Milestones in battery research
For about 5 years Fraunhofer IWS researchers have been working on the development of suitable electrode materials and manufacturing processes to produce high energy density battery cells based on lithium-sulfur technology in a cost effective manner. At the “Future Energy” conference in November 2015 researchers presented for the first time lithium-sulfur pouch cells with specific energy densities exceeding 300 Wh kg-1, which is an approximately 25 percent increase over classic lithium-ion technologies. With regard to an increasing demand for low-cost stationary energy storage, IWS researchers are also working on room temperature sodium-sulfur battery cells. Anode and cathode electrolytes were adapted so that such battery cells can now be operated at room temperature instead of 300 °C. These cells have discharge capacities of up to 980 mAh per gram of active cathode material. The charging efficiency exceeds 95 percent and the cells can be reversibly discharged and recharged more than 1000 times. An EU project (ALISE) started in June 2015 so that IWS can continue with these developments. A BMBF project (DryLIZ) was finished in 2015. Here the researchers showed ways to lower fabrication costs and to reduce processing times for cutting electrodes.