Phase transition driven tough hydrogel ionic thermoelectric cell with giant thermopower.

Shi, Xiaofang; Li, Yingjie; Shi, Nan; Ji, Chengyu; Hou, Lei; Shi, Yingkun; Xu, Jianyao; Lan, Yarong et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

The application of quasi-solid ionic thermoelectric (i-TE) cells holds great potential for powering ubiquitous wearable electronics without the need for cables or batteries. However, their practical application is restricted by low thermopower. Herein, a temperature-responsive supramolecular hydrogel, P(N-acryloylsemicarbazide-co-acrylic acid) (PNA), has been developed as a i-TE cell that integrates good mechanical and electrochemical properties. The volume phase transition (VPT) of PNA i-TE cell can generate a substantial ion entropy difference, thereby enhancing both the redox reaction efficiency and ionic thermodiffusion rate. A single PNA i-TE cell can generate a thermopower of 2.04 volts with a temperature difference of 50 K. The Seebeck coefficient (S<sub>e</sub>), specific output power density ( <math xmlns="http://www.w3.org/1998/Math/MathML"> <msub><mrow><mi>P</mi></mrow> <mrow><mi>max</mi></mrow> </msub> <mo>/</mo> <msup> <mrow><mrow><mo>(</mo> <mrow><mi>Δ</mi> <mi>T</mi></mrow> <mo>)</mo></mrow> </mrow> <mrow><mn>2</mn></mrow> </msup> </math> ) and figure of merit (ZT) of PNA i-TE cell can reach up to 40.9 mV K<sup>-1</sup>, 35.2 mW m<sup>-2</sup> K<sup>-2</sup> and 1.33 respectively. This ionic hydrogel is promising for the design of high performance polymer based i-TE cells in an environmentally friendly and cost-effective manner.