Carbon electrode with NiO and RuO₂ nanoparticles improves the cycling life of non-aqueous lithium-oxygen batteries

Carbon has been regarded as one of the most attractive cathode materials for non-aqueous lithium-oxygen batteries due to its excellent conductivity, high specific area, large porosity, and low cost. However, a key disadvantage of carbon electrodes lies in the fact that carbon may react with Li₂O₂ and electrolyte to form irreversible side products (e.g. Li₂CO₃) at the active surfaces, leading to a high charge voltage and a short cycling life. In this work, we address this issue by decorating NiO and RuO₂ nanoparticles onto carbon surfaces. It is demonstrated that the NiO-RuO₂ nanoparticle-decorated carbon electrode not only catalyzes both the oxygen reduction and evolution reactions, but also promotes the decomposition of side products. As a result, the battery fitted with the novel carbon cathode delivers a capacity of 3653 mAh g⁻¹ at a current density of 400 mA g⁻¹, with a charge plateau of 4.01 V. This performance is 440 mV lower than that of the battery fitted with a pristine carbon cathode. The present cathode is also able to operate for 50 cycles without capacity decay at a fixed capacity of 1000 mAh g⁻¹, which is more than twice the cycle number of that of the pristine carbon cathode.