Thermodynamic Stability and Cathode Performance of LiMn_2-xNi_xO₄ as an Active Material for Li Secondary Battery

Abstract

The spinel LiMn_2-xNi_xO₄ (x = 0~0.5) in which a part of Mn was substituted by Ni were prepared, and the Mn valence was determined by chemical analysis. Mn valence increased with increasing Ni content, x. The heats of dissolution of the samples were measured by the solution calorimetry method. The standard enthalpy of formation, Δ_fH⁰, and the enthalpy change of reaction, ΔH, were calculated from the heat of dissolution. Thermodynamic stability was examined by ΔH. From the relation between the cathode performance and the thermodynamic stability of LiMn_2-xNi_xO₄ (x = 0~0.5), a more thermodynamically stable sample was found to lead to a good cycle performance.