Issue 12, 2024

Ultra-high performance of ionic thermoelectric-electrochemical gel cells for harvesting low grade heat

Abstract

Gel-based ionic thermoelectric (i-TE) conversion systems have attracted more attention to harvest energy from ambient waste heat to power sensors in IoT systems, due to their high ionic thermopower, cost-effectiveness, and environmental friendliness. However, their thermoelectric performance, particularly output power density, remains low, hindering their further application. To date, there is still a lack of an effective strategy to reverse this serious situation. Herein, we originally designed an ionic thermoelectric-electrochemical (i-TE-EC) cell by combining two asymmetric gels into a double sandwich structure, resulting in high thermoelectric performance. By tailoring gel compositions, including the concentration and ratio of redox couples as well as additive contents, a maximum output power density Pmax/(ΔT)2 of 10.0 mW m−2 K−2, a cell ionic thermopower of 5.2 mV K−1, and an energy density of 3.4 J m−2 K−2 in two hours were obtained at 313 K for the i-TE-EC cell Gp | G-m/n FeCN4−/3− | Gp | G-x/y I/I3-z CF3SO3K | Gp (m/n = 0.175/0.025 M, x/y = 0.10/0.05 M, z = 0.4 M). Moreover, Pmax/(ΔT)2 increased to a higher value of 20.5 mW m−2 K−2 for the i-TE-EC cell using a CEM as a built-in electrode. A gel-device assembled by nine single i-TE-EC cells connected in series generated a voltage of 1.55 V and a high Pmax/(ΔT)2 of 5.2 mW m−2 K−2 at 313 K and ΔT = 5 K. This work provides a promising route for improving the gel-based thermoelectric performance, available for other energy conversion systems.

Graphical abstract: Ultra-high performance of ionic thermoelectric-electrochemical gel cells for harvesting low grade heat

Supplementary files

Article information

Article type
Paper
Submitted
13 Mar 2024
Accepted
07 May 2024
First published
08 May 2024

Energy Environ. Sci., 2024,17, 4104-4114

Ultra-high performance of ionic thermoelectric-electrochemical gel cells for harvesting low grade heat

Y. Zhu, C. Han, J. Chen, L. Yang, Y. Ma, H. Guan, D. Han and L. Niu, Energy Environ. Sci., 2024, 17, 4104 DOI: 10.1039/D4EE01150C

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