High intercalation pseudocapacitance of free-standing T-Nb2O5 nanowires@carbon cloth hybrid supercapacitor electrodes

Abstract

Li-ion hybrid electrochemical capacitors (Li-HECs) with higher energy density than electric double layer capacitors (EDLC) and larger power density than current rechargeable batteries are attractive candidates in future energy related applications. However, the electrochemical properties of current Li-HECs are greatly restricted by its Li-ion insertion type of electrode materials. Herein, we report an efficient approach to prepare one dimensional T-Nb2O5 nanowires growth on activated carbon cloth as freestanding hybrid electrodes for Li-HECs. The T-Nb2O5 nanowires with diameter of 20∼50 nm and length of several micrometers cross with each other and form a three dimensional (3D) porous network. The designed hybrid electrodes can deliver a gravimetric capacitance as high as 220 mAh g-1 at current density of 0.5 C and advanced cycle life with capacity retention of 86% after 1000 cycles at 5 C. The outstanding electrochemical performances are mainly attributed to the reduction in the lithium ion diffusion length brought by the crossed porous structure. And the enhancement of electron transportation enjoys the benefit from the in-situ growth of T-Nb2O5 nanowires on carbon cloth and the binder-free electrode structure.