18650 battery pack

　　BMW, Audi and many other car companies jointly develop key technologies for hydrogen fuel cell power 18650 battery pack stacks

　　In the "AutostackIndustrie" project, five OEMs and multiple suppliers are working together to bring key technologies in the manufacture of fuel cell stacks, the core components of fuel cell vehicles, to a mature industrialization level.

　　The project will last until the end of 2021, and its focus is on breaking through the high-speed process of fuel cell stack manufacturing. The challenges are huge, but the initial collaborative efforts are positive.

　　In addition to the FC unit, the drive system of a fuel cell (FC) vehicle also includes a battery to compensate for the reaction time of the system and improve the acceleration efficiency of the vehicle, an electric engine, a transmission, and a hydrogen fuel tank. In this regard, the complexity and number of components of the FC system are similar to those of an internal combustion engine. The key component is the FC stack. In contrast, from a process engineering perspective, this is very different from assembling a basic engine. Depending on the capacity, the stack part alone consists of up to 400 individual components (units) in addition to assembly components, end plates and system interfaces. The most important thing is the system technology for the operation of the stack in the vehicle. "There are more components on a fuel cell vehicle than on a pure electric vehicle, because the 'charging pole' is integrated into the vehicle and the electricity is generated on demand during the journey," says André Martin.

　　The project owners are coordinating the AutostackIndustrie project in cooperation with Ludwig Jorisson of the Ulm Research Institute ZSW. The project is funded by the German Federal Ministry of Transport and Digital Infrastructure (BMVI) in the National Innovation Program (NIP) for Hydrogen Fuel Cell Technology in the amount of 30 million euros and coordinated by NOW GmbH. Its goal is to bring the key technologies for fuel cell stack manufacturing to industrial maturity. In addition to ZSW, four original equipment manufacturers (OEMs), BMW, Daimler, Ford and Volkswagen, as well as numerous suppliers are also participating in the project. Audi has recently joined Volkswagen to develop the Fuel Cell (FC) brand.

　　The project started in 2017 and will run until the end of 2021, with three main objectives:

　　1. Automotive high-performance technology: highest power density, including lower platinum loading, full project maturity, achieving automotive target costs

　　2. Development of industrial scale economies: joint FC specifications and system interfaces, scalable FC output, common technology platform

　　3. Large-scale production capabilities: selection and evaluation of key processes, achieving automotive quality requirements, planning of fuel cell factories with annual capacity of 10,000 to 30,000 FC.

　　Leverage previous projects

　　Benefit from the results of previous projects: AutoStack (2009-2012, EU project, feasibility study) and AutoStackCore (2012-2017, EU project, technology proof of concept). Industrialization is the focus of AutostackIndustrie.

　　Martin explains: "So, with enough time, it will be possible to prepare for the production of large numbers of vehicles by developing and testing already industrialized high-speed FC manufacturing processes and to be able to meet future market requirements at the appropriate stage." Specifically, this means having a stack product manufacturing process that can be converted to industrial scale within 18 to 24 months after the project is completed. This fits in well with the plans of the German car manufacturer, which has announced an increase in the number of fuel cell (FC) vehicles from 2023 to 2024.

　　Regarding the resources allocated and the full budget of the project, Martin estimates that about two-thirds are allocated to product development, including solving scale issues, and one-third to production development. "We try to bring all the key points in the development of the stack together in one project," Martin emphasizes. "This is not about R&D, but about the product and manufacturing process," he makes clear.

　　The close cooperation between the project partners is particularly important. "It is extremely important that the experts of the main links work together during the development process," the coordinator explains. In the project, there is a main contact partner responsible for each of the main components - membrane electrode assembly (MEA), bipolar plate, gas diffusion layer (GDL) and catalyst. In addition, these responsible persons assume the roles of quality management, specification and manufacturing development.

　　The initial results of this cooperation are promising. It allows the original equipment manufacturers (OEMs) to agree on the specifications of the relevant interfaces and the basic system description. "This is a new and unique agreement", emphasizes Martin - and on the other hand, it is the result of many years of cooperation based on mutual trust. By the end of March 2020, the first stage of the stack development - "Evolution 1" - will be completed and the level achieved will be evaluated.

　　By 2021, around 60 FCs will be manufactured in two stages. They will be tested by the participating OEMs, ZSW and other project partners. Depending on the test objectives, stacks of different specifications will be used. "It is crucial for us to enter the second development phase with a robust design approach", emphasizes Martin, "in order to achieve sufficient maturity by the end of the project."

　　Challenges for long-term durability

　　There are certainly challenges to overcome before the product can reach maturity. These include long-term durability. According to Martin, the target has not yet been fully achieved. A degradation of 10% is allowed over the expected life cycle of a fuel cell vehicle of 6,000 operating hours. Basically, the membrane electrode (MEA) is affected by degradation. However, other components and the mode of operation also have an impact. For the latter, it is mainly the so-called stressors, such as temperature, pressure, humidity, etc., that are affected by dynamic load changes. Martin believes that these parameters can be adjusted to mitigate the loss of durability, but the development process of optimizing the parameters is very time-consuming.

　　An important lever is also the smooth cooperation of the main components. "Only in combination can we get the results we want. Model analysis and validation tests play an important role in the selection of the main components. There are many interdependent factors to consider in order to make the best choice," said the project coordinator. We are on the right track when it comes to reducing platinum. The platinum load of the anode can be reduced compared to previous models. What is important is that according to current calculations, the automotive target costs (in the context of mass production of about 30,000 stacks) can be achieved and reached under the premise of achieving today's charging levels and power densities.

　　Another task to be accomplished is to significantly reduce the time required for the stack startup operation. In this process, the electrochemical components of the stack are activated. The commissioning time must be reduced from hours to minutes to adapt the commissioning to the process sequence of mass production. In order to develop a suitable procedure, a lot of tests are required. Martin stressed that this example illustrates very clearly how closely product development and manufacturing process development are intertwined.

　　Nevertheless, fuel cell (FC) experts believe that the level of technological development of German FC technology is comparable to that of key competitive regions such as China, South Korea, Japan and the United States, while at the same time we should not forget the advantages that some countries have in industrialization. In the field of materials and components, German suppliers are among the world's leading technology suppliers. This is not the case with power lithium batteries, the main suppliers of which are in Asia. Therefore, the success of the Autostack industrialization project is undoubtedly of great significance for the industrial production of fuel cell vehicles. NOWGmbH

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