Flexible three-dimensional carbon cloth/carbon fibers/NiCo2O4 composite electrode materials for high-performance all-solid-state electrochemical capacitors

A flexible three-dimensional carbon cloth/carbon fibers/NiCo2O4 composite electrode is prepared via a two step method: first growth carbon fibers on flexible carbon cloth; second coating NiCo2O4 on the carbon cloth/carbon fibers composite. The carbon cloth guarantees the flexibility of electrodes. The three-dimensional carbon cloth/carbon fibers conductive network enhances the ionic transportation property and offer high conductivity. The ultrathin and porous NiCo2O4 nanosheet layers contribute high faradic capacity. The hierarchically porous electrode structure further facilitates to shorten the electrolyte diffusion path. When used as electrodes for electrochemical capacitor, the composite electrode exhibits superior energy storage performances with high specific capacitance of 1221 F g(-1) at 1 A g(-1), outstanding cycle stability (81% capacitance retention after 3000 cycles) and excellent flexibility. To further investigate the performances of the carbon cloth/carbon fibers/NiCo2O4 composite electrode, we assemble an all-solid-state symmetric electrochemical capacitors device using identical carbon cloth/carbon fibers/NiCo2O4 composite as electrodes. The assembled device delivers a high energy density of 27.2 Wh kg(-1) at a power density of 1.46 kW kg(-1) and outstanding cycling stability with 91% capacitance retention after 2000 cycles. The combination of excellent flexibility and outstanding energy storage performance of the device will help to pave the way to wearable electronics and devices. (C) 2017 Elsevier Ltd. All rights reserved.