Constructing T-Nb2O5@Carbon hollow core-shell nanostructures for high-rate hybrid supercapacitor

By Zhang, Songmin; Wu, Jiawen; Wang, Jitong; Qiao, Wenming; Long, Donghui; Ling, Licheng
Published in Journal of Power Sources 2018

Abstract

Orthorhombic (T-) Nb2O5 is an intercalation pseudocapacitive material that possesses fast Li+ diffusion pathways in its bulk crystalline structure. Herein, hollow core-shell nanostructures made up of T-Nb2O5 nanoparticles confined within porous carbon shells are constructed for further boosting its high-rate Li-insertion/extraction capability. By using different silica template precursors, carbon shells with mesoporous channels or relatively dense structure could be created, both of the T-Nb2O5@carbon hollow core-shell nanostructures demonstrate significant improvement on the rate capability compared to the T-Nb2O5 nanoparticles. Furthermore, it is found that the carbon shells with accessible mesopores of ?6 nm could provide a higher specific surface area and larger Li+ diffusion channels, and thus the T-Nb2O5@mesoporous carbon (Nb2O5@MC) hollow core-shell nanostructures show better high-rate properties with a capacity of 173 C g?1 at a current density of 50 A g?1. When paired up with mesoporous carbon hollow nanospheres (MCHS) cathode, the Nb2O5@MC//MCHS hybrid supercapacitor could deliver both ultrahigh power density and high energy density (?16 kW kg?1 with an energy density of 12 Wh kg?1), which is attractive for a wide range of power delivery applications.

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