1T-VS2/MXene Hybrid as a Superior Electrode Material for Asymmetric Supercapacitors: Experimental and Theoretical Investigations

The present work explores the electrochemical energy storage performance of Ti3C2Tx (MXene) and 1T-VS2 nanosheet hybrids synthesized by a simple in situ hydrothermal method. Different analytical methods such as X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared, Raman spectroscopy, and Brunauer–Emmett–Teller were employed to explore the structural and morphological properties and composition of electrode materials. Furthermore, the electrochemical characterization of 1T-VS2/MXene hybrid electrode materials with different concentrations of MXene was investigated systematically. The all pseudocapacitive asymmetric supercapacitor cell was fabricated by combining the best performing 1T-VS2/MXene and MXene, which displayed the highest specific capacitance of 115.7 F/g at a current density of 0.8 A/g in an expanded potential range of 1.6 V. Additionally, the highest energy density achieved was 41.13 W h kg–1 at a maximum power density of 793.50 W kg–1. The asymmetric supercapacitor was able to achieve a high capacitance retention of 85% and a coulombic efficiency of 100% after 5000 galvanostatic charge–discharge cycles. Moreover, the synergistic effect and charge storage kinetics of the 1T-VS2/MXene hybrid pseudocapacitive electrode material were investigated in detail using experimental and density functional theory calculations. Based on the results, we have further demonstrated the usage of 1T-VS2/MXene and MXene as a high-performance energy storage material for supercapacitor application with the dominating intercalation mechanism. The lower diffusion energy barrier for electrolytic ions in the case of hybrid 1T-VS2/MXene supports the higher charge storage. The enhanced density of states and lower diffusion barrier justify the superior charge storage performance for hybrid 1T-VS2/MXene.