聚丙烯腈/聚酯无纺布微孔复合锂电隔膜的制备及性能

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

为了改善锂电隔膜的耐热性、电解液亲和性和机械性能,本文以聚丙烯腈为主要材料,采用相转化法制备了聚酯无纺布支撑的聚丙烯腈微孔复合锂电隔膜,对隔膜的理化性能(孔道结构、机械性能、电解液性能和耐热性)和电池性能(循环性能、倍率性能)进行系统研究。结果表明,复合隔膜具有均匀的微孔结构,平均孔径约为425nm,孔隙率为74%,拉伸强度为30MPa;电解液亲和性良好,吸液率为385%,接触角接近0°,锂离子电导率较市售隔膜显著提高,达到1.65mS/cm;在150℃、0.5h的热处理条件下,复合隔膜的热收缩率为0。鉴于良好的理化特性,该隔膜所装配的钴酸锂/锂金属电池表现出优异的循环容量和倍率容量保持性,如在0.2C倍率下,经历200次循环后电池的放电容量保持率为95.2%,在10C倍率下电池的放电容量为0.5C倍率下的58.3%。因此,相转化法制备的聚丙烯腈基微孔复合隔膜在锂离子电池中显示出较好的应用前景。

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 nextgeneration lithium-ion batteries.