Abstract
Microsupercapacitors have attracted significant attention due to several of their advantageous characteristics such as lightweight, small volume, and planar structure that is favorable for high mechanical flexibility. Among the various micro supercapacitor forms, those with laser-induced graphene (LIG) electrodes are promising as flexible energy storage devices. While LIG microelectrodes can be fabricated simply by direct laser writing, the capacitance and energy density of these devices are limited because of the relatively low density of LIG, which leads to low surface areas. These limitations could be overcome by densifying the LIG. Here, we report the use of densified laser-induced graphene (d-LIG) to fabricate flexible micro supercapacitors. Interdigitated d-LIG electrodes were prepared by duplicate laser pyrolysis of a polyimide sheet by using a CO2 laser. A PVA-H2SO4 gel-type electrolyte was then applied to the d-LIG electrode surface to assemble a d-LIG micro supercapacitor. This d-LIG micro supercapacitor exhibited substantially increased capacitance and energy density versus conventional low-density LIG micro supercapacitors. While the d-LIG electrode exhibited a substantial change in resistance when subjected to bending at a radius of 3 mm, the change in the capacitance of the d-LIG micro supercapacitor was negligible at the same bending radius due to reinforcement by the infiltrated poly(vinyl alcohol) (PVA) electrolyte, demonstrating the potential application of d-LIG micro supercapacitors in wearable electronics.
Highlights
Electrochemical capacitors such as supercapacitors have recently become the focus of intense and broad research efforts to meet the increasing demand for high-performance devices for energy storage [1,2]
We have developed a flexible d-laser-induced graphene (LIG) Micro supercapacitors (MSCs) by exploiting the high-performance of densified laser-induced graphene (d-LIG)
A high-performance MSC was developed by using interdigitated d-LIG electrodes. d-LIG
Summary
Electrochemical capacitors such as supercapacitors have recently become the focus of intense and broad research efforts to meet the increasing demand for high-performance devices for energy storage [1,2]. Supercapacitors, in particular, have received much attention because of their low costs, long life cycles, rapid charging/discharging capabilities, high power densities, and lightweight. Previous research has focused on developing compact electronics with small sizes, mechanical flexibilities, and high energy and power outputs. Micro supercapacitors (MSCs) are excellent candidates for such micro-scale electronic applications because of several of their characteristic features, including flexibility, portability, and small sizes [3]. Devices that operate in this manner are known as electrical double-layer capacitors (EDLCs), which are highly desirable by providing high cycling stability and high-power density but suffer from relatively poor capacitance. High capacitance in EDLCs can be attained by using electrodes with high conductivities and large surface areas
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