Thermogalvanic Hydrogel Cools Electronics While Turning Excess Heat Into Electricity

Researchers from Wuhan University and the University of California Los Angeles have detailed a technique to cool electronics and turn their waste heat into additional power, using a thermogalvanic hydrogel film.

"Efficient heat removal and recovery are two conflicting processes that are difficult to achieve simultaneously," the team writes in the abstract of the paper. "Here, in this work, we pave a new way to achieve this through the use of a smart thermogalvanic hydrogel film, in which the ions and water undergo two separate thermodynamic cycles: thermogalvanic reaction and water-to-vapour phase transition.

"When the hydrogel is attached to a heat source, it can achieve efficient evaporative cooling while simultaneously converting a portion of the waste heat into electricity. Moreover, the hydrogel can absorb water from the surrounding air to regenerate its water content later on. This reversibility can be finely designed."

To prove the concept, the researchers applied their hydrogel film to the battery of a smartphone. Despite adding just 2mm to the thickness of the device, the gel performed well enough to reduce the operating temperature of the battery by 20°C while recovering 5μW of waste energy in the process. While water inside the hydrogel evaporated during the process, it recovered again afterwards by absorbing water from the surrounding air.

The team's work has been published under closed-access terms in the journal Nano Letters; thus far, no word on commercialization has been given.