A Micromolding Method for Transparent and Flexible Thin‐Film Supercapacitors and Hybrid Supercapacitors

Abstract

Thin-film supercapacitors are promising candidates for energy storage in wearable electronics due to their mechanical flexibility, high power density, long cycling life, and fast-charging capability. In addition to all of these features, device transparency would open up completely new opportunities in wearable devices, virtual reality or in heads-up displays for vehicle navigation. Here a method is introduced for micromolding Ag/porous carbon and Ag/ Ni x Fe y O z @reduced graphene oxide (rGO) into grid-like patterns on polyethylene terephthalate foils to produce transparent thin-film supercapacitors and hybrid supercapacitors. The supercapacitor delivers a high areal capacitance of 226.8 µF cm −2 at a current density of 3 µA cm −2 and with a transparency of 70.6%. The cycling stability is preserved even after 1000 cycles under intense bending. A hybrid supercapacitor is additionally fabricated by integrating two electrodes of Ag/porous carbon and Ag/Ni x Fe y O z @rGO. It offers an areal capacitance of 282.1 µF cm −2 at a current density of 3 µA cm −2 , a transparency of 73.3% and the areal capacitance only decreases slightly under bending. This work indicates that micromolding of nano-and micro-sized powders represents a powerful method for preparing regular electrode patterns, which are fundamental for the development of transparent energy storage devices.

High performance fully paper‐based all‐solid‐state supercapacitor fabricated by a papermaking process with silver nanoparticles and reduced graphene oxide‐modified pulp fibers

“…Paper‐based supercapacitors have gained popularity due to their inherent mechanical strength and flexibility, porosity, biocompatibility, low cost, environmental friendliness, and lightweight 7‐11 . Although cellulose paper is an insulating material, its hierarchical pores, hydrophilic surfaces make it a flexible substrate loaded with conductive materials and absorbing electrolyte 12,13 .…”

Recent Development of Flexible and Stretchable Supercapacitors Using Transition Metal Compounds as Electrode Materials

“…Niederberger's group. [ 240 ] used a micromolding strategy to design a nano/microsized Ag current collector for loading Ni x Fe y O z @rGO hybrid, leading to the formation of a transparent and flexible electrode for hybrid SC, as shown in Figure . The derived electrode showed a hexagonal grid structure, offered a high light transmission limit, and ensured close contact between the active material and current collector.…”

“…Reproduced with permission. [ 240 ] Copyright 2020, Wiley‐VCH. b) Schematic illustration of the preparation and the contract angle of NiCo–LDH/NCC.…”

Nickel Acetate-Assisted Graphitization of Porous Activated Carbon at Low Temperature for Supercapacitors With High Performances

“…Supercapacitors, as a kind of promising energy storage device with high power density and long service life, have excited great interest owing to their potential application in portable electronics and electric vehicles ( Qin et al, 2021 ; Reece et al, 2020 ; Yang L et al, 2021 ; Zhu et al, 2019 ). Based on different energy storage mechanisms, supercapacitors are mainly divided into two categories: faradic pseudocapacitors, in which transition metal oxides and conducting polymers are used as active materials, and electrical double-layer capacitors (EDLCs), in which carbon-based materials are often used as active materials ( Adhikari et al, 2020 ; Liu T et al, 2020 ; Say et al, 2020 ). The energy storage mechanism of EDLCs depends on the attraction of positive and negative charges at the interface of electrode and electrolyte, enabling high power density and ultralong cycling life of EDLCs ( Fleischmann et al, 2020 ; Pai et al, 2021 ; Pourhosseini et al, 2021 ).…”