Self-Standing Metallic Mesh with MnO₂ Multiscale Microstructures for High-Capacity Flexible Transparent Energy Storage

Abstract

Flexible transparent electrochemical supercapacitors are critical components for the rapid development of fully flexible transparent electronics; however, typical flexible transparent supercapacitor electrodes store limited energy due to the requirements of transparency. Self-standing core−shell structure metal oxide mesh electrodes with metal oxide as active "shell" and metallic mesh as current collector "core" are efficient for simultaneously achieving high capacity, flexibility, and transparency. In this work, we perform a morphology-controlled electrodeposition of MnO 2 on a self-standing flexible transparent metallic Ni mesh electrode to achieve a highcapacity flexible transparent supercapacitor electrode. Under optimized conditions, the MnO 2 nanosheet-composed flowerlike multiscale microstructure was constructed. The open, loose, and porous MnO 2 multiscale microstructure "shell" and high electrical conductivity of self-standing metallic mesh "core" synergistically enable efficient ionic and electronic transport and meanwhile retain high structural stability. The metal oxide mesh electrode yields an outstanding areal capacitance of 1.15 F/cm 2 at an optical transmittance of 69.4% and excellent cycling stability. The symmetric solid-state supercapacitor device exhibits a high areal capacitance value (78.46 mF/cm 2 ), superior cycling life, as well as high optical transmittance and mechanical flexibility, superior to the most reported flexible transparent supercapacitors. This work provides a comprehensive understanding on how to achieve high-capacity flexible transparent supercapacitor electrodes and solid-state devices.

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.…”

Transparent Supercapacitors: From Optical Theories to Optoelectronics Applications

“…The experimentally measured sheet resistance and transmittance of the metal-grid TCEs are well consistent with trends of the predicted values with a minimal deviation. Several approaches on the realization of TCEs were reported, including nanoimprinting, [139] photolithography, [140] wet etching, [141] laser direct writing lithography, [111,135,142,143] and direct printing technique. [136,137,144] Xu et al [111] fabricated the embedded Ag-grid TCE as a current collector for flexible transparent SCs.…”

“…Several approaches on the realization of TCEs were reported, including nanoimprinting, [ 139 ] photolithography, [ 140 ] wet etching, [ 141 ] laser direct writing lithography, [ 111,135,142,143 ] and direct printing technique. [ 136,137,144 ] Xu et al [ 111 ] fabricated the embedded Ag‐grid TCE as a current collector for flexible transparent SCs.…”

A self-healing hydrogel electrolyte towards all-in-one flexible supercapacitors

“…The capacitive materials for electrode application include carbon materials [29][30][31], metallic oxide [32,33], conductive polymer [34,35], and their composite. As one of the most widely studied conductive polymer electrode materials, polyaniline (PANI) shows the advantages of good thermal stability, biocompatibility [13], excellent capacitive property and cyclic stability.…”