关键词: 共沉淀法, 富锂锰基材料, 原位XRD, 阳离子混排

Abstract:

Lithium-rich manganese based cathode materials 0.6Li[Li_1/3Mn_2/3]O₂•0.4LiNi_xMn_yCo_1-x-yO₂ (x < 0.6, y > 0) were synthesized by carbonate co-precipitation and high temperature solid-state reaction. The structures and morphologies of the as-prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The results of high temperature in-situ XRD test show that the lattice parameters change significantly with increasing temperature and Ni content. The cation mixing gets serious and the spinel phase appears in the high Ni content samples when the temperature is up to 800 oC. Under voltages ranging from 2.0 to 4.6 V, the lower Ni content sample has the highest discharge capacity of 260.1 mA•g^-1 (the initial coulombic efficiency of 83.2%) at current density of 20 mA•g^-1, and the discharge capacity retention is up to 99.7% with the relatively smaller voltage decay after 50 cycles.

Key words: carbonate co-precipitation method, lithium-rich manganese based cathode materials, in-situ X-ray diffraction, cation mixing