Construction of strengthened crosslinked polymer coating using liquid-like nanoparticle on polyphenylene sulfide nonwoven as separator: Improved cycling performance in lithium-ion battery

Nonwoven-based separators have aroused widespread interest in the development of high-power lithium-ion battery (LIB). However, their commonly used coating, gel polymer electrolyte, is easily to shed off from the substrate during long-term swollen by electrolyte, thus further leading to micro-short circuit phenomenon and poor cycling performance. In this study, strengthened three-dimensional (3D) crosslinked coatings with different ratios of silica-based nanofluid were constructed on polyphenylene sulfide (PPS) nonwoven to give composite separators 3D. Compared with traditional nanoparticle, silica-based nanofluid has liquid-like property and is less prone to aggregation in polymer matrix. Importantly, amine terminal groups can be introduced when preparing fluid molecules, which will react with fluorinated polymer matrix to give strengthened 3D crosslinked coating. When the ratio of PVDF-HFP: fluid is fixed at 10:1, the porosity, electrolyte uptake and wettability, electrochemical performance of separator are found to display the optimum value, which finally endow battery with better discharge capacity (160.3 mAh g−1, 0.2 C). In addition, this composite separator is discovered to own superior tensile strength and Young’s modulus. This strengthened structure also makes separator withstand the oxidative decomposition potential up to 5.32 V and provides battery with excellent discharge performance retention (98.5%) even after 100 cycles. Therefore, this study will pioneer a new avenue for separator to realize higher mechanical and cycling performance. [Display omitted]