Ionic thermoelectric materials based on organic polymers are of great significance for low-grade heat harvesting and self-powered wearable temperature sensing. Here, we demonstrate a poly(vinyl alcohol) (PVA) hydrogel that relies on the differential transport of H+ in PVA hydrogels with different degrees of crystallization. After the inorganic acid is infiltrated into the physically cross-linked PVA hydrogel, the ionic conductor exhibits a huge ionic thermopower of 38.20 mV K-1, which is more than twice the highest value reported for hydrogen ion transport thermoelectric materials. We attribute the enhanced thermally generated voltage to the movement of H+ in the strong hydrogen bond system of PVA hydrogels and the restrictive effect of the strong hydrogen bond system on anions. This ionic thermoelectric hydrogel opens up a new way for thermoelectric conversion devices using H+ as an energy carrier.
Keywords: energy harvesting; giant thermopower; ionic thermoelectric capacitors; strong hydrogen bond system.