Do non-coordinating polymers function as host materials for solid polymer electrolytes? The case of PVdF-HFP

In the search for novel solid polymer electrolytes (SPEs), primarily targeting battery applications, a range of different polymers is currently being explored. In this context, the non-coordinating poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) polymer is a frequently utilized system. Considering that PVdF-HFP should be a poor solvent for cation salts, it is counterintuitive that this is a functional host material for SPEs. Here, we do an in-depth study of the salt dissolution properties and ionic conductivity of PVdF-HFP-based electrolytes, using two different fabrication methods and also employing a low-molecular-weight solvent analogue. It is seen that PVdF-HFP is remarkably poor as an SPE host, despite its comparatively high dielectric constant, and that the salt dissolution properties instead are controlled by fluorophilic interactions of the anion with the polymer.

Automated summary

By studying the salt dissolution properties and ionic conductivity of PVdF-HFP-based electrolytes using different fabrication methods and a low-molecular-weight solvent analogue, it is found that PVdF-HFP is a poor host for solid polymer electrolytes despite its high dielectric constant. The salt dissolution properties are instead controlled by fluorophilic interactions between the anion and the polymer.