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Exclusive Interview with Juliane Kluge
Juliane
Kluge
Head of Cell Chemistry and
Methods, Battery Cell
Competence Centre (BCCC),
BMW Group
One pillar of the BMW strategy on battery cells is the intense series development together with our cell suppliers. We define the next generations cells for our vehicles based on our deep competence and our cell suppliers industrialize these. This allows us to choose new partners with every cell generation and benefit from their innovations and cost potential. Moreover, large cell suppliers, which serve larger overall volumes, can use economies of scale and thus better optimize the entire value chain.
The second pillar of our strategy is the inhouse competence for which we have built up a dedicated organization since 2012, which goes far beyond the focused series development. This is the Battery Cell Competence Center (BCCC), where I am located. Here we focus on the fundamental understanding of battery cell technology, evaluate innovations and drive the BMW inhouse cell development starting from small lab cell to evaluate innovative battery materials up to designing and producing prototype cylindrical cells. Subsequently, in our pilot plant the Cell Manufacturing Competence Center (CMCC) we focus on understanding and optimizing the processes of cell manufacturing on a giga-watt scale. A cell design can only be as good as the implemented manufacturing process.
- BMW has consistently led battery advancements. Can you share the latest breakthroughs in battery cell chemistry that your team is working on?
We are working on a number of innovations such as high silicon anodes, new cathodes based on lithium manganese rich materials, solid state electrolytes or lithium metal anodes. However, even for the state-of-the-art lithium-ion technology we see the necessity to increase our fundamental understanding.
One of our recent key highlights at the Battery Cell Competence Centre (BCCC) is the identification of a novel cell aging mechanism for lithium-ion batteries. We proved that macroscopic electrolyte motion during charging and discharging in the fast-charging regime results in an inhomogeneous distribution of conductive salt in the cell leading to rapid lithium plating and, consequently, a dramatic capacity loss of the cell.
This aging mechanism was intensively studied using our in-house developed cylindrical cells, and the findings were published last year. Importantly, we have observed that this aging mechanism is not limited to cylindrical cell formats. Currently, a further scientific manuscript is preparation focusing on observations in hard-case prismatic cells. This research effort has been a truly collaborative endeavor, with more than 15 cell experts as a core team from development, simulation, prototyping, testing and analysis all working together in the BCCC and being supported by even more colleagues.
- How does BMW optimize cell chemistry to enhance energy density and cycle life while ensuring the highest safety standards?
At the BCCC, we take a proactive approach to innovation. Alongside our internal R&D efforts, we constantly scan our global network of academic, start-up, and industrial partners for the latest advancements. We carefully evaluate these external inputs and then conduct in-depth experimental studies on the most promising concepts within the BCCC facilities.
Through this holistic approach of combining cutting-edge research, experimental validation, and advanced simulation we have an in-depth understanding to design the optimal balance of energy density, power, and lifetime, without compromising on safety in accordance with the specific requirements for our vehicle applications.
We perform a full 360° evaluation inhouse at the BCCC from performance tests to safety tests of cells up to small modules for which we have developed methodologies (experiments and simulations) to fully understand the safety properties of cell.
- Sustainability is a major focus in the battery industry. How is BMW incorporating sustainable and recyclable materials into battery cell chemistry?
Promoting a circular economy is a key focus for BMW, applying principles of rethinking, reducing, reusing, and recycling across the vehicle lifecycle. This approach not only helps BMW develop more sustainable and recyclable products but also increases its supply chain resilience, ensuring a reliable and responsible source of critical raw materials.
For series development BMW demands the use of recycled materials in the product requirement documents addressed to our cell suppliers, pushing for the incorporation of recycled materials in our battery cells. BMW has also invested in its own research on innovative recycling processes, both in-house and through partnerships.
We recently announced a long-term collaboration that allows BMW to be directly involved in the practical recycling processes of its used high-voltage batteries from development, production, and markets in Europe to recover valuable materials like nickel, lithium, and cobalt, which are then reused in the production of BMW's new GEN 6 drive train. It should also be mentioned that BMW was part of the Battery Pass consortium, a collaboration on the development of a battery passport based on the new EU Battery Regulation with was finalized this February.
- Solid-state batteries are often cited as the next big leap in EV technology. What is BMW’s current stance on their development, and what hurdles remain before they can be mass-produced?
The key challenge for solid-state batteries is to demonstrate a clear added value in terms of performance and cost compared to the benchmark of conventional lithium-ion battery cells. To address this, we are evaluating a wide range of chemistries, from semi-solid-state to all-solid-state, complementary to our partnership with Solid Power. Our activities span from scouting, building, and evaluating lab cells for material benchmarking, to internal cell development at the lab level, and the creation of prototype cells. We also assess cell concepts from external partners.
Our efforts are not limited to intensive work on cells alone. Within BMW, we have also set up pre-development and prototype production of respective module and pack concepts for solid-state batteries.
It is important to note that the benchmark of lithium-ion battery cells is continuously improving. While a lithium metal anode can significantly increase energy density, the associated volumetric breathing during charging and discharging requires a more complex pack-level design, which can increase weight and costs compared to lithium-ion batteries.
Therefore, even though we see solid-state batteries as an innovation driver, in our understanding, solid-state batteries need to demonstrate competitiveness in terms of performance versus costs to be adopted for large series automotive applications.
- With evolving EU regulations on battery sustainability and recyclability, how is BMW ensuring compliance while continuing innovation in battery cell chemistry?
This is business as usual within BMW. We comply to all respective regulations and standards worldwide regarding our BMW cars and all components. Of course this is also true for the battery. The requirements for the battery cells and battery systems are continuously updated for any change in regulations.
- Europe is striving for battery supply chain independence. What challenges do you face in securing locally sourced raw materials for BMW’s battery production?
Our present supply chain follows our local for local strategy, i.e. battery cell production by our suppliers in each market are close to the respective BMW battery pack and vehicle production. Certainly, this is embedded in the local regulation framework such as local content or tariffs. And indeed, it is sometimes challenging as there exist strong dependencies of Asia on materials, sub-components and cells.
In general, we welcome activities to create local value chains creating competition and enhance the resilience towards distortion of the global trade system. For Europe the independence of the supply chain will be limited by the availability of raw materials and hence it has to include partnerships with countries that have the relevant resources.
- With emerging chemistries, rigorous testing is crucial. How does BMW’s Battery Cell Competence Centre ensure that new cell formulations meet real-world durability and efficiency benchmarks?
The Battery Cell Competence Centre is equipped with state-of-the-art cell testing facilities for electrochemical characterization from lab scale cells to full cells for series development. We have specifically designed test protocols to validate cells on energy density, power performance and aging behavior at different temperatures against our requirements derived from the vehicle. This is accompanied by rigorous safety and abuse testing performed by our inhouse safety lab allowing us to identify any potential safety issues or failure modes. Complementing these activities we also have built up extensive expertise in battery cell post-mortem analysis. This involves careful disassembling and analyzing tested or damaged battery cells to gain insights into their performance, degradation, and failure modes.
- Are there any promising alternatives to lithium-ion technology that BMW is exploring for its future EV lineup?
Beyond the conventional lithium-ion technology and in addition to our activities on solid state batteries, which we already touched upon, we continuously screen novel battery cell concepts to evaluate their chances and challenges such as sodium-ion batteries or lithium sulfur batteries. Decisive for us to intensify our efforts for a novel battery cell concept is the potential to achieve advantages in performance, cost, raw material sourcing, or sustainability compared to the conventional lithium-ion technology benchmark.
While not a battery technology per se, BMW is also exploring the use of hydrogen fuel cell systems as an alternative powertrain option for its future EV lineup. After successfully testing the BMW iX5 Hydrogen pilot fleet worldwide, the BMW Group is now preparing for series production of vehicles with hydrogen drive systems in 2028.
- Innovations often come with higher costs. How does BMW balance cost efficiency with cutting-edge R&D in battery cell chemistry?
We evaluate innovations from the beginning in a 360° approach. That means even in early phases of a R&D project we use our simulation tools to predict the performance in a large, industrialized cell and derive a detailed bill of materials. Based on that, our cost engineers can calculate the forecasted cost of the cell. Only if the added value to cost ratio is reasonable and enhances the customer benefit, we intensify our R&D efforts.
- Collaboration is key to accelerating innovation. How does BMW engage with industry partners, academia, and startups to push the boundaries of battery chemistry?
In the rapidly evolving R&D landscape of the automotive industry, establishing a global network of academic, start-up and industrial partners is crucial to identify and access the latest innovations. At BMW, we leverage our technology offices in the US, Korea, Japan, and China to serve as our eyes and ears to the world, providing us with invaluable insights and access to cutting-edge developments.
Our collaboration approach is tailored to the specific needs and maturity of the technology. We initially request samples for evaluation and benchmarking at our Battery Cell Competence Center. If the potential is deemed promising, we expand the partnership to a joint development agreement. Additionally, we actively participate in publicly funded pre-development projects, which not only contribute to the technical results but also provide our SME and academic partners with a deeper understanding of the R&D processes driving an OEM.
