The battery technology is a key element of electric mobility and has made significant progress in recent years. Lithium-ion batteries are the most common type used in electronics and electric vehicles today. In the years ahead this technology will continue to set the pace, but there is more to come.
The battery is not an off-the-shelf product, but an integral part of the vehicle architecture. The intelligence of the battery lies in a highly complex overall system, which defines the characteristics of the vehicle with respect to performance, range and charging times. As part of its research and development activities, Mercedes-Benz AG is currently going into a development partnership with Canadian battery material specialist Hydro-Québec on future technological leaps of electric vehicles. The focus: Solid state batteries.
A discussion with Andreas Hintennach, senior manager battery research at Mercedes-Benz AG and Karim Zaghib, General Manager of Hydro-Québec’s center of excellence in transportation electrification and energy storage.
Mercedes-Benz is quickly picking up the pace regarding electrification – therefore, the battery is the most important component, but it seems that the “God of battery” is not yet on the horizon - how do you handle this uncertainty?
Andreas Hintennach: While our all-new EQC model enters the markets already, we are preparing the way for next generations of powerful battery electric vehicles. Lithium-ion technology is currently the most efficient battery technology available, and still shows plenty of potential for the future. But we are consistently working on optimizations and alternatives beyond Li-Ion – not least regarding energy density and charging times, but sustainability as well. Our competencies for the technological evaluation of materials and cells as well as research and development activities are consistently expanded.
So how do your activities on those technological leaps at Mercedes-Benz look like?
Hintennach: Our research and development activities include the continuous optimization of the current generation of Li-Ion battery systems, the further development of cells bought on the world market and research of the next generation battery systems. You have to really understand the mechanism of technologies in order to be able to make the right decisions. But we do not work under a dome of glass – a successful R&D is based on sharing, discussing and always keeping your eyes open. The search for the Holy Grail means worldwide and cross-industry teamwork. That’s why we are always looking for cooperations and partnerships with strong industry partners and scientific institutes around the globe. We are very happy to have Hydro-Québec working with us right now.
Karim, what is your vision on future battery technologies?
Karim Zaghib: Our vision is very clear: We want to reinvent energy for a sustainable future. Our aim is to develop ultra-high-performance battery technologies and storage systems that will accelerate transportation electrification and make it possible to bring more renewables onto power grids, on a global scale. If we want to leave a viable planet to future generations, the time to act is now.
What #next big things are you currently working on?
Zaghib: My Center’s efforts are focused on advanced lithium ion batteries and solid state batteries. We developed a first-generation solid-state battery in the 1990s and have continued our R&D to improve both efficiency and manufacturing methods with a view to a new generation. Solid-state lithium metal batteries are supposed to be a next important technology milestone, having a very high energy density, are long lasting and very light moreover harnessing the potential of solid-state-materials on safety. With our latest developments we have achieved very promising results.
How do the activities of Hydro-Québec and Mercedes-Benz fit?
Zaghib: We’re pleased to be partnering with Mercedes-Benz, an automotive company with an enviable reputation, to pursue our research even further. Our development program will allow us to test new materials quickly in field conditions, and so accelerate the development cycle and respond to the concerns of automobile manufacturers.
What exactly is the difference between today’s Li-ion technology and solid-state?
Zaghib: Solid-state batteries use a solid electrolyte material instead of the typical liquid electrolyte. The electrodes are solid too. The job of the electrolyte is to transport ions between the electrodes, as the battery charges and discharges. Solid electrolytes open up the possibility of using new types of anode, such as lithium metal, which makes it possible to have higher energy content combined with optimized safety than today’s graphite anode. This is a very exciting field of research with still a lot of opportunities.
We have already heard a lot about solid-state batteries recently. What about the market readiness?
Hintennach: Due to the specific driving profile of passenger cars and trucks, the energy density of the technology isn't really suitable right now. Moreover, charging of large solid state cells still takes too much time. In other words, today it does not offer any advantages over Li-ion. There is still some research work to do. That means we're looking for more energy density and ways we get there. Regarding buses, It should be possible to have use cases there already in the early 2020s, because their driving profile is very predictable and space does not play such a big role as in a passenger car. Trucks are the most challenging application, because the current and volumetric density needs to be very high and fast charging plays an important role. Almost all solid state ion conductors still fail there today.
What ways to you see to reach market readiness?
Zaghib: Lithium-ion chemistry is a very powerful chemistry with great potential. The transformation from Li-ion to solid-state batteries is not going to happen overnight. Despite the first generation of Lithium-Metal Polymer solid state batteries with moderate energy density, further solid-state solutions aren’t production ready yet but are worth to work on further as they have some vital advantages. Note that for solid-state batteries, both the electrode and electrolyte types are made of a solid material. New generations of these materials will be quick to charge and are basically non-flammable. What we definitely can say is that the solid-state battery technology has made big steps during the last years. Currenty we are working on ceramic solution, for example. Both polymere or ceramic solid state electrolytes can be used. They have different characteristics and might be suitable for different use cases each. In particular ceramic materials offer very high stability against high temperatures and can tolerate higher temperatures during e.g. fast charging processes very well.
Do you understand that customers are still hesitant about buying electric vehicles and prefer to wait for the next technology?
Hintennach: In automotive industry there is a certain regulatory: you cannot make a technology revolution every year. Of course, the battery will continue to improve over the next few years and also change in terms of technologies. Moreover, we expect it to become cheaper. But as a manufacturer, you also need to look at how to handle this variance. We see in theory that cell efficiency statistically increases by a certain percentage each year. That does not mean that our cell suppliers have a new product ready every year. Before you are able to apply a new technology into a vehicle a huge amount of evaluation, testing, validation and certification has to be done. The effort won’t go below a certain level, it will not happen that every year a new market ready cell technology arises. It will be similar to today’s vehicle cycles - after three to four years, a new variant.
How important is sustainability for your development work?
Zaghib: (Laughs) The most important! Otherwise I would not do the job already for 30 years. When it comes to the sustainability of batteries, the question how to design and produce the battery sustainably is core. We need to further develop efficient recycling technologies for batteries. The choice of material plays a decisive role here. We have a long track record in working with sustainable materials and their application to large cells and battery packs.
Are solid state batteries the ultimate successor of li-ion based batteries?
Hintennach: It's a compagnion - not a successor, for one simple reason. The energy density is very high in solid state batteries, but the power density isn't. That means in uses where the battery is a bit bigger, starting at mid-size passenger cars, there's enough power there. But if you need a lot of power in a small package, like a sports car, it's probably the wrong solution. Moreover, there is also still a lot of room for further improvement in the existing lithium-ion technology. We will see several technologies in the future. It all depends on the application.''
Zaghib: I fully agree. We will need diverse energy storage technologies for a sustainable future. There is not one technology as a silver bullet for all industries and applications.
What fascinates you most about your research field?
Zaghib: The energy transition is the most exciting time for the industry for decades. Completely new markets are emerging. The development is incredible and it makes me happy to work in a field with so much potential.
Hintennach: Above all, my team and I focus on the long-term improvement of the battery. We look into the future and work on the answers to questions that will be asked in 10-15 years. Pushing the boundaries of technology is very exciting. We learn something new every day.
Hydro-Québec and its Center of Excellence in Transportation Electrification and Energy Storage is a world-class innovation hub in the field of battery materials for electric vehicles and other energy storage applications, both stationary and mobile. Directed by Karim Zaghib, an internationally renowned expert, the Center has a high-caliber team working to revolutionize the energy industry. Zaghib was recently named one of the World’s Most Influential Scientific Minds for the three years in a row. The center of excellence commercializes Hydro-Québec technologies protected by over a hundred of families of patents.