Aqueous thermogalvanic cells with a high Seebeck coefficient for low-grade heat harvest.

ABSTRACT: Thermogalvanic cells offer a cheap, flexible and scalable route for directly converting heat into electricity. However, achieving a high output voltage and power performance simultaneously from low-grade thermal energy remains challenging. Here, we introduce strong chaotropic cations (guanidinium) and highly soluble amide derivatives (urea) into aqueous ferri/ferrocyanide ([Fe(CN)6]4-/[Fe(CN)6]3-) electrolytes to significantly boost their thermopowers. The corresponding Seebeck coefficient and temperature-insensitive power density simultaneously increase from 1.4 to 4.2?mV?K-1 and from 0.4 to 1.1?mW?K-2 m-2, respectively. The results reveal that guanidinium and urea synergistically enlarge the entropy difference of the redox couple and significantly increase the Seebeck effect. As a demonstration, we design a prototype module that generates a high open-circuit voltage of 3.4?V at a small temperature difference of 18?K. This thermogalvanic cell system, which features high Seebeck coefficient and low cost, holds promise for the efficient harvest of low-grade thermal energy.

SUBMITTER: Duan J 

PROVIDER: S-EPMC6279834 | biostudies-other | 2018 Dec

REPOSITORIES: biostudies-other