Integrated Product and Process Model for Production System Design and Quality Assurance for EV Battery Cells

Abstract

The megatrend electric mobility induces a significant demand for high energy and high power secondary batteries. Currently lithium-ion technologies are the most promising solution for electrochemical energy storage in hybrid electric vehicles (HEV) and battery electric vehicles (BEV) [1; .Core factors that influence the quality, the performance and the cost of high energy lithium-ion batteries are production technologies, quality measurement techniques and quality management methods [3; . For this reason the Institute for Machine Tools and Industrial Management set up the Research Center for the Production of High-Energy Battery Cells (R-PHEB). In this research center production technologies are investigated according to industrial requirements. Research thrust areas are: first, process and assembly system design; second, quality assurance and management; and third, value chain analysis and design.The mass production of large lithium-ion cells for EV applications is an infant industry; new production technologies are often used in this field [. Hence, the influences of those processes on product properties are not known and the product quality can be evaluated only after the final production step. In order to obtain a resource efficient and economic production of lithium-ion cells, the correlations between the cell performance, the cell quality, the production processes and the assembly system design need to be revealed.This paper focuses on fundamental investigations of the process chain for the production of lithium-ion cells. It introduces a product-and a process-model, both of which specifically match the requirements in the field of battery production. The models can be used individually to describe the product structure or the process chain. Additionally they can be linked via a correlation matrix in order to visualize the dependencies between the requirement specifications of lithium-ion cells and the manufacturing processes (including process alternatives). Both models are based on a layered structure and contain information about battery cell design, battery type and production processes covering all tasks from coating the electrode coils to the start-of-operation of the cells.The product-model, the process-model and the correlation matrix will be implemented in a database, which in the future can be used for the methodical design of assembly systems as well as to investigate the correlations between process parameters and output quality. Furthermore, the database can assist when evaluating established process chains or preparing make-or-buy decisions in the context of battery cell production.

Investigation of the Influence of Deposition Accuracy of Electrodes on the Electrochemical Properties of Lithium‐Ion Batteries

“…In current industrial ESA production, an in‐line image processing is used to monitor the deposition accuracy of each electrode. The in‐line monitoring requires cost‐intensive hardware and often reduce the cycle time but is never the less used to analyse the deposition accuracy without knowing the actual effect of deposition errors. To reduce the risk of unwanted and mostly unknown effects of deposition errors, research strives to further increase the accuracy of stacking, and z ‐folding processes maybe beyond reasoning.…”

“…This article focuses on the process of building the ESA. To date, three methods prevail for ESA assembly, which differ in the feeding of materials . In winding, the separator and the electrode webs are continuously fed into the winding process around a winding core.…”

“…Existing experimental setups achieve an accuracy of ±2.5 mm, ±0.1 mm, and ±8 µm . Kurfer et al and Reinhart et al recommend that the anode should be circularly 2 mm larger than cathodes to compensate for handling deviations.…”

Including product features in process redesign

“…The way of linking the models is furthermore important, as it should highlight the problems in the process as effectively as possible. Compared with the matrix based methods of Reinhart et al (2014) and Nilsson and Fagerström (2003) the method presented here is more visually expressive. The method of listing the process steps where the features are specified, gives an immediate overview of possible process insufficiencies including features, which are repetitively entered.…”

“…In product development, the link between product architecture and manufacturing has been suggested to make the designers more aware of the limitations of the manufacturing process and to optimise quality attributes resulting from the manufacturing or life cycle processes (Tönshoff and Zwick, 1998). Reinhart et al (2014) present a framework for combining the product structure and production processes in the design of electric-vehicle (EV) battery cells, where production processes directly affect the achievable product quality enabling the design of manufacturing systems that result in the optimal product quality. The models are integrated via a correlation matrix, mapping the influences of production parameters on specific product attributes.…”