High-performance n-type flexible inorganic thermoelectric aerogel for energy harvesting.

Abstract

Despite their promise as lightweight, ultralow-thermal-conductivity thermoelectric (TE) materials, aerogels have been largely limited to p-type organic or carbon-based systems with modest <i>zT</i> < 0.1 at 300 kelvin. Here, we propose a stepwise synthesis strategy that yields the first inorganic aerogel exhibiting state-of-the-art n-type TE performance. Optimized aerogels with 95% porosity exhibit a high power factor of 34.8 microwatts per meter per square kelvin and an ultralow thermal conductivity of 0.061 microwatts per meter per kelvin, resulting in <i>zT</i> values of 0.17 at 300 kelvin and 0.24 at 383 kelvin. A vertical TE generator prototype with six TE-aerogel legs achieves a gravimetric output power of 76 microwatts per gram under a Δ<i>T</i> of ~60 kelvin. To address brittleness, a polyimide-encapsulated aerogel with bioinspired architecture was developed, achieving a high compressive strength to 1.4 kilopascals while maintaining excellent TE performance. This work establishes a generalizable method for designing high-performance flexible inorganic aerogels, opening more possibilities for lightweight wearable energy harvesting technologies.