Application of lamellar nickel hydroxide membrane as a tunable platform for ionic thermoelectric studies?

Materials Horizons Pub Date: 2023-05-10 DOI: 10.1039/D3MH00479A

Abstract

The recent trend in thermoelectric literature suggests that ionic thermoelectric (i-TE) materials are ideal for directly converting low-grade waste heat into electricity. Here, we developed a unique platform for i-TE studies by stacking two-dimensional sheets of β-Ni(OH)2 prepared by a bottom-up method. The lamellar membrane of β-Ni(OH)2 (Ni–M) itself does not display significant thermovoltages, but when doped with mobile anion-generating species (like aminopropyl functionalized magnesium phyllosilicate or organic halide salts), it exhibits significant negative Seebeck coefficient (up to ?13.7 ± 0.2 mV K?1). Similarly, upon doping with cation-generating species like poly(4-styrene sulfonic acid) (PSS), it displays positive Seebeck coefficient values (up to +12 ± 1.9 mV K?1). The positive and negative i-TE materials prepared by doping Ni–M are assembled into ionic thermopiles capable of generating thermovoltages up to 1 V, at ΔT = 12 K. The Ni–M-based nanofluidic systems demonstrated an additional path of electricity harvesting by connecting colder zones of the positive and negative i-TE materials with other ion conducting membranes. In contrast to organic polymer-based i-TE systems, the Ni–M based system exhibited consistent performance despite being exposed to high temperatures (～200 °C, 5 minutes).

Graphical abstract: Application of lamellar nickel hydroxide membrane as a tunable platform for ionic thermoelectric studies
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