A Highly Stretchable Multifunctional Ionic Thermoelectric Gel for Integrated Energy Harvesting and Wearable Sensing

Ionic thermoelectric (i-TE) gels offer a pathway for harvesting low-grade heat in flexible electronics, yet achieving the concurrent enhancement of thermoelectric efficiency, mechanical robustness, adhesion, and self-healing capabilities remains a significant challenge. Herein, sericin is incorporated into an ion-polymer matrix to construct a dual physical-chemical cross-linking network via hydrogen bonding, ion-dipole, and dipole-dipole interactions. This network restricts anionic phosphate migration and amplifies the thermal diffusion entropy difference between charge carriers, thereby coupling ionic transport modulation to mechanical reinforcement. Consequently, the Seebeck coefficient rises from 3.45 to 10.16 mV/K, electrical conductivity increases from 0.31 to 0.55 mS/cm, and fracture elongation reaches 2698% with a toughness of 2.13 MJ·m^-3. The resulting SHED gel adheres strongly to diverse substrates, undergoes rapid self-healing (94.65% tensile recovery; 330.7 ms conductivity restoration), and sustains performance under deformation. Molecular dynamics and density functional theory simulations corroborate the sericin-induced synergy in ion transport and network mechanics. This strategy resolves the mechanical-thermoelectric trade-off, advancing i-TE gels toward high-performance, wearable, self-powered sensors and human-machine interfaces.