High-Performance Aprotic Li–CO2 Battery Enabled by the Ru Heterophase Catalyst

Abstract

Aprotic Li–CO2 batteries (LCBs) hold promise for mitigating the greenhouse effect while generating electric power, yet their development remains nascent due to the sluggish CO2 activation and irreversible discharge product formation, requiring efficient catalysts to address these challenges. Herein, we developed ∼5.5 nm fcc + hcp Ru heterophase nanoparticles on a Ketjen black (KB) matrix (Rufcc+hcp/KB) as a dual-functional catalyst for LCBs. X-ray absorption spectroscopy revealed charge redistribution in the fcc + hcp heterophase and under-coordinated Ru sites, which serve as abundant active sites to boost catalytic activity. Theoretical calculations evidenced that the heterophase interface lowers the free energy barriers of the desorption of the *Li2CO3 step (*Li2CO3 → Li2CO3) and the decomposition of the *Li2C2O4 step (*Li2C2O4 → *LiC2O4 + Li), facilitating both the nucleation and decomposition of Li2CO3. Thus, the Rufcc+hcp/KB catalyst exhibited a low overpotential of 0.73 V and long-term cycling stability exceeding 2260 h (at 100 mA g–1 with a capacity of 1000 mA h g–1), outperforming Rufcc/KB (1.14 V, 1260 h), Ruhcp/KB (0.90 V, 1480 h), and previously reported Ru-based catalysts. Our findings highlight crystalline phase engineering as an effective strategy to enhance catalytic performance in LCBs. © 2025 American Chemical Society