<![CDATA[The separator plays a critical role as a physical barrier between the anode and cathode while simultaneously serving as an ion transport medium. Therefore, properties such as porosity, wettability, mechanical strength, and thermal stability are key parameters that determine battery performance. This review aims to provide a comprehensive overview of polymer-based membrane separators for lithium batteries. The literature survey was performed following the PRISMA framework using publications retrieved from Google Scholar between 2010 and 2026, with studies selected based on their relevance to separator materials, fabrication methods, characterization techniques, and electrochemical performance. Conventional polyolefin based separators, such as polyethylene (PE) and polypropylene (PP), have been widely utilized. Beyond polyolefins, alternative polymers including cellulose acetate and polyvinylidene fluoride (PVDF) have also been developed for lithium battery separators. Each polymer exhibits distinct physicochemical characteristics, leading to varied performance when employed as a separator. A range of characterization techniques has been employed to evaluate separator properties, including X-ray Diffraction (XRD), Linear Sweep Voltammetry (LSV), Electrochemical Impedance Spectroscopy (EIS), Scanning Electron Microscopy (SEM), and Galvanostatic Charge Discharge (GCD). Furthermore, the development of membrane separators has been significantly advanced through the incorporation of inorganic materials into the polymer matrix. The inclusion of such inorganic fillers has been shown to enhance thermal stability and wettability, thereby improving overall separator performance. Moreover, the utilization of nanoscale materials is strongly recommended to achieve superior and optimized electrochemical performance.]]>
