Abstract: Lithium-rich layered solid solution materials, Li_1+2xMn_0.3+xNi_0.3-3xCr_0.4O₂ (x=1/60, 1/30, 1/20, 1/15, 1/12), were synthesized by spray-drying process. Their crystal structures, element valences and the electrochemical performances were investigated by XRD, XPS, ICP, SEM, TEM and charge-discharge test. All samples have a typical solid solution feature in terms of their structure, and no impurity phase appears in their XRD profiles. Nevertheless, XPS results suggest that Cr³⁺ and Cr⁶⁺ co-exist in all samples. The presence of the Cr⁶⁺ in the as-prepared sample results in a high moisture absorption, which can be removed by water washed treatment. As to the electrochemical properties, the as-prepared samples have bad electrochemical performances due to the high moisture absorption. After washing with water, all samples exhibit solid solution behavior, and their initial specific capacities increase as the increase in the amount of Li and Mn. The discharge capacity of Li_1.17Mn_0.38Ni_0.05Cr_0.4O₂ can reach 203 mAh/g with a capacity retention of 71% after 50 cycles.

Key words: Li-ion battery, cathode materials, spray-dry, lithium-rich layered solid solution, electrochemical property