Completely stretchy lithium-ion battery for flexible electronics

When you think of a battery, you probably don't think stretchy. But batteries will need this shape-shifting quality to be incorporated into flexible electronics, which are gaining traction for wearable health monitors. Now, researchers report a lithium-ion battery with entirely stretchable components, including an electrolyte layer that can expand by 5000%, and it retains its charge storage capacity after nearly 70 charge/discharge cycles.