3D web freestanding RuO₂-Co₃O₄ nanowires on Ni foam as highly efficient cathode catalysts for Li-O₂ batteries

The mechanism of Li-O₂ batteries is based on the reactions of lithium ions and oxygen, which hold a theoretical higher energy density of approximately 3500 W h kg^-1. In order to improve the practical specific capacity and cycling performance of Li-O₂ batteries, a catalytically active mechanically robust air cathode is required. In this work, we synthesized a freestanding catalytic cathode with RuO₂ decorated 3D web Co₃O₄ nanowires on nickel foam. When the specific capacity was limited at 500 mA h g^-1, the RuO₂-Co₃O₄/NiF had a stable cycling life of up to 122 times. The outstanding performance can be primarily attributed to the robust freestanding Co₃O₄ nanowires with RuO₂ loading. The unique 3D web nanowire structure provides a large surface for Li₂O₂ growth and RuO₂ nanoparticle loading, and the RuO₂ nanoparticles help to promote the round trip deposition and decomposition of Li₂O₂, therefore enhancing the cycling behavior. This result indicates the superiority of RuO₂-Co₃O₄/NiF as a freestanding highly efficient catalytic cathode for Li-O₂ batteries.