A kind of online monitoring lithium-ion battery electrochemical impedance test method
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A lithium-ion battery, impedance testing technology, applied in the direction of measuring electricity, measuring devices, measuring electrical variables, etc., can solve the problems that the impedance test cannot be completed online, and achieve the effect of strong practicability and simple experimental process
Active Publication Date: 2021-07-13
HEFEI GUOXUAN HIGH TECH POWER ENERGY
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[0004] The present invention proposes an on-line monitoring lithium-ion battery electrochemical impedance test method, which can solve the technical problem that the existing test method cannot complete the impedance test on-line
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example 1
[0038] Example 1: When the ternary laminated full battery is 50% SOC, the electrochemical impedance test of the direct current method:
[0039] (1) Place the full battery to be studied in an incubator at 25°C, charge it to 50% SOC, and leave it for 1 hour;
[0040] (2) Perform AC impedance (EIS) test on the battery to be tested on the electrochemical workstation, voltage disturbance, disturbance frequency is 5mv, obtain its EIS impedance spectrum, and fitting analysis obtains the impedance value produced by each polarization; Wherein, such as figure 2 As shown, R s +R f +R ct The frequency time at the inflection point is recorded as t 1 ;
[0041] The EIS fitting data is as follows:
[0042] SOC / % R s / Ω
[0043] (3) Connect the battery after the EIS impedance test to a high-precision test cabinet, and perform different current pulses on it, the pulse current I=0.2C, 0.4C, 0.6C, 0.8C, 1C, and the pulse time is shown in the EIS impedance spectrum Rs +R f +...
example 2
[0052] Example 2: When the SOC of the ternary positive half-cell is 50%, the electrochemical impedance test of the direct current method
[0053] (1) Place the positive half-cell to be studied in a 25°C incubator, charge it to 50% SOC, and leave it for 1 hour;
[0054] (2) Conduct AC impedance (EIS) test on the electrochemical workstation, voltage disturbance, disturbance frequency is 5mv, obtain its EIS impedance spectrum, and fit analysis to obtain the impedance value generated by each polarization. Among them, R s +R f +R ct The frequency time at the inflection point is recorded as t 1 ;Such as Figure 6 shown.
[0055] The EIS fitting data is as follows:
[0056] SOC / % R s / Ω
R f / Ω
R ct / Ω
R s +R f +R ct / Ω
f / Hz t 1 / s
50 0.213 0.001 0.372 0.586 3.415 0.293
[0057] (3) Connect the battery after the EIS impedance test to a high-precision test cabinet, and perform different current pulses on it, the pulse c...
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Abstract
The electrochemical impedance testing method for on-line monitoring of the lithium-ion battery of the present invention can solve the technical problem that the existing testing method cannot complete the electrochemical impedance testing on-line. Including S100, placing the battery to be tested in a constant temperature box, and charging the battery to be tested to a certain SOC state; S200, performing an AC impedance (EIS) test on the battery to be tested, and analyzing the impedance value generated by each polarization; S300, placing the EIS The battery after the impedance test is connected to a high-precision test cabinet, and current pulses with different gradients are performed on it; S400, the shelving voltage before a certain pulse current I pulse is recorded as U 0 , pulse t 2 After the voltage is denoted as U t , then △U=U 0 -U t , take the graph of △U and pulse current I under different pulse currents, and perform linear fitting, and the slope obtained is the impedance value of the DCR test. The invention combines the direct current method and the alternating current method, and achieves the purpose of on-line monitoring the electrochemical impedance change of the battery through the direct current impedance test of the small rate current pulse. The method has simple experimental process and strong practicability.
Description
technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to an electrochemical impedance testing method for on-line monitoring of lithium-ion batteries. Background technique [0002] Internal resistance is a very important performance index of the battery, which has an important impact on the fast charging, heat generation and aging of the battery. At present, the methods commonly used to test the internal resistance of the battery include the direct current method (DCR) and the alternating current method (EIS). Among them, the DC method usually discharges the battery at a high rate of 3C or 5C, and then obtains the impedance of the battery within the pulse time according to the ratio between the voltage change value and the pulse current. The AC method is to perturb the battery with a small signal through the electrochemical workstation, and obtain the impedance spectrum of the battery while maintaining the internal stabil...
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