One-step solvothermal synthesis of nickel selenide nanoparticles as the electrode for high-performance supercapacitors

In this study, the nickel selenide (Ni0.85Se) nanoparticles with uniform size are synthesized in different solvents (glycerol, benzyl alcohol, and 2-phenylethanol) by one-step solvothermal method without any surfactant and template. The specific capacity of the Ni0.85Se nanoparticles prepared in benzyl alcohol is as high as 114.6 mA h g(-1) at 1 A g(-1) and exhibits a good cycling stability. Moreover, a novel asymmetric supercapacitor (ASC) device is devised and combined by exploiting Ni0.85Se nanoparticles as a positive electrode and activated carbon (AC) as a negative electrode in a safe KOH (2 M) aqueous electrolyte. The Ni0.85Se//AC ASC has an operating voltage reach up to 1.65 V, high energy density of 22.3 Wh kg(-1) at a power density of 829 W kg(-1) and the capacity can maintain of 76% after 5000 cycles. As a result, the Ni0.85Se nanoparticles synthesized in benzyl alcohol are good candidate electrodes for supercapacitor applications in the energy storage systems. (C) 2019 Elsevier B.V. All rights reserved.