Thermodynamic stability and cathode performance of Li1+xMn2-xO4 as a cathode active material for lithium secondary battery

Abstract

We investigated the relation between cathode performance and the thermodynamic stability of the spinel Li1+xMn2-xO4 (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, ΔfH°, and the enthalpy change of reaction, ΔH, were calculated from the heat of dissolution. ΔfH° and ΔH decreased and Mn valence increased with increasing Li content or higher Po2 annealing treatment, leading to a good cycle perfor-mance in spite of a moderate decrease of initial capacity.