An Ultra-Low Discharge and High Energy Efficiency Li-CO2 Battery Enabled by Plasmon-Enhanced AuRu-TiO2 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.