Modulating thermo-diffusion/galvanic coupling via ion speciation engineering enables high-performance ionic thermoelectric cells.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41620431.
- Also identified by DOI 10.1038/s41467-026-68721-9 and PMC identifier 12963541.
- Licence recorded as CC BY-NC-ND.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Ionic thermoelectric (i-TE) materials have demonstrated a high thermopower in harvesting low-grade heat, emerging as superior candidates for self-powered electronics. However, coupling two i-TE effects in n-type materials is scarce, which restricts the development of high-performance systems. Herein, we uncover an overlooked thermogalvanic redox reaction between Cu<sup>2+</sup> and Cu<sup>+</sup> stabilized by Cl⁻ and quantitatively track the progressive reaction process by operando characterization. In binary polyvinyl alcohol (PVA)-CuCl<sub>2</sub> gels, an interactive i-TE coupling effect driven by ion speciation is validated, which exhibits an enhanced thermogalvanic redox as CuCl<sub>2</sub> concentrations increase while suppressing the thermodiffusion contribution. By distinguishing and quantifying coordination species, we reveal the impact of [Cu-Cl] speciation on the i-TE effect contributions. Correspondingly, a giant thermopower of -30.6 mV K<sup>-1</sup> and a remarkable power density of 0.6 mW m<sup>-2</sup> K<sup>-2</sup> are achieved, respectively, by tuning ion coordination speciation. The long-term power generation exhibits a reversible and sustainable heat-to-electricity conversion. High output voltage of 3.5 V and power of 22 µW are produced in 16-cell i-TE modules when harvesting 15 K. Our findings reveal an interactive thermo-diffusion/galvanic coupling effect based on coordination chemistry, offering a potential design principle for high-performance i-TE materials.