Japan’s TDK is claiming a breakthrough in materials used in its small solid-state batteries, with the Apple supplier predicting significant performance increases for devices from wireless headphones to smartwatches. The new material provides an energy density—the amount that can be squeezed into a given space—of 1,000 watt-hours per liter, which is about 100 times greater than TDK’s current battery in mass production. The group plans to start shipping samples of its new battery prototype to clients from next year.