Ionic Liquid-Mediated Structure-Engineered Cellulose-Based Ionogel with Ion-Electron Cotransport for Boosted Thermoelectric Conversion

Abstract Low-grade heat (<373 K) remains an underutilized energy source due to inefficient conversion technologies. While ionic thermoelectric (i-TE) materials show promise for direct thermal-to-electrical energy conversion, simultaneously optimizing the conductivity and Seebeck effect remains a significant challenge. In this work, we proposed an ionic liquid [BMIM]Cl-assisted cellulose ionogel composited with single-walled carbon nanotubes (SWCNTs). [BMIM]+ adsorbed onto SWCNT surfaces effectively promotes uniform dispersion of SWCNTs in Cl–-mediated cellulose dispersion, thereby optimizing the microporous structure of the ionogel for enhanced ion transport. Moreover, [BMIM]+ induces free electrons within the SWCNT network to gather and create strong ion-electron coupling for synergistic cotransport. These combined effects enable rapid thermal-diffusion-driven ion transport, endowing the ionogel with remarkable ionic conductivity (34.6 mS cm–1), Seebeck coefficient (26.33 mV K–1), and thermoelectric figure of merit (2.58). Furthermore, the ionogel exhibits remarkable versatility for wearable multimode sensing and physiological monitoring. This work provides a scalable strategy for designing multifunctional, high-efficiency i-TE systems.