“The battery cell is the heart of electromobility,” said Michael Steiner, Chief Research Officer of Volkswagen Group. Battery production is set to become up to forty percent cheaper by 2035. At the same time, customers can expect improvements in charging speed, durability, range, recycling, sustainability and safety.
The VW Group sees standardization as one solution. “Battery systems account for around 40 percent of vehicle costs. It is therefore vital to standardize all components of a battery system in order to reduce complexity and to bring costs under control,” added VW battery expert Marcel Hollweg.
The VW standardization strategy ranges from design and production to the recycling of battery components. “In the future around eighty percent of the VW Group’s vehicles will be rolled out with the standardized unit cell,” explained Head of Development Arno Perner at the international symposium. All are prismatic, designed for 400 or 800 volts. In terms of cell chemistry, VW’s offer is broad. The range extends from low-cost sodium-ion cells to LFP cells with up to 450 watt hours per liter and NMC cells with up to 700 Wh/l to high-performance solid-state cells with up to 1000 watt hours per liter. By 2030, VW aims to produce around 50 percent (around 200 gigawatt hours) of these unit cells itself. According to VW, 95 percent of all battery cells worldwide currently are from Asia.
800 kilometers range?
With the promising solid-state cell, the liquid electrolyte will be replaced by semi-solid (gel-like) or solid electrolytes. These allow higher energy densities (more than 400 watt hours per kilogram) than current lithium batteries, as well as greater safety (less risk of fire) and faster charging. A range of 800 kilometers should be possible in the future. According to Fabian Duffner, battery expert at Porsche Consulting, Japan, South Korea, China and the US are leading the way in this development.
However, the industrialization of this technology is associated with numerous technical and financial hurdles. A further disadvantage being: “A solid-state battery requires significantly more lithium per kilowatt hour than a conventional lithium-ion battery,” said Duffner. It is therefore much more dependent on the price of lithium, which has fluctuated between 8,000 and 70,000 euros per tonne in recent years. Nevertheless, Duffner sees the market potential for solid-state batteries by 2035 at around sixty percent of an estimated battery requirement of 7.7 terawatt hours. Conventional lithium batteries will also continue to exist. In the cost-sensitive mass market sector, lithium iron phosphate batteries are widely
used for both trucks and cars. With 400 watt hours per liter, a long service life, low costs but a relatively modest range, they offer a good compromise, as Geon Seog Son, battery materials expert at Umicore in Korea, demonstrated in his presentation. According to Son, the cheaper but also safer sodium-ion cells are only available “in a very small sector in China. But they will expand.”
New materials for anodes and cathodes
The Belgian company Umicore is not only an important partner for VW on the path to better battery cells. It is one of the world’s leading suppliers of cathode and anode materials. The cathode alone accounts for around 50 percent of the costs,” said Son. It is also responsible for around 60 percent of a battery’s CO2 footprint. New materials should reduce both costs and CO2 emissions and improve the recyclability of battery cells. In addition, a partial replacement of graphite with silicon in the anodes could reduce the current high dependency on supplies from China. For the cathode, on the other hand, Umicore is among other things working on replacing cobalt with cheaper manganese.
Thermal management is particularly important when it comes to safe fast charging and the service life of batteries. According to Shell, fast charging can generate up to 20 kilowatts of thermal energy in the battery. When dealing with this thermal energy, Shell uses its long experience with cooling fluids for transformers or large data centers. According to Volker Null, tests with Shell’s immersive thermal management showed clear advantages in terms of fire risk and damage due to ageing caused by fast charging. The launch took place in the luxury class, for example in the Mercedes-AMG GT 63 S E or the McLaren Speedtail Hybrid.
But even in the mass market sector, improved liquid cooling, such as flexible cooling channels (Flex Cooler), can achieve major customer benefits in terms of range, fast-charging capability and battery service life, as Stefan Gaigg, Managing Director of Miba Battery Systems in Upper Austria, demonstrated.
225 tons of earth for one battery
The overall environmental balance, on the other hand, depends heavily on the recycling rate of the battery materials. André Ferrarese, Head of Research and Development at the Brazilian vehicle supplier Tupy explained that currently, the carbon footprint of battery electric vehicles in production can be two to three times higher than those with a combustion engine. Around 26,000 liters of water are required for one battery pack and up to 225 tons of earth mass have to be moved.
Together with the University of Sao Paolo, Tupy has developed a hydrometallurgical recycling process that allows recovery rates of more than 95 percent, even for lithium. The purity of the materials amounts to more than ninety percent. These recycled materials reduce the CO2 footprint of batteries by up to seventy percent – significantly more than previous pyrometallurgical processes.
Hope for lithium-air batteries
The higher the recycling rate, the lower the dependence on China for raw materials and the lower the fear of crazy price jumps as in the past. According to Fabian Duffner from Porsche Consulting, a stable lithium price and successful industrialization are the most important factors for competitive solid-state batteries. However, the great beacon of hope, lithium-air batteries, will be a long time coming. They should come close to the energy density of current fuels for combustion engines. Current batteries are a long way from achieving this.