聚偏氟乙烯结构对电池浆料流变性能的影响

锂离子电池浆料的分散均匀性对电池性能有重要影响,电池浆料良好的分散有赖于对浆料流变性能的充分认识。选用两种结构不同的商用聚偏氟乙烯（PVDF）分别作为黏结剂、镍钴锰酸锂为活性物质、导电炭黑为导电剂、N-甲基吡咯烷酮为溶剂制备了正极浆料。用旋转流变仪分析了聚偏氟乙烯结构对电池正极浆料流变性能的影响。结果表明：稳态剪切时,支链型聚偏氟乙烯黏结剂的浆料比直链型聚偏氟乙烯黏结剂的浆料具有更高的零切黏度、更低的屈服点,即浆料具有更好的抗沉降性、更优异的流动性;交变剪切时,直链型聚偏氟乙烯作黏结剂的浆料易发生屈服流动。扫描电镜观察发现：支链型聚偏氟乙烯可以与导电剂、活性物质黏结形成空间导电网络,各组分分布更均匀。该研究为锂离子电池浆料的缓存以及分散工艺的优化提供理论支持。

Effect of PVDF structure on rheological properties of cathode slurry

The dispersible uniformity of cathode slurry of Li-ion battery has significant influence on the performance of bat-tery.Fine dispersible uniformity of cathode slurry of Li-ion battery relied on the adequate knowledge of rheological properties of slurry.Cathode slurry was prepared by using two commercial PVDF with different structure as binder,Li（Ni,Mn,Co）O₂ as active material,carbon black as conducting additive（SP） and N-methy-2-pyrrolidone as solvent.The influence of PVDF structure on the rheological properties of cathode slurry of battery was analyzed using rotational rheometer.Results showed that,for steady shear,the slurry with branched PVDF as binder had higher zero-shear-rate viscosity and lower yield point than slurry with linear PVDF as binder,which meant slurry had higher anti-sedimentation and better fluidity.For oscillatory shear,slurry with linear PVDF as binder was prone to yield flow.SEM result showed that branched PVDF could bond with SP and active material to form a space conductive network,and the component distribution is more uniform.The research provided basis for technological optimization of storing and dispersion of Li-ion battery slurry.