Preparation And Electrochemical Properties Of Tungsten-based Lithium-ion Battery Anode Materials

Lithium-ion batteries dominate the consumer electronics market with their high energy density,no memory effect,long life and low self-discharge.However,the current demand for lithium-ion battery performance is also increasing,but the limited capacity of lithium-ion batteries cannot meet the urgent demand for high capacity.One of the major reasons for this is that the theoretical capacity of the electrode cathode material is not large enough,and the actual capacity decays after several cycles,which cannot provide sufficient energy demand.WO₃as anode material for lithium-ion batteries has a theoretical capacity of 693 m Ah·g^-1,which is higher than that of graphite anode,and tungsten is abundant in nature,so it has received much attention.However,WO₃ expands in volume during charge/discharge cycles,which can cause the electrode material to peel off from the collector fluid and reduce the cycle life of the battery,and the conductivity is poor.In order to improve its electrochemical performance,two methods are used:（1）To suppress the volume expansion during cycling and to improve the electrical conductivity,carbon materials are used to solve the above problems.The effect of the addition of carbon materials on the lithium storage performance of WO₃ was analyzed by preparing tungsten trioxide carbon nanofibers（WO₃ CNFs）and composites of tungsten trioxide carbon nanofibers and graphene oxide（WO₃ CNFs/GO）by electrostatic spinning technique.Electrochemical tests were performed on the WO₃ CNFs/GO electrode materials,and the results showed that the WO₃ CNFs and WO₃ CNFs/GO have reversible discharge specific capacities of 644.6 and 339.9 m Ah·g^-1 after 250 cycles at 0.2 C current density.（2）The electrochemical performance of the electrode materials was enhanced by preparing composite materials.The WO₃/Co WO₄/r GO composites were prepared by hydrothermal method using ZIF-67 as the substrate.The electrochemical performance of the electrode was enhanced by increasing the specific surface area of the material with the high porosity of ZIF-67 after carbonization,and the conductivity of the electrode was enhanced by using the carbon framework of ZIF-67 and r GO.The results show that WO₃/Co WO₄/r GO has a reversible specific capacity of 507.8 m Ah·g^-1 after 100 cycles at a current density of 100 m A·g^-1,andWO₃/Co WO₄/r GO has a superior diffusion coefficient compared with WO₃ monomer by GITT test.performance.By comparing the SEM images before and after cycling,it can be found that the WO₃/Co WO₄/r GO electrode structure has good stability,which is beneficial to improve the cycling stability of lithium-ion batteries.