Reversible flowering of CuO nanoclusters via conversion reaction for dual-ion Li metal batteries.

Dual-ion Li metal batteries based on non-flammable SO 2 -in-salt inorganic electrolytes ( Li-SO 2 batteries) offer high safety and energy density. The use of cupric oxide (CuO) as a self-activating cathode material achieves a high specific capacity with cost-effective manufacturing in Li-SO 2 batteries, but its cycle retention performance deteriorates owing to the significant morphological changes of the cathode active materials. Herein, we report the catalytic effect of carbonaceous materials used in the cathode material of Li-SO 2 batteries, which act as templates to help recrystallize the active materials in the activation and conversion reactions. We found that the combination of oxidative-cyclized polyacrylonitrile (PAN) with N-doped carbonaceous materials and multi-yolk-shell CuO (MYS-CuO) nanoclusters as cathode active materials can significantly increase the specific capacity to 315.9 mAh g - 1 (93.8% of the theoretical value) at 0.2 C, which corresponds to an energy density of 1295 Wh kg CuO -1 , with a capacity retention of 84.46% at the 200th cycle, and the cathode exhibited an atypical blossom-like morphological change.