(63d) Effect of Wool Substrate and Its Processing on the Performance of Conductive Textiles

Conductive textiles are being developed by applying electrically conductive material, such as MXenes, to various yarns and fabrics. While fundamental research has been conducted into the properties of the conductive materials and how these materials affect the performance of electric textiles, there is a gap in understanding of how the substrate properties affect the performance of conductive fabric. It is well established that increased porosity, surface area, hydrophilicity, and mass loading improve the electrical performance of the conductive fabric, but how the properties of the substrate influence the properties of the conductive textile is not well understood.

Here we report on the effect of wool substrate and its processing on the performance of textile supercapacitors. MXene conductive material was applied to wool yarn using two different methods referred to as submersion- and auto-coating. In this study, Ti₃C₂Txwas selected for its excellent cycling stability, high conductivity, non-toxicity, and hydrophilicity. Wool yarn was selected as the substrate due to its outstanding adsorption properties, negatively charged fiber surface, insulating properties, and sustainability. Wool is a protein-based fiber made from keratin; as a result, it is more sustainable than other fibers that require the planting of new crops or mining of oil for their fabrication. It also contains nitrogen and sulfur which give wool its adsorptive properties and negatively charged surface; as a result, this charged surface more readily interacts with dye and pigment particles, and the adsorptive properties mean the wool soaks up the electrolyte, decreasing the distance between electrolytic ions and the surface of the conductive material, allowing for faster charge and discharge of the TSCs. In the submersion method, wool yarn was submerged into MXene colloidal solution and dried under vacuum, and this two-step process repeated 4 times. Wool yarn was autocoated by pulling individual yarns through a MXene bath and threading the coated yarn through a drying system, a one-step process repeated 12 times.

X-Ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) were used to confirm the presence of MXene on the wool surface as well as to study the chemical bonds present at the surface. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the electrochemical performance of the yarn, and EIS was also used to inform equivalent circuit models (ECMs) to model the chemical reactions occurring in the system. Submersion-coated wool yarn had an intrinsic capacitance of 0.02 mF/cm, while autocoated wool yarn had an intrinsic capacitance of 0.49 mF/cm. This increase in specific capacitance in the autocoating method is attributed to the increased mass loading of MXene conductive material onto the wool yarn.