Research Article

Practical Flexible Asymmetric Supercapacitor Review-All-In-One Flexible Energy Storage Devices

Abstract

The rapid advancement of wearable electronics, flexible sensors, electronic textiles, and portable smart devices has created an urgent demand for lightweight, deformable, and high-performance energy storage systems. Among the various electrochemical energy storage technologies, flexible asymmetric supercapacitors (FASCs) have emerged as one of the most promising candidates because they combine the high power capability and long cycle life of conventional supercapacitors with enhanced energy density achieved through asymmetric electrode configurations. This review presents a comprehensive overview of the recent progress in flexible asymmetric supercapacitors, beginning with the fundamental charge storage mechanisms and the advantages of asymmetric configurations over conventional symmetric devices. Recent developments in flexible substrates, conductive polymers, carbon nanomaterials, transition metal oxides, sulfides, selenides, phosphides, MXenes, metal–organic frameworks, and other emerging electrode materials are critically discussed with respect to their structural design and electrochemical performance. In addition, advances in solid-state and gel polymer electrolytes, flexible device configurations, fabrication technologies, and performance evaluation under various mechanical deformation conditions are systematically summarized. The review further highlights the influence of material engineering, interface optimization, hierarchical nanoarchitectures, and hybrid composite strategies on improving capacitance, energy density, rate capability, and cycling stability. Current challenges related to large-scale manufacturing, mechanical durability, interfacial compatibility, environmental sustainability, and practical commercialization are critically analyzed. Finally, future perspectives focusing on multifunctional materials, self-healing and stretchable devices, additive manufacturing, artificial intelligence-assisted material discovery, and integrated wearable energy systems are presented. This review provides valuable insights into the rational design of next-generation flexible asymmetric supercapacitors and serves as a useful reference for developing high-performance, durable, and commercially viable flexible energy storage technologies.