Binding MoSe2 with Dual Protection Carbon for High-Performance Sodium Storage

Molybdenum selenide (MoSe2), a promising anode material for sodium ion batteries (SIBs), has generated intensive scientific interest due to its high theoretical capacity and favorable conversion kinetics. Nevertheless, its practical applications are seriously restricted by the volume variation, inferior structural stability and dissolved poly-selenides. Herein, we report the dual carbon protected MoSe2 (MoSe2@NC@rGO) and the intrinsic mechanism for their enhanced sodium storage performance. Organic-inorganic hybrid Mo3O10(C2H10N2) (MoOx-EDA) is used as self-sacrificing precursor. The synthesis processes involve a self-assembly of MoOx-EDA with functionalized graphene oxide (GO) and a subsequent thermal selenization. The dual protection carbon layers can block the poly-selenides shuttling, promote the electron transferring and buffer the huge volume change. When evaluated as an anode material for SIBs, the optimized MoSe2@NC@rGO electrode delivers a high reversible specific capacity of 447 mA h g-1 at 100 mA g-1 and maintains an appreciable capacity of 281 mA h g-1 at 5 A g-1. Moreover, the capacity retains 360 mA h g-1 after 200 cycles at 1 A g-1 with no obvious capacity decay. A full-battery configuration coupled with Na3V2(PO4)2/C cathode exhibits an average operating potential of 1.8 V and good cycling performance. Such a dual carbon-confined approach can also be extended to other electrode materials with large volume swelling.