Al2O3-assisted confinement synthesis of oxide/carbon hollow composite nanofibers and application in metal-ion capacitors

• Main Authors: Mao, Zhifei, Wang, Huanwen, Chao, Dongliang, Wang, Rui, He, Beibei, Gong, Yansheng, Fan, Hong Jin
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2020
• Subjects: Engineering::Materials; Atomic Layer Deposition; Hollow Fibers
• Online Access: https://hdl.handle.net/10356/144871
• Institution: Nanyang Technological University

Hollow micro-/nanostructures are widely explored for energy applications due to their unique structural advantages. The synthesis of hollow structures generally involves a "top-down" casting process based on hard or soft templates. Herein, a new and generic confinement strategy is developed to fabricate composite hollow fibers. A thin and homogeneous atomic-layer-deposition (ALD) Al2 O3 layer is employed to confine the pyrolysis of precursor fibers, which transform into metal (or metal oxide)-carbon composite hollow fibers after removal of Al2 O3 . Because of the uniform coating by ALD, the resultant composite hollow fibers exhibit a hollow interior from heads to ends even if they are millimeter long. V, Fe, Co, and Ni-based hollow nanofibers, demonstrating the versatility of this synthesis method, are successfully synthesized. Because of the carbon constituent, these composite fibers are particularly useful for energy applications. Herein, the as-obtained hollow V2 O3 -C fiber membrane is employed as a freestanding and flexible electrode for lithium-ion capacitor. The device shows an impressive energy density and a high power density.