At present, the coating of internal combustion engine components is the most important field of application for vacuum and plasma technology in automotive engineering. Engines are becoming more reliable and efficient thanks to these technologies. However, in the context of climate change, the need to switch from internal combustion engines to electric motors in order to achieve CO2 neutrality has become widely accepted as a consensus. The end of the dominance of the combustion engine in vehicle construction is foreseeable. Does this mean that vacuum and plasma technology will lose relevance in the automotive industry?
On the contrary, the upcoming transformation will tend to increase its importance, whether in battery cell production or in the areas of occupational safety and quality control. Vacuum technology is indispensable for various process steps, and progress in the development of vehicles and their components will go hand in hand with the development of the appropriate vacuum environment. The Fraunhofer Institute for Systems and Innovation Research estimated in 2020 that the energy density of lithium-ion batteries could be "doubled at most" again by 2030 - provided the corresponding R&D challenges are overcome.
Declared Goal: Store More Energy at Lower Manufacturing Costs
Where will vacuum and plasma technology play a role in the future? First of all, in coating. Electric motors require coatings in exactly the same way as internal combustion engines. Friction losses need to be reduced. After all, the energy generated should not be lost in the engine but be transferred to the road. All moving parts such as the bearings are coated with extremely smooth, abrasion-resistant layers. A welcome side effect is that the coatings, which are often only a few atomic layers thick, prevent unwanted electrical fluxes that can damage individual components or the entire electric motor.
Continuous Further Developments in Coating and Drying
Fraunhofer-Gesellschaft is working in conjunction with a Dutch governmental research organisation to develop the SALD process for production of atomic layer thin films. SALD stands for "Spatial Atom Layer Deposition". The accumulators produced using this process offer enormous advantages over the accumulators currently in use. They can be charged five times faster and are said to have three times the capacity and thus range. What is new about SALD is the "S", because the ALD processes already have a firm place in plasma technology. For example, VAT supplies valves of the 09 and 26.4 series as well as newly developed transfer valves to plant manufacturers working in this area.
The coating initially has the consistency of a "paste" and must dry. The focus is on shortening the time required for this. Short drying means increased system throughput, which in turn leads to lower unit costs. On the other hand, the long-term stability of the electrodes should be maintained or even improved, thus extending the service life of the accumulator. One task is to know exactly how the drying time and intensity interact with other cell properties and to bring the numerous parameters into the best possible relationship.
The drying itself takes place in a vacuum. This is the only way to avoid contamination, for example by residual solvent or residual moisture esters. In addition, the vacuum reduces energy consumption. Without a vacuum, significantly higher temperatures would be necessary which in turn could have a negative effect on the material properties of the electrode layers.
Each battery cell must be filled with electrolyte. Some drivers may still remember battery acid. They had to top it up regularly to maintain the charge level of the lead-acid battery installed in the car. Since the liquid consisted of 37 percent highly corrosive sulfuric acid - one of the strongest acids of all - extreme caution was required. The electrolytes currently in use, whether liquid or solid, also have their problematic sides. Many are highly flammable and very reactive, so for safety reasons filling must be carried out in the absence of oxygen.
The vacuum also ensures a high degree of cleanliness of the working environment - in other words, it prevents the entry of particles and residual moisture - and contributes to uniform wetting of the electrodes.
Leaking electrolyte poses an immense risk, so that at the end of production the leakage test under vacuum is a critical process step. In leak testing, however, the classic pressure decay test has had its day. Because of the very short cycle times, leak detectors with helium as the test gas are now mainly used.
Conclusion: Elementary Process Steps Take Place in a Vacuum Environment.
"Vacuum technology is an indispensable part of the production and development of accumulators and electric motors," emphasizes Christian Schmidt, VAT Sector Manager. A whole range of processes take place under vacuum and require compliance with high safety standards. Machine and plant manufacturers who supply battery manufacturers are just as dependent on valve technology as the battery manufacturers themselves.
Decisions for the future are made in research institutions that are involved in the further development of all components. The role of vacuum technology here is not just a strategic one: through its contribution to the production environment, it can address certain process challenges, offer solutions and become a driver of electromobility.
VAT is working with research institutions around the world. The aim is to gradually expand the existing vacuum valve portfolio for electromobility and drive it forward so it develops alongside current trends and advances. The spectrum ranges from fast-closing vacuum transfer doors for inline battery module production lines to modular isolation and control valve concepts that can be easily adapted to changing production conditions and the provision of complete vacuum process modules.
In short: VAT offers producers and plant engineers customized valve solutions for a wide range of applications that will help in the course of the mobility transformation.