In-situ synthesis of V2O5 hollow spheres coated Ni-foam as binder-free electrode for high-performance symmetrical supercapacitor

V2O5 hollow spheres coated Ni-foam (VO-HS/NF) is hydrothermally synthesized by an in-situ strategy. Diameter of VO-HS ranges from 300 nm to 500 nm, and the shell thickness is about 40 nm on average. The electrochemical properties of VO-HS/NF electrode demonstrate that it chemically stores charges by redox via the intercalation pseudocapacitance. The symmetrical supercapacitor (SSC) device is assembled using VO-HS/NF as the binder-free electrode and its electrochemical performance is studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). VO-HS/NF SSC device exhibits the pseudocapacitive behavior with specific capacitance of 135 mF.cm(-2) at 0.5 mA.cm(-2) and energy density of 356 mW.h.m(-2) at 3.5 W.m(-2) owing to the good ion response and high-quality contact between VO-HS and NF. This work provides an effective and facile strategy for synthesizing additive-free VO-HS/NF as high-performance electrodes for energy storage devices. (C) 2019 Elsevier B.V. All rights reserved.