Li-CO₂ batteries are regarded as promising energy storage system due to their high energy density, CO₂ fixation ability and environmental friendliness. However, Li-CO₂ batteries are still suffering from large overpotential and poor cycling performance, which severely hinder their practical applications. Therefore, it is vital to design highly efficient cathode catalysts to improve the performance of Li-CO₂ batteries. Here, we designed a highly efficient synergistic catalyst by incorporating ultrafine Ru nanoparticles on N, S co-doped graphene (Ru/NS-G) as cathode for Li-CO₂ batteries. The ultrafine Ru catalyst can reduce the decomposition voltage of the discharge product Li₂CO₃. In addition, N, S co-doped graphene (NS-G) with a three-dimensional structure provides excellent conductivity and adequate space for the reversible reactions in batteries. The Ru/NS-G catalyst achieves enhanced catalytic activities for the CO₂ reduction/evolution reactions, assigned to the strong synergistic effect between the bifunctional catalyst Ru nanoparticles and the NS-G substrate with numerous defect structures and accessibly active sites. The batteries achieve an impressive discharge capacity (12448 mA h g⁻¹ at a current density of 100 mA g⁻¹), high Coulombic efficiency (94.6 %) and excellent cycling stability (over 100 cycles) with a low overpotential of 1.40 V. This work provides an engineering strategy on the cathode design for metal-gas batteries and other devices that are not limited to Li-CO₂ batteries.

Li-CO ₂电池因其高能量密度，CO ₂固定能力和环境友好性而被视为有前途的储能系统。但是，Li-CO ₂电池仍存在较大的过电势和较差的循环性能，这严重阻碍了其实际应用。因此，设计高效的阴极催化剂以改善Li-CO ₂电池的性能至关重要。在这里，我们通过在N，S共掺杂石墨烯（Ru / NS-G）上掺入超细Ru纳米颗粒作为Li-CO ₂电池的阴极，设计了一种高效的协同催化剂。超细Ru催化剂可以降低放电产物Li ₂ CO的分解电压₃。此外，具有三维结构的N，S共掺杂石墨烯（NS-G）为电池中的可逆反应提供了出色的导电性和足够的空间。Ru / NS-G催化剂提高了CO ₂还原/释放反应的催化活性，这归因于双功能催化剂Ru纳米颗粒与具有众多缺陷结构和可接近的活性位的NS-G底物之间的强大协同作用。电池实现令人印象深刻的放电容量（12448毫安汞柱^-1在100mA g的电流密度^-1），高库仑效率（94.6％）和出色的循环稳定性（超过100个循环），1.40 V的低过电位。这项工作为金属气体电池和其他不限于Li的器件的阴极设计提供了工程策略-CO ₂电池。