锂与Nafion膜相互作用的电化学交流阻抗、SEM和EDAX研究

STUDY ON INTERACTION OF LITHIUM AND DRY NAFION MEMBRANE WITH AC IMPEDANCE, SEM AND EDAX

Nafion 膜是一种重要的全氟离子膜,有广泛的用途。本文对 Nafion 膜在锂电池中应用的可能性进行了研究。结果表明,锂金属与干的Nafion膜发生化学反应,反应产物在锂表面形成表面膜层,它不能保护锂,防止锂的进一步腐蚀。膜层的电阻率约为109 ohm.cm数量级,基本上不具电子和离子导电性。因此,Nafion 膜不能直接作为电解质用在锂电池中,除非对锂表面进行某种修饰,形成性能良好的保护膜。

For application of Nafion in lithium batteries a basic and important issue is the interaction of lithium and Nafion membrane. It was studied with ac impedance, scanning electronic microscopy and x-ray energy dispersion analysis technologies in this paper. The results indicate that lithium reacts chemically with dry Nafion membrane and forms a three-dimension porous layer on the surface of the lithium at ambient temperature. The specific resistance of the surface layer is high up to 109~1010 ohm.cm at about 100 days after contacting of lithium with Nafion membrane. No reaction products adhere on the surface of Nafion membrane and the morphology of surface of Nafion membrane has no obvious change as Nafion is in contact with lithium for a long time. Thus, Nafion membrane cannot be directly used in lithium batteries as an electrolyte.