Lithium-Ion Battery\nSeparator with Dual Safety of\nRegulated Lithium Dendrite Growth and Thermal Closure by Assisted\nAssembly Technology

Lithium\nmetal batteries offer a huge opportunity to develop energy\nstorage systems with high energy density and high discharge platforms.\nHowever, the battery is prone to thermal runaway and the problem of\nlithium dendrites accompanied by high energy density and excessive\ncharge and discharge. This study presents an assisted assembly technique\n(AAT) based on flexible barium titanate (BTO) and poly(vinylidene\nfluoride-<i>co</i>-hexafluoropropylene) (PVDF-HFP) nanofibers\nfor preparation of a battery separator. AAT was used to combine the\nBTO diaphragms with high thermal stability and the PVDF-HFP diaphragms\nwith good Elasticity and piezoelectricity, and the thermal stability\nwas improved by 200 and 125% increase in battery cycle life compared\nto PVDF-HFP diaphragms alone. And demonstrated excellent thermal closure\nperformance between 160 and 200 °C. Furthermore, the piezoelectric\neffect of the composite film prevents the growth of lithium dendrites\nin the vertical direction, avoiding the trouble of lithium dendrites\npenetrating the battery separator. Therefore, the two safety guarantee\nproperties of the composite separator greatly enhance the safety and\nservice life of the battery, which allows the application of lithium\nbatteries to be further improved in the application scenario and application\nscale.