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Hierarchical NiCo2O4 nanosheets on carbon nanofiber films for high energy density and long-life Li–O2 batteries

Designing oxygen cathodes with both high energy density and excellent cycling stability is a great challenge in the development of lithium–oxygen (Li–O2) batteries for energy storage systems. Herein, we design a novel structure of hierarchical NiCo2O4 nanosheets on porous carbon nanofiber films (denoted as NiCo2O4@CNFs) as an oxygen cathode for lithium–oxygen batteries. The NiCo2O4@CNFs cathode delivers a high specific discharge capacity of 4179 mA h g−1, a high energy density of 2110 W h kg−1 and superior cycling stability over 350 cycles. The excellent electrochemical performance of the NiCo2O4@CNFs cathode can be attributed to the rational design and engineering of catalysts and porous conductive electrodes. These results indicate that the NiCo2O4@CNFs electrode is a promising candidate for high energy density and long-life Li–O2 batteries. Additionally, the rational design of the hierarchical catalyst constructed low-dimensional nanostructure and the lightweight porous carbon nanofiber electrode can be also used for other metal–oxygen batteries, such as zinc–oxygen (Zn–O2) batteries, aluminum–oxygen (Al–O2) batteries, and sodium–oxygen (Na–O2) batteries.