Ionic Thermoelectric Paper

Ionic thermoelectric materials, such as polyelectrolyte like polystyrene sulfonate sodium (PSSNa), constitute a new class ofmaterial attracting interest due to their large Seebeck coefficient and the possibility to be used in ionic thermoelectricsupercapacitors (ITESCs) and field effect transistors. However pure polyelectrolyte membranes are not robust neitherflexible. In this article, we demonstrate the preparation of ionic thermoelectric paper by a simple, scalable and cost-effectivemethod. After composite with nanofibrillated cellulose (NFC), the resulting NFC-PSSNa paper is flexible and mechanicallyrobust; which is desirable of using roll-to-roll processes. The robust thermoelectric paper NFC-PSSNa combines high ionicconductivity (9 mS/cm), high ionic Seebeck coefficient (8.4 mV/K) and low thermal conductivity (0.75 Wm-1K-1) at 100 RH%,resulting in overall figure-of-merit of 0.025 at room temperature slightly better than the PSSNa. Enabling flexibility androbustness by compositing with cellulose constitutes an advance for scaling up the manufacturing of ionic thermoelectricsupercapacitors; but also enables new applications for conformable thermoelectric devices and flexible electronics
Funding agencies: European Research Council (ERC Starting Grant) [307596]; Swedish Foundation for Strategic Research (SSF); Knut and Alice Wallenberg foundation (KAW); Swedish Energy Agency; Advanced Functional Materials Centre at Linkoping University; United States Nation