Reasarch On Synthesis And Electrochemical Properties Of Li₂FeSiO₄/peanut Shell Carbon Composites

As an emerging cathode material,lithium iron silicate has advantages that many other materials do not have,such as abundant raw materials,high specific capacity,high working voltage,stability and environmental friendliness.In addition,lithium iron silicate materials also have their own poor conductivity and low lithium-ion diffusion coefficient,which restricts the development of the cathode material.Therefore,improving the electronic conductivity of lithium iron silicate and increasing the lithium ion diffusion coefficient are the problems to be solved in this paper.In this paper,Peanut-C was used as the carbon skeleton.Li₂FeSiO₄/Peanut-C cathode material was prepared by solvothermal sol-gel method.Based on the suitable amount of peanut-C and glucose,Ce³⁺-substituted Li₂Fe_1-xCe_xSiO₄/Peanut-C/C?x=0,0.01,0.03,0.05?cathode materials were prepared by the same method,The effects of the amount of peanut hull carbon and glucose coating and Ce³⁺doping on the composite materials were investigated by structural characterization?XRD,SEM and TEM?and galvanostatic charge-discharge tests?first charge-discharge cycle performance test and rate performance test?.The first discharge capacity of Li₂FeSiO₄/Peanut-C/C at a current density of 0.1C with 5 wt.%peanut hull and 20 wt.%glucose is 100 mAh·g^-1.The capacity retention rate is 75%after 10 cycles.The synthesized cathode materials are orthorhombic structure with the space group of Pmn2₁.The glucose is distributed evenly in the cladding layer.and the carbon content of 10.6 wt.%can be calculated from Li₂FeSiO₄/Peanut-C/C composite according to TGA data.Based on the above experimental results,the first discharge capacity of the composite Li₂Fe_0.97Ce_0.03SiO₄/Peanut-C/C electrode is up to 154.55 mAh·g^-1,and the lithium ion diffusion is 6.40×10^-1313 cm²s^-1,which has the best cycling performance,the best rate performance and the largest lithium ion diffusion.Dispersibility of the material particles is improved by Ce³⁺substitution,the carbon content in the composite is 11.0 wt.%according to TGA data.Both the appropriate carbon coating and Ce³⁺substitution improve the electrochemical properties of Li₂FeSiO₄ electrode material.