PEM Researches Faster Electrolyte Filling

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The chair "Production Engineering of E-Mobility Components" (PEM) of RWTH Aachen University, together with numerous other institutes, is investigating the filling and wetting of lithium-ion batteries as part of the "Cell-Fill" project. The primary goal of the joint project is to expand the understanding of the process and to develop a time- and cost-optimized filling and wetting strategy. The plan is to reduce the time required for filling electrolytes by 30 percent. The project is part of the federally funded competence cluster ProZell.

Method for characterizing battery wetting state

The PEM team's focus is on optimizing the material by surface modifying the separator during the stacking process using an inline method. To do this, the researchers will investigate different modification processes and agents on different separators. In the end, an inline-capable characterization method of the wetting state of a large-format lithium-ion battery is to be developed.

Filling state hardly an issue despite optimization potential

The background to the project is that battery cell production has to date been a cost-intesive process due to the high safety and environmental requirements. Electrolyte filling is of particular importance in this context. In this production step, the cell is stored for several hours after filling the electrolyte to ensure complete wetting of the separator with the electrolyte liquid. While it is considered certain that increasing the speed and throughput in this process step would generate an elementary improvement in economic efficiency, little scientific attention has been paid to the study of the filling process.



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The project

  • "Cell-Fill": Process-structure-property relationship for filling and wetting processes of large-size lithium-ion batteries

Research objectives

  • Expansion of process understanding and development of a time- and cost-optimized filling and wetting strategy for third-generation cells
    • Further development of process structure and quality property functions
    • Reduction of process times through use of innovative electrolytes
    • Development and validation of guidelines for a cell design suitable for filling and processes
    • Simulative description of the micro- and macroscopic wetting processes in lithium-ion batteries
  • Development and validation of an inline-capable analysis method for process control of the filling process based on ultrasound
  • Transfer of process knowledge to the infiltration of cathode composites with solid-state electrolyte slurries for ASSB production

Research and project partners

Institute of Machine Tools and Production Technology (IWF) (TU Braunschweig) (project coordinator)
PEM of RWTH Aachen University
Institute for Machine Tools and Industrial Management (iwb) (TU Munich)
Münster Electrochemical Energy Technology (MEET) (WWU Münster)
Fraunhofer Institute for Industrial Mathematics (ITWM)
Fraunhofer Institute for Ceramic Technologies and Systems (IKTS)
Fraunhofer Institute for Silicate Research (ISC)


  • 10/01/2019 through 03/31/2023

Project management

Projektträger Jülich (PtJ)

Funding code

  • 03XP0237E


Federal Ministry of Education and Research (BMBF)