Ionic Thermoelectric Materials Based on the Thermodiffusion Effect: Mechanism, Advancements, and Applications

The relentless increase in global energy consumption, coupled with the detrimental effects of over-reliance on non-renewable fossil fuels, has necessitated a paradigm shift in the energy industry towards sustainable energy sources. Thermoelectric materials have emerged as a promising avenue for harnessing waste heat, offering a viable solution to the dual challenges of energy scarcity and environmental pollution. Compared with traditional electronic thermoelectric materials, ionic thermoelectric (i-TE) materials have received increasing attention. This review provides an overview of the recent advancements in i-TE materials based on the thermodiffusion effect, including an in-depth analysis of the fundamental principle, material design, and potential applications. The significance of material selection is highlighted, with types of i-TE materials ranging from liquid to quasi-solid and solid states, each presenting unique advantages and challenges. The innovative microstructural engineering and regulating interactions are identified as key strategies to enhance the thermoelectric performance of i-TE materials. Furthermore, the applications in capacitors and generators and sensing devices are summarized, demonstrating their potentials in varieties of scenarios. Encouraged by the recent rapid progresses, it is believed that the ionic i-TE materials and related technology are expected to generate practical impacts in the future solutions for sustainable energy.