Lithium ion battery pole piece expanding fracture test method

Abstract

The present invention provides a lithium ion battery pole piece expanding fracture test method. The method is characterized in that by winding the conducting wires of different fracture force values on an electronic core, and monitoring the change of the resistance values of the conducting wires, a relation of the battery charging/discharging circulation times and the fracture force values F of the conducting wires is obtained, and a corresponding curve chart of the electronic core expansion forces and the battery charging/discharging circulation times is drawn; and by analyzing the corresponding curve chart of the electronic core expansion forces and the battery charging/discharging circulation times, a corresponding relation of the lithium ion battery charging/discharging circulation times and the pole piece fracture can be obtained. Compared with the prior art, the lithium ion battery pole piece expanding fracture test method of the present invention determines the pole piece fracture situation by monitoring the change of the resistance values at the two ends of the conducting wires, so that the method has the advantages of being short in test cycle, wide in application range, high in accuracy and little in resource consumption, being simple and convenient to operate, being not interfered by the environment temperature, etc.

Description

technical field [0001] The invention relates to the field of analysis and testing of lithium ion batteries, in particular to a test method for expansion and fracture of pole pieces of lithium ion batteries. Background technique [0002] During the charge-discharge cycle of lithium-ion batteries, the pole piece will gradually expand. Obviously, the layer-by-layer transmission of the expansion force makes the outermost pole piece become the most stressed pole piece; as the number of cycles increases, the outermost pole piece There is a risk of chip breakage. In order to ensure the reliability of lithium-ion batteries in the actual use process, it is necessary to study how many times the battery charge and discharge cycles will cause the pole pieces to break. [0003] At present, the commonly used method is to perform CT scan (computerized tomography) on the lithium-ion battery every certain charge-discharge cycle time, and determine the relationship between the number of batt...

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Problems solved by technology

[0004] 1) The test cycle is long: the above method needs to cycle the battery charge and discharge until the pole piece breaks, in order to determine the corresponding relationship between the number of charge and discharge cycles and the pole piece fracture;

[0005] 2) The operation is cumbersome: the above method needs to frequently suspend the charge and discharge cycle test of the battery for CT scanning;

[0006] 3) Ambient temperature has a great influence: the above method needs to take the battery out of the temperature environment of the charge-discharge cycle test, and then take it to a CT machine under normal temperature conditions for scanning, and then put it back into the temperature environment of the cycle test to continue the cycle Therefore, during the whole process, frequent changes in ambient temperature will have a great impact on the performance and test results of lithium-ion batteries;

[0007] 4) There are restrictions on the battery fixture: In order to simulate the stress of the lithium-ion battery in the module, the lithium-ion battery is usually tested with a fixture during the charge-discharge cycle test; Thinner aluminum plate fixtures are deformed, so thick aluminum or steel plate fixtures are required, but CT scans can only penetrate thinner aluminum plate fixtures;

[0008] 5) The test error is large: the lithium-ion battery is taken out for a CT scan after a period of charge-discharge cycle each time to observe whether the pole piece is broken, so there is still an error in the observation time lag;

[0009] 6) Consumption of resources: The above method requires frequent CT testing, which consumes resources, manpower and funds

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