Ru-doping to enhance electrochemical performance of co-free Li-rich layered cathode materials

The development of high-capacity cathode materials is one of most effective strategies to improve the energy density of Li-ions batteries. Layered Li-rich manganese-based cathode materials have attracted much attention from researchers due to their ultra-high specific capacity (>250 mAh g^-1) and low cost. However, Li-rich cathode materials still suffer some drawbacks especially its poor cycle performance due to the necessary high operation voltage, which accelerated structural deterioration toward inactive rock-salt phase and greatly limit their practical application. Herein, Ru are proposed as a doping element to substitute TM in Li_1.2Ni_0.2Mn_0.6O₂ as a prototype materials. The XRD and EDS mapping results indicate the Ru has been successfully doped in the layered structure and can restrain the structural degradation during cycling. The electrochemical tests present that the Li-rich cathode with 1 wt% Ru-doping displays the highest capacity retention with nearly no capacity fade over 40 cycles. This work should shed light on the structural and electrochemical enhancement of lithium-rich cathode materials for the most advanced Li ions batteries.