochemical performances in terms of high energy density,good mechanical/thermal stability,environmental friendliness and low cost for practical applications.To accomplish these goals,combining active materials with other active/inactive materials for complementary strengthen‐ing is an efficient approach,among these active materials,carbon materials are of great importance to a range of battery chemistries,be‐cause of it is the most versatile element on the periodic table,and its various allotropes make for highly diverse properties and applica‐tions.Nowadays,carbonaceous and carbon-containing composite materials have attracted great attention because of their high specific surface area,good active center,adjustable morphology,and excellent mass transfer and diffusion properties.For example,biomass de‐rived carbon had the advantage of being a renewable,low-cost source,and also can provide excellent porous 3D nanostructure.N-dop‐ing of carbon have been proven to improve the electrochemical performance,as it enhances the electrical conductivity and also provide more sites.Furthermore,N-doped carbons are synthesized typically using various expensive,toxic N containing precursors following rigorous/complex experimental procedures.In this point,preparation of N-doped carbon from naturally occurring bio waste/biomass is very appealing as it reduces the environmental pollution,lessens the usage of toxic chemicals and is very inexpensive both in terms of source cost and processing cost.Graphene is regarded as the ideal conductive substrate to disperse and confine active materials because of its excellent conductivity,large specific surface area,robust mechanical strength and remarkable stability.In the field of recharge‐able lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs),as the next-generation large-scale energy storage systems,have been widely studied.However,its energy density,power density,and cycle performance are still the main challenges faced by LIBs/SIBs,especially as the anode of the bottleneck.Graphite is the most widely used anode material for commercial lithium-ion batteries be‐cause of its flat potential profile,high columbic efficiency,and good cycling stability.However,the relatively low theoretical capacity(372 mAh·g^(-1))greatly limited the energy density of lithium-ion batteries.To address such issues,many carbonaceous materials with various morphologies and structures have been applied.For instance,porous carbon,carbon nanotubes(CNTs)or reduced graphene oxide,owing to their high conductivity and mechanical strength,are widely employed as matrix to loading the anode materials.Mean‐while,extensive researches have proved that nanostructured materials can effectively enhance electrochemical performance by reducing the diffusion lengths,improving kinetics,and increasing electrolyte contact area.However,because of their high surface energy,the nanostructured materials always tend to aggregation.Nowadays,metal-organic frameworks(MOFs)are a class of crystalline porous ma‐terials composed of metal units and organic linkers.MOFs used as promising precursors to construct carbon coated metal-based compos‐ites with enhanced individual-particle conductivity for electrocatalysis and energy storage.Moreover,interconnecting isolated MOF de‐rived nanoparticles can enhance interparticle conductivity and accommodate large volume changes during cycles.Transition-metal ox‐ide/sulfide have attracted considerable attention in recent years because of their unique properties and promising applications in electro‐chemical energy storage and conversion.However,the limited number of active sites and inherent low conductivity severely impair their electrochemical performance.To top it off,the fatal volume changes happened in cycling processes due to the oxidation-reduction reac‐tion could lead to the pulverization and exfoliation of active material.Thus,like almost all transition metal oxygen/chalcogenide showed terrible cyclability,it is the main bottleneck of their application for LIBs/SIBs.Carbon materials had good cycle performance during cy‐cling because of their good conductivity.Therefore,as a load of most negative electrode materials,carbon materials can improve the conductivity and cycle performance of composite materials.Numerous studies showed that the structure of anodes was crucial for good electrochemical performance.Hollow spheres with nanometer-to-micrometer dimensions,controlled internal structure,and shell com‐position have attracted tremendous attention because of their potential application in catalysis,drug delivery,nanoreactors,energy con‐version and storage systems,photonic devices,chemical sensors,and biotechnology.Single-shell and double-shell hollow spheres of various compositions have been synthesized by a number of methods,such as vesicles,emulsions,micelles,gas-bubble,and hard-tem‐plating methods.Recently,more efforts have focused on the fabrication of hollow spheres with multiple shells,as these materials are ex‐pected to have better properties for applications such as drug release with prolonged release time,heterogeneous catalysis,lithium-ion batteries,and photocatalysis.The construction of three-dimensional(3D)architectures from transition metal oxygen/chalcogenide nano‐materials provides an effective strategy to solve these issues.Generally,these 3D architectures possess large specific surface area which nanosheets can be maintained in the 3D transition metal oxygen/chalcogenide architecture as the restacking of nanosheets is effectively inhibited.Therefore,a great number of electrochemically active sites are exposed to the electrolyte,thus enabling sufficient electro‐chemical reactions.This paper systematically summarized the types of supported carbon in lithium/sodium ion batteries and the synthe‐sis method of composite materials,starting from the materials commonly used for transition metal oxide/sulfide/selenide and carbon com‐posites for lithium/sodium ion battery anode materials and looking forward to the challenges faced by carbon-loaded anode materials.