Pure Phase Disordered LiMn_1.45Cr_0.1Ni_0.45O₄ by Post-Annealing Treatment

A new post-annealing treatment at ca. 600 °C was used to modify the oxygen deficiency during the synthesis of the spinel LiMn_1.45Cr_0.1Ni_0.45O₄ cathode for Li-ion batteries. It is an effective way to eliminate the impurity phase without changing the crystal chemistry. Small amount of substituting Cr leads to better rate performance and cyclability at room temperature, compared to commercial LiMn_1.5Ni_0.5O₄. LiMn_1.45Cr_0.1Ni_0.45O₄ delivered a reversible capacity of 104 mAh g^-1 at 1C rate. After 125 cycles, about 99% of reversible capacity was retained for the LiMn_1.45Cr_0.1Ni_0.45O₄ in contrast with 6% capacity loss for the commercial LiMn_1.5Ni_0.5O₄. Electrochemical impedance spectroscopy measurements revealed that the LiMn_1.45Cr_0.1Ni_0.45O₄ had a smaller surface resistance, which may be due to the segregation of Ni from the surface to the bulk.