Plasma treatment of polypropylene membranes coated with zeolite/organic binder layers: Assessment of separator performance in lithium-ion batteries

Abstract

This work aims at improving the state-of-the art of lithium-ion battery (LIB) scientific know-how by presenting a new fabrication protocol for the separator element. A polypropylene (PP) separator is coated on both sides with 4A zeolite using PVDF as binder, and then plasma treated from both sides. The novel separator possesses a substantial higher LiPF6 electrolyte wettability, uptake and ionic conductivity compared to the sole plasma treated PP, PP coated with zeolite 4A on both sides and the PP itself. This behavior is ascribed to the partial disintegration of PVDF polymer upon plasma treatment and the creation of oxygenated groups on its particles and on the internal surface of the PP separator, together with substantial porosity increase of the latter. Using a Li(Ni0.8Co0.1Mn0.1)O2/separator/Li metal coin-cell assembly, it is shown that the cell performance in terms of rate capability is increased more than 30% at C rates of 0.1, 0.2, 0.5 and 1.0 with respect to the LIB constructed using the pristine PP separator.