Abstract: The spinel Li_1.02Co_xCr_yMn_2-x-yO₄ as a cathode of lithium ion secondary battery was synthesized by a solid-state method. The influences of the different Cr and Co content in the LiMn₂O₄ on phase constitution and structure, lattice parameters and electrochemical properties were investigated. The spinel structure was kept still with inserting a small amount of Cr and Co to Li_1.02Mn₂O₄. The Jahn-Teller distortion and the Mn³⁺ disproportionation reaction were restrained efficiently. With the substitution content of Cr and Co increased, the lattice parameters of Li_1.02Mn₂O₄ decreased, while specific surface area was increased, and the specific capacity of the cell was improved. In addition, the initial capacity was decreased, but the cycle performance of materials was improved obviously.

Key words: solid-state method, doping Cr and Co, electrochemical performance, AC impedance