Abstract: The layered Li_0.7Co_xMn_1-xO₂ cathode materials with O₂-type structure were synthesized by using improved
solid-state reaction and ion exchange reaction in atmosphere. The influence of sinter temperature and the content of doping cobalt of the precursor
alkali bronzes was investigated, and XRD analysis, SEM analysis and electrochemical test were used to study the structure and electrochemical
properties of the precursors and samples. The results show that the precursor Na_0.7Co_0.2Mn_0.8O₂ sintered at 900℃ for 16h
has an obviously layered P2 structure. The electrochemical tests show that the sample Li_0.7Co_0.2Mn_0.8O₂ has the best electrochemical
properties which has an initial discharge capacity of 162 mAh·g^-1 cycled between 2.25～4.20V and shows only one charge-discharge plateau of
2.70～2.90V. A significant structure transformation to the spinal-type phase on cycling was not found for the material and a stabilization of
the specific capacity around 153 mAh·g^-1 remained after the 40 cycles for the material.

Key words: lithium ion battery, cathode material, layered Li_0.7Co_xMn_1-xO₂