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

We investigated the relation between cathode performance and the thermodyna mic stability of the spinel Li1+xMn2-xO4 (x= 0-0.1) as a cathode active mat erial for lithium secondary battery. The Mn valence was controlled by annea ling conditions or changing the Li content. The heats of dissolution of the samples were measured by the solution calorimetry method. The standard ent halpy of formation, Delta(f)H(o) and the enthalpy change of reaction, Delta H, were calculated from the heat of dissolution. Delta(f)H(o) and Delta H decreased and Mn valence increased with increasing Li content or higher P-o . annealing treatment, leading to a good cycle performance in spite of a mo derate decrease of initial capacity.