An Ultra‐Low Discharge and High Energy Efficiency Li‐CO 2 Battery Enabled by Plasmon‐Enhanced AuRu‐TiO 2 Bifunctional Cathode

The extremely sluggish kinetics of CO₂ evolution reaction of the lithium-carbon dioxide (Li-CO₂) 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 TiO₂ nanowire array (TiO₂-NWs), an ultra-low charge overpotential and high energy efficiency solid-state Li-CO₂ battery via plasmon-enhanced Au/Ru-TiO₂-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 CO₂ reduction and evolution reaction kinetics by reducing the reaction kinetic barriers. As a result, the solid-state Li-CO₂ battery based on Au/Ru-TiO₂ cathode achieves a record ultra-low charging potential (≈2.57 V) and high energy efficiency (≈96.1%), far exceeding that of reported Li-CO₂ 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.