Rational designing of tree-like polymer gel membrane based on PVDF/lamellar organic montmorillonite nanofiber with excellent flame retardancy and superior ion conductivity for high-performance lithium-ion capacitor

Abstract A tree-like structured gel nanofibrous membrane (TLNM) including lamellar organic montmorillonite (OMMT) is designed and prepared via one-step electrospinning method. And its application as promising separator for lithium-ion capacitor were systematically researched. Based on the special structure and the addition of lamellar OMMT, the TLNMs are endowed improved mechanical performance, excellent thermal stability and flame-retardant, and good electrochemical properties for Li ion capacitor (LIC). As a result, the nanofibrous membranes exhibits enhanced electrolyte uptake performance (~870%, with an electrolyte contact angel of 0°) and robust thermal dimensional stability (stable at 160°C for 1.5 h). Furthermore, the limiting oxygen index of this membrane is as high as ~30%, which can significatively improve the safety of the nanofiber separator. And the assembled Li ion capacitor with the membrane presented superior ion conductivity (3.95*10−3 S cm−1). Additionally, the LIC also shows enhanced cycling stability (~60% capacity retention after 10,000 cycles at 0.5C), and favorable rate capability. All of the results indicate that the novel polymer gel membrane including excellent flame retardancy and superior ion conductivity is expected to be used for high-performance lithium-ion capacitor.