In electromobility, ensuring the quality of lithium-ion batteries along the manufacturing process and balancing environmental compatibility and economic efficiency is a key task. In battery manufacturing, a significant fraction of energy consumption results from the running of drying rooms, which are used to create a low-moisture process atmosphere. One process step that requires this special process atmosphere is cell production. This is due to quality-degrading reactions of cell components with water. In particular, the electrodes and electrolyte of lithium-ion batteries show an increased hygroscopic as well as reactive behavior with water, so that the atmospheric moisture content has an influence on the electrochemical properties of the cell. To determine the moisture of the atmosphere, the dew point is measured by means of a dew point mirror. Due to insufficient knowledge of required moisture contents of the process atmosphere during cell production with high energy materials, the selected dew point is often oversized to guarantee the quality targets. A high energy saving potential can be realized by a dew point optimization based on real requirements.
In this work, at the beginning, a detailed experimental design is elaborated, which includes the experimental scope and the manufacturing parameters (dew point, exposure time). Using a moisture setting test station, the electrodes are exposed to an atmosphere with a precisely set dew point for a specified period of time. Test cells are then assembled from the electrodes of the different atmospheres. The battery cells are characterized in terms of their electrochemical properties and compared with one another. Based on the test results, the influence of moisture during the manufacturing process can be deduced and a better understanding of necessary measures for moisture control in battery manufacturing can be generated. The knowledge gained can reduce manufacturing costs and increase environmental compatibility.