Ultrahigh Capacity Due to Multi-Electron Conversion Reaction in Reduced Graphene Oxide-Wrapped MoO2 Porous Nanobelts

Multivalent transition metal oxides (MOx ) containing redox centers which can theoretically accept more than one electron have been suggested as promising anode materials for high-performance lithium ion batteries (LIBs). The Li-storage mechanism of these oxides is suggested to involve an unusual conversion reaction leading to the formation of metallic nanograins and Li2 O; however, a full-scale conversion reaction is seldom observed in molybdenum dioxide (MoO2 ) at room temperature due to slow kinetics. Herein, a full-scale multi-electron conversion reaction, leading to a high reversible capacity (974 mA h g(-1) charging capacity at 60 mA g(-1) ) in LIBs, is realized in a hybrid consisting of reduced graphene oxide (rGO) sheet-wrapped MoO2 porous nanobelts (rGO/MoO2 NBs). The rGO wrapping layers stabilize the nanophase transition in MoO2 and alleviate volume swing effects during lithiation/delithiation processes. This enables the hybrid to exhibit great cycle stability (tested to around 1900 cycles) and ultrafast rate capability (tested up to 50 A g(-1) ).