MnO2包覆改性富锂锰基正极材料作用机理的电化学研究

Electrochemical Studies on the Working Mechanism of Lithium-rich Manganese Based Material Coated by MnO_2

采用固相反应制备了富锂锰基正极材料,并利用化学沉淀及热处理工艺进行MnO_2表面包覆改性.通过恒流充放电、循环伏安及交流阻抗谱对所得材料进行电化学性能测试,通过改性前后电化学反应的变化研究了MnO_2对富锂锰基材料包覆改性的作用机理.研究结果表明,MnO_2包覆层能发挥储锂作用.在热处理过程中,富锂锰基材料中的锂、镍元素发生迁移扩散,在MnO_2包覆层中形成新的尖晶石复合相,并可逆地参与后续循环反应,这对材料电化学性能的提升具有积极作用.

In order to investigate the characteristic reactions and structural changes of lithium-rich manganese based material coated by MnO 2,the lithium-rich manganese based material was prepared by solid state reaction,and then modified with MnO 2 by chemical precipitation and heat treatment.The electrochemical performances of the obtained materials were characterized by constant current charge-discharge,cyclic voltammetry and electrochemical impedance spectroscopy.The working mechanism of lithium-rich manganese based materials coated by MnO 2 was studied by discussing the changes of the electrochemical reactions before and after the modification.The results show that the coating MnO 2 can work as the container of lithium.During the heat treatment process,lithium and nickel elements of the lithium-rich manganese based material migrate and diffuse into the MnO 2 coating to form a new spinel composite phase,which reversibly participates in the subsequent cyclic reactions and makes its contribution to enhance the battery electrochemical performances.