Experimental investigation of the multi-layer wetting behavior of electrode-separator-composites in lithium-ion batteries

The success of lithium-ion batteries and their application in electromobility is highly dependent on their scalable and cost-efficient manufacturing. Herein, electrolyte filling and wetting are time-consuming and quality-critical process steps, which have been, on the material level, primarily researched on an intra-material level for single-cell components while lacking overarching investigations for inter-material effects during wetting. This study demonstrates for the first time an experimental methodology designed to systematically quantify the interaction effects between different electrode-separator-composites during wetting by varying product components and process parameters. The investigation reveals a quantifiable interaction within a two- or three-layer material combination of anode, separator, and cathode, which can be discerned into distinct anode and cathode interaction effects, maintaining consistency across the product and parameter variations. Through the analysis of activation energy using the Arrhenius equation, the study observe a combinatorial relationship for modeling multi-layer wetting. Multi-layer wetting rates increase by 215 % compared to single material rates. Higher temperatures boost penetration rates due to lower viscosity, but reduce the interaction effect. These insights contribute to an application-orientated understanding of electrode-separator-composite wetting behavior and open up more possibilities for an optimized manufacturing process through expanding methodical exploration of strategies for counterbalancing poor wettability. • Multi-layer wetting is quantifiable via interaction effect measurement method. • Multi-layer wetting rates increase by at least 215 % over single material rates. • Multi-layer wetting reduces intra-material wetting differences in separators. • NMC811 cathodes show higher interaction effects than NMC622.