In this work, the ternary hybrid structure VSe 2 / SWCNTs/rGO is reported for supercapacitor applications. The ternary composite exhibits ah igh specific capacitance of 450 Fg À1 in as ymmetric cell configuration, with maximum energy density of 131.4 Wh kg À1 and power density of 27.49 kW kg À1 .The ternary hybrid also shows acyclic stability of 91 %a fter 5000 cycles. Extensive density functional theory (DFT) simulations on the structure as well as on the electronic properties of the binary hybrid structure VSe 2 /SWCNTsa nd the ternary hybrid structure VSe 2 /SWCNTs/rGO have been carriedo ut. Due to as ynergic effect, there are enhanced density of states near the Fermi level and higher quantum capacitance for the hybrid ternary structure compared to VSe 2 /SWCNTs, leading to higher energy and powerd ensity for VSe 2 /SWCNTs/rGO, supporting our experimental observation. Computed diffusione nergyb arriero fe lectrolyte ions (K + )p redicts that ions move faster in the ternary structure, providing higherchargestorage performance.[a] K. A. Sree Raj Centre for Nanoa nd MaterialS cience, Jain University Jain global campus,J akkasandra, Ramanagaram, Banglore562112 (India)

Excellent cyclic stability and fast charge/discharge capacity demonstrated by supercapacitors foster research interest into new electrode materials with 100% cycle life and high specific capacitance. We report an improvement in the electrochemical performance of MoS2/multiwalled carbon nanotubes (MWCNT) nanohybrid and intensively explored its performance in symmetric and asymmetric supercapacitor (ASC) assembly. The symmetric assembly of MoS2/MWCNT exhibits capacitance of around 274.63 F g−1 at 2 A g−1 with higher specific energy/power outputs (20.70 Wh kg−1/1.49 kW kg−1) as compared to the supercapacitor based on pristine MoS2 (5.82 Wh kg−1/1.07 kW kg−1). On the other hand, a unique all-carbon-based ASC assembled with MoS2/MWCNT and VSe2/MWCNT composite with K2SO4 as electrolyte delivers the highest energy density of 32.18 Wh kg−1 at a power density of 1.121 kW kg−1 with exceptional cycling stability and excellent retention of about 98.43% even after 5000 cycles. These outstanding results demonstrate the excellent electrochemical properties of both symmetric and asymmetric systems with high energy density and performance, which further enable them to be a potential candidate for supercapacitor applications.

MXene-based hybrid materials have been expedited extensively for supercapacitors and energy storage applications. In this work, we have grown the metallic VSe2 layered material on MXene sheets to achieve enhanced energy storage performance. The VSe2/MXene heterostructures showed improved energy storage performance with a specific capacitance of 144 F/g at a specific current of 1 A/g and a cycling life of 92.8% after 5000 charge–discharge cycles in a two-electrode symmetric configuration. Further, we have presented extensive density functional theory simulations to study the bonding interaction and electronic properties of VSe2 and its hybrid VSe2/MXene. The enhanced states near the Fermi level, superior quantum capacitance, and lower diffusion barrier of hybrid VSe2/MXene over the VSe2 support the improved charge storage and better capacitive behavior of the hybrid, as indicated by experimental observations. The interaction between VSe2 and the MXene is due to the electronic charge transfer from the Ti 3d orbital of the MXene to V 3d orbital of VSe2, in addition to weak van der Waals forces. An asymmetric supercapacitor was also constructed to exploit the high energy storage performance of the VSe2/MXene electrode. Further, the VSe2/MXene//MoS2/MWCNT asymmetric electrode assembly delivered an energy density of 42 W h/kg at power density of 2316 W/kg with a capacitance retention of 90% after 5000 charge–discharge cycles.

Hybrid structure of VSe2 and multiwalled carbon nanotube for high performance supercapacitor applications.