Dispersion method for positive electrode slurry of lithium ion battery

Abstract

The invention discloses a dispersion method for positive electrode slurry of a lithium ion battery. The dispersion method comprises the following steps in sequence: pre-preparing a water system or oil system adhesive solution at certain concentration through an adhesive making tank; adding the adhesive solution, a conductive agent, a dispersing agent and a solvent into a stirring bucket, performing full pre-mixing by a high-speed dispersing machine to obtain a pre-dispersed solution; adding a positive electrode active material in two times, performing pre-mixing in the first time, and performing high-speed dispersing and mixing after adding in the second time, performing high-speed dispersing for a certain time to obtain a high-viscosity dispersing turbid liquid; and adding a certain amount of solvent to further perform high-speed dispersing until the slurry reaches proper viscosity and solid content to obtain the positive electrode slurry with excellent performance and to complete the overall process. By making full advantage of a mechanical relation between high-viscosity heterogeneous fluids, and by adopting the simple and convenient method, the dispersing effect of a stirrer is given into full play, uniform applying of shearing force on super-fine powder in the slurry in the stirring process is promoted, the stirring time is saved, and the uniformity, the stability and the consistency of the slurry are improved.

Description

technical field [0001] The invention relates to the technical field of preparation and homogenization of positive electrode slurry of lithium ion batteries, in particular to a dispersion method of positive electrode slurry of lithium ion batteries. Background technique [0002] In the manufacturing process of lithium-ion batteries, the uniformity, stability, and consistency of the slurry often affect the performance of the battery. The uneven dispersion of the binder in the slurry will lead to a large internal resistance of the battery, hindering the migration of lithium ions during charge and discharge, and may also cause electrode materials to fall off during charge and discharge due to poor adhesion, affecting battery life . The currently used positive electrode materials often have low ionic conductivity, and it is necessary to add a conductive agent to enhance its performance during the rate charge and discharge process. The uneven dispersion of the conductive agent wi...

AI Technical Summary

Problems solved by technology

The uneven dispersion of the binder in the slurry will lead to a large internal resistance of the battery, hindering the migration of lithium ions during charge and discharge, and may also cause electrode materials to fall off during charge and discharge due to poor adhesion, affecting battery life

The currently used positive electrode materials often have low ionic conductivity, and it is necessary to add a conductive agent to enhance its performance during the rate charge and discharge process. The uneven dispersion of the conductive agent will reduce the ionic conductivity during the charge and discharge process of the lithium-ion battery and weaken its Rate charge and discharge performance

In addition, under the current general trend of nanotechnology, nanomaterials tend to enhance the activity of materials, and can maximize their performance. Nanomaterials are often difficult to disperse, and poor dispersion will lead to secondary agglomeration, sedimentation, etc. of materials, and eventually Affect the performance of battery capacity

[0003] In the traditional preparation process of electrode slurry, the commonly used method is simple mechanical stirring and dispersing. This method is widely applicable and easy to operate, but it is often difficult to disperse evenly, especially when dispersing ultrafine powder, it is easy to agglomerate and cannot reach good effect

This kind of dispersion method usually takes a long time to stir, the stability of the obtained slurry is not good, and a large number of conductive agent aggregates and active material aggregates will be generated in a short period of time, which affects the final battery performance

At present, there are many patents on homogenization of positive electrode slurry in China: 1) The patent application number is 201110268040.0, which uses spraying method to pre-mix the material. Although this method can achieve the mixing effect, the spray dryer is expensive and the output is limited. , the preparatory work is cumbersome, and mass production is more difficult

2) The patent application number is 201110060625.3, which uses ultrasonic dispersion to disperse the slurry for the second time during the stirring process. Although this method is beneficial to the dispersion of nano-active substances, the stability of this kind of dispersed slurry is poor, and precipitation and secondary agglomeration are prone to occur , the energy of the ultrasonic vibrator is unstable after long-term use, resulting in unstable dispersion process and poor slurry consistency

Images