Core-Shell-Structured CNT@RuO2 Composite as a High-Performance Cathode Catalyst for Rechargeable Li-O2 Batteries

A RuO2 shell was uniformly coated on the surface of core CNTs by a simple sol–gel method, and the resulting composite was used as a catalyst in a rechargeable Li–O2 battery. This core–shell structure can effectively prevent direct contact between the CNT and the discharge product Li2O2, thus avoiding or reducing the formation of Li2CO3, which can induce large polarization and lead to charge failure. The battery showed a high round‐trip efficiency (ca. 79 %), with discharge and charge overpotentials of 0.21 and 0.51 V, respectively, at a current of 100 mA gtotal−1. The battery also exhibited excellent rate and cycling performance. Get your battery going: Core–shell‐structured CNT@RuO2, a good catalyst for oxygen‐reduction and oxygen‐evolution reactions, was used to construct a Li–O2 battery with a low overpotential (0.72 V) and thus a high round‐trip efficiency (ca. 79 %). By preventing the direct contact of Li2O2 with the carbon nanotube (CNT), the uniform RuO2 coating hinders the formation of Li2CO3 to improve round‐trip efficiency and cycling performance (see picture).