Lithium-Ion Battery Separator Prepared by Double-Matrix Encapsulation and Penetration

A new lithium-ion battery separator and preparation method are proposed based on double-matrix encapsulation and penetration (DMEP). A coaxial nozzle was used to control the output of solutions with a certain ratio of injection rates, and DMEP was realized after spinning. The conflict between high porosity and strong tensile properties of the membrane was solved in one step. The PAN matrix is encapsulated on the fiber surface, and the DMEP membrane exhibits better surface wettability, electrolyte uptake (473.1%), and porosity (65.3%). Moreover, the tensile strength and strain until the fracture of the membrane were increased by almost 142% and 75%, respectively. This result was based on the irregular mutual penetration of the double matrixes (PAN and PVA) of the fiber and the multipoint bonding between the fibers. The DMEP membrane also shows excellent ionic conductivity (1.77 mS cm–1), thermal stability (270 °C), and electrochemical performance. The good mechanical properties, ionic conductivity, and electrochemical properties clearly indicate the potential of using PAN/PVA DMEP composite separators in lithium-ion batteries.