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.