Preparation and performance of polyacrylonitrile/polyester nowoven microporous composite separator for lithium-ion batteries

In order to improve the thermal resistance and electrolyte affinity of separators for lithium-ion batteries, a composite separator (PPCS) based on polyethylene terephthalate (PET) nonwoven and polyacrylonitrile (PAN) resin was prepared by the phase inversion method. The physical-chemical properties and battery performances of PPCS were systematically characterized, such as the structure, tensile strength, electrolyte property and thermal resistance as well as the charge-discharge performance. The results indicated that PPCS had a uniform microporous structure with an average pore diameter of about 425nm and a porosity of 74%, and its tensile strength was up to 30MPa. Compared with commercial separators, PPCS exhibited better electrolyte properties (electrolyte uptake of 365%, contact angle of 0°) and higher ion conductivity (1.65mS/cm). Meanwhile, this composite separator possessed superior thermal stability with a shrinkage ratio of about 0 at 150℃ for 0.5h. Based on the above advantages, lithium cobalt oxide/Li cells assembled with PPCS exhibited good battery performances. For example, the discharge capacity retention was 95.2% after 200 cycles at 0.2C and the discharge capacity retention at 10C was 58.3% of that at 0.5C. Thus, this composite separator showed a good application prospect for next-generation lithium-ion batteries. © 2022, Editorial Board of CIESC Journal. All right reserved.