A universal strategy for ultra-flexible inorganic all-solid-state supercapacitors

Emerging, flexible, textile-based supercapacitors have attracted considerable research interest in energy storage devices. However, very few flexible supercapacitors with good mechanical stability have been successfully developed based on traditional current collectors, especially for brittle transition metal oxides/hydroxides electrode material. This work reports a rational design of a nickel-deposited fiber fabric current collector, which displays excellent conductivity with sheet resistances of 0.355 Omega cm(-2) before and 0.537 Omega cm(-2) after 100,000 bending cycles. Further, a series of transition metal oxides/hydroxides were fabricated on the Ni-fabric current collector via an electrodeposition approach. The prepared Co(OH)2, NiO, and NiCo2O4 electrodes showed specific capacitances of 880.1, 589.1, and 725.7 F g(-1) at 1 A g(-1), respectively. In addition, when the electrodes with activated carbon (AC) were assembled into all-solid-state asymmetric supercapacitors, the as-prepared Co(OH)(2)//AC, NiO//AC, and NiCo2O4//AC devices delivered specific capacitances of 170.3, 265.6, and 219.8 mF cm(-2), respectively, with energy densities of 1.24,1.63, and 1.35 mWh cm(-3 )at 1 mA cm(-2). The capacitances of these devices retained high values of 92.8%, 94.4%, and 95.1% even after 1000 cycles of bending and folding by the automatic test machine. These results indicate that metal oxide compound electrodes based on a Ni-fabric current collector provide a universal strategy for high-performance and ultra-flexible supercapacitors. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study presents a rational design of nickel-deposited fiber fabric current collector for flexible supercapacitors, achieving excellent conductivity and mechanical stability. Transition metal oxides/hydroxides electrodes fabricated on the current collector showed high specific capacitance and energy density. The devices exhibited high capacitance retention even after 1000 cycles of bending and folding, indicating that metal oxide compound electrodes based on a Ni-fabric current collector offer a universal strategy for high-performance and ultra-flexible supercapacitors.