Study On The Preparation Of Spinel LiMn₂O₄ Anode Material By Slo-gel And Doping Modification

Lithium-ion batteries have a good prospect in application for its favorable advantages of high voltage,big specific capacity,long cycling life and non-pollution. Anode material is the key to the development of lithium-ion batteries.Due to its high safety,low cost and non-toxicity,significant attention has been focused on the development of Spinel LiMn₂O₄ in recent years.However,the bad cycle ability at high temperature is the main barrier limiting its application.The research and the development on the current situation of the lithium-ion battery anode materials are reviewed in this paper.To resolve the problems of the the spinel LiMn₂O₄ anode material low actual specific capacity,cycle deficiencies,capacity fading fast,the preliminary study on the influence discipline of the structure and electrochemical properties of the spinel LiMn₂O₄ anode material by sol-gel synthesis process and Co³⁺-doped modified.The spinel LiMn₂O₄ anode material was synthesized by sol-gel method.The effects of pH value,calcining temperature,insulation methods on structure and performance of spinel was investigated by XRD,SEM and electrochemical methods.The results show that the high specific capacities,and poor cycling performance of LiMn₂O₄ were obtained when it was during the short insulation time,long synthesized time;the low specific capacities,good cycling performance of LiMn₂O₄ were obtained when it was during the long insulation time,short synthesized time,and along with the increase of calcination temperature,the cycle performance has been greatly improved.The first discharge specific capacities of the spinel LiMn₂O₄ is 103.63mAh/g.The discharge specific capacities could still retain about 91.28mAh/g gafter 30 cycles and the specific capacity retention is 88%.One of the important investigation points in the present thesis was modification of spinel LiMn₂O₄ by ions-doping.Co³⁺-doping spinel LiMn₂O₄ was prepared.It stucture and electrochemical properties were characterized by means of XRD,SEM techniques. The XRD results show that the synthesized material doped with Co³⁺ was pure spinel. The results of electrochemical test show that the cycle performance of LiMn₂O₄ at room temperature was improved,but it decreases the capacity of LiMn₂O₄ at some degree. The first discharge specific capacity of Co³⁺-doped LiMn₂O₄ to LiCo_0.05Mn_1.95O₄ is 96.68mAh/g.The discharge specific capacity could still retain about 94.84mAh/g,after 20 cycles and the specific capacity retention is 98.1%.The cycle performance of the material is improved obviously.