Trace-level ruthenium incorporated with transition metal components enabled the development of high-efficiency Li-CO2 batteries.

Li-CO2 batteries offer high energy density and carbon neutrality potential, whereas their practical applications are severely hampered by low energy efficiency arising from sluggish redox kinetics and tough mass transfer. Herein, trace-level noble metal ruthenium (Ru) could boost the performance of Li-CO2 batteries through hybridization of 4d orbitals with multi transition metal components (Ni, Cu, Zn, and Cd) and following electronic redistribution. The rich electronic environment and diverse metal sites could tune the adsorption energies of CO2 and reaction intermediates to accelerate the reaction kinetics. The NiCuZnCdRu/CF cathode displays an ultralow voltage gap (1.19 V) with a high energy efficiency of 97.2% as well as stable service life exceeding 2500 h at 20 µA cm-2. This study offers feasible design for durable cathodes in advanced Li-CO2 batteries through multi-metallic synergy which could optimize the charge transfer and enable the spatial distribution of Li2CO3.