Austria-based battery research firm Varta Micro Innovation (Varta) has researched anode materials for lithium-ion batteries using a customised rolling-ball viscometer.
Varta researched the qualification and optimisation of new electrolytes such as silicon and discovered that the mobility of lithium-ions is greatly dependent on the viscosity of the electrolyte and that viscosity should be a key focus in technology research.
According to the Graz-headquartered company, the main reason why the viscosity was not previously the focus of research is due to the fact that there were no suitable measuring instruments available and analyses were very time-consuming and costly.
The viscometer that Varta used was jointly developed by Austrian testing equipment company Anton Paar and enables to qualify electrolytes while being resistant to chemicals, such as lithium hexaflurophosphate and hydrofluoric acid.
“Very aggressive chemicals are brought into the electrolytes via the conducting salt. Hardly any sample vials are inert enough to withstand corrosion from hydrofluoric acid. The low temperature is also a topic, which has gained importance in recent years, especially in the automobile industry. We must be able to determine the viscosity at -20 °C and at best at even lower temperatures,” said Stefan Koller, CEO of Varta.
Koller also emphasized the better storage capacity of silicon in comparison of graphite. “As silicon has a storage capacity for lithium-ions, which is around ten times higher than that of commercially used graphite, the new material can store more than double the amount of lithium ions and still have the same battery lifetime,” said Koller.
Varta Micro Innovation GmbH is a joint venture between Varta Microbattery and the Graz University of Technology.