Urchin-like γ-MnO₂/Carbon Nanotubes as an Efficient Cathode Catalyst for Durable Solid-State Lithium and Sodium-CO₂ Batteries

Metal-CO 2 batteries integrate the benefits of carbon dioxide capture and efficient energy storage, representing a prospective innovation in energy storage systems. In particular, most of the research attention has been concentrated on Li-CO 2 and Na-CO 2 batteries due to their high energy density and discharge potential. However, the excessive accumulation of discharge products and the volatilization of the liquid electrolyte restrict the further advancements of these batteries. Herein, we synthesized an urchin-like γ-MnO 2 cathode catalyst that enables a rapid and reversible CO 2 reduction reaction (CO 2 RR) and the CO 2 evolution reaction (CO 2 ER). The assembled solid-state Li/Na-CO 2 batteries with Li 7 La 3 Zr 2 O 12 - and Na 3 Zr 2 Si 2 PO 12 -based composite solid electrolytes facilitate uniform stripping/deposition of metallic anodes, thereby ensuring the long-term cycling stability of batteries. The assembled Li/Na-CO 2 batteries exhibit cycling stability for 240 and 100 cycles, respectively, at a current density of 200 mA g –1 and a cutting-off capacity of 500 mAh g –1 . Even at a high current density of 500 mA g –1, the batteries still possess excellent rate capability. This work provides a promising solution to reduce the costs of cathode catalysts and enhance safety for Li/Na-CO 2 batteries.