PVA/APP改性锂电隔膜的制备与性能

Preparation and performance of PVA/APP modified lithium battery separators

摘要:

以高聚合度的聚磷酸铵(APP)作为阻燃剂，聚乙烯醇(PVA)为成膜骨架材料，通过相转化的方法制备PVA/APP改性隔膜，使用在锂电池中。对改性隔膜的机械强度、湿润性、热稳定性、微观形貌以及电化学性能进行表征。探究不同APP添加量对隔膜性能的影响，对其组装电池的循环倍率性能进行评价。结果表明，当PVA质量分数为10%、APP添加量为8%时，改性隔膜具有优异的电解液湿润性以及热稳定性，吸液率达到215%，在200 ℃下几乎不收缩；拉伸强度达到47.4 MPa。使用改性隔膜组装电池，在0.1 C放电条件下循环50次，放电比容量为143.2 mAh/g，库伦效率均大于97%，容量保持率达到95.1%，而商用锂电池隔膜所组装电池的容量保持率只有82.8%。改性隔膜在具有阻燃性能的同时所组装电池能保持良好的电化学性能。

Abstract:

Using high degree of polymerization ammonium polyphosphate (APP) as a flame retardant and polyvinyl alcohol (PVA) as a film-forming framework material, a PVA/APP modified separator was prepared through phase conversion method and used in lithium batteries. Characterize the mechanical strength, wettability, thermal stability, microstructure, and electrochemical performance of the modified separator. Explore the effect of different APP additions on the performance of the separator and evaluate the cycling rate performance of its assembled battery. The results showed that when the PVA mass fraction was 10% and the APP addition was 8%, the modified separator had excellent electrolyte wettability and thermal stability, with a liquid absorption rate of 215% and almost no shrinkage at 200 ℃; The tensile strength reaches 47.4 MPa. The battery was assembled using a modified separator and cycled 50 times under a discharge condition of 0.1 C. The specific discharge capacity was 143.2 mAh/g, and the Coulombic efficiency was higher than 97%. The capacity retention rate reached 95.1%, while the capacity retention rate of the battery assembled with a commercial lithium battery separator was only 82.8%. The modified separator has flame retardant properties while maintaining good electrochemical performance in the assembled battery.