Enhanced Cycling Performance of a Li-Excess Li 2 CuO 2 Cathode Additive by Cosubstitution Nanoarchitectonics of Ni and Mn for Lithium-Ion Batteries.

The adoption of Li 2 CuO 2 has drawn interest as a Li-excess cathode additive for compensating irreversible Li + loss in anodes during cycling, which would move forward high-energy-density lithium-ion batteries (LIBs). Li 2 CuO 2 provides a high irreversible capacity (>200 mAh g -1 ) in the first cycle and an operating voltage comparable with commercial cathode materials, but its practical use is still restricted by the structural instability and spontaneous oxygen (O 2 ) evolution, resulting in poor overall cycling performance. It is thus crucial to reinforce the structure of Li 2 CuO 2 to make it more reliable as a cathode additive for charge compensation. Pursuing the structural stability of Li 2 CuO 2 , herein, we demonstrate cosubstitution by heteroatoms, such as nickel (Ni) and manganese (Mn), for improving the structural stability and electrochemical performance of Li 2 CuO 2 . Such an approach effectively enhances the reversibility of Li 2 CuO 2 by suppressing continuous structural degradation and O 2 gas evolution during cycling. Our findings provide new conceptual pathways for developing advanced cathode additives for high-energy LIBs.