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Probing Clustering Dynamics between Silicon and PAA or LiPAA Slurries under Processing Conditions

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journal contribution
posted on 16.04.2021, 14:33 authored by Mary K. Burdette-Trofimov, Beth L. Armstrong, Ryan P. Murphy, Luke Heroux, Mathieu Doucet, Alexander M. Rogers, Gabriel M. Veith
This work explores the complex interplay between slurry aggregation, agglomeration, and conformation (i.e., shape) of poly­(acrylic acid) (PAA)- and lithiated PAA-based silicon slurries as a function of the shear rate and the resulting slurry homogeneity. These values were measured by small-angle neutron scattering (SANS) and rheology-coupled ultra-SANS at conditions relevant to battery electrode casting. Different binder solution preparation methods, either a ball milling (BM) process or a planetary centrifugal mixing (PCM) process, dramatically modify the resulting polymer dynamics and organization around a silicon material. This is due to the different energy profiles of mixing where the more violent and higher energy PCM causes extensive breakdown and reformation of the binder, which is now likely in a branched conformation, while the lower energy BM results in simply lower-molecular weight linear polymers. The breakdown and reorganization of the polymer structure affect silicon slurry homogeneity, which affects subsequent electrode architecture.