PI/SiO_(2)-PVDF作为锂贮备电池隔膜的性能

Performance of PI/SiO_(2)-PVDF as separator for lithium reserve battery

锂贮备电池需兼具高能量密度和高安全性。聚酰亚胺(PI)隔膜具有高热稳定性,有望提高锂贮备电池的安全性,但PI隔膜存在孔隙率过大带来的自放电问题。以聚偏氟乙烯(PVDF)为黏结剂,用微米级二氧化硅(SiO_(2))对PI隔膜进行表面涂覆,制备PI/SiO_(2)-PVDF复合隔膜。通过SEM、接触角、电化学阻抗谱(EIS)及放电测试等方法,对复合隔膜的物理性能和电化学性能进行分析。5μm粒径SiO_(2)修饰的复合隔膜具有良好的吸液性、导电性和低自放电率,组装的LiCoO_(2)/Li电池以0.1 C放电至3 V,中值电压及LiCoO_(2)的比容量分别为3.91 V和142.7 mAh/g。PI/SiO_(2)-PVDF复合隔膜在锂贮备电池中具有良好的应用前景。

Lithium reserve battery needed both high energy density and high safety.Polyimide(PI)separator had high thermal stability,which was expected to improve the safety of lithium reserve battery.However,PI separator had the problem of self discharge caused by excessive porosity.Sub-micron silicon dioxide(SiO_(2))was coated on PI separator with polyvinylidene fluoride(PVDF)as binder to prepare PI/SiO_(2)-PVDF composite separator.The physical properties and electrochemical performance of the composite separator were analyzed by SEM,contact angle,electrochemical impedance spectroscopy(EIS)and discharge tests.The composite separator modified by 5μm SiO_(2)had good liquid absorption,conductivity and lower self-discharge rate.When the assembled LiCoO_(2)/Li battery was discharged to 3 V at 0.1 C,the mid-voltage and specific capacity of LiCoO_(2)was 3.91 V and 142.7 mAh/g.PI/SiO_(2)-PVDF composite separator had a good application prospect in lithium reserve battery.