Self‐Healable Organic–Inorganic Hybrid Thermoelectric Materials with Excellent Ionic Thermoelectric Properties

Abstract Self‐healable and stretchable thermoelectric (TE) materials provide new possibilities for self‐powered flexible wearable devices to self‐repair mechanical damage. However, developing high‐performance materials with such desirable TE and mechanical properties is a significant challenge. In this work, organic–inorganic ionic TE composites (OITCs) with an unprecedently high ionic TE figure of merit (ZT i = 3.74 at 80% relative humidity) and robust properties of simultaneous self‐healing and stretching are reported. The OITCs are developed by incorporating inorganic SiO 2 nanoparticles (SiO 2 ‐nps) in a polyaniline: poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid): phytic acid (PANI:PAAMPSA:PA) ternary polymer. The incorporated SiO 2 ‐nps constructively interact with the hybrid polymer to provide autonomous self‐healability and stretchability while augmenting the mobile proton concentration in OITCs, which substantially improves their ionic TE properties (i.e., ionic Seebeck coefficient and ionic conductivity). Moreover, the OITCs remain repeatedly stretchable and self‐healable under severe external stresses (50 cycles of 100% strain and 25 cycles of cutting/healing) without degradation of their TE properties. Using the OITCs with multi‐walled carbon nanotube electrodes, an ionic TE supercapacitor (ITESC) with a maximum energy density of 19.4 mJ m −2 is demonstrated upon a temperature difference of 1.8 K.