Lithium battery ohmic resistance test method based on double-pulse current

Abstract

The invention provides a lithium battery ohmic resistance test method based on a double-pulse current. A lithium battery is statically placed, the lithium battery is then made to realize first instant discharging through a pulse current, and first instant charging is then carried out; the lithium battery is made to realize second instant charging through the pulse current, second instant discharging is then carried out, and charging ohmic resistance and discharging ohmic resistance of the lithium battery are finally calculated. According to the method, the double-pulse current is employed, for a single-pulse charging or discharging current, the pulse current is improved by one times, a voltage response amplitude of the battery is improved through increase of the pulse amplitude, and errors of test equipment and a data acquisition system are reduced; SOC of the lithium battery during a test is guaranteed to be unchanged through employing the double-pulse current, change of a lithium battery open circuit voltage caused by change of the SOC of the lithium battery can be avoided, lithium voltage drop completely depends on change of a DC resistor, so a test value is closer to the ohmic resistance, and thereby test precision of the ohmic resistance is improved.

Description

technical field [0001] The invention relates to a test method, in particular to a test method for the ohmic internal resistance of a lithium battery based on a double pulse current. Background technique [0002] The internal resistance of the lithium battery is one of the important characteristic parameters of the battery. It is an important parameter that characterizes the life of the battery and the operating state of the battery. To ensure that the battery can exert its high-power characteristics, it is of great significance to accurately and conveniently test the internal resistance of lithium batteries. [0003] At present, the internal resistance of lithium batteries is different according to the test principle during use. The test methods for ohmic internal resistance mainly include DC pulse test method and electrochemical impedance test method. The test principle of the DC pulse method is to apply a large current (charging or discharging) to the battery, the duratio...

AI Technical Summary

Problems solved by technology

Most of these methods use high-rate current for battery charge and discharge pulse tests. High-rate charge and discharge will have a certain impact on the battery and cannot eliminate polarization resistance.

[0007] The electrochemical impedance test method is an electrochemical test method that applies a small-amplitude sine wave voltage or current signal to the battery, and then tests the battery response. By changing the frequency of the sine wave, the impedance at different frequency points in a frequency domain is obtained, and Establish the equivalent circuit model of the battery impedance, and then obtain the Nyquist plot of the battery impedance spectrum, in which the intersection point of the high-frequency part curve and the real axis can be approximately equivalent to the ohmic internal resistance of the battery. This method has higher accuracy, but AC impedance spectroscopy instruments with high precision are required, and it takes a long time to complete the impedance test of the entire frequency band

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