Self-growing graphite felt/vanadium pentoxide/polyindole ternary composite as binder-free electrode for supercapacitor with 1.8 V operating potential window and excellent electrochemical performance

Abstract

Vanadium pentoxide and conducting polymers have promising applications in the field of electrical energy storage devices and combine flexible substance to form binder-free ternary electrodes, which would pave a new way for designing supercapacitors. Herein, graphite felt (GF)@V2O5 nanosheets is synthesized by hydrothermal and calcinating treatment, on the surface of which polyindole (PIn) nanospheres are anchored orderly using electrochemical deposition to obtain GF@V2O5@PIn ternary electrode material. The pseudocapacitive properties of both V2O5 nanosheets and PIn nanospheres are fully demonstrated through the synergistic effect of them, enabling ternary composite GVP-3 to exhibit superior electrochemical properties than two binary materials. The area capacitance of GVP-3 reaches 2254 mF/cm2, which is significantly higher than that of GF@V2O5 with 1431 mF/cm2 and GF@PIn with 647 mF/cm2. The flexible quasi-solid-state asymmetric supercapacitor (FASC) can be operated at the potential window of 1.8 V with a significant energy density of 1.423 mWh/cm3 (64.404Wh/kg) The excellent electrical capacitance and prominent energy density of our device endow it with an overall improvement of electrical performance from 25% to 30%, which is compared to present researches. Two devices connected in series are able to make a 3.5 V LED bump light up normally for 2 min, illustrating desirable practicality.