A Long-Cycle-Life Reversible Li-CO₂ Battery Enabled by Engineering the Active Sites of Graphene with Pd Nanoparticles

Li-CO₂ batteries have been recognized as an emerging technology for energy storage systems owing to their high theoretical specific energy and environmentally friendly CO₂ fixation ability. However, their development for applications requires a high energy efficiency and long cycle-life, this is currently limited to the formation of wide-bandgap insulator Li₂CO₃ during discharge. Here, nanoparticle Pd supported on reduced graphene oxide (rGO) is utilized as cathodes for Li-CO₂ batteries, Pd nanoparticles as active centers significantly enhance CO₂RR/CO₂ER reaction activity, which can support the fast formation and decomposition of Li₂CO₃ in organic electrolytes and achieve a high discharge capacity of 7500 mAh g^-1. It also performs remarkably high cycling stability of over 500 cycles with a long cycle-life of 5000 hours. The observed super electrochemical performance is attributable to the thick electrode design and uniform distribution of ultrafine catalyst nanoparticle Pd. When Li₂CO₃ is adsorbed on Pd particle, the Li-O bond in Li₂CO₃ will be elongated due to the interactions of two nucleophilic O atoms with Pd, resulting in a weakening of the Li-O bond and activation of Li₂CO₃. Our work suggests a way to design catalysts with high activity that can be used to activate the performance of Li-CO₂ batteries.