Bioinspired Self‐Assembled Single‐Atom Iron‐Based Biodegradable Supercapacitors with Intensified Capacitive Kinetics for Implantable Acupoint Electrostimulation

ABSTRACT Biodegradable supercapacitors represent a promising alternative to conventional power sources for implantable electrical stimulation therapies. However, their development has been impeded by the lack of electrode materials that simultaneously offer high‐density redox‐active sites, efficient charge transport, and biocompatibility under physiological conditions. To overcome these challenges, we developed a biodegradable supercapacitor incorporating iron single‐atom catalysts anchored on carbonized bioinspired self‐assembled architectures (Fe SA/cBSAs). Electrochemical experiments and density functional theory (DFT) calculations revealed that the single‐atom Fe sites not only introduced additional pseudocapacitance via the reversible Fe 3 + /Fe 2 + redox pair but also weakened the Na─O interaction through surface‐potential redistribution, accelerating Na + desorption and diffusion. This dual mechanism—combining enhanced redox activity with weakened Na + binding—intensifies capacitive kinetics to synergistically improve both faradaic and electric‐double‐layer charge storage efficiencies, thereby yielding a marked increase in areal capacitance, energy density, and voltage stability without compromising charge‐discharge rate capability. Fabricated using a polyvinyl alcohol/phosphate‐buffered saline (PVA/PBS) hydrogel electrolyte and polylactic acid (PLA) encapsulation, the device exhibited excellent biocompatibility and outstanding biodegradability in vivo. In a murine inflammatory pain model, electrical stimulation delivered at the ST36 acupoint via our biodegradable supercapacitor markedly alleviated pain behavior and reduced inflammatory markers, confirming its therapeutic potential.