A flexible all-solid-state micro-supercapacitor based on hierarchical CuO@layered double hydroxide core-shell nanoarrays

Flexible and lightweight wire-shaped supercapacitors (WSSCs) have recently attracted increasing interest, due to their versatility in the device design and application potentials in portable or wearable electronics. However, practical applications of WSSCs are still limited by the relatively poor performances, owing to the challenges in the rational modification of one-dimensional (1D) substrates with sophisticated nanostructure. Herein, we demonstrate a WSSC by virtue of material exploration and fabrication strategy. A 1D nanoarray electrode consisting of CuO nonowires core and CoFe-layered double hydroxide (CoFe-LDH) nanoplatelets shell supported on a copper wire is prepared with fine control over the structure/morphology, which displays a largely improved specific capacitance, high rate capability and long cycling lifespans. Based on this sophisticated core-shell nanostructure, a flexible all-solid-state asymmetric WSSC was fabricated, which exhibits excellent supercapacitive performances with a high energy density (1.857 mWh cm(-3)) and long-term cycling stability (99.5% device capacitance retention over 2000 cycles). By virtue of the versatility of metal wire substrates, transition metal oxides and LDHs materials, the synthesis strategy presented here can be extended to the fabrication of other portable and flexible micro energy storage devices. (C) 2016 Elsevier Ltd. All rights reserved.