Comprehending the Frontiers of Flexible Supercapacitors: Materials, Fabrication Techniques, and Performance Metrics

The accelerating development of wearable electronics encompassing flexible sensors, displays, and health monitoring systems has driven strong demand for lightweight, deformable, and high-performance energy storage technologies. With the increasing attention in these fields, flexible and wearable supercapacitors (FSCs) have gained significant attention due to their fast charge-discharge rates, excellent mechanical resilience, and long-term cycling stability. This review presents a comprehensive analysis of recent advances in FSC research, focusing on both material-level engineering and device-level integration. Electrode materials, including carbon-based frameworks, transition metal-based materials, conductive polymers, and their hybrids, are critically examined, with an emphasis on structural design strategies. Fabrication techniques are discussed by dimensional configuration, including 1D fiber-shaped, 2D planar, and multidimensional structures, with a focus on scalable and application-oriented processes. Furthermore, representative demonstrations in wearable, transparent, and sensor-integrated devices are explored to illustrate the practical potential of FSCs. Finally, future directions are proposed, including light and moisture stability, as well as electrolyte degradation, to realize next-generation multifunctional flexible energy storage systems.