High-Performance Textile Microsupercapacitors Based on Laser-Induced Graphene Composite Electrodes

Electronic textiles (E-textiles) have garnered extensive attention due to their extended usage in various applications such as sensors, actuators, and energy harvesting, and storage devices, and even displays. While individual functions of each E-textile have been separately researched, the energy storage device to power E-textiles should be integrated in the form of textile for practical applications. Microsupercapacitors (MSCs), thin-film energy storage devices, have received a great deal of attention as power sources for wearable, textile or stretchable electronic devices due to their fast charging capability, long life cycle, and good safety. Various ink printing techniques (screen printing, inkjet printing, 3D printing) have been employed to fabricate electrode patterns of textile MSCs. Even though these ink printing techniques are considered to be compatible with large-scale production, the preparation of inks based on high performance nanomaterials requires a costly, time-consuming and complicated process including high temperature synthesis or dispersion in an organic solvent. A cost-effective and facile textile MSC fabrication process without ink materials is thus required.<br/>Laser-induced graphene (LIG), obtained by the direct laser writing of various types of carbon precursors, have widely researched as electrode materials of flexible microsupercapacitors with the advantages of 3D porous electrodes with high crystallinity, hierarchical porosity, and high surface area. However, these superior properties of LIG electrode were not applied in textile energy storage devices yet.<br/>In this work, LIG-based textile MSCs (LIG-MSCs) were fabricated by thermal transfer printing. A LIG directly laser-written on a PI film was transferred onto the adhesive film area of textile substrates during thermal transfer printing. The electrochemical performances of the as-fabricated textile LIG-MSCs were investigated. Especially, LIG-MSCs based on LIG-metal composite electrodes exhibit fast ion transport for high-rate performance with capacitive rectangular shapes at high scan rates of up to 20V/s, suggesting outstanding rate capability among graphene-based textile MSCs. Moreover, LIG-MSCs demonstrated the possibility of practical usage as textile energy storage devices such as cyclic stability, a waterproof property, and control of the working voltage or capacitance by series or parallel connection.