Homogenizing Li2CO3 Nucleation and Growth through High-Density Single-Atomic Ru Loading toward Reversible Li-CO2 Reaction.

ABSTRACT

The high activation barrier and sluggish kinetics of Li2CO3 decomposition impose a severe challenge on the development of a Li-CO2 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 CO2 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 CO2 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 Li2CO3 formation/decomposition, facilitated by the homogenized and downsized Li2CO3 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-CO2 reaction by mediating product morphology.