Ultrathin, Wrinkled, Vertically Aligned Co(OH)₂ Nanosheets/Ag Nanowires Hybrid Network for Flexible Transparent Supercapacitor with High Performance

Abstract

Developing high-performance, flexible, transparent supercapacitors for wearable electronics represents an important challenge, as it requires active materials to be sufficiently transparent without compromising energy storage. Here, we manipulate the morphology of the active materials and the junctions on the current collector to achieve optimum electronic/ionic transport kinetics. Two-dimensional Co­(OH)2 nanosheets with single or two layers were vertically aligned onto a modified Ag nanowires (AgNWs) network using an electrochemical deposition–UV irradiation approach. The metallic AgNWs network endows high transparency while minimizing the contact resistance with the pseudocapacitive Co­(OH)2 nanosheets. The Co­(OH)2 nanosheets self-assembled into a three-dimensional array, which is beneficial for the fast ion movements. The rational materials design greatly boosts the electrochemical performance of the hybrid network, including an ultrahigh areal capacitance up to 3108 μC cm–2 (5180 μF cm–2) coupled with long cycle life (20 000 cycles). As a prototype device, the symmetric supercapacitor well combines high energy/power density and excellent mechanical flexibility and long-term performance, suggesting a promising application for the next-generation wearable electronics.

Flexible Transparent Supercapacitors: Materials and Devices

“…Their close contact can largely reduce R s and improve the flexible stability, thus bringing about high‐power density. To date, these active materials including 1T‐MoS 2 , [ 21a ] Co(OH) 2 , [ 58 ] and NiCo/NiCo(OH) 2 , [ 59 ] have been used to composite with Ag networks for Ag‐based FTCEs.…”

“…[ 78,131 ] Due to the presence of gel electrolyte, the assembled FTSCs possess a slightly decreased optical transmittance than that of a single electrode at a certain wavelength. In this study, the gel electrolyte mainly involves in PVA‐containing hydrogels, such as PVA/LiCl, [ 7b,20a ] PVA/H 2 SO 4 , [ 46b,157 ] PVA/H 3 PO4, [ 36,158 ] PVA/LiClO 4 , [ 82 ] PVA/PAAS/KCl, [ 58 ] and PVA/KOH. [ 131 ] The voltage window of symmetrical FTSCs is equal to the potential window of a single electrode in a three‐electrode system.…”

Recent Advances of Energy Solutions for Implantable Bioelectronics

“…Unlike batteries, supercapacitors can store energy and deliver it to an active device at appropriate rates, while offering high power densities and a long lifetime. [ 84–86 ] Such devices are well suited as a backup source of energy, eliminating adverse consequences caused by unexpected interruptions in power supply. Generally, the charge storage mechanisms of supercapacitors depend either on ionic electrosorption at the electrode/electrolyte interfaces (called electrical double layer capacitance, EDLC) or rapid redox reactions occurring on (or near) electrode surfaces (called pseudocapacitance).…”

Transparent Electrodes for Energy Storage Devices

“…Considering the high aspect ratio of nanowires, metallic grids are believed to be more desirable for portable and flexible electronics. To date, various metallic grids have been developed and applied in TESEs, including Ag, [24,27,[77][78][79][80][81][82][83][84][85][86][87] Au, [16,[88][89][90][91] Ni, [92][93][94] and so on. Many of them exhibit good mechanical stability, flexibility, and even stretchability.…”