Advances in Biodegradable Supercapacitors for Implantable Bioelectronics: Materials, Energy Storage, Degradation, and...

The emergence of transient bioelectronics has accelerated the development of biodegradable supercapacitors as promising energy-storage systems for temporary medical implants, including neural stimulators, cardiac pacemakers, controlled drug delivery devices, and biosensors. Biodegradable supercapacitors can safely resorb after completing their function, eliminating secondary surgical removal and reducing long-term foreign-body complications, unlike conventional batteries. This review comprehensively discusses recent advances in degradable supercapacitors, focusing on biocompatible polymers, bioresorbable electrodes, separators, electrolytes, and current collectors. This review critically evaluates the electrochemical performance of biodegradable supercapacitors under physiological conditions, including capacitance retention, cycling stability, and degradation behaviour. Current challenges, such as limited energy density, mechanical instability, precise bioresorption kinetics, and scalability, are discussed. This study addresses key regulatory and safety considerations, including biocompatibility, toxicity, immunogenicity, and pathway approval. Further, outlines strategic future directions: bio-derived carbon, biologically synthesized conductors, self-healing hydrogel electrolytes, stimulus-responsive programmable degradation, and energy-harvesting integration. Emerging frontiers at the intersection of bioelectronics, neuromorphic computing, and living devices, and advocates for standardized benchmarking and circular-economy integration. This comprehensive analysis aims to accelerate the rational design, validation, and clinical translation of degradable supercapacitors toward autonomous, patient-friendly implantable systems.