High-Performance Aprotic Li–CO<sub>2</sub> Battery Enabled by the Ru Heterophase Catalyst
Liang Sun, Qinfen Gu, Jodie A. Yuwono, Jingwen Zhou, Bernt Johannessen, Lingfei Zhao, Chaofeng Zhang, Guanjie Li, Zaiping Guo, Shilin Zhang
Abstract
Aprotic Li–CO 2 batteries (LCBs) hold promise for mitigating the greenhouse effect while generating electric power, yet their development remains nascent due to the sluggish CO 2 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 (Ru fcc+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 *Li 2 CO 3 step (*Li 2 CO 3 → Li 2 CO 3 ) and the decomposition of the *Li 2 C 2 O 4 step (*Li 2 C 2 O 4 → *LiC 2 O 4 + Li), facilitating both the nucleation and decomposition of Li 2 CO 3 . Thus, the Ru fcc+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 Ru fcc /KB (1.14 V, 1260 h), Ru hcp /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.