Swelling and plasticization of polymeric binders by Li-containing carbonate electrolytes using quartz crystal microbalance with dissipation

Lithium ion battery electrodes are highly engineered, but their performance can be impacted by the properties of the polymeric binder in the electrode. Here, the swelling and plasticization of PVDF, PAA, BPEI and SEPDM by common carbonate-based electrolytes is probed using quartz crystal microbalance with dissipation (QCM-D). The swelling of the PVDF increased with increasing temperature and decreased slightly with addition of Li salt. The composition of ethylene and propylene carbonate in the electrolyte impacts the swelling more significantly than salt selection. Despite the large differences in the swelling (25%–75%), the high frequency shear modulus of the swollen PVDF remains nearly invariant for all conditions examined, which is attributed to its semi-crystalline network. In contrast, BPEI, SEPDM, and PAA are marginally swollen by carbonate electrolytes. These measurements provide insight into the electrolyte-binder interactions to help select pairs for emerging high-performance electrodes.