Ionic Thermoelectric Properties of Reconstructed Lamellar Vanadium Pentoxide Membranes

Abstract In recent years, the application of ionic thermoelectric (TE) materials to convert low‐grade waste heat into electricity has become a subject of intense scientific research. However, most of the efforts are focused on organic polyelectrolytes or ionic‐liquids embedded in polymeric gels. Here, for the first time, it is demonstrated that nanofluidic membranes of reconstructed layered materials like vanadium pentoxide (V 2 O 5 ) exhibit excellent ionic‐TE characteristics. The high Seebeck coefficient (S = 14.5 ± 0.5 mV K ‐1 ) of the V 2 O 5 membrane (VO‐M) is attributed to temperature gradient‐induced unidirectional transport of protons through the percolated network of 2D nanofluidic channels. The TE characteristics of VO‐M show nearly 80% improvement (S = 26.3 ± 0.7 mV K ‐1 ) upon functionalizing its percolated network with ionic polymers like poly(4‐styrenesulfonic acid) (PSS). Further, unlike organic polymer‐based TE systems, VO‐M not only sustains exposure to high temperatures (≈200 °C, 5 min) but also protects the PSS molecules intercalated into its interlayer space. Moreover, V 2 O 5 ‐based TE materials can self‐repair any damage to their physical structure with the help of a tiny water droplet. Thus, nanofluidic membranes of reconstructed layered materials like VO‐Ms demonstrate vast robustness and great ionic‐TE performance, which can provide a novel platform for scientific studies and futuristic applications.