Model-Based Optimization of Web Tension Control for the Flexible Cell Stack Assembly of Lithium-Ion Battery Cells

Abstract

The transformation toward electromobility presents a significant challenge to the battery cell production processes. It is, therefore, necessary to establish efficient and robust operations and machines to meet the forecasted demand for manufactured cell capacity. Currently, the development and ramp-up phases of production machines, especially for cell stack assembly, are characterized by high material scrap rates and large personnel expenses. Aspects such as the web tension of electrodes or separator materials during separation and stack assembly have a significant influence on the subsequent intermediate product properties, and therefore present a key challenge. Herein, the optimal methodology for the web tension control of electrode materials is determined via a model-based approach by the means of a digital twin. The focus is hereby set on a production machine for the flexible cell stack assembly. Appropriate control methods are implemented and validated on the real system, thus reducing material scrap rates and overall costs. The control of the web tension by means of an unwinder and material storage was found to be optimal on the basis of the model and confirmed experimentally.