搅拌时间和混合顺序对锂离子电池正极浆料分散特性的影响

Influence of mixing time and sequence on the dispersion properties of the cathode slurry of lithium-ion battery

综合采用电阻抗谱(electrical impedance spectroscopy,EIS)方法、扫描电子显微镜(scanning electron microscopy,SEM)方法和流变法,分析了锂离子电池正极浆料(cathode slurry)的电化学特性、形貌特性和流变特性,并总结出了正极浆料的分散特性。基于COMSOL Multiphysics软件建立了正极浆料的静态仿真模型,从电化学特性角度出发,验证了EIS实验结果的正确性。综合考虑实验分析与仿真验证,结果表明:搅拌时间对正极浆料的分散特性影响较大,较长(9 min以上)或者较短(3 min以下)的搅拌时间会增加阻抗值从而恶化正极浆料内粒子的分散;而6 min的搅拌时间则会减小阻抗值从而使正极浆料内粒子分散。先将炭黑(CB)与PVDF-NMP溶液混合制成CB浆料,后将钴酸锂(LiCoO2)粒子与CB浆料混合的顺序,能使锂电池正极浆料具有较好的分散特性。最后,提出了一套提高正极浆料分散特性的制浆方案,为高性能锂电池的制备提供了理论依据与实验参考。

This paper comprehensively used electrical impedance spectroscopy(EIS)method,scanning electron microscopy(SEM)method and rheological method to analyze the electrochemical,morphological and rheological properties of the cathode slurry of lithium-ion battery,as a result,the dispersion properties of the cathode slurry are summarized.In addition,based on the COMSOL Multiphysics software,a static simulation model of the cathode slurry was established,and the correctness of the EIS experimental results was verified from the perspective of electrochemical characteristics.Taking into account experiment analysis and simulation verification,the results show that stirring time has a significant impact on the dispersion properties of the cathode slurry,and more(more than 9 min)or less(less than 3 min)stirring time is able to increase the impedance value and deteriorate the dispersion of particles in the positive electrode slurry,while 6 min stirring time is able to reduce the impedance value,thereby dispersing the particles in the cathode slurry.Carbon black(CB)is pre-mixed with PVDF-NMP solution to form CB slurry,and then lithium cobalt oxide(LiCoO2)particles are mixed with CB slurry to form cathode slurry.This slurry preparation order enables cathode slurry to have good dispersion properties.Finally,this paper proposed a slurry preparation scheme to improve the dispersion properties of cathode slurry with the aim of providing theoretical basis and experimental reference for the preparation of high-performance lithium batteries.