Thermodynamic Stability and Cathode Performance of Li_(1+x)Mn_(2-x)O_4 as a Cathode Active Material for Lithium Secondary Battery

摘要

We investigated the relation between cathode performance and the thermodynamic stability of the spinel Li_(1+x)Mn_(2-x)O_4 (x = 0-0.1) as a cathode active material for lithium secondary battery. The Mn valence was controlled by annealing conditions or changing the Li content. The heats of dissolution of the samples were measured by the solution calorimetry method. The standard enthalpy of formation, #DELTA#_fH deg, and the enthalpy change of reaction, AH, were calculated from the heat of dissolution. #DELTA#_fH deg and #DELTA#H decreased and Mn valence increased with increasing Li content or higher P_(O_2), annealing treatment, leading to a good cycle performance in spite of a moderate decrease of initial capacity.