Manufacturing of tabless cylindrical lithium-ion cells: Quantifying the influence of cell dimensions and housing material via process-based cost modeling

The cost saving potential of large-format tabless cylindrical lithium-ion cells has been widely recognized since Tesla announced their plans to produce and BMW has confirmed to adopt this type of cells due to economic benefits among other reasons. However, a quantification and deep analysis of the cost reduction emerging from enlarged dimensions and further innovations such as different housing materials has not been reported in scientific literature so far. In this study, the process steps of manufacturing a large-format tabless cylindrical cell are examined and published in detail for the first time. A model is established that incorporates all manufacturing steps as a function of cell dimensions and choice of housing material. It was found that enlarging the dimensions from the conventional 2170 to the 4680 format achieved a cost reduction of 10.9% for two main reasons. First, the manufacturing cost per kWh decreases due to certain manufacturing steps being directly dependent on the number of cells produced. Second, the cells volumetric energy density itself increases due to a better volume efficiency of the active material share which further decreases the number of cells required. Introducing aluminum housings offers additional cost saving potential of as much as 2.5% of the total cost of 4680 cells due to an efficient backwards impact extrusion manufacturing process and lower cost of the aluminum raw material compared to nickel-plated steel.