CR2025 battery

What is the technical test method for CR2025 battery diaphragm?

1. Thickness

There are two important online control technologies for lithium-ion battery diaphragm thickness, one is MD (longitudinal) control and CD (transverse) control; the other is online machine vision test technology for diaphragms. The so-called MD control and CD control refer to the closed-loop control of thickness in the MD direction by controlling the speed of the feeding screw or the traction speed; and the data measurement through the scanning frame, and finally the data closed-loop control in the CD direction.

2. Curvature

Some companies also call it arch degree, which refers to the arc shape generated after the lithium-ion battery diaphragm is cut. When the arc shape is clear, it will cause uneven stacking, and vortex shape will be generated when winding, causing the pole piece to be exposed and short-circuited. The detection method is to lay the diaphragm strip flat on the table and compare the parallelism with the edge of the steel ruler to obtain the curvature of the diaphragm.

3. Air permeability

The time required for a certain volume of air to pass through the diaphragm under certain conditions is also called the Gurley value. Its size has a certain impact on the performance of lithium-ion batteries. The ASTM detection method is generally used.

4. Porosity

The ratio of the volume of the voids to the total volume. The detection methods include the liquid absorption calculation method and the detection method. The liquid absorption calculation method is to soak the CR2025 battery diaphragm in a known solvent, and calculate the volume of the voids occupied by the diaphragm by the liquid by measuring the mass difference before and after the diaphragm is soaked. The mercury intrusion detection method is to use external force to apply pressure to the diaphragm to press mercury into the pores of the diaphragm, and then calculate the porosity of the diaphragm by measuring the volume of the pressed mercury, and take the average value after multiple measurements.

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