Flexible Transparent Supercapacitors: Materials and Devices

Abstract

The progressive development of flexible transparent portable electronic devices is in urgent need of matching power sources. Flexible transparent supercapacitors (FTSCs) are the core resources due to their high optical transmittance, endurable mechanical flexibility, excellent electrochemical performance, and facilely accessible device configuration. This review organizes the rational design of nanostructured electrode materials toward FTSCs. First, the structure, mechanism, and property of FTSCs are introduced. Then, the design principles of diverse electrode materials are discussed to achieve flexible transparent conductive electrodes (FTCEs) with different figure of merits (both electrical FoMe and capacitive FoMc), mechanical strength, and environmental stability. Following the achievements in multifunctional FTSCs focusing on film‐supercapacitors, micro‐supercapacitors, electrochromic supercapacitors, photo‐supercapacitors, and battery‐like supercapacitors are also highlighted. Finally, the current challenges and future perspectives on viable materials in the construction of FTSCs to power portable electronics are outlined.

Electrodeposition of the MnO2 on the Ag/Au Core–Shell Nanowire and Its Application to the Flexible Supercapacitor

“…The areal capacitances calculated from the CV curves were 0.09 mF/cm 2 for the AACS NW electrode and 4.3, 8.7, and 12.2 mF/cm 2 for Ag/Au/MnO 2 core–shell NW electrodes. The areal capacitances were calculated according to , where is the current, and are the initial and final voltage of the CV curve, ν is the scan rate, and is the geometric area of the electrode [ 26 ]. To identify the charge-storage mechanism of the suggested Ag/Au/MnO 2 core–shell NW electrode, we conducted additional CV tests in various voltage scan rates, as shown in Figure S9a .…”

“…After 500 times repeated bending cycles, the capacitance was maintained at 94%, confirming the mechanical stability and flexibility of the suggested Ag/Au/MnO 2 core–shell NW network electrodes. Finally, we evaluated the performance of the fabricated flexible supercapacitor through a Ragone plot, as shown in Figure 6 d. The energy and power density were calculated according to and , respectively [ 26 ]. From the Ragone plot, it was confirmed that the suggested Ag/Au/MnO 2 flexible supercapacitor was able to store 0.41 μWh/cm 2 at 12.9 μW/cm 2 , which is comparable (or even better) to some of the previously reported flexible supercapacitors using various materials such as the MnO 2 /Au (4.2 μWh/cm 2 at 0.51 μW/cm 2 ), the GO/CNT (25.5 nWh/cm 2 at 1.25 μW/cm 2 ), the rGO/Cu-MOF (0.51 μWh/cm 2 at 2.54 μW/cm 2 ), the ZnO NW (0.03 μWh/cm 2 at 14 μW/cm 2 ), and the MnO 2 /Ti3C2Tx MXene (0.7 μWh/cm 2 at 80.0 μW/cm 2 ).…”

“…IdV, where I is the current, v i and v f are the initial and final voltage of the CV curve, ν is the scan rate, and A is the geometric area of the electrode [26]. To identify the charge-storage mechanism of the suggested Ag/Au/MnO 2 core-shell NW electrode, we conducted additional CV tests in various voltage scan rates, as shown in Figure S9a.…”

In situ deposited multilayer integrated hydrogels for deformable and stretchable supercapacitors

“…Flexible electronic devices with prominent scalability and portability have been proposed for use in a wide array of wearable devices, electronic skins, smart textiles, and others [1,2]. The development of flexible electronic devices strictly relies on stretchable functional components and energy storage modules.…”

Free-Standing, Flexible Nanofeatured Polymeric Films Prepared by Spin-Coating and Anodic Polymerization as Electrodes for Supercapacitors

“…In recent years, flexible, lightweight, and environmentally friendly electrodes for SCs have attracted increasing attention since they meet the needs for portable (e.g., foldable phones) and wearable (e.g., smart textiles) electronics [ 24 , 25 , 26 , 27 ]. In these devices, which exhibit high specific energy and power densities and long life cycles, all components, including the electrodes, are flexible.…”