An Ultra‐Low Discharge and High Energy Efficiency Li‐CO2 Battery Enabled by Plasmon‐Enhanced AuRu‐TiO2 Bifunctional Cathode

Abstract The extremely sluggish kinetics of CO 2 evolution reaction of the lithium‐carbon dioxide (Li‐CO 2 ) batteries lead to a high charging potentials (over 4.0 V) and large over‐potentials (over 1.0 V), thus limiting its development. Herein, by synergistically exploiting the energetic hot carriers and photogenerated electron‐hole pairs generated by plasmonic Au/Ru assembled on wide bandgap TiO 2 nanowire array (TiO 2 ‐NWs), an ultra‐low charge overpotential and high energy efficiency solid‐state Li‐CO 2 battery via plasmon‐enhanced Au/Ru‐TiO 2 ‐NWs cathode, where solar energy can be efficiently harvested (over 96% absorptivity from 200 to 1500 nm), concentrated, and converted on the cathode is reported. The dual‐active‐site design of the Au/Ru catalysts not only enhances the localized surface plasmon resonance, but also facilitates CO 2 reduction and evolution reaction kinetics by reducing the reaction kinetic barriers. As a result, the solid‐state Li‐CO 2 battery based on Au/Ru‐TiO 2 cathode achieves a record ultra‐low charging potential (≈2.57 V) and high energy efficiency (≈96.1%), far exceeding that of reported Li‐CO 2 batteries. Notably, the battery remains ≈2.64 V charge potential and ≈95.3% energy efficiency after 150 h. This work paves a way for developing high‐energy‐efficiency solid‐state battery with a carbon neutral effect.