CN115015784A - Method for testing charging performance of battery - Google Patents

Abstract

The embodiment of the invention provides a method for testing the charging performance of a battery, which comprises the following steps: performing constant-current charging test on a battery to be tested, and determining a first negative reference potential in a balanced state, a second negative reference potential in a pulse time and a debugging current, wherein the battery to be tested comprises a reference electrode; determining initial pulse current according to the first negative reference potential, the second negative reference potential, the debugging current and the precipitation potential of the battery to be tested; carrying out pulse charging test on the battery to be tested through the initial pulse current to obtain a third negative reference potential when the pulse charging test is finished; and determining the maximum pulse current according to the third negative reference potential and the precipitation potential. The testing method can furthest exert the power performance of the battery per se under each SOC on the basis of reducing the risk of lithium or sodium precipitation of the battery; and the test method does not depend on the simulation technology, thereby effectively reducing the test time and the test period and improving the test efficiency.

Description

A kind of test method of battery charging performance

technical field

The invention relates to the technical field of battery charging, in particular to a method for testing battery charging performance.

Background technique

In recent years, the new energy vehicle industry has developed rapidly. Due to the advantages of high operating voltage, high energy density, long cycle life, low self-discharge rate and no memory effect, lithium-ion batteries have been widely used in new energy vehicles. applications, especially in pure electric vehicles.

At present, there are two main methods for determining the pulse charging current under the state of charge (SOC) of different power batteries at different temperatures:

1. Adjust the state of charge of the battery at room temperature to the required SOC, put it aside for a certain period of time at each temperature, and then perform the hybrid power pulse capability (HPPC) test of different currents at the temperature, and finally estimate the temperature-specific SOC according to the test results. The maximum pulse current under ;

2. Use the electrochemical simulation method to carry out simulation estimation and then carry out experimental verification.

The above method not only cannot prevent the influence of the obtained current on the risk of lithium or sodium precipitation of the battery, but also the simulation method needs to be verified in combination with the experiment, and the test cycle is long and the efficiency is low, which greatly affects the experimental process.

SUMMARY OF THE INVENTION

The purpose of the embodiment of the present invention is to provide a test method for the charging performance of a battery, which can maximize the power performance of the battery itself under each SOC on the basis of reducing the risk of lithium or sodium evolution of the battery; The test method does not depend on the simulation technology, which effectively reduces the test time and test cycle, and improves the test efficiency.

The invention provides a method for testing the charging performance of a battery, which includes: performing a constant current charging test on a battery to be tested, determining a first negative parameter potential in a balanced state, a second negative parameter potential in a pulse time, and a debugging current, and the The test battery includes a reference electrode; the initial pulse current is determined according to the first negative parameter potential, the second negative parameter potential, the debugging current and the precipitation potential of the battery to be tested; the battery to be tested is determined by the initial pulse current A pulse charging test is performed to obtain the third negative parameter potential at the end of the pulse charging test; the maximum pulse current is determined according to the third negative parameter potential and the precipitation potential.

Optionally, the determining the initial pulse current according to the first negative parameter potential, the second negative parameter potential, the debugging current and the precipitation potential of the battery to be tested includes: according to the first negative parameter potential, the second negative parameter potential, The parameter potential and the debugging current determine the resistance at the pulse time; the initial pulse current is determined according to the first negative parameter potential, the precipitation potential and the resistance at the pulse time.

Optionally, the determining the initial pulse current I ₁ according to the first negative parameter potential, the precipitation potential and the resistance at the pulse time includes: I ₁ =ΔU/R, where ΔU is the first negative parameter potential minus the To the difference of the precipitation potential, R is the resistance at the pulse time.

Optionally, the pulse charging test is performed on the battery to be tested by the initial pulse current to obtain the third negative parameter potential at the end of the pulse charging test, which is determined according to the third negative parameter potential and the precipitation potential. The maximum pulse current includes: if the difference between the third negative parameter potential and the precipitation potential does not meet the potential threshold range, then adjust the size of the initial pulse current, and then use the adjusted pulse current to measure the to-be-measured current. The battery is subjected to the pulse charging test again, until the difference between the negative parameter potential and the precipitation potential at the end of the pulse charging test meets the potential threshold range; if the difference between the third negative parameter potential and the precipitation potential meets the potential threshold range , then the maximum pulse current is equal to the initial pulse current.

Optionally, adjusting the size of the initial pulse current if the difference between the third negative parameter potential and the precipitation potential does not meet the potential threshold range, including: if the third negative parameter potential is different from the precipitation potential. If the difference of the precipitation potential is greater than the maximum value of the potential threshold range, then increase the initial pulse current; if the difference between the third negative parameter potential and the precipitation potential is less than the minimum value of the potential threshold range , the initial pulse current is reduced.

Optionally, the actual capacity of the battery to be tested is determined before the constant current charging test is performed on the battery to be tested.

Optionally, the test conditions of the constant current charging test include test temperature, pulse charging time and state of charge.

Optionally, the test temperature of the constant current charging test is the same as the test temperature of the pulse charging test.

Optionally, the precipitation potential is the potential between the reference electrode of the battery to be tested and the negative electrode.

Optionally, the battery to be tested is a lithium ion battery, and the precipitation potential is a lithium evolution potential; or, the battery to be tested is a sodium ion battery, and the precipitation potential is a sodium evolution potential.

Through the above technical solutions, the present invention reduces the risk of battery precipitation while obtaining the maximum pulse current, and maximizes the power performance of the battery. And the test method does not depend on the simulation technology, which effectively reduces the test time and test cycle, and improves the test efficiency.

Other features and advantages of embodiments of the present invention will be described in detail in the detailed description section that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification, and are used to explain the embodiments of the present invention together with the following specific embodiments, but do not constitute limitations to the embodiments of the present invention. In the attached image:

1 is a schematic flowchart of a method for testing battery charging performance of the present invention;

FIG. 2 is a graph of the maximum pulse current data of the present invention under fixed test conditions.

Detailed ways

The specific implementations of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

1 is a schematic flow chart of a method for testing the charging performance of a battery according to the present invention. As shown in FIG. 1 , step S101 is to perform a constant current charging test on the battery to be tested, and determine the first negative parameter potential in the equilibrium state, the first negative parameter potential under the pulse time The second negative parameter potential and debugging current. The test conditions of the constant current charging test include test temperature, pulse charging time and state of charge. According to a specific embodiment, the constant current charging refers to fixing the test temperature and the pulse charging time, and the current is maintained at a constant value. value of charging, wherein the test temperature and pulse charging time are determined according to the actual test situation.

The measuring method of the present invention is suitable for any kind of battery with implantable reference electrode, such as lithium ion battery and sodium ion battery. For example: if the battery to be tested is a lithium-ion battery, the precipitation potential is a lithium-evolution potential; or, if the battery to be tested is a sodium-ion battery, the precipitation potential is a sodium-evolution potential. The battery to be tested is a three-electrode battery, which includes a positive electrode, a negative electrode and a reference electrode. The reference electrode can be an electrode used as a reference and comparison when measuring various electrode potentials, and the battery to be tested includes a liquid battery, a mixed solid-liquid battery or an all-solid-state battery. Hybrid solid-liquid batteries and all-solid-state batteries are generally collectively referred to as solid-state batteries.

According to a preferred embodiment, the battery to be tested is subjected to a low current test at room temperature before the constant current charging test is performed to determine the actual capacity of the battery to be tested, which is used to set the state of charge (SOC); then Determine the temperature of the battery test and the time of pulse charging. The pulse charging time is generally greater than 0s and less than or equal to 180s. For example, it can be 3s, 10s, 30s, 60s, 90s, 120s, 160s, etc. Combined with the pulse charging time and test The debugging current value and test temperature are determined empirically; then the SOC is debugged with a small magnification (preferably below 50%), and during the debugging process, the negative parameter potential under the equilibrium state of each SOC, the negative parameter potential under the required pulse time, and the SOC used for debugging are recorded. the current I. The SOC equilibrium state is a state in which each component in the battery reaches a dynamic equilibrium without the influence of other factors (eg, the battery voltage is basically stable, etc.). The method for obtaining the SOC equilibrium state is as follows: after the battery is debugged to the SOC, it is allowed to stand for at least 1 hour, and then each component in the battery will gradually reach an equilibrium state. The debugging current used by the SOC is the current magnification. Preferably, it meets the range of 0.1 to 0.5C. The specific value can be determined according to experience, or it can be determined according to the test temperature. 0.1C. The negative parameter potential at the required pulse time, that is, the negative parameter potential corresponding to the battery to be tested at the end of the pulse time.

Step S102 is to determine the initial pulse current according to the first negative parameter potential, the second negative parameter potential, the debugging current and the precipitation potential of the battery to be tested, including: according to the first negative parameter potential and the second negative parameter potential and the debugging current to determine the resistance at the pulse time. Specifically, using Ohm's law (R=ΔU ₁ /I), divide the difference between the first negative parameter potential and the second negative parameter potential ΔU ₁ by the debugging current used for debugging the SOC I. Calculate the resistance R at the pulse time; determine the initial pulse current according to the first negative parameter potential, the precipitation potential and the resistance at the pulse time. The precipitation potential is the potential between the reference electrode of the battery to be tested and the negative electrode. Taking a lithium-ion battery as an example, the precipitation potential is the critical precipitation potential, and the critical precipitation potential is the minimum applied voltage at which the lithium ions in the battery are reduced to elemental substances and deposited on the surface of the cathode. The specific value of the critical precipitation potential is based on The types of battery reference electrodes are different. For example, the precipitation critical potential of the lithium titanate reference electrode is 1.5V, and the precipitation critical potential of the lithium iron phosphate reference electrode is 3.45V.

The determination of the initial pulse current I ₁ according to the first negative parameter potential, the precipitation potential and the resistance under the pulse time includes: I ₁ =ΔU/R, where ΔU is the first negative parameter potential minus the precipitation potential. difference, R is the resistance at the pulse time.

Step S103 is to perform a pulse charging test on the battery under test through the initial pulse current to obtain the third negative parameter potential at the end of the pulse charging test, the pulse charging test is a single pulse charging test, and the pulse current in the whole process is is fixed. The pulse charging is a method of charging the battery with a high current in a short time at the moment when the current is turned on. The test temperature of the constant current charging test is the same as the test temperature of the pulse charging test, and the test temperature is determined according to experience.

Step S104 is to determine the maximum pulse current according to the third negative parameter potential and the precipitation potential.

The determining the maximum pulse current according to the third negative parameter potential and the precipitation potential is: if the difference between the third negative parameter potential and the precipitation potential does not meet the potential threshold range, then adjust the initial pulse current Then, the battery to be tested is subjected to a pulse charging test again through the adjusted pulse current until the difference between the negative parameter potential and the precipitation potential meets the potential threshold range, for example, the adjusted pulse current is used to charge the battery to be tested. Test the battery to perform the pulse charging test again to obtain the fourth negative parameter potential at the end of the pulse charging test, and then continue to compare the fourth negative parameter potential and the precipitation potential, and repeat until the negative parameter potential at the end of the pulse charging test and the precipitation potential. The difference of the precipitation potential satisfies the potential threshold range; if the difference between the third negative parameter potential and the precipitation potential satisfies the potential threshold range, the maximum pulse current is equal to the initial pulse current, preferably, the potential The threshold range is: -5～5mV.

The if the difference between the third negative parameter potential and the precipitation potential does not meet the potential threshold range, then adjusting the size of the initial pulse current, including: if the difference between the third negative parameter potential and the precipitation potential If the difference is greater than the maximum value of the potential threshold range, the initial pulse current is increased; if the difference between the third negative parameter potential and the precipitation potential is less than the minimum value of the potential threshold range, the initial pulse current is decreased. the initial pulse current. The raising of the initial pulse current may be the initial pulse current multiplied by 1.01-1.1, and the reduction of the initial pulse current may be the initial pulse current multiplied by 0.9-0.99, and the specific ratio may be determined according to actual conditions. Through the above method, the maximum current value under the closest pulse condition can be obtained conveniently and quickly through the initial pulse current.

Example 1:

1. Prepare a three-electrode lithium-ion battery with a reference electrode. The three-electrode lithium-ion battery can monitor the negative parameter, and the capacity of the battery is fixed with a small current at room temperature, and the actual capacity of the battery is recorded as 110Ah.

2. Set the test conditions for the constant current charging test: the test temperature is 25°C, the state of charge SOC is 50% SOC, and the pulse charging time is 10s.

3. Perform a constant current charging test on the battery, as shown in Table 1 below, record the first negative parameter potential of each SOC equilibrium state is 0.1045V, the second negative parameter potential under the required pulse time (10s) is 0.0715V and The debug current I used to debug the SOC is 36.272A.

4. Using Ohm's law (R=ΔU ₁ / _I ), divide by The debug current I used to debug the SOC is used to calculate the resistance R at this pulse time.

5. Further, using the first negative parameter potential in the SOC equilibrium state, the critical lithium deposition potential of the negative parameter, and the resistance R under the pulse time, the formula I ₁ =ΔU/R is used to estimate the required SOC state. The initial pulse current I ₁ corresponding to the pulse time; the critical lithium deposition potential between the reference electrode used in the present invention and the negative electrode is 0V.

Table 1 Data record table for maximum pulse current

6. Carry out a pulse charging test on the debugged battery under the above-mentioned initial pulse current I ₁ , and then obtain the third negative parameter potential of the battery at the end of the pulse test, if the difference between the third negative parameter potential and the critical lithium precipitation potential is greater than 5mV , it can be appropriately adjusted on the basis of the initial pulse current. If the difference between the third negative parameter potential and the critical lithium-evolution potential is less than -5mV, it can be adjusted down on the basis of the initial pulse current, and then pulse test the battery. verify.

7. Finally, according to the actual measurement of the pulse, on the premise of not touching the dynamic lithium-evolution potential of the battery (the lithium-evolution potential is the potential of the negative parameter to lithium), that is, under the condition that the battery will not precipitate lithium, complete the battery at a specific temperature, The adjustment of the maximum pulse current Imax under SOC and pulse time maximizes the power performance of the battery.

8. Repeat the above operations to obtain the maximum pulse current at a certain pulse time under each required SOC. Similarly, repeating the above operations to test the battery at different temperatures can also obtain the maximum pulse current of each SOC and pulse time at different temperatures.

2 is the maximum pulse current data diagram of the present invention under fixed test conditions, specifically the maximum pulse current data diagram of each SOC (0% SOC to 95% SOC) at 20° C. and 10s pulse charging time. The method can conveniently and quickly calculate the maximum pulse current under specific pulse conditions on the premise of ensuring the safety of the battery, so as to maximize the power performance of the battery.

The method for testing the charging performance of the battery of the present invention includes: performing a constant current charging test on the battery to be tested, and determining the first negative parameter potential in the equilibrium state, the second negative parameter potential in the pulse time, and the debugging current, and the battery to be tested includes: reference electrode; determine the initial pulse current according to the first negative parameter potential, the second negative parameter potential, the debugging current and the precipitation potential of the battery under test; perform pulse charging on the battery under test through the initial pulse current test to obtain the third negative parameter potential at the end of the pulse charging test; the maximum pulse current is determined according to the third negative parameter potential and the precipitation potential. The present invention does not need to separately test HPPCs with different magnifications and pulse times corresponding to multiple states of charge, effectively reduces the test time and test cycle, and improves the test efficiency, and the present invention reduces the risk of lithium or sodium precipitation in the battery. , to maximize the power performance of the battery itself under each SOC, without relying on the simulation technology, the experiment can be carried out alone to achieve the required results.

The optional embodiments of the embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details of the above-mentioned embodiments. A variety of simple modifications are made to the technical solution of the invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

In addition, it should be noted that each specific technical feature described in the above-mentioned specific implementation manner may be combined in any suitable manner under the circumstance that there is no contradiction. To avoid unnecessary repetition, various possible combinations are not further described in this embodiment of the present invention.

It should also be noted that the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device comprising a series of elements includes not only those elements, but also Other elements not expressly listed, or which are inherent to such a process, method, article of manufacture, or apparatus are also included. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, method, article of manufacture or apparatus that includes the element.

The above are merely examples of the present application, and are not intended to limit the present application. Various modifications and variations of this application are possible for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the scope of the claims of this application.

Claims (10)

1. a test method of battery charging performance, is characterized in that, comprises: Carry out a constant current charging test on the battery to be tested, and determine the first negative parameter potential in the equilibrium state, the second negative parameter potential and the debugging current in the pulse time, and the battery to be tested includes a reference electrode; Determine the initial pulse current according to the first negative parameter potential, the second negative parameter potential, the debugging current and the precipitation potential of the battery to be tested; The battery to be tested is subjected to a pulse charging test through the initial pulse current to obtain the third negative parameter potential at the end of the pulse charging test; The maximum pulse current is determined according to the third negative parameter potential and the precipitation potential. 2. The test method according to claim 1, wherein the initial pulse current is determined according to the first negative parameter potential, the second negative parameter potential, the debugging current and the precipitation potential of the battery to be tested, comprising: Determine the resistance at the pulse time according to the first negative parameter potential, the second negative parameter potential and the debugging current; The initial pulse current is determined according to the first negative parameter potential, the precipitation potential and the resistance at the pulse time. 3. The test method according to claim 2, wherein the determination of the initial pulse current I ₁ according to the first negative parameter potential, the precipitation potential and the resistance under the pulse time comprises: I ₁ =ΔU/R, Among them, ΔU is the difference between the first negative parameter potential minus the precipitation potential, R is the resistance at the pulse time. 4. testing method according to claim 1, is characterized in that, described by described initial pulse current to described battery to be tested is carried out pulse charging test, obtains the third negative parameter potential when the pulse charging test ends, according to the The third negative parameter potential and the precipitation potential determine the maximum pulse current, including: If the difference between the third negative parameter potential and the precipitation potential does not meet the potential threshold range, adjust the size of the initial pulse current, and then perform a pulse charging test on the battery under test again through the adjusted pulse current , until the difference between the negative parameter potential and the precipitation potential at the end of the pulse charging test meets the potential threshold range; If the difference between the third negative parametric potential and the precipitation potential satisfies the potential threshold range, the maximum pulse current is equal to the initial pulse current. 5. testing method according to claim 4 is characterized in that, described if the difference of described third negative parameter electric potential and described precipitation electric potential does not satisfy electric potential threshold value range, then adjust the size of described initial pulse current, include: If the difference between the third negative parameter potential and the precipitation potential is greater than the maximum value of the potential threshold range, increasing the initial pulse current; If the difference between the third negative parametric potential and the precipitation potential is smaller than the minimum value of the potential threshold range, the initial pulse current is reduced. 6. test method according to claim 1, is characterized in that, this test method also comprises: The actual capacity of the battery to be tested is determined before the constant current charging test is performed on the battery to be tested. 7. testing method according to claim 1, is characterized in that, The test conditions of the constant current charging test include test temperature, pulse charging time and state of charge. 8. testing method according to claim 1, is characterized in that, The test temperature of the constant current charging test is the same as the test temperature of the pulse charging test. 9. test method according to claim 1, is characterized in that, The precipitation potential is the potential between the reference electrode of the battery to be tested and the negative electrode. 10. test method according to claim 1, is characterized in that, The battery to be tested is a lithium-ion battery, and the precipitation potential is a lithium precipitation potential; or, The battery to be tested is a sodium-ion battery, and the precipitation potential is a sodium precipitation potential.

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