NiCo2O4/MnO2 core/shell arrays as a binder-free catalytic cathode for high-performance lithium–oxygen cells

Abstract

Lithium–oxygen (or Li–air) cells have attracted increasing interest in recent years due to their extremely high theoretical energy density. A reasonable design of the catalytic cathode is essential to realize a high performance of Li–O₂ cells. In this work, a unique core–shell MnO₂@NiCo₂O₄ array cathode with a porous structure has been deposited directly on carbon cloth by a facile hydrothermal route. The array structure facilitates electrode wetting and oxygen gas transportation. The porous structure supplies free space for Li₂O₂ loading. The MnO₂@NiCo₂O₄ array cathode exhibits a high catalytic effect enabling the conformal growth of Li₂O₂ with the array structure retained. This growth behavior of Li₂O₂ makes the decomposition of Li₂O₂ easy upon charging. Li–O₂ cells with the MnO₂@NiCo₂O₄ cathode can sustain a stable cycling of 168 cycles with a limited capacity of 500 mA h g⁻¹ at 400 mA g⁻¹, which is superior to those with the NiCo₂O₄ cathode.