Battery Cell Production

Our R&D Activities on the Topic "Battery Cell Production" Include:

• Assembly of Pouch Cells
• Process Optimization in-Cell Assembly
• Characterization, Post-Mortem Investigations, and Safety Tests
• Digitization and Traceability in Cell Production
• Validation of New Battery Technologies and Sensor Concepts

With our cell production line, we manufacture pouch cells in electrode formats ranging from 50x50 to 200x200 mm² (standard format 120x70 mm²) as single or multi-layer cells. Thanks to our flexible production, we are able to test various materials such as active and binder materials as well as conductive additives in the electrodes, separators, electrolytes, housing and materials for the lead tabs in a commercial battery cell format and under controlled atmospheric conditions.   

The cell stack is assembled fully automatically with high electrode placement accuracy using a continuous z-folding process or single-sheet stacking. The pouch cell is completed via the processes of ultrasonic welding of the electrodes and the lead tab, pouch film preperation including deep drawing, heat sealing of the pouch film, and electrolyte filling in a vacuum chamber. After a defined wetting time, the cell is formated (under defined axial pressure) and cycled after degassing.

We offer process optimization for all stages in the cell production. In the mechanical punching production step, for example, the web edge quality can be visually checked after the punching process. In the area of stacking, we validate gripping and holding properties on Bernoulli and vacuum suction grippers and test the processability of various separator materials. Processes can also be optimized in ultrasonic welding, for example by adjusting parameters such as pressure, energy, and time. For composite film, both the deep-drawing behavior can be optimized by adjusting the hold-down pressure, speed, depth, and acceleration or deceleration, and the sealing properties can be modified by adjusting the temperature, time, and pressure. In the electrolyte filling process, we can flush the vacuum chamber with different inert gases (argon, nitrogen), are flexible in setting the pressure profiles for filling and degassing within safety limits, and can fill different electrolytes into the pouch cells in a single or multi-stage filling process, for example as part of an electrolyte study.

The characterization of our pouch cells includes electrochemical tests for aging and performance behavior, high and low temperature behavior, and tests with electronic impedance spectroscopy (EIS). The pouch cells are axially pressurized in a modular cell carrier. Formation and cycling take place in climate chambers. 

In addition, our characterization equipment allows us to mechanically test battery materials such as electrodes, separators, and housing materials for adhesion, tensile strength, peel strength, and other mechanical properties. 

Furthermore, we are able to use a special test bench to quantitatively determine the expansion of pouch cells during current application in a uniaxial and three-dimensional manner. 

In addition to electrochemical and mechanical tests, we can also examine pouch cells post mortem, i.e., after they have reached their defined service life limits. Here, we can analyze deposits on the electrode materials or examine the electrolyte, for example. Our reinforced bunker rooms also allow safety-critical tests to be carried out, e.g., overloading, cell behavior as a result of overheating, and mechanical misuse. 

With a specially developed digitalization solution, we can track and store machine and process data of our cell assembly machines as well as infrastructure data from our dry room (e.g., dew point) in real time. These parameters can be made available upon request and after prior clarification. 

In order to document materials from top (e.g., electrical cell parameters) to bottom (e.g., active mass fractions in the electrodes), we are currently developing and implementing a “track & trace” solution that allows materials to be labled and then scanned. 

With our production line for pouch cells, we can also validate and test other battery technologies and their materials. Sodium-ion technology is a drop-in technology regarding to the lithium-ion technology, meaning that sodium-ion pouch cells can be manufactured and characterized quickly and without major modifications in an existing line for lithium-ion cells. (All-)solid-state pouch cells can also be manufactured on the line. 

In addition to other cell technologies, there is also the option of validating promising new sensor concepts in an industry-oriented environment. All of the processes and equipment described are available for this purpose, from mechanical separation of the electrodes to electrolyte filling.