Korean battery maker LG Chem is developing "cable batteries" that could be integrated into headphones to help power your cell phone, or woven into jewelry or textiles to recharge wearable electronics (see "Stretchable Silicon Could Make Sports Apparel Smarter").
The lithium-ion batteries keep working even when tied into knots and otherwise abused. The novel design doesn't put out very much power, but researchers at the company are developing more-efficient formulations, and they say the lithium-ion cable batteries could be ready for mass production in about five years.
Flexible batteries have been made before, but normally in the form of sheets, which limits what designers can make from them, and they usually can't store very much energy, says Je Young Kim, general manager of battery R&D at LG Chem.
Kim's team found a way around these limitations with a spring-like, spiral electrode design that incorporates the inorganic materials used in conventional lithium-ion batteries. "This structure allows the device to compensate for any external mechanical distortion while maintaining its structural integrity, and it enables the battery to be more flexible in three dimensions," he says. LG Chem's cable battery prototype is described online this month in the journal Advanced Materials.