Recent Advancements in Polymer and Graphene-Based Composites for High-Performance Supercapacitor Applications: Progress, Challenges, and Future Perspectives

The increasing worldwide need for sustainable and high-performance energy storage systems has accelerated significant interest in the development of advanced electrode materials for supercapacitors (SCs). SCs have attracted considerable attention as advanced energy storage devices because they offer high power output, rapid energy delivery and recharge, excellent rate capability, and outstanding stability over prolonged charge–discharge cycles, making them suitable for diverse energy storage and power-management applications. Nonetheless, the relatively low specific energy of conventional electrode materials remains a major obstacle to their widespread commercialization. In this context, polymers and graphene-derived electrode materials have gained substantial consideration owing to their complementary physicochemical characteristics. Conducting polymers (CPs), which include polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy), and polythiophene (PTh) derivatives, and hypercross-linked polymers (HCPs) offer high pseudocapacitance through reversible redox reactions, whereas graphene and its derivatives provide extraordinary electrical conductivity, higher specific surface area (SSA), outstanding mechanical strength, and excellent chemical durability. The synergistic integration of these materials into polymer/graphene composites has begun as an efficient approach to overcome the intrinsic limitations of individual components and significantly improve electrochemical behavior. This review summarizes recent advances in polymer and graphene-derived composites for high-performance supercapacitor applications, focusing on preparation strategies, structural features, charge-storage mechanisms, and electrochemical properties of conducting polymer/graphene hybrids. The effects of morphology, porosity, surface area, electrical conductivity, mechanical flexibility, and ion transport on device performance are critically discussed. Recent progress in flexible and wearable supercapacitors, along with challenges related to cycling stability, graphene restacking, large-scale production, and device integration, is also highlighted. Furthermore, future perspectives, including multifunctional electrode design, sustainable materials, and artificial intelligence-assisted material development, are presented to provide insights into the design of next-generation supercapacitor electrodes.