Analytics for battery technology

Battery storage systems play a decisive role in the transformation towards the utilization of renewable energies. Next-generation battery systems must achieve a higher storage capacity, a longer service life, a lower environmental impact and a high level of safety. In addition to the development of battery materials and battery cells, the Fraunhofer IST offers comprehensive possibilities for the characterization of these materials and cells, thereby enabling an in-depth understanding of the materials and properties of batteries. 

Sample preparation under exclusion of air

Many battery materials degrade upon contact with air, which restricts the application of analytical methods under atmospheric conditions. At the Fraunhofer IST, a transfer shuttle is available which makes it possible to prepare battery samples in a glovebox and then transfer them to a scanning electron microscope (SEM) under inert gas. This enables high-resolution imaging as well as chemical analyses of the uninfluenced materials. In cases where the utilization of a shuttle is, however, not possible, customized concepts are developed at the Fraunhofer IST in order to ensure measurement quality while simultaneously preventing contact with the air.

Material analytics for novel solid-state electrolytes

Solid-state electrolytes have the potential to replace liquid electrolytes and to thereby enable improved properties. Solid electrolytes facilitate the application of lithium metal anodes, for example, and can therefore significantly increase the energy density, amongst other things. Material analytics enables the targeted optimization of properties and is therefore essential for development. In particular, sulfide solid-state electrolytes can be analyzed in terms of their phase purity by means of Raman spectroscopy, for example. The particle morphologies and the electrodes produced on the basis of these solid-state electrolytes can be examined with the aid of an SEM. Furthermore, energy dispersive X-ray spectroscopy (EDX) enables precise analysis of the elemental compositions, whilst X-ray diffraction (XRD) can be applied to determine the crystallinity. Through the combination of these methods, a comprehensive material analysis is achieved that provides valuable insights into the properties and behavior of novel solid-state electrolytes.

Electrochemical characterization

Whilst the analysis of the individual materials provides valuable information regarding their suitability for utilization in batteries, the actual functionality can only be assessed in practical application. By means of electrochemical characterization, the behavior of the battery during the charging and discharging process can be comprehensively characterized. Cyclization experiments are performed in order to evaluate not only the service life but also the charging and discharging properties of the battery cells. A detailed insight into the electrochemical processes can be gained through electrochemical impedance spectroscopy. This method allows the individual transport processes within the battery to be analyzed in detail and their influence on the overall performance to be understood.

Post-mortem analysis - Troubleshooting in the event of battery failure

In the case of defective batteries, identification of the cause of the failure is often of interest. Firstly, the electrochemical data recorded shortly before the defect can provide valuable information. Secondly, the opening of the cells and the subsequent analysis enables insightful information to be acquired regarding the cause of the fault. Furthermore, microscopic imaging methods in combination with elemental analysis can provide detailed information concerning interfaces and material alterations. This information can be validated using further analytical methods in order to gain a comprehensive understanding of the damage mechanisms and to prevent problems in the future.