Constructing Seamless Interfaces for Ultrastable Flexible Supercapacitors

ABSTRACT Flexible supercapacitor (SC) represents a promising power source for wearable electronics, but its cycling and flexible stabilities are currently limited by the weak interaction at the electrode/electrolyte interface. We construct a covalent electrode/electrolyte interface by anchored interfacial polymerization and a topologically entangled electrolyte/electrolyte interface by in situ polymerization in one SC. The interfacial toughness and adhesion strength between electrode and electrolyte reach 2965.3 J m −2 and 241.6 kPa, respectively, which are two orders and one order of those assembled by the traditional stacking approach. The seamless interfaces efficiently promote ion transport ability among them, which provides the SC with a three‐time enhancement of specific capacitance, compared with the device by the DS method. The developed SC exhibits high capacitance retention of 89.5% for 10 5 charge/discharge cycles and 96.2% after folding for 10 5 times, indicating outstanding stability of structure and performance. The demonstrated seamless interfacial engineering can be easily expanded in the field of other flexible electronics.