Homogenizing Li 2 CO 3 Nucleation and Growth through High-Density Single-Atomic Ru Loading toward Reversible Li-CO 2 Reaction.

The high activation barrier and sluggish kinetics of Li 2 CO 3 decomposition impose a severe challenge on the development of a Li-CO 2 battery with high Coulombic efficiency. To tackle this issue, herein we devise a novel synthetic tactic by combining electrostatic assembly with in situ polycondensation to obtain a single-atomic Ru catalyst of high density up to ∼5 wt %. When deployed to the CO 2 cathode, the catalyst delivered an extraordinary capacity of 44.7 Ah g -1 , an ultralow charge/discharge polarization of 0.97 V at 0.1 A g -1 (1.90 V at 2 A g -1 ), and a long-term cycling stability up to 367 cycles at 1 Ah g -1 (196 cycles at 2 Ah g -1 ), outshining most of the state-of-the-art CO 2 cathode catalysts reported today. Further through extensive in situ and ex situ electroanalytical, spectroscopic, and microscopic characterizations, we attribute the superb battery performance mainly to the highly reversible Li 2 CO 3 formation/decomposition, facilitated by the homogenized and downsized Li 2 CO 3 nucleation and growth on account of the high density single-atomic Ru loading. This work not only offers a facile method to fabricate single-atom catalysts with high mass loading but also sheds light on promoting the reversible Li-CO 2 reaction by mediating product morphology.