Rapid Preparation of Multifunctional Hydrogel Electrolytes with Excellent Adhesion and Self-Healing Capability for High-Performance Supercapacitor

The limited functionality of hydrogel electrolytes constrains their applications, necessitating the urgent development of multifunctional electrolytes that simultaneously exhibit high strength, strong adhesion, excellent self-healing properties, and electrical conductivity. Here, poly(acrylic acid) (PAA) hydrogels were prepared rapidly and simply at room temperature by a dopamine–Fe 3+ (DA–Fe 3+ ) self-catalytic system. By introducing the Hofmeister effect from Na 2 SO 4 and the coordination of Fe 3+ with the O atom in PAA, the mechanical strength of DFM–Na 2 SO 4 (1.0)–PAA enhanced from 74.4 to 311.1 kPa. Meanwhile, the ionic conductivity reached 31.5 mS·cm −1 . Moreover, due to the coordination interactions and multiple hydrogen bonds, DFM–Na 2 SO 4 (1.0)–PAA exhibits excellent adhesion and self-healing properties. Through in situ polymerization of pyrrole on the surface of DFM–Na 2 SO 4 (1.0)–PAA, an all-hydrogel supercapacitor was developed. The resulting supercapacitor demonstrated exceptional characteristics, including remarkable capacitive performance (461.4 mF·cm −2 at 0.4 mA·cm −2 ), good cycling stability (98.72% capacitance retention after 5000 cycles), and enhanced self-healing capability and flexibility, highlighting its promising applications in flexible wearable devices.