The impact of binder polarity on the properties of aqueously processed positive and negative electrodes for lithium-ion batteries

The surface free energy of materials plays a crucial role in defining the interactions between interfaces. In this study, we introduce the theory behind surface free energy and extend its application to solvent-based manufacturing processes of positive (cathode) and negative (anode) electrodes for lithium-ion batteries. By employing binders, namely polyvinylidene difluoride latices and sodium carboxymethyl cellulose, with differing surface free energy compositions, we systematically investigate how surface free energy influences key electrode properties. The binder properties are shown to affect adhesion strength, electrical resistance, and water retention in electrodes, with analogous effects observed in both cathodes and anodes. For cathodes, these differences translate to measurable impacts on cell performance, particularly in terms of rate capability and long-term cycling stability. We also explore how binder induced variations in water retention influence the formation and stability of the solid electrolyte interphase. The findings highlight the critical role of the binder's surface free energy composition in optimizing electrode manufacturing and provide new insights into the interplay between electrode surface chemistry, microstructure, and electrochemical performance.