Nanostructured cellulose ionogels with selective anion confinement for high-efficiency thermoelectric harvesting.

The performance of ionic thermoelectric materials (i-TEs) for low-grade heat harvesting is fundamentally hampered by the coupled transport of ions and heat. Overcoming this to simultaneously achieve high ionic conductivity and low thermal conductivity remains a paramount challenge. We address this by designing a nanostructured ionogel through a thiol-ene click reaction between allyl cellulose and sulfhydryl-functionalized organosiloxanes (POSS-8SH). This creates a microphase-separated architecture with continuous ion-conducting channels. Crucially, the POSS cages serve as multifunctional nodes that selectively nanoconfine anions to widen the cation-anion mobility disparity, while their heterogeneous dispersion effectively scatters phonons to suppress thermal conductivity. Molecular dynamics simulations confirm this mechanism, quantifying a cation diffusion coefficient 5.2 times greater than that of the anion. This strategic decoupling culminates in a high ionic power factor of 15 669.5 µW m-1 K-2. The practical viability of this ionogel was demonstrated by constructing a wearable module that generates 800 mV from body heat. This work establishes a foundational paradigm for advancing thermal energy harvesting and self-powered wearable systems.