Hollow mesoporous silica sphere-embedded composite separator for high-performance lithium-ion battery

Abstract

A high-performance composite separator based on hollow mesoporous silica spheres, poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), and poly(ethylene terephthalate) nonwoven was explored as lithium-ion battery separator via a dip coating technique followed by a phase separation wet process. Systematical investigations including morphology characterization, porosity measurement, electrolyte wettability, thermal shrinkage testing, and cell performance examination are carried out. It is demonstrated that the unique mesoporous structures of silica spheres endow the composite separator with well-defined microporous structure. Owing to the preferable microstructure and relatively polar constituents, the composite separator exhibits higher porosity, superior electrolyte wettability, and outstanding thermal stability. Based on the above advantages, the composite separator shows better electrochemical performances, such as the discharge C-rate capability and cycling performance, as compared to the commercialized PE separator. This research presents a simple approach to prepare high-performance separator, which is demonstrated to be a good candidate for lithium-ion batteries.