Enhanced Cycling Performance of a Li-Excess Li₂CuO₂ Cathode Additive by Cosubstitution Nanoarchitectonics of Ni and...

The adoption of Li₂CuO₂ 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). Li₂CuO₂ 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 (O₂) evolution, resulting in poor overall cycling performance. It is thus crucial to reinforce the structure of Li₂CuO₂ to make it more reliable as a cathode additive for charge compensation. Pursuing the structural stability of Li₂CuO₂, herein, we demonstrate cosubstitution by heteroatoms, such as nickel (Ni) and manganese (Mn), for improving the structural stability and electrochemical performance of Li₂CuO₂. Such an approach effectively enhances the reversibility of Li₂CuO₂ by suppressing continuous structural degradation and O₂ gas evolution during cycling. Our findings provide new conceptual pathways for developing advanced cathode additives for high-energy LIBs.