Thermo-osmotic ionogel enabled high-efficiency harvesting of low-grade heat

Low efficiency in recovering low-grade heat remains unresolved despite decades of attempts. In this research, we designed and fabricated a novel thermo-osmotic ionogel (TOI) composite to recover low-grade heat to generate electric power through a thermo-induced ion gradient and selective ion diffusion. The TOI composite was assembled with a crystalline ionogel (polymer-confined LiNO3-3H(2)O) film, ion selective membrane, and hydrogel film. With a 90 degrees C heat supply, the single TOI composite produced a high open-circuit voltage of 0.52 V, a differential thermal voltage of similar to 26 mV K-1, a peak power density of 0.4 W m(-2), and a ground-breaking peak energy conversion efficiency of 11.17%. Eight pieces of such a TOI composite were connected in series, demonstrating an open-circuit voltage of 3.25 volts. Such a TOI system was also demonstrated to harvest body temperature for powering a LED, opening numerous opportunities in powering wearable devices.

Automated summary

A novel thermo-osmotic ionogel composite was designed and fabricated to recover low-grade heat and generate electric power. The composite demonstrated high open-circuit voltage, power density, and energy conversion efficiency under heat supply, with the potential for series connection to increase output voltage. Furthermore, the system was able to harvest body temperature for powering a LED, opening up possibilities for wearable devices.