Functional modification of polypropylene separators with solid electrolyte LATP and SiO2 coatings for lithium batteries

Abstract

The separator is crucial to the performance and safety of the battery. This study prepared a polypropylene (PP) /solid electrolyte Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) /SiO₂ composite separator (PP/LATP/SiO₂). The experimental results demonstrate significant enhancements in the electrolyte wettability and thermal stability of the separator. Furthermore, the lithium-ion transference number ($t^{+}$) has been raised from 0.22 to 0.56. In electrochemical performance tests, the lithium symmetric battery assembled with the PP/LATP/SiO₂ composite separator exhibits an exceptionally long cycle life, sustaining stable cycling for 900 h at a current density of 0.5 mA cm⁻². This composite separator, combining the solid electrolyte and SiO₂ layer, effectively facilitates lithium-ion transport and reduces the occurrence of electrode side reactions, thereby enhancing the performance and safety of the battery.