Thermodynamic stability and crystal structure dependence of Li content for LixMn2-yMyO4(M = Mg, A1, Cr, Mn) as a cathode active material for Li secondary battery

Abstract

We investigated the relation between the thermodynamic stability and crystal structure dependence of Li content for the substituted spinel, Li xMn2-yMyO4 (M = Mg, Al, Cr, Mn). The enthalpy change per mole of atoms for the formation reaction, ΔH R, were calculated from the heat of dissolution. ΔH R increased with the decreasing Li content. ΔHR of the all amounts of Li content for LixMn2-yM yO4 (M = Mg, Al, Cr, Mn) decreased compared to that of LixMn2O4. The crystal structure analysis by powder neutron diffraction was examined for LixMn2-yM yO4 (M = Mg, Al, Cr, Mn). The Madelung energy increases with decreasing Li content for LixMn2O4, and it was associated with the thermodynamic data. From these results, the host structure is structurally and thermodynamically stable of the all amounts of Li content with the substitution of M for LixMn2-yM yO4.