Modern small medical devices, such as hearing aids or cardiac pacemakers, have to be as light and compact as possible. For this reason, they are operated with small batteries, mainly button cells. In medical applications, these batteries have to have maximum storage capacity, frequent exchange is to be avoided. Often, fluorinated graphite is used as cathode material for batteries that cannot be recharged (primary batteries). Thanks to its nature, the mixture can store a large fraction of energy per mass or volume. The drawback: It is a strong non-conductor and very slow when discharged. To reach sufficient conductivity, the material therefore has to be enriched with a larger amount of carbon that does not contribute to energy storage.Scientists of the KIT Institute of Nanotechnology (INT) have now developed a new and simple process for the treatment of graphite fluoride for primary batteries: Pre-treatment of the material by high-energy ball milling. Thanks to crushing and compaction in the mill, bulk density of graphite fluoride is increased by a factor of three. Storage capacity, hence, is improved considerably. The battery possesses a much longer service life and can be discharged more rapidly. As the researchers additionally succeeded in reducing the conductive carbon fraction and the battery supplies an increased discharge voltage, energy density is enhanced.The advantage for the user is that battery exchange intervals are longer. Much longer service lives result at a similar price, costs and expenditure are saved. Medical applications become less complicated and more reliable.KIT looks for partners interested in applying this technology in practice.