2024/01/10 by Xin Qian, Zhihao Ma, Qian, Xin +7 · 2 citations
Engineering · Materials Science · #Advanced Thermoelectric Materials and Devices #Advancements in Solid Oxide Fuel Cells #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Fuel Cells and Related Materials #Materials Science (cond-mat.mtrl-sci)
paper · pdf · doi:10.48550/arxiv.2401.04886
openalex publication_date 2024/01/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
More than half of the waste heat rejected into the environment has temperatures lower than 100 ^∘ C, which accounts for nearly 85 PWh/year worldwide. Efficiently harvesting low-grade heat could be a promising step toward carbon neutrality. Recent developments of ionic thermoelectrics (i-TE) with giant thermopower have provoked intensive interest in using ions as energy and charge carriers for efficient thermal energy harvesting. However, current literature primarily focuses on improving thermopower only, while the ion transport and thermodynamics affecting the efficiencies have been largely neglected. This review article clarifies the fundamentals of electrochemistry and thermodynamics for developing highly efficient i-TE devices. Two major types of i-TE devices, thermo-ionic capacitors (TIC) and thermogalvanic cells (TGC), are discussed in detail. The article analyzes the methods of enhancing ionic thermopower in the literature by taking an entropic point of view. We also derived modified thermoelectric factor Z for both TICs and TGCs that fully incorporate the dynamics of ion transport and electrochemical reactions. Recent developments of hybrid devices showing improved efficiencies, power density, and multifunctionality are reviewed. Finally, we comment on the remaining challenges and provide an outlook on future directions.