VOx anchored Ti3C2Tx MXene heterostructures for high-performance 2.2 V supercapacitors

Abstract

Pseudocapacitive materials with superior electrochemical properties have attracted significant interest in developing high-performance supercapacitors. Herein, VOx anchored Ti3C2Tx MXene pseudocapacitive materials are synthesized via a solvothermal method to synergize metallic electrical conductivity and redox activity. Pure vanadium oxide synthesis results in VO2 formation, while in the presence of Ti3C2Tx, quasi-metallic V2O3 and VO2 (VOx) are observed due to the decomposition of surface functionalities of Ti3C2Tx. The growth of the V2O3 phase increases with an increase in the weight concentration of Ti3C2Tx. The optimal composition of heterostructure delivers a specific capacitance of 364 F g−1 in a stable potential window of −0.9 V–1 V, surpassing the specific capacitance of pure VO2 (245 F g−1) and Ti3C2Tx (140 F g−1) in 0.5 M K2SO4 electrolyte. Furthermore, the developed symmetric supercapacitor (SSC) delivers an energy density of 45.7 Wh kg−1 at a power density of 1.1 kW kg−1 with cyclic stability of 78 % for 10000 cycles with a self-discharge open circuit potential of 1.34 V. This work highlights a strategy to develop anodic and cathodic active pseudocapacitive material based SSC to improve energy density and mitigate self-discharge.