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Introduction

Towards the Battery of the Future

Battery technology may be the keystone of the energy transition, facilitating the decarbonization of the transportation sector while providing a critical backstop for intermittent solar and wind power generation. Both the energy and automobile industries are currently involved in extensive battery research. The trend for electromobility adds extra weight to the subject. Research labs, universities and manufacturers worldwide are working to drive lithium ion battery (Li-ion) technology forward. One of them is the Materials Research Institute (“Institut für Materialforschung IMFAA”) at Aalen University (Germany) where Andreas Kopp is working.



For our 2021 ZEISS Microscopy Image Contest Mr. Kopp submitted an image of fluorides on an anode surface of a Li-ion battery, taken with a ZEISS Crossbeam 550 scanning electron microscope at 7,350x magnification. His image was awarded second place.

Interview

Tell us about your research.

My research focus is the quality assessment of Li-ion batteries using imaging techniques like light microscopy and secondary electron microscopy. The quality and performance of a battery is mainly determined by the microstructure of the electrodes. We use a combination of large-scale microscopy images and machine learning algorithms to find defects and failures in Li-ion batteries. Typical defects are pores, foreign particles, deviations in the layer thickness of the electrode coating or poor electrode alignment. Some of these defects have a negative influence on the performance and lifetime. Other defects, like foreign particles, can damage the separator layer. This is a potential risk for causing internal short cuts and a thermal runaway. The analysis of microscopy images is a powerful tool for the evaluation of the quality of Li-ion batteries. The tools and workflows that we develop can be used by battery manufactures to support the development and improvement of production processes. Additionally, buyers of Li-ion batteries may use these tools for benchmark analysis and supplier selection.

Fluorides on an Anode Surface of a Li-Ion Battery

  • Second Prize Image: Fluorides on an anode surface of a Li-ion battery

    Second Prize Image: Fluorides on an anode surface of a Li-ion battery, acquired with a ZEISS Crossbeam 550 focused ion beam scanning electron microscope; Courtesy: A. Kopp, Aalen University, Germany

For this image, during sample preparation and image acquisition, the batteries must be opened. The electrolyte is washed away and the conductive salt in the electrolyte forms these cubes on the electrode surface.

Andreas Kopp | Materials Research Institute at Aalen University

What was the most challenging part of acquiring an image such as this?

The most challenging part is the sample preparation before the sample goes into the microscope. Any contaminations and damages of the samples must be avoided because they can influence further investigations. Depending on the investigation topic, different preparation techniques and analysis methods must be combined. Batteries in particular are very challenging for sample preparation because the porous microstructure is filled with a wet electrolyte that has to be removed and many materials used in Li-ion batteries are still chemically active during the preparation.

What about this image stands out to you?

In general, we seldom can see the crystal structure of the materials in nature. The growth of nearly perfect cubes is directly linked to the crystal system of the materials. The crystal system correlates to the macroscopic cubic morphology of the cubes. To observe these geometric particles is always fascinating and creates interesting images.

Get some insights into IMFAA Aalen and Mr. Kopp’s research:

#measuringhero | Episode 57: Battery Deep Dive

Jay took his e-scooter to Aalen University in order to talk to Andreas to learn more about batteries.

#measuringhero | Episode 58: Battery Deep Dive Part 2

This is the second part of the battery deep dive. Jay took his e-scooter to Aalen University and talked to Andreas to learn more about batteries.


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