Hierarchical Transition Metal Oxide Arrays Grown on Graphene‐Based Fibers with Enhanced Interface by Thin Layer of Carbon toward Solid‐State Asymmetric Supercapacitors. Issue 8 (5th February 2020)

• Record Type: Journal Article
• Authors: Xu, Ting; Yang, Dongzhi; Liu, Yaxin; Zhang, Shiyi; Zhang, Ming; Zhao, Tianyu; Li, Xiaofeng; Yu, Zhong‐Zhen
• Is Part Of: ChemElectroChem. Volume 7:Issue 8(2020)
• Page Start: 1860
• Page End: 1868
• Publication Date: 2020-02-05
• Subjects: fibrous electrode -- graphene -- nickel cobaltate -- interfacial interaction -- carbon layer; Electrochemistry -- Periodicals; 541.37
• DOI: 10.1002/celc.201902144
• Languages: English
• ISSNs: 2196-0216

Abstract

Abstract: Carbon‐based asymmetric supercapacitors with high performance hold broad application prospects in wearable devices. Forming a smooth interface between the active transition metal oxides and carbon substrate for providing electron‐transfer channels and accommodating the volume contraction for hybrid electrodes is a key issue to be tackled. Herein, both fibrous cathode and anode are designed on the basis of conductive graphene/carbon nanotube hybrid fibers by introducing pseudocapacitive NiCo2 O4 nano‐grass arrays or forming interconnected pores, respectively. For hierarchical positive fibers, a nitrogen‐doped carbon (NC) middle layer is employed to effectively regulate the electronic structural states between NiCo2 O4 and fiber substrate. The cycling and rate performance of cathode are significantly improved due to the strong interfacial bonding and abundant electrochemical active sites. Moreover, an interconnected porous structure is also developed to provide both unlimited axial and radial channels to promote electrolyte ion diffusion sufficiently in the porous negative electrode. The assembled solid‐state flexible asymmetric supercapacitor delivers a high energy density of 11.2 μWh cm −2 with a power density of 472.1 μW cm −2, as well as an excellent long cycling performance with 93 % capacitance retention after 10000 cycles. Abstract : The grass is always greener : Both fibrous cathode and anode are designed on the basis of conductive graphene/carbon nanotube hybrid fibers by introducing pseudocapacitive NiCo2 O4 nano‐grass arrays or forming interconnected pores to enhance energy density and cycle life of graphene‐based fibrous flexible asymmetric supercapacitor without sacrificing its power density. The assembled asymmetric supercapacitor with a potential window of 1.55 V delivers not only high stack energy density of 11.2 μWh cm −2 and power density of 2860.3 μW cm −2, but also exhibits a long cycling performance for only 7 % capacitance loss after 10000 cycles.