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

Abstract 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.