Ru-decorated knitted Co3O4 nanowires as a robust carbon/binder-free catalytic cathode for lithium-oxygen batteries

The working principle of Li-air (Li-O-2) batteries is based on the formation/decomposition of Li2O2 on the catalytic electrode, which is basically different from the shuttle mechanism of Li-ion batteries. The successful operation of Li-O-2 batteries requires an optimized cathode that is electrochemically/chemically stable, mechanically robust, and catalytically active. In this work, we proposed a unique design of a binder/carbon-free catalytic cathode consisting of knitted Co3O4 nanowires and decorated Ru nanoparticles. It was found that the Co3O4/Ru-catalyzed Li-O-2 batteries exhibit considerably higher capacity and much improved cycling performance than the Co3O4-catalyzed ones. When the capacity is limited at 500 mA h g(-1), the Co3O4/Ru-catalyzed battery can sustain a stable cycling of 29 times. The stable cycling can last 122 times at a limited capacity of 300 mA h g(-1). This result indicates that the catalytic performance and structural stability of the cathodes are equally important to achieve a high performance of Li-O-2 batteries.