Rational construction of rGO/VO2 nanoflowers as sulfur multifunctional hosts for room temperature Na-S batteries

摘要

Developing high energy density room-temperature sodium sulfur (RT Na-S) batteries relies on the design of delicate structure that can be efficiently injected sulfur and enhance the cycle life of electrode active material. Herein, a three dimensional (3D) hierarchical cathode substrate with VO2 nanoflowers as catalyst in situ grown on reduced graphene oxide (rGO) for sulfur cathodes are designed and prepared. In this novel structure, the electronic conductivity of sulfur cathode can be greatly improved due to the high electrical conductivity of rGO substrate. More importantly, the catalytic effect of VO2 accelerates the conversion long-chain NaPSs to Na2S2/Na2S, and enhances the cycle capability, which can be validated by experimental data. As a result, the asobtained rGO/VO2/S composites achieves an initial reversible capacity of 876.4 mAh g(-1) at 0.2C. Moreover, the capacity of 156.1 mAh g(-1) is demonstrated after long-cycling term of 1000 cycles at 2C and high cycle stability of only 0.07% capacity decay per cycle is exhibited.