Polypropylene/silica nanocomposite membranes for lithium-ion battery separator: Studies on interfacial tuning of pore structure, mechanical and thermal properties

Energy storage and mobility industries use polypropylene (PP) nanocomposites. The energy storage applications of newly made microporous SiO₂ filled, porous PP nanocomposites combining PP, natural rubber, and SiO₂ nanoparticles then subsequently removing natural rubber from the nanocomposite were explored in this paper. SEM pictures showed how the pore morphology was altered by nanofillers. Mechanical tensile tests reveal that the SiO₂ nanofiller enhances the mechanical properties of microporous polypropylene. XRD and DSC experiments have shown that SiO₂ nanoparticles works as a nucleating agent but has no impact on the crystallinity of PP. The electrolyte absorption, porosity, ionic conductivity, wettability and charge–discharge performance were investigated for PP/SiO₂ nanocomposite separator. SiO₂ nanoparticles in the matrix have a significant impact on the wettability of PP membrane, since the presence of SiO₂ nanoparticle reduces the contact angle from 24° to 15°. SiO₂ filled PP membrane outperformed microporous PP and celgard separator in terms of electrolyte uptake (230%) and porosity (62%). In comparison to microporous PP, the PP/SiO₂ membrane demonstrated a better ionic conductivity (5.9 × 10⁻⁴ S cm⁻¹). Finally, Li/PP-SiO₂/LiFePO₄ coin cells (2320 type) were fabricated and delivered a discharge capacity of 138 mAh g⁻¹.