Progress and prospects of conductive polymers for high-performance supercapacitor electrodes

Abstract

The increasing demand for efficient and sustainable energy storage has identified supercapacitors as notable devices due to their high power density, fast charge-discharge ability, and long lifespan. Though, conventional electrode materials such as carbon and metal oxides face limitations including low energy density, poor cycling stability, and high cost, restricting their broad application in renewable energy systems. Conductive polymers, such as polyaniline, poly-o-toluidine, polypyrrole, and polythiophene, have emerged as promising alternatives because of their good nature, low cost, good conductivity, and pseudocapacitive behavior. They store charge through fast and reversible redox reactions, making them attractive for pseudocapacitors, while also enhancing conductivity and stability when combined with carbon materials in electric double-layer capacitors. Recent studies in nanostructuring, morphology control, and composite strategies with nanomaterials and transition metal oxides have notably improved their capacitance, rate performance, and cycle life. Despite challenges such as mechanical degradation and stability issues during cycling, ongoing efforts in molecular designing, hybrid formation, and green synthesis methods continue to improve their performance and sustainability. This review presents the progress of conductive polymers as supercapacitor electrodes, covering their fundamentals, structures, synthesis approaches, and hybridization with advanced materials. It also discusses major challenges and proposes future directions, including flexible and wearable devices, integration with nanotechnology, and eco-friendly large-scale production. By addressing current limitations, conductive polymers hold strong potential to move forward the development of next-generation supercapacitors for renewable energy and advanced electronic applications.