Changes for Development of Al2O3 Coated PVA (Polyvinyl Alcohol) Composite Nonwoven Separator For Improving Thermal and Electrochemical Properties

In the modern world, lithium-ion batteries are widely used in electronic devices, such as smartphones, laptops, and electric cars. However, they are highly unstable during charging and their capacity drops significantly over time, despite that they are highly efficient and easy to use. Therefore, it is imperative to develop more efficient batteries. Polyolefin-based lithium-ion battery separators are limited by their weak thermal stability. In order to overcome such limitations, we developed a ceramic coated and nonwoven materials based composite separator. We hypothesized that the method used to develop the separator will have improved thermal and electrochemical properties because of superior air permeability and electrolyte uptake. This separator was manufactured by utilizing the Dip-coating method, whereby ceramic layers composed of Al2O3 nanoparticles and Polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) were coated to both sides of a Polyvinyl alcohol (PVA) support which was fabricated by electrospinning. The ventilation map and electrolyte uptake demonstrated that the composite non-woven separator had superior electrolyte uptake properties when compared to conventional PE separators. This resulted in excellent electrochemical properties - especially a great increase in high-rate discharge characteristics. Finally, thermal shrinkage was improved compared to conventional PE separators indicating greater thermal stability. Overall, our PVA separator displayed superior thermal and electrochemical properties. By gaining knowledge on improving heat and thermochemical properties, we can gain critical insight on future lithium-ion battery designs that have to work in extreme conditions.