Verifying the Rechargeability of Li‐CO₂ Batteries on Working Cathodes of Ni Nanoparticles Highly Dispersed on N‐Doped Graphene

Abstract

Li-CO₂ batteries could skillfully combine the reduction of "greenhouse effect" with energy storage systems. However, Li-CO₂ batteries still suffer from unsatisfactory electrochemical performances and their rechargeability is challenged. Here, it is reported that a composite of Ni nanoparticles highly dispersed on N-doped graphene (Ni-NG) with 3D porous structure, exhibits a superior discharge capacity of 17 625 mA h g^-1, as the air cathode for Li-CO₂ batteries. The batteries with these highly efficient cathodes could sustain 100 cycles at a cutoff capacity of 1000 mA h g^-1 with low overpotentials at the current density of 100 mA g^-1. Particularly, the Ni-NG cathodes allow to observe the appearance/disappearance of agglomerated Li₂CO₃ particles and carbon thin films directly upon discharge/charge processes. In addition, the recycle of CO₂ is detected through in situ differential electrochemical mass spectrometry. This is a critical step to verify the electrochemical rechargeability of Li-CO₂ batteries. Also, first-principles computations further prove that Ni nanoparticles are active sites for the reaction of Li and CO₂, which could guide to design more advantageous catalysts for rechargeable Li-CO₂ batteries.