Fast Li₂O₂ Electrochemistry Enabled by Co-Nx/Co (111) with Optimized Intermediate Adsorption.

Abstract

The practical development of Li-O₂ batteries (LOBs) urgently needs to explore robust cathode catalysts to boost the sluggish Li₂O₂ reaction kinetics and parasitic reactions despite their theoretically high specific energy. Profound understanding of the cathode properties and the battery performance is rather critical in developing rational-designed electrocatalysts. In this study, a Co-N_x/Co (111) decorated N-doped hierarchical carbon framework (Co-N_x/Co@NHCF) is proposed as an efficient cathode in LOBs. Spectroscopic analysis coupled with experimental results suggests that the Co-N_x/Co (111) catalytic center can significantly reduce the battery overpotential, and meanwhile, the hierarchical carbon framework ensures rapid mass transportation and provides sufficient space to accommodate Li₂O₂ deposition. Density functional theory calculations reveal that the incorporated Co (111) facet can effectively regulate the electronic distribution of N-carbon, optimize the adsorption of desirable intermediates, and eventually facilitate oxygen reduction reaction/oxygen evolution reaction kinetics. As expected, the Co-N_x/Co@NHCF catalyzed LOBs deliver a high discharge/charge capacity of 6.15/ 6.22 mAh cm^-2 with a columbic efficiency of 98.9%, along with a high rate cycling of 700 h at 0.3 mA cm^-2. This work provides valuable instruction for the rational design of efficient catalysts for high-performance LOBs via optimization of the crystal structure and the adsorption of intermediates.