Realizing a high-performance n-type thermogalvanic cell by tailoring the thermodynamic equilibrium

Abstract

Ionic thermogalvanic cells (TGCs) have attracted interest for their superior thermopower (α) compared to electronic systems. To maximize the thermopower and overall device performance, it is necessary to integrate both p- and n-type TGCs. However, while high-performance p-type TGCs have been well reported, there are few reports on n-type TGCs. Here, an innovative high-performance n-type TGC is proposed based on an anionic polymer (AP) and hydroquinone (HQ). The AP facilitates self-regulation of the pH in the polymer matrix, which controls the equilibrium between the HQ and its redox partner, benzoquinone (BQ). Moreover, the AP enables the selective transport of the target redox material, leading to the accumulation of HQ near the cold electrode and the spontaneous reaction of HQ to form BQ. The resulting n-type TGC exhibits a superior α of 4.29 mV K⁻¹ compared to previously-reported n-type quasi-solid systems. Moreover, a high Carnot-relative efficiency (1.05%) was achieved in n-type TGCs.