High-performance separator for lithium-ion battery based on dual-hybridizing of materials and processes

Abstract

• The composite separator had high mechanical strength after heat treatment. • The composite separator had high porosity and electrolyte uptake after hydrolysis. • After heat treatment and hydrolysis, the composite separator had a complete profile at 200 °C. • After heat treatment and hydrolysis, the composite separator had a satisfactory performance. A preparation method for a lithium-ion battery separator was developed based on the dual hybridizing of materials and processes. This preparation method aimed to prepare a new composite separator by electrospinning various polymer materials with different properties. In addition to the characteristics of each material, multiple corresponding processes were used for post-treatment of the composite separator to enhance the comprehensive performance of the separator. The prepared composite separator polyacrylonitrile (PAN) / polyvinylidene fluoride hexafluoropropylene (PVDF-HFP) / Polyvinyl Pyrrolidone (PVP) allows the use of various raw materials. PAN with high thermal stability is suitable as a framework to support the separator structure. PVDF-HFP are binders that can crosslink the fibers after heat treatment (HT), thereby increasing the tensile strength of the separator threefold. PVP, which is easily soluble in water, was used as a pore-forming agent. After hydrolysis (HD), the fiber of the separator formed a porous structure with high porosity, high electrolyte absorption, and high ionic conductivity. After a heat treatment combined with hydrolysis (HT-HD) to improve the mechanical strength and porosity, the composite separator showed excellent thermal dimensional stability. Its profile integrity was maintained, even at 200 °C. The HT-HD separator produced outstanding electrochemical performance. Hence, the HT-HD separator with comprehensive performance has potential applications in lithium-ion batteries.