How Collaboration Aids in Sustainable Battery Manufacturing

insights from industryClemens LischkaResearch AssistantKarlsruhe Institute of Technology (KIT)

Battery costs continue to be a barrier to the widespread adoption of electric vehicles. Dry battery manufacturing techniques can help solve this issue by enabling more sustainable, lower-cost cell manufacture. Clemens Lischka highlights the use of continuous twin-screw extruders for dry processing and the collaborative investigations that are helping KIT reach its full potential.

Could you provide a brief introduction to your research institute and group?

KIT is one of Germany’s 11 Universities of Excellence, with specialized knowledge and extensive research in energy, mobility, and information. I am a research assistant in a 35-person group led by Professor Hermann Nirschl.

A part of this group is involved in the analysis and optimization of Li-ion battery manufacturing processes as part of ProZell, an inter-university competency cluster seeking to build world-leading battery cell production technology.

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Can you explain how your research aligns with market needs for better battery technology?

Reducing battery production costs is critical to the broad adoption of electromobility. Currently, batteries account for a large amount of an electric vehicle’s cost—between 30 and 40 percent.

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Both academic and industrial groups, particularly global big vehicle manufacturers, are working hard to reduce unit costs. At the same time, it is vital to maintain or improve cell performance.

We are aiming to unleash the full potential of dry manufacturing, which has the potential to revolutionize industrial practices. Conventional wet manufacturing procedures involve covering current collectors with a low-viscosity electrode slurry and then removing the solvent.

The drying operations are energy-intensive and time-consuming, and they might cause defects in the coated electrode. The solvents’ health and environmental repercussions exacerbate the problem.

Dry processing, by eliminating the need for solvents, has the potential to alter manufacturing economics by lowering both investment and operational costs while also enhancing sustainability and safety, resulting in a win-win situation.

What are the major challenges of dry processing?

Battery manufacturers understand how to use classic, wet production processes; they scale well and produce good cell performance. There is obvious space for improvement in both consistency and performance, but both may be kept within acceptable limits. These are the standards against which dry processing choices are evaluated.

The objective is to discover how to create processable mixes with scalable technologies that can result in a homogeneous electrode coating. At the particle level, this involves managing the distribution, packing, and contact between various electrode materials.

Creating the desired homogeneity is a significant issue, as uniformity of coating thickness and material dispersion is currently well below that obtainable with wet techniques. This is mostly owing to the suboptimal flowability of dry powder combinations, which results in uneven deposition and limited repeatability.

What is the specific focus of your research?

I concentrate on the initial mixing operations that bring the active components into close contact during the early phases of manufacturing. My job entails characterizing and modeling these processes to improve their performance and cost-effectiveness.

We are particularly interested in how the force exerted during mixing affects the comminution of the electrode’s carbon black component and, hence, influences its form. Particle morphology impacts processability, packing behavior, and, as a result, finished cell performance, so knowing it is critical.

What types of mixers look most promising for dry processing?

The industry has traditionally used batch mixers for slurry blending, but continuous mixer types such as extruders are gaining favor since they can assist optimize stand and setup times.

We focused our research on continuous twin-screw extruders because we feel this technology is particularly promising for developing a scalable and cost-effective process.

At the same time, we are monitoring alternative batch technologies, which are currently considered the industrial state of the art. It is too early to say which mixer type will ultimately be selected, but history suggests that continuous production will win out due to manufacturing scale.

What tools are you using for your research?

We work extensively with simulation models. A good simulation model allows you to swiftly and efficiently navigate many processing situations, yet it does not require any resources.

We utilize these models to examine performance factors such as throughput and material residence time and to investigate the stress intensities that different mixers and topologies impose on electrode materials. However, comparative testing with real systems is required to validate and improve our models.

As a result, we evaluate laboratory-scale mixers from various manufacturers and analyze their results, such as mixing homogeneity or the degree of comminution of specific components. The main emphasis is on experiments with lab-scale twin-screw extruders.

With this tandem approach, we aim to create a strong digital representation of the process, a “digital twin” that captures our understanding of the activities occurring in the mixer.

It is important to determine the necessary conditions for establishing good uniformity and ideal morphology. Predictive models would make it quick and straightforward to discover appropriate operating conditions for certain materials.

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This information has been sourced, reviewed, and adapted from materials provided by Thermo Fisher Scientific – Production Process & Analytics.

For more information on this source, please visit Thermo Fisher Scientific – Production Process & Analytics.