Engineers at the University of British Columbia have developed a flexible waterproof battery that is durable enough to go through multiple wash cycles. The battery is so pliable that it can still function when stretched to double its original length. It’s made from inexpensive materials, so it may be great for wearable health monitoring technology like clothing, patches, or watches that monitor vital signs.
Providing a source of power for wearable technology is a mystery, as most batteries are fragile, inflexible, and certainly don’t get along well with liquids like body sweat or washing machine water. These problems led the UBC researchers to develop a new type of battery specifically designed for wearables.
“Wearable electronics is a big market and expandable batteries are essential to their development,” says Ngoc Tan Nguyen, one of the leading designers of the new battery. “Up to now, however, expandable batteries were not washable. This is an indispensable addition to withstand the demands of daily use. ”
Typically batteries are made of rigid materials, but to achieve some flexibility, the research team ground the main components manganese dioxide and zinc into small fragments, which they then embedded in a flexible polymer to form ultra-thin plates. These sheets were then gathered together and embedded in the same rubbery polymer to form a waterproof coating.
The researchers chose zinc and manganese dioxide because the battery should be worn close to the skin and be as safe as possible in the event of a leak. “We chose zinc-manganese because it is a safer chemistry than lithium-ion batteries in devices that are worn next to the skin, which can produce toxic compounds when broken,” said Nguyen.
The end result is incredibly robust and can withstand multiple wash cycles without any 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 an actual wash cycle in household and commercial washing machines. They were intact and functional, and that’s why we know this battery is really tough, “said Bahar Iranpour, another researcher who was involved in the study.
Studies in Advanced Energy Materials: Washable and stretchable rechargeable Zn-MnO2 cell
