Study On Preparation Of Vanadium-based Lithium-ion Battery Cathode Materials With Vanadium Slag Leaching Liquid As Raw Material

With the high-quality development of electronic equipment and new energy vehicles,there are higher requirements for the capacity and miniaturization of lithium-ion batteries.The main factor limiting the capacity of lithium-ion batteries is the low actual capacity of the cathode material.The search for high-capacity lithium-ion battery cathode materials has great theoretical and practical significance.V₂O₅ is currently the material with the highest theoretical specific capacity among transition metal oxides,and is considered to be a new generation of positive electrode material for green lithium ion batteries.However,due to the low conductivity and poor cycle performance of V₂O₅,it faces great challenges in practical applications.One of the effective ways to solve the above problems is to use V₂O₅ and carbon material composite.Vanadium slag is a typical solid waste,and it is a common raw material for vanadium extraction in industry.Extraction of vanadium from vanadium slag can solve the accumulation of solid waste and environmental pollution.Functional materials,especially V₂O₅ lithium ion battery cathode materials,can be extracted from vanadium slag,which can both solve the problem of environmental pollution and provide a new choice as a source of V₂O₅.Reduce V₂O₅ preparation cost.Therefore,in this paper,the magnesium roasting experiment of vanadium slag and the preparation of V₂O₅/C composite materials are carried out.The main contents are as follows:1.First,the thermodynamic analysis of the vanadium slag magnesium roasting reaction was performed.Using vanadium slag and magnesite as raw materials,the roasting experiment was conducted under conditions such as roasting temperature,roasting time,and magnesite addition amount to determine the optimum roasting experiment temperature,time,and raw material ratio.The thermodynamic analysis shows that the vanadium slag magnesiumization roasting experiment is carried out spontaneously in the roasting temperature range.The results of roasting experiments show that the influence levels of various factors from the vanadium leaching rate from high to low are roasting temperature,additive ratio and roasting time.The best parameters are roasting temperature 900℃,n（MgO）/n（V₂O₅）=2.8,and roasting time is 2h,the vanadium leaching rate is 95.3%.2.A waste cigarette filter（CY）was studied as a carbon skeleton,and a CY-based V₂O₅/C composite was prepared by a solution impregnation-low temperature roasting method.XRD and SEM were used to characterize the crystal phase and micromorphology of V₂O₅/C composites,constant current charge and discharge,cyclic voltammetry and AC impedance tests,and the electrochemical performance of V₂O₅/C composites.XRD analysis showed that the composite was a singleα-V₂O₅ phase.SEM shows that V₂O₅ whiskers grow on the surface and pore size of CY.Electrochemical test analysis shows that the composite material has a good specific capacity.The first cycle can reach 261mAh/g,and even at a rate of 20C,the capacity can reach 125mAh/g.3.The waste foam（CP）was studied as a carbon skeleton,and CP-based V₂O₅/C composites were prepared by solution impregnation-low temperature roasting.XRD and SEM were used to characterize the crystal phase and micromorphology of V₂O₅/C composites,constant current charge and discharge,cyclic voltammetry and AC impedance tests,and the electrochemical performance of V₂O₅/C composites.XRD analysis showed that the composite was a singleα-V₂O₅ phase.SEM shows that CP is a disordered network structure with V₂O₅ attached to its surface.Electrochemical test analysis shows that as the immersion time,the concentration of the leaching solution and the roasting temperature increase,the specific discharge capacity increases successively.The best parameters are 40 hours of immersion,the concentration of V^x+solution is 8.7g/L,and the roasting temperature is 750℃.The composite has the highest discharge specific capacity for the first time,up to 385mAh/g（0.5C）,and after 30cycles,it can still obtain a discharge specific capacity of 257mAh/g,with excellent rate performance.