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

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.