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The lithium battery membrane electrode material made of PVDF has good chemical stability, temperature stability and good workability. However, some problems may arise during the preparation of PVDF membranes.
① The resulting film is curled;
②The film made has water lines one after another;
What is causing it? The following points may be influencing factors:
1 Influence of solvent;
When preparing the PVDF ultrafiltration membrane, first choose an appropriate solvent to dissolve it into a casting solution. Because different solvents have different dissolving powers for PVDF, the expansion state of PVDF macromolecules is different: In addition, the speed of diffusion into the gel is different during the gel process of different solvent systems, which ultimately leads to different structure and porosity of the formed film.
2 The influence of PVDF concentration;
Increasing the initial polymer concentration in the casting solution will increase the polymer concentration at the interface, increase the polymer volume fraction, and decrease the porosity.
3 The influence of the type and concentration of additives;
4 The influence of gel bath composition and temperature;
5 Influence of evaporation time and temperature;
Control the solvent volatilization rate: at room temperature, the petri dish is covered, and the film forming time is extended to 2 to 3 days. After setting, take it out and heat and dry appropriately（Heat Drying Small Vacuum Oven） Finally, consider fixing with a splint when heating and drying.
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