Flexible Planar‐Integrated Micro‐Supercapacitors from Electrochemically Exfoliated Graphene as Advanced Electrodes Prepared by Flash Foam–Assisted Stamp Technique on Paper

Abstract

One of the key challenges of integrated energy storage devices is to develop a simple, low‐cost, and environmental‐friendly planar patterning technology. Herein, an ingenious and feasible laser‐engraved flash foam–assisted stamp technique of preparing flexible paper‐based planar‐integrated micro‐supercapacitors based on interdigital electrodes of self‐depositing electrochemically exfoliated graphene is proposed. The as‐synthesized flexible paper‐based planar‐integrated graphene micro‐supercapacitors exhibit excellent electrochemical performances with a remarkable area‐specific capacitance of 3.1 mF cm−2, and an excellent cycling stability in that capacitance retention reaches 95.8% even after 10 000 cycles. Furthermore, the paper‐based graphene micro‐supercapacitors are bent at different angles without significant electrochemical performance loss, and thus have outstanding mechanical flexibility. Therefore, such flexible paper‐based planar‐integrated graphene micro‐supercapacitors are expected to be applied in flexible wearable and portable electronics.

Versatile Strategy to Design Flexible Planar-Integrated Microsupercapacitors Based on Co3O4-Decorated Laser-Induced Graphene

“…EIS data (Nyquist plot) further disclosed the capacitive behavior of Co 3 O 4 /LIG MSC (Figure f). The normalized equilibrium series resistance (ESR) obtained from the depressed semicircle in the Nyquist plot is equal to 150.2 Ω, which is made up of the ionic resistance of the gel electrolyte, the intrinsic resistance of the electrode, the charge-transfer resistance, and the interfacial contact resistance. , The high resistance may be caused by the low ionic conductivity of the ionic gel electrolyte and a disordered LIG. Moreover, the complex-plane plot of the impedance tends to become an almost perpendicular line in the low-frequency domain, indicating the nearly pure capacitive behavior …”

“…Flexible planar-integrated microsupercapacitors (MSCs), as a new-fashioned class of microscale, lightweight, and environmentally friendly energy storage devices, possess superior characteristics of rapid charge–discharge ability, high power density, long cycle life, and good safety performance and have been widely used in wearable, foldable, and portable electronic devices on account of the advantages of simple structure, facile expansion, and easy integration with on-chip electronics. − Routine microfabrication techniques have been exploited to produce flexible planar MSCs, including photolithography, , oxidative channel etching, vacuum filtration, , flash foam-assisted stamping, , inkjet printing, , screen printing, , etc. However, there are several serious shortcomings that have prevented their widespread production.…”

Paper-based laser-induced graphene for sustainable and flexible microsupercapacitor applications

“…Most importantly, paper is composed of intertwined cellulose fibers; therefore, it is a biocompatible and low-cost substrate, which can be easily recycled or disposed of without long-lasting harmful effects on the environment [ 13 ]. MSCs on paper have been fabricated by different approaches, namely stamping [ 8 , 14 – 16 ], spraying [ 17 ], ink-jet, and 3D printing [ 18 , 19 ]. However, despite their more than confirmed merits, these techniques may require several production steps and/or exhibit limited pattern configuration and speed [ 20 ].…”

Flexible planar supercapacitors by straightforward filtration and laser processing steps

“…The films can also be patterned into an interdigital structure by etching the filtered thin film [14] or by multi-step photolithography process [37]. Other reported methods of making carbon-based interdigital electrodes on flexible substrates have been inkjet printing [18,35], mask-assisted spray coating [18] layer-by-layer assembly [22,36], film transfer [17,27,[29][30][31] and 3D-printing [46]. Moreover, laser processing is one of the most promising method to reduce process steps in microelectronics patterning as it does not require time consuming photolithography steps or vacuum equipment and is capable to process large areas.…”