Given the widespread infrastructure for slurry-based battery electrode production, this method remains the predominant and most critical process route for manufacturing battery electrodes. Here, traditional rotation tests, typically conducted at fixed shear rates steps, offer quick viscosity estimates and are essential for production processes, such as mixing, coating as well as quality control. However, while these tests deliver key data on slurry viscosity, they do not capture the detailed structural interactions among the active and inactive material components within the slurry. To address this gap, our study highlights stress-controlled measurements and advanced oscillatory analyses as essential tools for a more comprehensive rheological perception.
Defining the rheological characteristics of an optimal electrode slurry is essential for enhancing electrode performance, yet this aspect is often inadequately addressed in battery slurry formulation. We examine how Large Amplitude Oscillatory Shear (LAOS) analysis provides a unique opportunity to address this challenge by examining non-linear behaviour and complex structural responses within the slurry under realistic processing conditions. As rheological testing beyond basic viscosity measurement remains uncommon in battery research, we delve into a specific approach that incorporates both linear and non-linear rheological testing for a more complete analysis of stability, viscoelasticity, and component interactions.
In our study, various parameters—including binder type (CMC,SBR), solids content (up to 60 wt%), and choice of active materials (Carbon based, Sodium)—were systematically varied to observe effects on flow behaviour, viscosity, and the stability of slurries. Additionally, we address practical challenges encountered with highly filled suspensions, mixtures containing a large volume of solid particles dispersed within a liquid medium which gives the suspension unique properties like shear thinning, resulting in measuring with oscillatory methods and propose steps to ensure high-quality, reliable rheological data.
The insights gained from this study establish a valuable knowledge framework to optimize slurry formulation in regards to the inactive part and improve electrode consistency and performance in battery production.