Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM
Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM
© Fraunhofer IFAM

© Fraunhofer IFAM

Battery laboratory for the development of solid-state batteries

Technologies for processing of solid-state battery materials and cell assembly under inert atmosphere (glovebox)

Currently, in particular the automotive industry is focusing on the solid-state battery for electric vehicles. New materials and manufacturing processes are needed for the development of rechargeable batteries based on solid-state technology, in which solid instead of liquid electrolytes are used. Fraunhofer IFAM is investigating different techniques for the development and processing of raw materials as well as the cell assembly of solid-state batteries. In the battery laboratory, all methods can be applied in a micro-environment using a glovebox under inert atmosphere.

 

Technologies for every step of battery development   

The battery laboratory at Fraunhofer IFAM has the suitable technologies for each step of battery development:

 

Material development Selection of the right materials is important for the successful development of a solid-state battery. In addition to selecting the right storage materials/active materials, the correct use of additives such as conductive additives and binders is particularly crucial.
For the evaluation of individual materials (binder systems) in conjunction with other components, Fraunhofer IFAM relies on extensive chemical analytical methods (NMR, XPS, XRD, SEM), which allow sample transfer under inert conditions, as well as electrochemical methods.
Karl Fischer titration is used for quality control of the starting materials.
Slurry / composite development For the preparation of solvent-based dispersions (pastes / slurries) for the production of coating compounds, different mixing aggregates such as stirrers with various mixing heads or mixers (intensive mixer, paddle mixer) are available. Alternatively, a three roll mill can be used for homogenization.
A twin-screw extruder is available at Fraunhofer IFAM for the evaluation of innovative mixing processes without the use of solvents.
Accompanying the formulation development, analytical methods are available to determine the essential process parameters (such as viscometry and surface tension) under argon atmosphere.
© Fraunhofer IFAM
Twin-screw extruder under inert conditions.
© Fraunhofer IFAM
Eirich-mixer for large scale slurry preparation.
© Fraunhofer IFAM
Femix-mixer for dry processing of thermoplastic polymers.
Coating technology for component development The production of individual battery components (cathode and electrolyte / separator) on a small scale for material evaluation is carried out by means of automatic film applicator and doctor blade technology. The different widths and film thicknesses are realized using different doctor blades.
For the application of thin films on a larger scale, a sheet-to-sheet slot die coater is available.
Screen printing equipment is available as an alternative technique for the production of solid-state batteries.
A glovebox is equipped for physical vapor deposition (PVD) for the application of thin lithium metal anodes as well as the deposition of intermediary layers in Li-free cell concepts.
© Fraunhofer IFAM
Slot die coater under inert conditions.
© Fraunhofer IFAM
Testing screen printing as an innovative technology for electrode production.
© Fraunhofer IFAM
Sputtering system integrated in glovebox for PVD processes.
Cell assembly (pressing, calendering, compaction) For the performance of the solid-state battery, the joining of the individual layers is a significant process step. For this purpose, hydraulic presses and a laboratory calander are available for cell assembly. The applied pressure can be detected in a spatially resolved manner.
Measurement technology For electrochemical characterisation, several potentiostats and cell test systems are available. The tests can be conducted under controlled environmental conditions.
For post-mortem analysis, scanning electron microscopy (SEM) under inert condition is used.
© Fraunhofer IFAM
Calander for compaction and transfer of solid-state cell components.
© Fraunhofer IFAM
Pressure setup for solid-state battery cycling.

Glovebox: Manufacturing of solid-state batteries in micro-environment

Many materials that are considered for use as electrolytes in solid-state batteries are not stable under normal ambient conditions. Either they are hydrophilic, i.e. they collect water from the ambient air, or they even react with water or oxygen. This leads to a reduction in performance in the final battery and must be avoided at all costs during cell assembly. To protect sensitive materials from moisture and air, they are handled in micro-environments under inert gas (argon). Working in gloveboxes allows ideal control of the environmental conditions, which can be transferred to the requirements of later scaled production steps. Here, we are primarily answering the question of whether battery cell production should also take place in micro-environments or in large dry rooms from an economic and ecological point of view.

 

Exemplary applications of the technologies in BMBF projects

Alternative anode concepts for safe solid-state batteries - ALANO (BMBF)  

The tasks of Fraunhofer IFAM in the sub-project "Processing, manufacturing and recycling of lithium metal solid-state batteries" include, on the one hand, production of cell components such as separators and composite cathodes based on sulfide ion conductors and, on the other hand, full cell assembly with the anode systems developed by project partners. The cell components are successively adapted based on the knowledge gained in the overall project. In addition to the type and quantity of polymer binders used, the process techniques will also be optimized to improve the microstructure and mechanical properties. Then, full cells will be produced in the form of pouch cells employing the lithium metal anodes developed in the overall project. The aim here is to evaluate both possible cell designs (e.g. monopolar / bipolar) and the necessary operating conditions (temperature and pressure).

Continuous, solvent-free electrode production with intelligent quality assurance and process monitoring coupled with AI - KontElPro (BMBF Competence Cluster Intelligent Battery Cell Production - InZePro)

The aim of KontElPro is to extend existing, innovative and well-scalable processes for solvent-free electrode manufacturing (extrusion, dry transfer processes) with inline process control and a cross-site, networked database. Fraunhofer IFAM is optimizing extrusion processes for the continuous production of battery components by monitoring and controlling process parameters. In the project, polymer electrolytes are extruded and the process data temperature, torque, and pressure are recorded. In the course of developing a digital workflow, the process data will be evaluated with the project partners.

 

Cell platform Thiophosphates - FB2-Thio (BMBF competence cluster for solid-state batteries - FestBatt) 

At Fraunhofer IFAM, the focus of the sub-project "Process technology for the production of thiophosphate-based solid-state battery cells" (PhatBatt) is on the processing of thiophosphate-based separators using scalable methods. For this purpose, the use of a slot die coating in particular is pursued as a novel approach. On the one hand, chemically stable and rheologically adapted slurries have to be produced and, on the other hand, the process parameters have to be evaluated. In addition, this method will also be used directly for cell construction by coating separators directly onto composite electrodes.

 

Cross-sectional Platform Production - FB2-Prod (BMBF Competence Cluster for Solid-state Batteries - FestBatt)

The central goal of the project is the research and development of a scalable, quality-assured production of high-performance solid-state batteries based on the solid electrolytes investigated in the cell platforms. To this end, the consortium is mapping the entire chain of production on a small pilot scale starting with the production of composite cathodes and separators of the various material classes using different scalable approaches to cell assembly and conditioning, as well as electrochemical characterization, to both an economic and ecological evaluation of the complete production process. At Fraunhofer IFAM, processes for manufacturing of polymer-based separators are being developed. Processes for the production of free-standing polymer separators as well as for direct application on composite cathodes are considered. Reproducibility is continuously improved over the course of the project by selecting suitable processes (doctor blade, slot die, printing) and adjusting the process parameters (application speed, temperature).

 

Alternative process technology: solid-state batteries with 3D printing technologies

3D printing represents a novel process technology for manufacturing battery cell components such as separators, cathodes, and anodes. Based on the expertise of Fraunhofer IFAM in additive manufacturing technologies, manufacturing scenarios are being evaluated which produce solid-state batteries which can be flexibly adapted to demanding installation spaces.