A flexible battery made from hydrogel can withstand being run over by a car, blows from a hammer and temperatures as low as 鈭�77掳C (-106.6掳F). It could potentially be used in phones or wearable electronics.
Most commercial batteries are solid and based on lithium, but these can be easily damaged in accidents and cope badly at very cold temperatures.
Now, at the University of California, Los Angeles, and her colleagues have developed a hydrogel that can act as the conductive electrolyte inside a battery. In the hydrogel, long molecules are linked together in a network that can hold water and is flexible and resistant to freezing.
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鈥淚t could be very attractive for personal devices or flexible electronics because of this high flexibility while being highly robust,鈥� says He. 鈥淎t the same time, it can work at pretty low temperatures, so our phones, for example, wouldn鈥檛 die in cold weather.鈥�
To create the electrolyte hydrogel, the team mixed together two liquid polymers made from the plastic polyvinyl alcohol, and slowly added zinc and potassium ions to form salt crystals to make the hydrogel conductive.
The team then sandwiched the hydrogel between a zinc anode and conductive polymer cathode to make a thin battery that might be suitable for wearable electronics. In this form, it could survive eight hammer blows or being run over with a car weighing more than 1700 kilograms, and suffered no drop in performance at -20掳C (-4掳F). The battery also continued to function after being cooled to 鈭�77掳C and warmed up again.
The performance of the entire battery isn鈥檛 as good as that of some lithium batteries, because the work focused on making the electrolyte, but future battery designs could improve performance, says He.
鈥淭his could be an interesting route to further stabilise other electrolytes for other alternative aqueous batteries,鈥� says at the University of Birmingham, UK. However, the materials used in the batteries are expensive compared with commercial ones, which could be a barrier to it being adopted, she says.
Advanced Materials
