The graphite mixture, viscous as honey, drips out of the beaker. “This is the slurry,” Dr. Calin Wurm says. Pipettes, tongs and jars with chemical formulas surround him in the lab. Wurm, the director of the research laboratory, holds the beaker with the slurry in one hand. It’s made of graphite powder and an ultrapure putty-like solution. He carefully pours the slurry into the coating equipment. The system spreads it out to wafer-thinness onto a copper foil, sends it all through the dryer, and at the end a finished anode foil emerges. Wurm is pleased. What he just accomplished by hand is something that happens on a very large scale at battery manufacturers all around the world. “We want to work as closely as possible with our customers,” Wurm explains. That’s why he is currently reconstructing the individual work steps of industrial battery production in SGL’s new and expanded battery laboratory in Meitingen, Germany. This isn’t so he can produce the batteries himself, but rather to gather knowledge to support major manufacturers as a development partner, technology expert and materials specialist.
In the battery and energy-storage business, this combination is becoming more and more important. While raw materials, components and end products are standardized down to the last detail in many other industries, lithium-ion batteries and their components differ enormously from one another. Composition, further processing, size: almost everything varies depending on the field of application and the objective. At the same time, the demand for lithium- ion batteries is rapidly increasing. Highly efficient and safe batteries are required almost everywhere— whether in electric cars, e-bikes, smartphones or laptops.
Power cells made of lithium metal oxides, electrolytes, separators and graphite are becoming increasingly indispensable, especially in electromobility. According to a study by the International Energy Agency (IEA), 130 million new electric cars could be registered in 2030—almost all of which will contain lithium-ion batteries. The rapid demand is already leading to shortages of raw materials, strengthening the market power of the source countries. The market is divided into about half natural graphite and half synthetic graphite. Natural graphite mainly comes from China and is less flexible, technically speaking. “You have much more freedom with synthetic graphite,” Wurm says. Furthermore, it can be customized to the respective battery to a higher degree. This advantage is particularly important in battery manufacturing and is an advantage from which SGL Carbon, as one of the market leaders in the field of synthetic graphite, benefits.
“All of a battery’s parts are interconnected,” Wurm says in his lab. It’s what makes them so complex. The company that wants to offer the best materials for the best battery must therefore understand precisely how these interconnections work. That’s the goal that Wurm has set for himself in Meitingen—and why he returned to SGL Carbon to accomplish it. As he walks through the lab, he talks about how, as a young student in Bucharest, he discovered his fascination for batteries, then moved from his birthplace Romania to Paris to complete his doctoral thesis, then to Amiens, France, then in 2004 went to Ellwangen, Germany, to develop batteries for Varta, and finally joined SGL for the first time in 2008.
Even back then, Wurm was one of the leading experts on graphite anodes on the market. After completing his doctoral dissertation, he worked for many years for cell manufacturers and purchased, tested and incorporated graphite anode materials for production. At SGL, Wurm used this experience to advance research into graphite. In 2012, when Bosch offered him the position of cell development manager at the battery factory being planned in Eisenach, Germany, Wurm followed his passion for batteries and continued to expand his knowledge and expertise. He returned to Meitingen in August 2018 with even more experience and motivation. “When it became clear that Bosch would not become a cell manufacturer, I had a choice,” Wurm recalls. Should he stay with Bosch and simply do something different or remain loyal to batteries? “My heart once again chose the battery—and SGL.”
When Wurm talks about a battery’s assorted components, you can sense just how enthusiastic he is about them. The 47-year-old can talk about hexagonal graphite structures, discharge cycles and intercalation stages and, in the next sentence, quite clearly explain why the electrolytes in a lithium-ion battery take on the function of trucks. What fascinates him about batteries is their enormous diversity. “You never get bored and there’s always room for improvement,” he says.
In the coming years he wants to use his enthusiasm and experience to get the most out of lithium-ion batteries with SGL Carbon’s various grades of special graphite. Wurm fishes something out of a drawer in the laboratory that looks like a folded survival blanket. “This is what the completed battery cell looks like,” he explains. There’s an anode consisting of a copper foil coated with graphite, binder and conductive additives; a cathode made of an aluminum foil coated with lithium metal oxide, binder and conductive additives; and a separator between them. The components are surrounded by a casing and impregnated with an electrolyte.
“It sounds simple, but it’s incredibly complex,” Wurm says. Depending on the application, the cells are either coiled or stacked. The casing may be a hard enclosure or a flexible composite material such as special foils for pouch cells. There are various electrolytes with differing conductive salts and solvents. Even the manufacturing method used for the copper foils affects the final product.
My heart once again chose the battery.
Calin Wurm, Head of the battery application laboratory at SGL Carbon in Meitingen and Director Technical Marketing Product Segment Battery Solutions
Wurm knows from his own experience that the countless interactions pose an enormous challenge for lithium-ion battery manufacturers. When he used to build batteries himself, using graphite, he repeatedly witnessed how the material in different battery types often had different performance parameters and lifetimes in practice. As he knows all too well: “Not all graphite is created equal. The art is knowing in advance which graphite is the best fit for the special cell design.”
It is precisely for this reason that SGL intends to begin offering comprehensive services in the application laboratory. Instead of having one, two or three standard materials in its repertoire, SGL Carbon is starting to focus more on customized battery graphite products for the future. “We want to be able to sell our customers exactly what they need,” Wurm says. “Our advantage is that we know exactly how to produce a particular type of graphite and what its properties are. Now the idea is to utilize this knowledge even more effectively for designing batteries.”
This expertise has even more benefits. Battery manufacturers often test their suppliers’ materials in their own laboratories, which is an expensive, complicated and time-consuming process. “We can carry out such tests much more effectively, accurately and quickly for the customer using our accumulated expertise and knowledge,” Wurm says.
The strategy for the new battery laboratory perfectly implements the new SGL approach: “Customer orientation is even more important in our graphite anode business these days,” says Vice President of Product Segment Battery Solutions, Dr. Peter Roschger. “We are continually evolving from a materials supplier to a solutions provider in this area, as well.”
SGL Carbon has already made additional investments in order to successfully follow this path. Graphite production facilities in Poland and the United States have been upgraded, and the laboratory in Meitingen is being expanded, where Wurm will also be adding needed personnel for the new facility. Together with their colleagues in sales and production, everyone is now working on a common vision.
In one of the laboratory rooms that are crucial to making this vision a reality, hundreds of lights are blinking. Dozens of cables snake their way through the room, and a wide screen displays a rising curve. In what are known as battery testers, hundreds of prototypes are transferred from the laboratory to the test station. This is the only way to produce statistically valid results. Wurm enters the room and quickly closes the door behind him. “If the temperature changes in here, it distorts our findings,” he explains. Lithium-ion batteries are sensitive components. A couple of degrees of warmth shouldn’t disturb the battery revolution in Meitingen.