Engineers at the University of British Columbia created a flexible waterproof battery that is durable enough to withstand several wash cycles. The battery is so flexible that it can still work when stretched to double its original length. It is made of low-cost materials, which makes it potentially very suitable for portable health control technology, such as clothing, patches, or watches that control vital signs.
Providing a power source for portable technology is a bit of an enigma, as most batteries are delicate, inflexible, and certainly do not work well with fluids such as body sweat or washing machine water. These problems prompted UBC researchers to develop a new type of battery, which is specifically designed to include wearables.
“Portable electronics is a big market and expandable batteries are essential for its development,” says Ngoc Tan Nguyen, one of the leading designers of the new battery. “However, so far, the extendable batteries have not been able to be washed. This is an essential addition if they want to withstand the demands of everyday use.”
Batteries typically consist of rigid materials, but to introduce some flexibility, the research team crushed the primary components of manganese dioxide and zinc into small fragments, which they then embedded in a flexible polymer to form ultra-thin sheets. These sheets were then assembled and embedded in the same rubber polymer, to form a waterproof coating.
The researchers chose zinc and manganese dioxide because the battery is designed to carry it close to the skin and they wanted it to be as safe as possible in the event of a leak. “We opted for zinc-manganese because for devices that are worn on the skin, it is a safer chemical than lithium-ion batteries, which can produce toxic compounds when broken,” Nguyen said.
The end result is incredibly robust and can withstand multiple wash cycles without loss of performance. So far, UBC researchers have subjected a battery to 39 wash cycles and it was still working. “We put our prototypes through a real laundry cycle in both domestic and commercial washing machines. They came out intact and functional and that’s how we know this battery is really durable,” said Bahar Iranpour, another researcher involved in the study.
Study a Advanced energy materials: Washable and stretchable Zn – MnO2 rechargeable cell