Herein, ruthenium (Ru) nanoparticles were anchored on carbon nanotubes (Ru/CNTs) functionalized as catalyst cathodes for non-aqueous Li–CO2 cells.

An effective Ru/CNT electrocatalyst plays a crucial role in solid-state lithium–carbon dioxide batteries. In the present article, ruthenium metal decorated on a multi-walled carbon nanotubes (CNTs) is introduced as a cathode for the lithium–carbon dioxide batteries with Li1.5Al0.5Ge1.5(PO4)3 solid-state electrolyte. The Ru/CNT cathode exhibits a large surface area, maximum discharge capacity, excellent reversibility, and long cycle life with low overpotential. The electrocatalyst achieves improved electrocatalytic performance for the carbon dioxide reduction reaction and carbon dioxide evolution reaction, which are related to the available active sites. Using the Ru/CNT cathode, the solid-state lithium–carbon dioxide battery exhibits a maximum discharge capacity of 4541 mA h g–1 and 45 cycles of battery life with a small voltage gap of 1.24 V compared to the CNT cathode (maximum discharge capacity of 1828 mA h g–1, 25 cycles, and 1.64 V as voltage gap) at a current supply of 100 mA g–1 with a cutoff capacity of 500 mA h g–1. Solid-state lithium–carbon dioxide batteries have shown promising potential applications for future energy storage.