Tailored Tough, Self-Healing, and Antimicrobial Double Cross-Linked Hydrogel Supercapacitor Electrodes with Excellent Capacitive Properties and Stable Conductivity

With the widespread use of portable electronic devices, high-performance supercapacitors and flexible strain sensors have attracted great interest. However, previously reported supercapacitors usually suffer from drawbacks such as low energy density, poor toughness, and irreversible fracture, which limit further applications. Herein, a three-dimensional (3D) porous structure hydrogel (pAAm/pAA/SiO2@Ti3C2Tx-ILs) was synthesized by in situ radical polymerization. The electrostatic interaction and hydrogen bonding from modified SiO2 inhibited the self-restacking of Ti3C2Tx. As intercalators and stabilizers, ionic liquids (ILs) further increased the layer spacing of Ti3C2Tx and promoted electrolyte ion transfer. Consequently, the hydrogel electrode materials exhibited high area specific capacitance (231.3 mF·cm–2 at 1 mA·cm–2), energy density, and outstanding cycling stability (retention rate of 92.1% after 3000 cycles). The hydrogel exhibited excellent mechanical properties (superior toughness (13.26 MJ·m–2) and strain (4153.75%)). Moreover, the ILs otherwise enabled the hydrogels with excellent antibacterial activity against Staphylococcus aureus and Escherichia coli. As strain sensors, the hydrogels exhibited a wide operating range (gauge factor = 11.17, up to 800%) and high sensitivity to monitor human activities in different exercise states. Thus, this unique, multifunctional, and biofriendly gel-based electrode material will hold considerable promise for energy storage, human–machine interfaces, and other fields.