Single-Atom Cadmium-N₄ Sites for Rechargeable Li–CO₂ Batteries with High Capacity and Ultra-Long Lifetime

The rechargeable Li–CO₂ battery shows great potential in civil, military, and aerospace fields due to its high theoretical energy density and CO₂ capture capability. To facilitate the practical application of Li–CO₂ battery, the design of efficient, low-cost, and robust non-noble metal cathodes to boost CO₂ reduction/evolution kinetics is highly desirable yet remains a challenge. Herein, single-atom cadmium is reported with a Cd-N₄ coordination structure enable rapid kinetics of both the discharge and recharge process when employed as a cathode catalyst, and thus facilitates exceptional rate performance in a Li–CO₂ battery, even up to 10 A g⁻¹, and remains stable at a high current density (100 A g⁻¹). An unprecedented discharge capacity of 160045 mAh g⁻¹ is attained at 500 mA g⁻¹. Excellent cycling stability is maintained for 1685 and 669 cycles at 1 A g⁻¹ and capacities of 0.5 and 1 Ah g⁻¹, respectively. Density functional theory calculations reveal low energy barriers for both Li₂CO₃ formation and decomposition reactions during the respective discharge and recharge process, evidencing the high catalytic activity of single Cd sites. This study provides a simple and effective avenue for developing highly active and stable single-atom non-precious metal cathode catalysts for advanced Li–CO₂ batteries.