Li Content Dependence of Crystal Structure and Electronic Structure for Chemical Delithiation of Li_xMn_2-yM_yO₄ (M = Mg, Al, Cr, Mn, Co, Zn, Ni) as a Cathode Active Material for Li Secondary Battery

Abstract

We investigated the crystal structure, electronic structure and nuclear state of chemical delithiated spinel Li_xMn_2-yM_yO₄ (M = Mg, Al, Cr, Mn, Co, Zn, Ni) dependence Li content, x. We obtained the electronic and nuclear density distributions of the samples from XRD and neutron diffraction data using the maximum entropy method. Li content of Li_xMn_2-yM_yO₄ was controlled by changing concentration of H₂SO₄-H₂O aqueous solution. Mn valence increased and lattice parameter, a, decreased with decreasing Li content. The electron of Li_0.095Mn₂O₄ was delcolization from the results of electronic density distribution. The amount of change of covalent bonding of (Mn, M)-O for Li_xMn_2-yM_yO₄ (M = Mg, Al, Cr, Co, Zn, Ni) decreased in comparison with that of Li_xMn₂O₄ when Li content changed. From the results, the host structure is stable with the substitution of M for Li_xMn_2-yM_yO₄.