Poly(4-vinylbenzoicacid): A Re-Engineered Binderfor Improved Performance from Water-Free Slurry Processing for SiliconGraphite Composite Electrodes

In silicon lithium-ion batteries, polymeric binders play the crucial role of “gluing” the electrode matrix together, providing strong adhesion between the active silicon (Si) and conductive carbon particles and keeping them in electric contact, despite considerable volumetric changes during cycling. While remarkable progress has been seen in the development of binders, improved cycling performance is still needed to fully enable Si anodes. Achieving that end requires in turn a better understanding of the relationship between binder properties and cell cycling performance. In this study, we describe a novel polymer binder, poly(4-vinylbenzoic acid) (P4VBA), developed by re-engineering the widely used polyacrylic acid (PAA) binder to explore that relationship. The modified structure produces a binder that is more compatible with 1-methyl-2-pyrrolidinone (NMP) slurries and affords much improved cycling performance of the fabricated cells. Compared with PAA binders, P4VBA provides higher initial and average c...