Controlled growth of Li₂O₂ by cocatalysis of mobile Pd and Co₃O₄ nanowire arrays for high-performance Li-O₂ batteries

For Li-O₂ batteries, a challenge still remains to achieve high discharge capacity and easy decomposition of the discharge product (Li₂O₂) simultaneously. In this work, conformal growth of thin-layered Li₂O₂ on Co₃O₄ nanowire arrays (Co₃O₄ NAs) during discharge is realized through the cocatalytic effect of solid/immobile Co₃O₄ NAs and mobile Pd nanocrystals (Pd NCs), rendering easy decomposition of Li₂O₂ during recharge. Meanwhile, high discharge capacity is also ensured with unique array-type design of the catalytic cathode despite the surface growth mode of Li₂O₂. The Li-O₂ cells can deliver a high discharge capacity of 5337 mAh g^-1 and keep a stable cycling of 258 cycles at a limited capacity of 500 mAh g^-1. The achievement of excellent electrochemical performance is attributed to the highly efficient cocatalytic ability of Co₃O₄ NAs and Pd NCs as well as the desirable array-type architecture of the catalytic electrode free of carbon and binder. The cocatalytic mechanism of Co₃O₄ NAs and Pd NCs is clarified by systematic electrochemical tests, microstructural analyses, and ζ-potential measurements.