Hierarchical MoS2-Coated V2O3 composite nanosheet tubes as both the cathode and anode materials for pseudocapacitors

Abstract

Pseudocapacitors are promising energy storage devices combining the merit of fast charging ability and high energy density. Constructing electrode materials for pseudocapacitors with two-dimensional (2D) materials has become a trending topic. However, it is still a challenge to address the restacking propensity of the 2D materials and to broaden the operational potential window of pseudocapacitors. We herein demonstrate a facile hydrothermal reaction of synthesizing a three-dimensional V2O3 tubes (assembled with ultrathin nanosheets) coated with MoS2 nanosheets and explore their electrochemical properties for pseudocapacitors. The V2O3 tubes prevent the restacking of MoS2 nanosheets and serve as conductive scaffold for fast electron transport. Owing to the multi-valence of both Mo and V, the potential window of composite is able to straddle between negative and positive potentials. Therefore, the V2O3@MoS2 composite electrode exhibits a broad operational potential range between −1.0 V and +1.0 V, and a high reversible capacitance of 655 F g−1 at 20 mV s−1. Moreover, an asymmetric pseudocapacitor with our composite as a positive electrode achieves a high specific capacitance (108.7 F g−1 at 0.5 A g−1), high energy density (31.8 W h kg-1) and excellent cycling stability (no capacitance decay after 35000 cycles).