Asymmetric Fibre Supercapacitors for Sustainable Energy Storage in Next-Generation Soft Textile Wearables

Abstract

The rapid advancement of wearable technologies demands the development of flexible, lightweight, and high-performance energy solutions. Fibre supercapacitors (FSCs) have emerged as a promising wearable energy storage system that can be integrated into everyday fabrics, powering other embedded devices. Asymmetric FSCs (AFSCs), made of two electrodes of different kinds, offer superior voltage and energy density compared to the symmetric designs with two electrodes of the same materials. This review provides a comprehensive analysis of AFSCs, beginning with their role in advancing energy-autonomous wearable electronics. Various charge storage mechanisms are discussed along with key performance metrics. This is followed by a discussion of relevant fabrication methods and role of colloidal dispersions in the production of electrode fibres with excellent electrochemical properties. Subsequently, it is shown that AFSCs offer more practical solutions for wearable applications by addressing voltage and energy density restrictions of symmetric FSCs. The role of electrolytes in ensuring long-term stability and safety in wearable applications is then explained. The thorough analysis of positive and negative electrodes for AFSCs is presented to understand the emerging trends and their impact on wearability and electrochemical performance.The potential of AFSCs is also explored in various wearable technologies for powering health monitors and medical implants to motivate researchers to develop sustainable and biocompatible AFSCs. The emerging impact of machine learning tools in optimising electrode designs and device performance is also highlighted. The review finally emphasizes the need to address the existing gaps in scalability, stability under deformations, fabric integration, and multifunctional fibre-based systems. It provides platform to bridge the gap between laboratory scale prototypes to real-world implementation, establish AFSCs as sustainable power fibres within intelligent fabrics for autonomous wearables.