Mitigating Voltage Decay of Li-Rich Layered Oxide by Incorporation of 5d Metal Rhenium

Voltage decay in a charging-discharging cycle restricts the commercial application of Li-rich layered oxides as a cathode material for next-generation lithium-ion batteries with high energy density. Considering the relationship between transition-metal ion migration and voltage decay, the size of doped ions and the bond dissociation between metal and oxygen play an important role in suppressing voltage decay. Herein, 5d metal rhenium has been incorporated into lithium-rich layered oxides for the first time. By replacing Mn4+ by Re7+ with the same ionic radius in the metal layer rather than the Li layer, the as-prepared rhenium-doped material could deliver a reversible capacity of 202 mAh.g(-1) under a current density of 400 mA.g(-1) and exhibit a significant mitigation of the voltage decay with a voltage retention of 81% in a voltage range of 2.0-4.8 V (vs Li+/Li) after 300 cycles. The improved electrochemical performance is resulted from the enhanced oxygen stability induced by local structural variation around doping Re. Also, this convenient method may be applied to other high-capacity cathode materials in the future.