An advance in making flexible, stretchable batteries may help push these compliant energy storage devices closer to production. Researchers are making rapid progress with flexible electronics for wearable applications and body implants, but progress developing the required power sources lags behind. Numerous research teams have demonstrated approaches to making flexible batteries, for example, ones based on stretchable or coiled interconnects and various wire-battery designs. But those devices have not proved durable enough to withstand thousands of simultaneous multidirectional flexing motions, as needed to commercialize products with long lifetimes. So Ana Claudia Arias of the University of California, Berkeley, and coworkers designed batteries in which current collectors with helical springs or serpentine shapes support all battery components, which are deposited sequentially onto the support (Sci. Adv. 2017, DOI: 10.1126/sciadv.1602051). During testing, the helical batteries withstood more than 17,000 small-radius flexing and bending cycles with no loss in electrochemical performance. And serpentine batteries also continued to function properly after repeated multidirectional flexing and stretching motions. The team stresses that their durable stretchy batteries, which are based on silver-zinc chemistry, are inherently safe and nonflammable, unlike lithium-ion batteries.