Ultra‐Long Cycle Life in Lithium‐Carbon Dioxide Batteries via Synergistic Solution Pathway Regulation and Redox‐Mediating Effect of Mo/Co Species

ABSTRACT During the CO 2 reduction reaction (CO 2 RR) process in Li‐CO 2 batteries, molybdenum carbide (Mo 2 C) catalysts have attracted wide attention owing to the 2‐electron lithium oxalate (Li 2 C 2 O 4 ) route, while the formation of lithium carbonate (Li 2 CO 3 ) is often inevitable due to the disproportionation of C 2 O 4 2− . In this study, benefit from the introduction of Co to Mo n+ C catalyst, a rapid diffusion of Li 2 C 2 O 4 has been realized with a solution‐mediated dissolution process, leading to heterostructure products with mixed growth of Li 2 CO 3 and C. Furthermore, in this Co‐loaded Mo n+ C catalyst, the Mo +2/+3 C serves as a solid redox mediator and facilitate electron transfer from Mo +2/+3 C to the CO 2 molecule through the formation of C─O─Mo bond, then they achieved an ultrahigh discharge voltage of 3.1 V in the CO 2 RR process. Through the regulation of the CO 2 − and Li 2 CO 3 absorbing of Mo 2 C, the synchronous decomposition of both discharge products, Li 2 CO 3 and C is achieved, avoiding the irreversible accumulation of carbon that leads to capacity decay. This enables Li‐CO 2 batteries to achieve an ultra‐long cycle life exceeding 4800 h. This design provides new insights for the future optimization of charge/discharge pathways, especially the synchronous decomposition of two solid‐phase products Li 2 CO 3 and C in Li‐CO 2 batteries.