Poly(Vinylidene Fluoride)-Based Blends as New Binders for Lithium-Ion Batteries

Polymer binder plays a critical role in controlling the microstructure of electrode composites. Compared to synthesizing new binder molecules, polymer blends combining the advantages of different polymers represent a low-cost, facile, and effective strategy for the design of advanced binder systems. In this study, we aim to improve the poly(vinylidene fluoride) (PVDF) binder performance by blending with other functional polymers, including polyethylene-block-poly(ethylene glycol) (PE-PEG) co-polymer and poly(propylene carbonates) (PPCs). It is found that the PE-PEG co-polymer acting as a surfactant for carbon black (CB) can improve the dispersion of CB and, thus, result in a more uniform conductive network in the electrode composites. The addition of PPC, an amorphous polymer with good affinity to liquid electrolytes, can reduce the crystallinity of PVDF and improve the component interactions. Benefiting from the improved structure uniformity, the specific capacity and Crate performance of the resultant electrodes were notably improved, as compared with that of pure PVDF binder. These results indicate that polymer blending is a facile method to modify the PVDF binder and improve the uniformity and interfaces of electrode composites.