Mussel-Inspired Interfacial Modification of MXene-Based Electrode and Silk-Based Hydrogel Electrolyte for Flexible Supercapacitors

Abstract

Flexible supercapacitors have emerged as a promising energy supply candidate for wearable electronic devices, yet their practical applications are severely constrained by the insufficient energy-storage capabilities of conventional electrodes and electrolytes. Herein, inspired by the interfacial adhesion of mussels, tannic acid is introduced via an immersion strategy as an interlayer spacer to achieve secondary intercalation and modification of vacuum-filtrated Ti₃C₂T_x MXene/PEDOT:PSS composite films. The prepared MPT composite film electrode exhibits an enhanced toughness for flexible electronics to resist mechanical stimulation, as well as high areal specific capacitance suitable for charge storage (328.08 mF cm^–2 at 1 mA cm^–2). Meanwhile, a silk fibroin-reinforced polyacrylamide hydrogel with stable lithium-ion transport performance is fabricated and employed as a flexible solid electrolyte. Benefiting from the synergistic advantages of the MPT film electrode and conductive hydrogel electrolyte, the assembled symmetric all-solid-state flexible supercapacitor achieves a high energy density of 14.1 μW h cm^–2 at a power density of 323.3 μW cm^–2. Moreover, the device exhibits good long-term cycling stability and flexible energy-storage performance, with negligible capacitance degradation under bending deformation. This work could provide a way for the design of high-performance flexible supercapacitors.