Al_2O_3/PVA涂层改性聚丙烯隔膜的制备与性能

Preparation and Performance of Polypropylene Separators Modified by Al_2O_3/PVA layer

以氧化铝(α-Al_2O_3)为陶瓷填料、聚乙烯醇(PVA)为粘结剂、去离子水为溶剂,制备了涂覆浆料Al_2O_3/PVA,采用刮涂法在传统聚丙烯(PP)隔膜表面涂覆上Al2O3/PVA层。通过XRD、SEM、接触角测试、润湿性能测试和耐热性能测试对改性前后隔膜进行了表征,并将改性前后的隔膜组装成纽扣电池进行了电化学性能测试。结果表明:在PP隔膜表面成功引入Al2O3/PVA涂层后,PP隔膜的润湿和耐热性能以及电化学性能均得到了明显改善,吸液率由98%提高到203%,在170℃下热处理1 h的热收缩率由46.1%减小至24.4%,不同倍率下改性隔膜组装的电池的放电容量总是高于原隔膜组装的电池的放电容量,0.5 C倍率下循环80次后,原隔膜组装的电池的容量保持率仅为79.07%,而改性隔膜组装的电池的容量保持率达到了90.84%。

Al2O3/PVA-coated polypropylene separators were prepared through a direct coating process with Al2O3 as ceramic particle, polyvinyl alcohol as binder and deionized water as solvent. The bare polypropylene （PP） separator and coated separator were characterized by XRD, SEM, contact angle testing, electrolyte wettability and thermal resistance testing, as well as electrochemical testing when assembled in lithium-ion batteries. It was found that the introduction of Al2O3/PVA layer can improve the wettability, thermal resistance and electrochemical properties of the separator. The electrolyte uptake of the Al2O3/PVA-coated separator increased from 98% to 203% , and the thermal shrinkage decreased from 46. 1% to 24.4% at 170 ℃ for 1 h. Moreover, compared to the bare PP separator, the coated separator always exhibited higher discharge capability at different Coulomb rates. The capacity retention of the bare PP separator was only 79.07% at 0.5C charge-discharge rate in 80 cycles, while that of coated separator reached 90. 84% at the same condition.