Investigations On Electrochemical Performances Of Spinel Lithium Manganese Oxide/LiPF₆-(EC+DEC) Interface

Electrochemical performances of LiMn2O4/LiPF6-(EC+DEC) solution interface are investigated with powder microelectrode technique. Several electrochemical and nonelectrochemical methods including AC impedance, cyclic voltammetry, potential decay, XRD, SEM, etc. are used. Firstly, Electrochemical impedance spectroscopies of insertion and deinsertion of Li ion in spinel lithium manganese oxide with different contents of inserted lithium ions are studied in detailed. Secondly, the Changes in interface performances of LiMn2O4/LiPFe-(EC+DEC) solution are studied before and after charge-discharge cycling ,after storage and under overcharge. At last, the influences of the synthetic methods on the interface performances are studied. Following results are obtained:1. New equivalent circuits modeling the insertion and deinsertion of Li ion in LiMn2O4 is proposed to fit the experimental electrochemical impedance spectroscopies. The Warburg impedance describing the diffusion and the insertion capacitance describing the accumulation or consumption of Li ion in the oxide are in series when jc^O.5, but in paralell when 0.5