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

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.