Electronics appears everywhere: in our laps, in pockets and purses and, increasingly, curled up against our skin or sewn into our clothes.
But the adoption of portable electronic devices has so far been limited by its need to obtain energy from bulky and rigid batteries that reduce comfort and may present safety risks due to chemical leakage or combustion.
Now Stanford researchers have developed a soft and elastic battery that relies on a special type of plastic to store energy more safely than the flammable formulations used in today’s conventional batteries.
“So far we have not had a source of energy that can stretch and bend the way our bodies do it, so that we can design electronic devices that people can use comfortably,” said chemical engineer Zhenan Bao, who partnered with the Materials scientist Yi Cui to develop the device described in the November 26 issue of Nature Communications.
The use of plastics or polymers in batteries is not new. For some time, lithium-ion batteries have used polymers as electrolytes, the source of energy that carries negative ions to the positive pole of the battery. Until now, however, those polymer electrolytes have been fluid gels that could, in some cases, leak or burst into flame.
To avoid such risks, Stanford researchers developed a polymer that is solid and elastic rather than sticky and potentially permeable, and still carries an electrical charge between the battery’s poles. In laboratory tests, the experimental battery maintained a constant output power even when it was squeezed, bent and stretched to almost twice its original length.
The prototype has a miniature size and stores approximately half the energy, ounce per ounce, than a conventional battery of comparable size. Graduate student David Mackanic said the team is working to increase the energy density of the stretchable battery, build larger versions of the device and conduct future experiments to demonstrate its performance outside the laboratory. A potential application for such a device would be to feed stretchable sensors designed to adhere to the skin to control heart rate and other vital signs as part of the BodyNet portable technology that is being developed in the Bao laboratory.
David G. Mackanic et al., Decoupling of mechanical properties and ionic conductivity in supramolecular lithium ion conductors, Nature Communications (2019) DOI: 10.1038 / s41467-019-13362-4
A new stretchable battery can power portable electronic devices (2020, January 24)
Retrieved on January 24, 2020
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