Anionic entanglement-induced giant thermopower in ionic thermoelectric material Gelatin-CF3SO3K–CH3SO3K

Abstract

Ionic thermoelectric (i-TE) technologies can power Internet of Things (IoT) sensors by harvesting thermal energy from the environment because of their large thermopowers. Present research focuses mostly on using the interactions between ions and matrices to enhance i-TE performance, but i-TE materials can benefit from utilizing different methods to control ion transport. Here, we introduced a new strategy that employs an ion entanglement effect. A giant thermopower of 28 ​mV ​K⁻¹ was obtained in a quasi-solid-state i-TE Gelatin-CF₃SO₃K–CH₃SO₃K gel via entanglement between ${{{CF}_{3}SO}_3}^{-}$ and ${{{CH}_{3}SO}_3}^{-}$ anions. The anionic entanglement effect involves complex interactions between these two anions, slowing anionic thermodiffusion and thus suppressing bipolar effects and boosting p-type thermopower. A Au@Cu | Gelatin-CF₃SO₃K–CH₃SO₃K | Au@Cu i-TE device with a generator mode delivers a specific output energy density of 67.2 ​mJ ​m⁻² K⁻² during 2 ​h of discharging. Long-term operation of the i-TE generator for 10 days shows that the harvested energy density offers an average of 2 ​J ​m⁻² per day in a cyclic working-reactivation model at a temperature difference of 6 ​K. The results demonstrate that anionic entanglement is an effective strategy for achieving giant thermopower with i-TE gels, so they have excellent potential for powering IoT sensors.