Influence of the Inclusion of Propylene Carbonate Electrolyte Solvent on the Microstructure and Thermal and Mechanical Stability of Poly(l-lactic acid) and Poly(vinylidene fluoride-co-hexafluoropropylene) Battery Separator Membranes

The influence ofthe inclusion of the organic solvent propylenecarbonate (PC) in microporous membranes based on poly-(l-lacticacid) (PLLA) and poly-(vinylidene fluoride-co-hexafluoropropylene)P-(VDF-HFP) has been studied based on its relevance for the applicationof those separator membranes in lithium-ion batteries. The membraneshave been produced through solvent casting and characterized withrespect to the swelling ratio originated by the uptake of the organicsolvent. The organic solvent uptake affects the porous microstructureand crystalline phase of both membrane types. The organic solventuptake amount affects the crystal size of the membranes as a consequenceof the interaction between the solvent and the polymer, since thepresence of the solvent modifies the melting process of the polymercrystals due to a freezing temperature depression effect. It is alsoshown that the organic solvent partially penetrates into the amorphousphase of the polymer, leading to a mechanical plasticizing effect.Thus, the interaction between the organic solvent and the porous membraneis essential to properly tailor membrane properties, which in turnwill affect lithium-ion battery performance.

Automated summary

The influence of propylene carbonate (PC), an organic solvent, on microporous membranes based on PLLA and P-VDF-HFP has been studied. The swelling ratio, microstructure, and crystalline phase of the membranes were affected by the uptake of the organic solvent. The organic solvent also modified the crystal size and partially penetrated into the amorphous phase of the polymer, leading to a mechanical plasticizing effect. The interaction between the organic solvent and the membrane plays a crucial role in tailoring the membrane properties and affecting lithium-ion battery performance.