The global automobile industry is in a state of profound transition, and Bühler is well positioned to be a key solution provider. It is not just how cars are powered that is changing. As the internal combustion engine is slowly replaced, many of the old conventions around how a car is manufactured, who manufactures it, what it is designed to do, and even who owns it are being questioned. Bühler’s Advanced Materials business is part of this transformation story
Stuart Spear, June 2022
“There is a big wave sweeping across the car industry and we are planning to surf this wave with some of our solutions,” says Markus Hofer, Head of Business Development at Bühler Advanced Materials. “Unlike the food sector, where we may provide total solutions, in Advanced Materials we provide essential steps in a very long supply chain with all three of our businesses involved in battery production, die casting, and sensor coatings, providing key solutions in this process of transition.”
Electric cars are simpler to design and manufacture compared to models based on the internal combustion engine. Sophisticated supply chains are replacing the massive capital-intensive factories that in the past acted as barriers to entry. This means newcomers are now building cars, too. Tesla has been shaking up the traditional way of doing things while cash-rich, high-tech companies like Google are preparing to enter the market with a vision of cars as platforms for sophisticated software solutions enabling connectivity and automation.
When it comes to the mixing of the slurry, we have years of in-house knowledge about how to fine-tune the required properties and how to execute a production plan
Philipp Stössel , Team Manager Process Technology, Battery Solutions, Grinding & Dispersing at Bühler
At the heart of this change lies the electric vehicle and at the heart of every electric vehicle lies a battery. As governments scramble to meet global greenhouse emission targets and cities regulate to improve air quality for their citizens, the shift away from the internal combustion engine is accelerating. Global sales of electric vehicles more than doubled last year as they hit 6.6 million, with growth expected to surge to 40 million by 2030.
Until recently, one of the inhibitors to the growth of the electric vehicle market was battery performance and cost. Constituting around a third of the manufacturing cost of an electric car, the ability to drive down costs while improving performance has been key to making affordable electric cars. A Bühler solution providing a novel way to mix battery electrodes slurry that has been developed for over a decade has been part of the story behind achieving this all-important efficiency.
The first production stage in any battery production plant is mixing materials into an extremely high quality and consistent viscous paste that will ultimately coat the anode and cathode that create the electric current. Known as battery slurry or electrode slurry, nano- and micro-scale particles of lithium metal oxides, graphite, silicon, conductive additives, and polymer binders are dispersed according to strict parameters. It is the chemical formulation and constitution of this paste that will dictate the performance of the battery. In the case of car batteries, the anode formulation is predominantly based on graphite and silicon/silicon oxide, while the cathode is composed of lithium nickel manganese cobalt oxide or lithium iron phosphate. “While we only supply a small part of the entire value chain, we are actually deep in the industry because it is only when the slurry is mixed to the strictest parameters that high battery performance can be achieved,” says Philipp Stössel, Team Manager Process Technology, Battery Solutions, Grinding & Dispersing at Bühler. “When it comes to the mixing of the slurry, we have years of in-house knowledge about how to fine-tune the required properties and how to execute a production plant, and it is this experience that sets us apart from the competition.”
In an industry where Asian battery manufacturers have historically been the world leaders, the traditional way to mix battery slurry involves all the elements being mixed in large vats. Slurry processing times are lengthy, and labor-intensive cleaning is needed of each vat after a mix has been completed. Samples are taken to a laboratory for analysis with the potential for batch wastage if there is found to be a quality issue. Ten years ago, Bühler came up with the idea of using twin-screw mixers to create a continuous mixing process. It cut operation time and produced higher consistency, better quality, and less wastage. By leveraging its knowledge about continuous production of high-tech, non-food products and applying technologies used in other business areas, Bühler had created a radical alternative to the traditional batch-mixing method.
“The beauty of this process is that it is continuous, so all the raw materials go in at different points and after just one or two minutes the final slurry is discharged,” explains Stössel. “One of the huge benefits of this continuous process is the ability to automate it and have it running 24 hours a day with no need to interrupt production for the cleaning of equipment.” Bühler then launched QuaLiB, a quality control expert system that provides real-time digital data on the automated mixing parameters and continual sampling of slurry quality. With real-time data flows of production parameters, quality can now be tightly controlled, improving the process safety, product quality, and overall yield.
Bühler is also involved in research into new technologies such as solid-state lithium-ion batteries or fully dry-processed electrode formulations, which are cheaper to produce as they do not require solvent drying in the electrode coating process. “This is a field in which we are highly active and are constantly gaining experience. The twin-screw mixer is the ideal platform to explore novel process technology,” says Stössel. There is a growing realization that in today’s megacities, where car sharing is anticipated to become more common, the desire for maximum distance on a single charge may not be the holy grail it is for other consumers. For those manufacturers who want maximum range, the weight of the car is also an important factor. Here again, Bühler is playing a key role in supporting change in the way cars are constructed. In the summer of 2019, Elon Musk announced his company would make larger car components rather than continuing the traditional method of producing multiple steel stamping parts and relying on robots to weld the parts together. It was the start of a trend in the automotive industry that led to ever-larger Carat die-casting machines.
The largest Carat die-casting machines are as big as a house, at 8 meters high, and stand on a floor space of nearly 100 square meters. “The Carat 920 is able to inject over 200 kilograms of liquid aluminum into a die within milliseconds, thereby holding the die tight by applying to it a force of 92,000 kN. Imagine locking the die with the weight of the Eiffel tower – that’s 9,000 tons every single shot,” explains Michael Cinelli, Product Manager Die Casting at Bühler.
There is a big wave sweeping across the car industry and we are planning to surf this wave with some of our solutions.
Markus Hofer , Head of Business Development at Bühler Advanced Materials
A few disruptors have basically reinvented how a car body structure is produced, which has been a profound change for the die-casting industry.
Martin Lagler , Global Director Product Management & Marketing at Bühler Die Casting