摘要
聚偏氟乙烯(PVDF)溶液的干燥条件对其结晶性、粘结强度有很大影响,对制备锂离子电池的电极材料亦有影响.为此,设计了一种薄膜剥皮试验来评估PVDF附着于石墨的机械强度;以XRD和电池循环来测量不同热处理条件下PVDF粘结剂的影响.结果表明,在高于PVDF熔点的温度处理的样品,PVDF具有更高的结晶性和附着力,从而改善了石墨电极的循环性能,还观察到前150次循环过程中的容量逐步上升现象.PVDF的逐渐溶胀被认为是出现该现象的原因.
The drying conditions of a poly（vinylidene fluoride） （PVDF） solution have a great influence on its crystalinity and binding strength during the preparation of electrode laminates for lithium ion batteries. A peeling experiment was designed to evaluate the mechanical strength of the PVDF adhering to graphite. X-ray diffraction and galvanostatic cell cycling were used to evaluate the influence of PVDF binder treated under different thermal conditions. The results indicate that for the PVDF binder that is dried and crystallized at a temperature slightly higher than its melting temperature, it has higher crystallinity and adhesion strength to the graphite particles, whether it is soaked in electrolyte or not. This binder-related mechanical property of the electrode can improve the cycling performance of the graphite electrode although the capacity may undergo a gradual rising process during the first 150 or so cycles due to the partial blocking of the electrical conduction path by PVDF initially.
基金
National Natural Science Foundation of China(50372064).
关键词
聚偏氟乙烯
石墨
结晶性
附着力
锂电池
poly （vinylidene fluoride）
graphite
crystallinity
adhesion
lithium batteries
