New Analysis Method for Battery Cell Aging Mechanisms Developed
Silicon is considered the most promising anode material for next-generation batteries. Understanding the degradation mechanisms of negative electrodes based on nanoparticles like silicon is key for paving the way to application. A team of MEET Battery Research Center at the University of Münster developed a new analysis method that provides detailed insights into the aging of electrodes during battery operation. With the new method degradation mechanisms such as active material cracking, pulverization, or extensive growth of the solid electrolyte interphase (SEI) can be analysed and solutions can be developed.
New Method Overcomes Previous Analysis Challenges
Imaging techniques such as scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) are common ex situ methods for post mortem analysis of battery materials. Beyond that, in situ/operando methods provide more accurate insights. The challenges here so far: With ex situ SEM measurements, small structural changes in the particles cannot be observed and images of different spots from different electrodes are often hardly comparable. On the other hand, in situ SEM requires a complex analysis setup and works only with a limited selection of electrolytes that does not reflect the cell conditions in a commercial application. The team led by MEET researcher Iris Dienwiebel has now succeeded in overcoming these challenges: “For the first time, we have combined aspects of in situ and ex situ SEM/EDX measurements and developed a new method (quasi in situ) that provides very detailed insights into the aging of electrodes in a conventional cell setup with a carbonate-based electrolyte,” explains the MEET PhD student. “We could show that for silicon nanoparticle-based composite electrodes irreversible volume expansion is dominant especially at low C rates, whereas pulverization is dominant when cycling at higher C rates. Furthermore, we showed that the choice of conductive additive plays a crucial role on the homogeneity of the SEI.”
Dienwiebel and her co-authors Prof. Dr Martin Winter, MEET Battery Research Center at the University of Münster and Helmholtz Institute Münster of Forschungszentrum Jülich, and Dr Markus Börner, MEET Battery Research Center, published the complete study in “The Journal of Physical Chemistry C”.
MEET Poster on Study Received “Highly Commended Poster Certificate” at International Conference
The current research results were also recognized at the 21st International Meeting on Lithium Batteries (IMLB) in Sydney, Australia: MEET researcher Iris Dienwiebel received the “Highly Commended Poster Certificate” for her presentation from a total of 500 posters.