Multicomponent Synergistic Optimization of Thermoelectric Properties in PVDF-HFP Ionogels

Ionic thermoelectric materials are typically composed of polymers, ions, and solvents. The interplay among these components governs the material's thermoelectric properties. And most of the current research focuses on the optimization of the single component of the material. To achieve enhanced performance, this study proposes a multicomponent synergistic optimization strategy for a gel system. Specifically, a PVDF-HFP/EMIM:DCA ionogel (poly(vinylidene fluoride-co-hexafluoropropylene)/1-ethyl-3-methylimidazolium dicyanamide), is synergistically optimized by the functional incorporation of three components: polyethylene glycol (PEG), sodium dicyanamide (Na:DCA), and ethanol. The experimental results show that, compared to the single-factor modulation scheme, the multicomponent synergistic optimization scheme significantly enhances the thermoelectric performance of the ionogel. This is achieved by mitigating the confinement of ions within the polymer matrix, amplifying the difference in diffusion rates between cations and anions, and thus establishing percolating pathways for efficient ion transport. The obtained ionogel exhibits significantly enhanced performance at 80% relative humidity (RH), achieving ionic Seebeck coefficient of 32.89 mV/K, ionic conductivity of 15.63 mS/cm, and ionic power factor of 1690.77 µW/(m·K²). These values are substantially higher than those of the unmodified ionogel. This optimization strategy for the material system provides both a theoretical basis and experimental reference for the design of novel ionic thermoelectric materials.