In-situ recomposition of polyethyleneimine additive enables a multiprocess long-lifetime thermocell.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41794850.
- Also identified by DOI 10.1038/s41467-026-70392-5 and PMC identifier 13096117.
- Licence recorded as CC BY-NC-ND.
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Abstract
Ionic thermocells offer a compelling route for converting low-grade heat into electricity, yet their real-world deployment is hindered by performance decay under fluctuating conditions and limited synergistic pathways. Herein, we introduce polyethyleneimine as a self-limiting sacrificial additive in a K<sub>3</sub>Fe(CN)<sub>6</sub>/K<sub>4</sub>Fe(CN)<sub>6</sub> thermocell. During initial operation, only a fraction of amine groups in polyethyleneimine engages in redox with Fe(CN)<sub>6</sub><sup>3-</sup>/Fe(CN)<sub>6</sub><sup>4-</sup>, while the remaining amine groups mediate thermally induced adsorption-desorption, selective condensation, and homogeneous catalysis. These cascaded effects boost the thermopower from 1.4 mV K<sup>-1</sup> to 7.76 mV K<sup>-1</sup>. Crucially, the self-limiting nature and temperature-dependent reactivity of polyethyleneimine-Fe(CN)<sub>6</sub><sup>3-</sup> reaction not only generates solvation-perturbing species but also ensures long-term functional stability (>1000 hours). A proof-of-concept panel delivers over 5 V and 7.5 mW under a 50 K temperature difference, demonstrating system scalability. This work highlights the potential of sacrificial additive engineering to enable durable and high-performance thermocells for sustainable heat-to-electricity conversion.