title: Robust electrodes based on coaxial TiC/C-MnO2 core/shell nanofiber arrays with excellent cycling stability for high-performance supercapacitors.
abstract: A coaxial electrode structure composed of manganese oxide-decorated TiC/C core/shell nanofiber arrays is produced hydrothermally in a KMnO4 solution. The pristine TiC/C core/shell structure prepared on the Ti alloy substrate provides the self-sacrificing carbon shell and highly conductive TiC core, thus greatly simplifying the fabrication process without requiring an additional reduction source and conductive additive. The as-prepared electrode exhibits a high specific capacitance of 645 F g(-1) at a discharging current density of 1 A g(-1) attributable to the highly conductive TiC/C and amorphous MnO2 shell with fast ion diffusion. In the charging/discharging cycling test, the as-prepared electrode shows high stability and 99% capacity retention after 5000 cycles. Although the thermal treatment conducted on the as-prepared electrode decreases the initial capacitance, the electrode undergoes capacitance recovery through structural transformation from the crystalline cluster to layered birnessite type MnO2 nanosheets as a result of dissolution and further electrodeposition in the cycling. 96.5% of the initial capacitance is retained after 1000 cycles at high charging/discharging current density of 25 A g(-1). This study demonstrates a novel scaffold to construct MnO2 based SCs with high specific capacitance as well as excellent mechanical and cycling stability boding well for future design of high-performance MnO2-based SCs.
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P. R. China.
authors.forename: Xuming
authors.initials: X
authors.lastname: Zhang
authors.forename: Xiang
authors.initials: X
authors.lastname: Peng
authors.forename: Wan
authors.initials: W
authors.lastname: Li
authors.forename: Limin
authors.initials: L
authors.lastname: Li
authors.forename: Biao
authors.initials: B
authors.lastname: Gao
authors.forename: Guosong
authors.initials: G
authors.lastname: Wu
authors.forename: Kaifu
authors.initials: K
authors.lastname: Huo
authors.forename: Paul K
authors.initials: PK
authors.lastname: Chu
keywords: MnO2; TiC/C; cycling stability; electrodes; nanostructures; structural transformations; supercapacitors