Amorphous MoO2/C Nanospheres–Porous Graphene Composites for Pseudocapacitive Li Storage

Abstract

Amorphous MoO2 nanostructures are regarded as promising anode materials for lithium-ion batteries (LIBs) due to their unusually high capacity. However, designing an amorphous MoO2 nanostructure with satisfactory performance still remains greatly challenging owing to the poor conductivity and unstable structure. In this study, a hierarchically porous composite composed of amorphous MoO2/C nanospheres and interconnected graphene networks (MoO2/C-rGO) was fabricated by a convenient route. Thanks to the oxygen-deficient amorphous nanostructure, open diffusion channels, and continuous conductive networks, the electrochemical performance of the composite has been significantly enhanced. Specifically, it delivers an extraordinary initial discharge capacity of 1328 mA h g–1 at 0.1 A g–1, a high initial Coulombic efficiency (CE) of 82.6%, an impressive rate capability of 444 mA h g–1 at 8.0 A g–1, and a good cyclability with 642 mA h g–1 after 500 cycles at 1.0 A g–1. Electrochemical analysis indicates that the Li storage of MoO2/C-rGO is dominated by a pseudocapacitive mechanism, which allows rapid insertion/extraction of Li+ without damaging the structure of the electrode, thus achieving structural and electrical integrity.