A method for testing battery charging performance

Abstract

The embodiment of the present invention provides a method for testing the charging performance of a battery, comprising: performing a constant current charging test on a battery to be tested, determining a first negative reference potential in an equilibrium state, a second negative reference potential under a pulse time, and a debugging current, wherein the battery to be tested includes a reference electrode; determining an initial pulse current according to the first negative reference potential, the second negative reference potential, the debugging current, and the deposition potential of the battery to be tested; performing a pulse charging test on the battery to be tested by the initial pulse current to obtain a third negative reference potential at the end of the pulse charging test; determining a maximum pulse current according to the third negative reference potential and the deposition potential. This testing method can maximize the power performance of the battery itself at each SOC on the basis of reducing the risk of lithium or sodium deposition in the battery; and this testing method does not rely on simulation technology, effectively reduces the test time and test cycle, and improves the test efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of battery charging, and in particular to a method for testing battery charging performance. Background Art

[0002] In recent years, the new energy vehicle industry has developed rapidly. Due to the advantages of lithium-ion batteries such as high operating voltage, high energy density, long cycle life, low self-discharge rate and no memory effect, they have been widely used in new energy vehicles, especially in pure electric vehicles.

[0003] 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:

[0004] 1. Adjust the battery state of charge to the required SOC at room temperature, leave it at each temperature for a certain period of time, then perform a hybrid power pulse capability characteristic (HPPC) test at different currents at the temperature, and finally estimate the maximum pulse current at the specific SOC at the temperature based on the test results;

[0005] 2. Use electrochemical simulation methods to perform simulation estimates and then conduct experimental verification.

[0006] The above method not only cannot prevent the influence of the obtained current on the risk of lithium or sodium deposition in the battery, but also its simulation means needs to be verified in combination with experiments, the test cycle is long and the efficiency is low, which greatly affects the experimental process. Summary of the invention

[0007] The purpose of an embodiment of the present invention is to provide a method for testing the charging performance of a battery, which can maximize the power performance of the battery itself at each SOC while reducing the risk of lithium or sodium deposition in the battery; and the test method does not rely on simulation technology, effectively reduces the test time and test cycle, and improves the test efficiency.

[0008] The present invention provides a method for testing the charging performance of a battery, comprising: performing a constant current charging test on a battery to be tested, determining a first negative reference potential in an equilibrium 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 an initial pulse current according to the first negative reference potential, the second negative reference potential, the debugging current, and a deposition potential of the battery to be tested; performing a pulse charging test on the battery to be tested by using the initial pulse current, and obtaining a third negative reference potential at the end of the pulse charging test; and determining a maximum pulse current according to the third negative reference potential and the deposition potential.

[0009] Optionally, determining the initial pulse current according to the first negative parameter potential, the second negative parameter potential, the debugging current and the deposition potential of the battery to be tested includes: determining the resistance under the pulse time according to the first negative parameter potential, the second negative parameter potential and the debugging current; determining the initial pulse current according to the first negative parameter potential, the deposition potential and the resistance under the pulse time.

[0010] Optionally, determining the initial pulse current I1 according to the first negative parameter potential, the deposition potential and the resistance at the pulse time includes: I1=ΔU / R, wherein ΔU is the difference between the first negative parameter potential and the deposition potential, and R is the resistance at the pulse time.

[0011] Optionally, the battery to be tested is pulse charged by the initial pulse current to obtain a third negative parameter potential at the end of the pulse charging test, and the maximum pulse current is determined according to the third negative parameter potential and the deposition potential, including: if the difference between the third negative parameter potential and the deposition potential does not meet the potential threshold range, the initial pulse current is adjusted, and then the battery to be tested is pulse charged again by the adjusted pulse current until the difference between the negative parameter potential at the end of the pulse charging test and the deposition potential meets the potential threshold range; if the difference between the third negative parameter potential and the deposition potential meets the potential threshold range, the maximum pulse current is equal to the initial pulse current.

[0012] Optionally, if the difference between the third negative parameter potential and the deposition potential does not satisfy the potential threshold range, the size of the initial pulse current is adjusted, including: if the difference between the third negative parameter potential and the deposition potential 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 deposition potential is less than the minimum value of the potential threshold range, the initial pulse current is reduced.

[0013] Optionally, the actual capacity of the battery to be tested is determined before the battery to be tested is subjected to a constant current charging test.

[0014] Optionally, the test conditions of the constant current charging test include test temperature, pulse charging time and charge state.

[0015] Optionally, the test temperature of the constant current charging test is the same as the test temperature of the pulse charging test.

[0016] Optionally, the deposition potential is the potential between the reference electrode and the negative electrode of the battery to be tested.

[0017] Optionally, the battery to be tested is a lithium ion battery, and the deposition potential is a lithium deposition potential; or, the battery to be tested is a sodium ion battery, and the deposition potential is a sodium deposition potential.

[0018] Through the above technical solution, the present invention reduces the risk of battery precipitation while obtaining the maximum pulse current, and maximizes the battery power performance. In addition, the test method does not rely on simulation technology, effectively reduces the test time and test cycle, and improves the test efficiency.

[0019] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0021] Figure 1 It is a flow chart of a method for testing battery charging performance of the present invention;

[0022] Figure 2 It is a maximum pulse current data diagram of the present invention under fixed test conditions. DETAILED DESCRIPTION

[0023] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0024] Figure 1 is a flow chart of a method for testing battery charging performance of the present invention, such as Figure 1 As shown, 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 second negative parameter potential under the pulse time, and the debugging current. The test conditions of the constant current charging test include the test temperature, the pulse charging time, and the state of charge. According to a specific implementation, the constant current charging refers to charging with a fixed test temperature and pulse charging time, and the current is maintained at a constant value, wherein the test temperature and pulse charging time are determined according to the actual test situation.

[0025] The determination method of the present invention is applicable to any battery such as lithium-ion batteries and sodium-ion batteries that can be implanted with a reference electrode. For example: if the battery to be tested is a lithium-ion battery, the precipitation potential is a lithium precipitation potential; or, if the battery to be tested is a sodium-ion battery, the precipitation potential is a sodium precipitation potential. The battery to be tested is a three-electrode battery, that is, it includes a positive electrode, a negative electrode and a reference electrode. The reference electrode can be an electrode used as a reference comparison when measuring various electrode potentials. The battery to be tested includes a liquid battery, a hybrid solid-liquid battery or an all-solid-state battery. Hybrid solid-liquid batteries and all-solid-state batteries are generally referred to as solid-state batteries.

[0026] According to a preferred embodiment, before the battery to be tested is subjected to a constant current charging test, a small current test is performed on the battery to be tested at room temperature to determine the actual capacity of the battery to be tested, which is used to set the state of charge (SOC); then the temperature of the battery test and the time of pulse charging are determined, and 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., and the debugging current value and the test temperature are determined in combination with the pulse charging time and test experience; then the SOC is debugged at a small rate (preferably less than 50%), and during the debugging process, the negative parameter potential under each SOC equilibrium state, the negative parameter potential under the required pulse time, and the current I used to debug the SOC are recorded. The SOC equilibrium state is a state in which the components in the battery reach a dynamic equilibrium (such as the battery voltage is basically stable and unchanged, etc.) without the influence of other factors. The method for obtaining the SOC equilibrium state is: after the battery is debugged to the SOC, it is left to stand for at least 1h, at which time the components in the battery will gradually reach a equilibrium state. The debugging current used for SOC is the current multiplier, preferably, it meets the range of 0.1-0.5C, and its specific value can be determined based on experience or the test temperature. For example, under low temperature conditions, a small multiplier is selected as much as possible, such as 0.1C. The negative parameter potential under the required pulse time is the negative parameter potential corresponding to the battery under test when the pulse time ends.

[0027] Step S102 is to determine the initial pulse current according to the first negative reference potential, the second negative reference potential, the debugging current and the deposition potential of the battery to be tested, including: determining the resistance under the pulse time according to the first negative reference potential, the second negative reference potential and the debugging current, specifically, using Ohm's law (R=ΔU1 / I), dividing the difference ΔU1 between the first negative reference potential and the second negative reference potential by the debugging current I used to debug the SOC, and calculating the resistance R under the pulse time; determining the initial pulse current according to the first negative reference potential, the deposition potential and the resistance under the pulse time. The deposition potential is the potential between the reference electrode of the battery to be tested relative to the negative electrode. Taking lithium-ion batteries as an example, the deposition potential is the critical deposition potential, which is the minimum external voltage at which lithium ions in the battery are reduced to a single substance and deposited on the surface of the cathode. The specific value of the critical deposition potential varies according to the type of the battery reference electrode, for example: the deposition critical potential of the lithium titanate reference electrode is 1.5V, and the deposition critical potential of the lithium iron phosphate reference electrode is 3.45V.

[0028] The determining of the initial pulse current I1 according to the first negative parameter potential, the deposition potential and the resistance under the pulse time includes: I1=ΔU / R, wherein ΔU is the difference between the first negative parameter potential and the deposition potential, and R is the resistance under the pulse time.

[0029] Step S103 is to perform a pulse charging test on the battery to be tested by the initial pulse current to obtain the third negative reference potential at the end of the pulse charging test. The pulse charging test is a single pulse charging test, and the pulse current is fixed during the whole process. The pulse charging is a positive pulse charging method, which is a method of charging the battery with a high current for 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 based on experience.

[0030] Step S104 is to determine the maximum pulse current according to the third negative reference potential and the deposition potential.

[0031] The maximum pulse current is determined according to the third negative reference potential and the deposition potential as follows: if the difference between the third negative reference potential and the deposition potential does not satisfy the potential threshold range, the size of the initial pulse current is adjusted, and then the pulse charging test is performed on the battery to be tested again with the adjusted pulse current until the difference between the negative reference potential and the deposition potential satisfies the potential threshold range, for example, the pulse charging test is performed on the battery to be tested again with the adjusted pulse current to obtain the fourth negative reference potential at the end of the pulse charging test, and then the fourth negative reference potential and the deposition potential are continuously compared, and this is repeated until the difference between the negative reference potential at the end of the pulse charging test and the deposition potential satisfies the potential threshold range; if the difference between the third negative reference potential and the deposition potential satisfies the potential threshold range, the maximum pulse current is equal to the initial pulse current. Preferably, the potential threshold range is: -5 to 5 mV.

[0032] If the difference between the third negative parameter potential and the deposition potential does not meet the potential threshold range, the size of the initial pulse current is adjusted, including: if the difference between the third negative parameter potential and the deposition potential 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 deposition potential is less than the minimum value of the potential threshold range, the initial pulse current is reduced. The increase in the initial pulse current can be the initial pulse current multiplied by 1.01 to 1.1, and the reduction in the initial pulse current can be the initial pulse current multiplied by 0.9 to 0.99, and the specific ratio can be determined according to the actual situation. The above method can be used to more conveniently and quickly obtain the maximum current value under the closest pulse conditions through the initial pulse current.

[0033] Embodiment 1:

[0034] 1. Prepare a three-electrode lithium-ion battery containing a reference electrode. The three-electrode lithium-ion battery can monitor negative parameters. The capacity of the battery is constant at room temperature and a small current is used to record the actual capacity of the battery as 110Ah.

[0035] 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.

[0036] 3. The battery was subjected to a constant current charging test, as shown in Table 1 below, recording the first negative reference potential of each SOC equilibrium state as 0.1045 V, the second negative reference potential under the required pulse time (10 s) as 0.0715 V, and the debugging current I used for debugging the SOC as 36.272 A.

[0037] 4. Using Ohm's law (R=ΔU1 / I), the difference ΔU1 between the first negative reference potential of the SOC equilibrium state recorded in step 3 and the second negative reference potential under the pulse time (10s) is divided by the debugging current I used to debug the SOC, so as to calculate the resistance R under the pulse time.

[0038] 5. Further, the first negative reference potential under the SOC equilibrium state, the critical lithium deposition potential of the negative reference and the resistance R under the pulse time are used to estimate the initial pulse current I1 corresponding to the required pulse time under the SOC state by the formula I1=ΔU / R; wherein the critical lithium deposition potential between the reference electrode and the negative electrode used in the present invention is 0V.

[0039] Table 1 Data record table of maximum pulse current

[0040]

[0041] 6. Perform a pulse charging test on the debugged battery under the above-mentioned initial pulse current I1 to 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 deposition potential is greater than 5mV, it can be appropriately adjusted upward based on the initial pulse current. If the difference between the third negative parameter potential and the critical lithium deposition potential is less than -5mV, it is adjusted downward based on the initial pulse current, and then the battery is pulse tested to verify the current.

[0042] 7. Finally, according to the actual pulse measurement, under the premise of not touching the dynamic lithium deposition potential of the battery (the lithium deposition potential is the potential of the negative reference to lithium), that is, when the battery will not deposit lithium, the maximum pulse current Imax of the battery at a specific temperature, SOC and pulse time is adjusted to maximize the power performance of the battery.

[0043] 8. Repeat the above operation to get the maximum pulse current at a certain pulse time under each required SOC. Similarly, repeat the above operation and test the battery at different temperatures to get the maximum pulse current at different SOC and pulse time under different temperatures.

[0044] Figure 2This 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 ~ 95% SOC) under 20°C and 10s pulse charging time. This method can calculate the maximum pulse current under specific pulse conditions more conveniently and quickly while ensuring battery safety, maximizing the power performance of the battery.

[0045] The battery charging performance testing method of the present invention includes: performing a constant current charging test on the battery to be tested, determining the first negative parameter potential in the equilibrium state, the second negative parameter potential under the pulse time, and the debugging current, wherein the battery to be tested includes a reference electrode; determining the initial pulse current according to the first negative parameter potential, the second negative parameter potential, the debugging current, and the deposition potential of the battery to be tested; performing a pulse charging test 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; determining the maximum pulse current according to the third negative parameter potential and the deposition potential. The present invention does not need to test HPPCs of different rates and different pulse times corresponding to multiple charge states separately, effectively reducing the test time and test cycle, and improving the test efficiency. Moreover, the present invention maximizes the power performance of the battery itself at each SOC on the basis of reducing the risk of lithium or sodium deposition of the battery, does not rely on simulation technology, and can be tested separately to achieve the required results.

[0046] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0047] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0048] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0049] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for testing battery charging performance, characterized in that: include: Performing a constant current charging test on a battery to be tested, determining a first negative reference potential in an equilibrium state, a second negative reference potential under a pulse time, and a debugging current, wherein the battery to be tested includes a reference electrode; Determining an initial pulse current according to the first negative parameter potential, the second negative parameter potential, the debugging current and the deposition potential of the battery to be tested; Performing a pulse charging test on the battery to be tested by using the initial pulse current to obtain a third negative reference potential when the pulse charging test ends; Determining a maximum pulse current according to the third negative reference potential and the deposition potential; The step of determining the initial pulse current according to the first negative reference potential, the second negative reference potential, the debugging current and the deposition potential of the battery to be tested comprises: Determine the resistance under the pulse time according to the first negative reference potential, the second negative reference potential and the adjustment current; The initial pulse current is determined according to the first negative reference potential, the deposition potential and the resistance under the pulse time.

2. The testing method according to claim 1, characterized in that: The determining of the initial pulse current I1 according to the first negative reference potential, the deposition potential and the resistance under the pulse time comprises: I1=ΔU / R, Where ΔU is the difference between the first negative reference potential and the deposition potential, R is the resistance at the pulse time.

3. The testing method according to claim 1, characterized in that: The method of performing a pulse charging test on the battery to be tested by using the initial pulse current to obtain a third negative parameter potential at the end of the pulse charging test, and determining a maximum pulse current according to the third negative parameter potential and the deposition potential, comprises: If the difference between the third negative reference potential and the deposition potential does not meet the potential threshold range, the magnitude of the initial pulse current is adjusted, and then the pulse charging test is performed again on the battery to be tested by the adjusted pulse current until the difference between the negative reference potential and the deposition potential at the end of the pulse charging test meets the potential threshold range; If the difference between the third negative reference potential and the deposition potential satisfies the potential threshold range, the maximum pulse current is equal to the initial pulse current.

4. The testing method according to claim 3, characterized in that: If the difference between the third negative reference potential and the deposition potential does not satisfy the potential threshold range, adjusting the magnitude of the initial pulse current includes: If the difference between the third negative reference potential and the deposition potential is greater than the maximum value of the potential threshold range, increasing the initial pulse current; If the difference between the third negative reference potential and the deposition potential is smaller than the minimum value of the potential threshold range, the initial pulse current is reduced.

5. The testing method according to claim 1, characterized in that: The test method also includes: The actual capacity of the battery to be tested is determined before the constant current charging test of the battery to be tested is performed.

6. The testing method according to claim 1, characterized in that: The test conditions of the constant current charging test include test temperature, pulse charging time and charge state.

7. The testing method according to claim 1, characterized in that: The test temperature of the constant current charging test is the same as the test temperature of the pulse charging test.

8. The testing method according to claim 1, characterized in that: The deposition potential is the potential between the reference electrode and the negative electrode of the battery to be tested.

9. The testing method according to claim 1, characterized in that: The battery to be tested is a lithium ion battery, and the deposition potential is a lithium deposition 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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