Synthesis of nanosphere-like vanadium selenide cathode for high performance asymmetric hybrid supercapacitors

Vanadium selenide electrodes exhibit promising candidates for supercapacitor application, owing to their exotic electronic properties. Exploring more facile synthesis strategies undoubtedly promote the development of va-nadium selenide electrodes that from laboratory to practical application, while it was still a challenging. In this work, we provided a facile electrodeposition method to prepare vanadium selenide cathodes for asymmetric hybrid supercapacitors. By controlling the deposition technique, nanosphere-like vanadium selenide cathode or microrod-like selenium were achieved. Electrochemical tests indicated that the prepared vanadium selenide cathode exhibited high capacitance feature (921.6 F/g at a current density of 1 A/g), due to the high ion diffusion ability in the vanadium selenide nanosphere electrode. The charge storage mechanism and reaction kinetics of the prepared vanadium selenide were further investigated and results indicated a mixed effect of pseudocapa-citance and battery-type together contributed to the energy storage, meaning a hybrid capacitor. The further assembly hybrid supercapacitor exhibited excellent rate performance and good cycling stability. Moreover, density functional theory calculations demonstrated that the electrode material possessed appropriate adsorption energy of OH- with a low ion diffusion barrier.

Automated summary

In this work, a facile electrodeposition method was used to prepare vanadium selenide cathodes for asymmetric hybrid supercapacitors. Nanosphere-like vanadium selenide cathode or microrod-like selenium were achieved by controlling the deposition technique. The prepared vanadium selenide cathode exhibited high capacitance feature and a hybrid capacitor behavior, and the assembled hybrid supercapacitor showed excellent rate performance and good cycling stability. Density functional theory calculations also demonstrated the appropriate adsorption energy and low ion diffusion barrier of the electrode material.