The ability to store energy is one of the basic requirements for technical progress. The popularity of electric vehicles, for example, increases with increasing range and performance and decreasing charging time. At the same time, it is desired that the respective storage batteries are lightweight, low-priced and long-lived and can be charged and discharged many thousand times. Today, electric energy is often stored in lithium-ion storage batteries. When charging and discharging such batteries, the lithium ions move between negative (anode) and positive electrode (cathode). The latter often consists of crystalline lithium metal oxides e.g., of low-priced, long-lived spinel. For use in electric vehicles, it is however, of advantage to further increase the energy density i.e., the energy storage capacity per unit weight.
Researchers at KIT's Institute for Applied Materials (IAM) have succeeded in developing a cathode material with a higher energy density compared to conventional materials. The base material consists of a so-called high-voltage spinel which, in addition to lithium, manganese, and oxygen, contains nickel. Doping of such spinel with titanium, iron, and fluorine effects an additional increase in energy density. The novel cathode material allows discharge down to voltage values lower than those of conventional storage batteries. High-voltage spinel has a higher cycle stability as compared to undoped spinel and thus can be charged and discharged more often before the capacity of the storage battery is getting weaker. In terms of an electric vehicle, this deep-discharge ability would correspond to an electric reserve tank which, if necessary, could be tapped to increase the range of the car. Another advantage of doping is the cathode material's improved stability at high temperatures.
The KIT is looking for partners interested in enhancing and applying the technology described.