In Situ Derived Sites Govern Redox Electrolyte Migration for High-Performance Flexible All-Solid-State Supercapacitors

Supercapacitors (SCs) are fascinating energy storage devices due to their delivery of exceptional power density and long cycling stability. Unfortunately, their practical applications are still impeded by the inferior energy density derived from sluggish electrolyte transports. Herein, we demonstrate a strategy via the in situ electrochemically derived flexible metallopolymer electrode to precisely govern the directional migration of redox-active electrolytes. As a result, the assembled SC achieves a high areal capacitance of 2729 mF cm–2 at 1 mA cm–2, together with remarkable rate capability and cycling stability. Further fabrication of the solid-state device exhibits an ultrahigh areal capacitance of 1440 mF cm–2 and energy density of 0.5 mW h cm–2 at the power density of 0.8 mW cm–2. Systematic experimental characterizations combined with thermodynamic and kinetic simulations reveal that electrolytes are directionally guided to specific active sites on the electrode surface, where accelerated I–/I3– faradaic reactions occur, highlighting a synergistic kinetic interplay between the electrode surface and electrolyte that enables high-performance flexible supercapacitors.