Modelling and Understanding the Mechanism of Electrode Densification for Sulfidic All-Solid-State Lithium-Ion Batteries

• Applicant: Dr. Peter Michalowski
• Subject Area: Synthesis and Properties of Functional Materials ; Glass, Ceramics and Derived Composites ; Mechanical Process Engineering
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 514726960

All-solid-state batteries (ASSBs), in which the flammable electrolyte is replaced by an inorganic powder solid electrolyte (SE), are expected to be next-generation rechargeable batteries with high capacity, charge/discharge rate, and safety. In conventional liquid-based batteries, the solid-liquid interface is formed spontaneously as the electrolyte permeates the voids between active material particles. On the other hand, in ASSBs, the solid-solid interface must be artificially constructed, and high-density electrodes must be fabricated by compression. The manufacturing process currently under consideration requires an expensive slurry processing of wet coating and drying followed by a batch-type compression process with ultra-high loads and extended holding times. The slurry and compression processes are the bottlenecks for the practical application of ASSBs. Truly understanding the “electrode densification (compression) mechanism” is crucial to overcoming the current challenges.In this project, Osaka Metropolitan University (OMU) in Japan and the Institute for Particle Technology (iPAT) at Technical University of Braunschweig in Germany will team up to solve the current challenges in ASSB manufacturing processes. The OMU will mainly provide a dry composite technology and numerical modeling for the compression process. At the same time, the iPAT will contribute to the ASSB field through its experience in investigating conventional liquid-based batteries from lab to pilot scale, namely silicon as an anode active material and high-viscous electrode processing, as well as the mechanochemical synthesis of SE.To elucidate the mechanism of electrode densification and propose an optimal coating-drying and compression process, the following four points are the purposes of this study:i) Investigating the influence of the particle sizes of SE and anode active materials and the structure of the coated particles on the electrode structure and hence the battery performanceii) Measurement of pressure change related to a densification strategy to investigate battery performance degradation due to chemo-mechanical volume changes in the electrode during cyclingiii) Elucidation of electrode densification mechanism based on numerical analysis of the compression process and search for conductive pathwaysiv) Systematic investigation of slurry processing and calendering compression process from a cost-saving and ecological point of viewThis project will significantly improve the understanding of the processing of solid electrolytes with different mechanical behavior, particle contacting, and densification procedure. It can give concrete recommendations for the scalable processing of ASSBs.

• DFG Programme: Research Grants
• International Connection: Japan
• Co-Investigators: Dr.-Ing. Christine Friederike Burmeister; Professor Dr.-Ing. Arno Kwade; Dr.-Ing. Kevin Voges
• Cooperation Partners: Dr. Eiji Hayakawa; Dr. Hideya Nakamura; Dr. Shuji Ohsaki; Professor Dr. Satoru Watano