Standing carbon-coated molybdenum dioxide nanosheets on graphene: morphology evolution and lithium ion storage properties

Abstract

Transitional metal oxides are a class of high-capacity anodes for lithium ion batteries. Drastic volume changes during cycling and intrinsically poor electronic conductivity diminish their electrochemical performances such as cycliability and high-rate capabilities. This study reports an unprecedented MoO₂/carbon network, consisting of the standing carbon-coated MoO₂ nanosheets on graphene nanosheets to solve these problems. The obtained MoO₂ products can be tuned to have particle-like, rod-like, or sheet-like morphologies (standing MoO₂@C core–shell nanosheets or flat-lying MoO₂ nanosheets) on graphene by adjusting the experimental parameters. Due to the unique three dimensional porous MoO₂@C/graphene hierarchical structure, the composite manifests excellent electrochemical properties including high capacity, long cycle life and stable high-rate performances. A large reversible capacity of above 500 mA h g⁻¹ can be achieved after 200 cycles at a large current of 5 A g⁻¹.