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.