What are the detection methods of lithium battery separator technology?
There are two important on-line control technologies for lithium-ion battery separator thickness, one is MD (longitudinal) control and CD (transverse) control; the other is the on-line machine vision inspection technology of the separator. The so-called MD control and CD control refers to the closed-loop control of the thickness in the MD direction by controlling the speed of the feeding screw or the pulling speed; and the data measurement through the scanning frame, and finally the data closed-loop control in the CD direction is realized.
Some companies also call it camber, which refers to the arc after the lithium-ion battery separator is cut. When the arc is obvious, the lamination will be uneven, and the vortex will appear during winding, causing the pole pieces to be exposed and short-circuited. The test method is to lay the diaphragm strip on the table, and compare the parallelism with the edge of the steel ruler to obtain the radian of the diaphragm.
3. Air permeability
The time required for a certain volume of air to pass through the diaphragm under certain conditions, also known as the Gurley value, has a certain impact on the performance of the lithium-ion battery, and the ASTM test method is generally used.
The volume of the void accounts for the proportion of the entire volume. The test methods include the liquid absorption calculation method and the test method. The liquid absorption calculation method is to infiltrate the lithium battery diaphragm in a known solvent, and calculate the amount of the diaphragm occupied by the liquid by measuring the mass difference before and after the diaphragm is infiltrated. Void volume, mercury intrusion test 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 indented mercury, and take the average value after multiple measurements.(Lithium - Ion Battery Equipment)
5. Pore size distribution
The mercury porosimeter can also be used for measurement. The mercury porosimetry method is used to measure the pressure exerted by the mercury into the hole to calculate the pore size parameters, but it should be noted that the results measured by the mercury porosimeter include through holes and non-through holes, and the dry method When the lithium battery diaphragm is immersed in mercury, stress will damage the microporous structure of the diaphragm. Therefore, a capillary flow analyzer is also used to measure the actual test. The inert gas is used to break through the wetted diaphragm, and the pressure value of the gas outflow is measured, which is obtained by calculation. Aperture parameters.
The contact angle measurement method is generally used, and its principle has been introduced in detail in the introduction of negative electrode related knowledge, and will not be repeated here.
7. Electrical properties
The lithium battery separator, positive and negative electrodes, and electrolyte are assembled together to test the rate, high and low temperature, storage, circulation, internal resistance, safety, etc. to compare the performance of different separators.