May 2018

Eight thousand two hundred and fifty – about this number of cylindrical 18650 lithium-ion cells are required to produce a 100 kWh battery module. With good batteries, a fully charged 100 kWh battery module can power the car over a distance of more than 500 km. In the event of an accident or faulty cells, it is possible that the battery overheats due to an internal short circuit and ignites the liquid electrolyte contained inside the cells. The 18650 cells contain about 10 wt.% of liquid electrolyte. At a weight of about 48 g per cell, the 100 kWh battery module contains in total about 40 kg of flammable liquid electrolyte. This corresponds approximately to the amount of gasoline in a full fuel tank of a car with internal combustion engine, thus posing a safety risk in case of an accident.In solid-state batteries, a solid electrolyte is used as ion conductor instead of the liquid electrolyte. Thus, the entire cell is built up of solids, which significantly reduces the risk of self-ignition of the battery. In addition, solid electrolytes offer a research approach to allow use of lithium metal as anode material, so that energy density of the cells can be increased. Due to lithium dendrite growth and the resulting short circuit of the lithium-ion battery, lithium metal cannot be used as the anode material in combination with a liquid electrolyte. In the project FELZIA (Festelektrolyte als Enabler für Lithium-Zellen in Automobilen Anwendungen), funded by the Bundesministerium für Bildung und Forschung, we explore solid-state batteries with lithium metal in cooperation with partners from industry and other academic research institutions. The goal is to develop solid-state batteries with high energy and power density. (Picture submitted by Felix Richter)