Housed in a stylish rectangular silver pouch, the “Separion” consists of two lithium electrodes in an electrolyte, or liquid conductor. What differentiates it from similar batteries is that the electrodes are separated by a flexible ceramic membrane that provides greater thermal stability, according to the German group. A drawback of lithium-ion batteries is a risk of explosion if they overheat. According to Felix von Borck, director of the Akasol research center in western Darmstadt, the Separion goes a long way towards resolving that problem.