A method and system for testing factors affecting battery charge and discharge performance

Abstract

The application discloses a kind of battery charging and discharging performance influencing factor test method and system, method includes: battery is cycled under low temperature condition and does performance test, collects voltage capacity data;The collected cycle performance test data is handled, and dQ / dV-V curve is made;According to the change of redox peak of each week dQ / dV-V curve of cycle, it is judged that the factor that influences battery low temperature charging and discharging performance is the positive pole of battery or negative pole;The application has the advantages that: the influence of positive pole and negative pole on lithium battery low temperature charging and discharging performance is tested, and it provides guidance for the design improvement of battery low temperature performance.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, specifically to a method and system for testing factors affecting battery charge and discharge performance. Background Technology

[0002] A common problem with various rechargeable batteries is that their performance deteriorates significantly at low temperatures compared to room temperature. This manifests as a sharp drop in discharge voltage, discharge capacity, and charging speed. Lithium-ion batteries store and discharge energy through the migration of Li+ ions between the positive and negative electrodes. However, this migration is greatly affected by temperature, especially at low temperatures. Deteriorating electrode kinetics, increased electrolyte viscosity, and decreased conductivity lead to a sharp decline in battery performance. Studies show that commonly used lithium-ion batteries experience a significant decrease in capacity and operating voltage at -10°C and a marked deterioration at -20°C. Mismatches in the activity of the positive and negative electrode materials or between the materials and the operating conditions can cause battery performance defects. If the lithium intercalation / deintercalation capability of the positive electrode is lower than that of the negative electrode at low temperatures, the discharge capacity will not be fully utilized, resulting in low charge / discharge efficiency (discharge capacity / charge capacity). If the lithium intercalation / deintercalation capability of the positive electrode is much higher than that of the negative electrode at low temperatures, lithium plating will occur during low-temperature charging. Therefore, testing the factors affecting the low-temperature charge / discharge performance of batteries is crucial.

[0003] Chinese Patent Publication No. CN114361446A discloses a method for testing the low-temperature performance of lithium iron phosphate cathode materials. The method includes the following steps: S1, cathode preparation; S2, anode preparation; S3, battery assembly: fabricating button-type batteries from the cathode and anode sheets; S4, pretreatment: performing formation treatment on the button-type batteries until fully charged, aging treatment, cooling to room temperature, and cycling charge and discharge at room temperature 2-4 times to obtain a fully charged battery; S5, discharge testing. This method can be used to test the low-temperature performance of lithium iron phosphate cathode materials, and it has the advantages of simple testing steps, short testing cycle time, and simple procedures. However, this patent application cannot test the influence of the cathode and anode on the low-temperature charge and discharge performance of lithium batteries. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to test the influence of positive and negative electrodes on the low-temperature charge and discharge performance of lithium batteries, so as to provide guidance for designing and improving the low-temperature performance of batteries.

[0005] This invention solves the above-mentioned technical problems through the following technical means: a method for testing factors affecting battery charge and discharge performance, comprising the following steps:

[0006] Step 1: Perform cycle performance testing on the battery under low temperature conditions and collect voltage and capacity data;

[0007] Step 2: Process the collected cyclic performance test data and plot the dQ / dV-V curve;

[0008] Step 3: Based on the changes in the redox peaks of the dQ / dV-V curves during each cycle, determine whether the factor affecting the low-temperature charge-discharge performance of the battery is the positive or negative electrode.

[0009] Furthermore, the low-temperature condition refers to a temperature below zero degrees Celsius.

[0010] Furthermore, the low temperature condition is -10° or -20°.

[0011] Furthermore, the sampling interval for collecting the voltage capacity data is 1 to 10 seconds.

[0012] Furthermore, the sampling interval is 1 second, 5 seconds, or 10 seconds.

[0013] Furthermore, step two includes:

[0014] The cyclic data of the first, middle, and last cycles in the entire cycle are processed, and dQ / dV-V curves are plotted for each cycle.

[0015] Furthermore, step two also includes:

[0016] The system was subjected to cyclic testing at -10℃ for 21 weeks, and voltage and capacity data were collected. dQ / dV-V curves were plotted for the data from weeks 1, 11, and 21.

[0017] Furthermore, step three includes:

[0018] As the number of low-temperature cycles increases, if the oxidation peak of the dQ / dV-V curve remains unchanged while the reduction peak shifts successively, it indicates that the chemical behavior during charging is consistent across the above cycles, while the polarization during discharging gradually intensifies. This suggests that the factor affecting the battery's low-temperature charge-discharge performance is the positive electrode of the battery. Conversely, if the oxidation peak of the dQ / dV-V curve shifts successively while the reduction peak remains unchanged, it indicates that the polarization during charging gradually intensifies across the above cycles, while the chemical behavior during discharging remains consistent. This suggests that the factor affecting the battery's low-temperature charge-discharge performance is the negative electrode of the battery.

[0019] This invention also provides a battery charge / discharge performance influencing factor testing system, comprising:

[0020] The data acquisition module is used to perform cycle performance tests on batteries under low-temperature conditions and collect voltage and capacity data.

[0021] The data processing module is used to process the collected cyclic performance test data and generate dQ / dV-V curves.

[0022] The results analysis module is used to determine whether the factor affecting the low-temperature charge and discharge performance of the battery is the positive or negative electrode, based on the changes in the redox peaks of the dQ / dV-V curves each cycle.

[0023] Furthermore, the low-temperature condition refers to a temperature below zero degrees Celsius.

[0024] Furthermore, the low temperature condition is -10° or -20°.

[0025] Furthermore, the sampling interval for collecting the voltage capacity data is 1 to 10 seconds.

[0026] Furthermore, the sampling interval is 1 second, 5 seconds, or 10 seconds.

[0027] Furthermore, the data processing module is also used for:

[0028] The cyclic data of the first, middle, and last cycles in the entire cycle are processed, and dQ / dV-V curves are plotted for each cycle.

[0029] Furthermore, the data processing module is also used for:

[0030] The system was subjected to cyclic testing at -10℃ for 21 weeks, and voltage and capacity data were collected. dQ / dV-V curves were plotted for the data from weeks 1, 11, and 21.

[0031] Furthermore, the result analysis module is also used for:

[0032] As the number of low-temperature cycles increases, if the oxidation peak of the dQ / dV-V curve remains unchanged while the reduction peak shifts successively, it indicates that the chemical behavior during charging is consistent across the above cycles, while the polarization during discharging gradually intensifies. This suggests that the factor affecting the battery's low-temperature charge-discharge performance is the positive electrode of the battery. Conversely, if the oxidation peak of the dQ / dV-V curve shifts successively while the reduction peak remains unchanged, it indicates that the polarization during charging gradually intensifies across the above cycles, while the chemical behavior during discharging remains consistent. This suggests that the factor affecting the battery's low-temperature charge-discharge performance is the negative electrode of the battery.

[0033] The advantages of this invention are:

[0034] (1) This invention performs low-temperature cycle testing on batteries and analyzes the data to produce dQ / dV-V curves of the cycle data. Based on the changes in the redox peaks of the dQ / dV-V curves each cycle, it can be determined whether the factors affecting the low-temperature charge and discharge performance of the battery are the positive or negative electrode. This allows us to understand whether the low-temperature charge and discharge performance of the positive or negative electrode needs to be optimized, providing a direction for optimizing the low-temperature performance of the battery.

[0035] (2) As the number of low-temperature cycles increases, if the oxidation peak of the dQ / dV-V curve does not change and the position of the reduction peak shifts successively, it indicates that the chemical behavior during charging is consistent in the above cycles, while the polarization during discharging gradually intensifies. This indicates that the factor affecting the low-temperature charge-discharge performance of the battery is the positive electrode of the battery; conversely, it indicates that the factor affecting the low-temperature charge-discharge performance of the battery is the negative electrode of the battery. The changes in the oxidation-reduction peaks can accurately determine whether the low-temperature performance of the battery is affected by the positive or negative electrode of the battery, providing guidance for designing and improving the low-temperature performance of the battery. Attached Figure Description

[0036] Figure 1 This is a flowchart of a method for testing factors affecting battery charging and discharging performance as disclosed in an embodiment of the present invention;

[0037] Figure 2 The dQ / dV-V curve of a lithium-ion battery in a single-cycle test method for factors affecting battery charge and discharge performance disclosed in an embodiment of the present invention;

[0038] Figure 3 The dQ / dV-V curve is shown in the test method for factors affecting battery charge and discharge performance disclosed in this embodiment of the invention, which is based on a 21-cycle test at -10℃. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] like Figure 1 As shown, the present invention provides a method for testing factors affecting battery charge and discharge performance, comprising the following steps:

[0042] S1. The battery undergoes cycle performance testing under low-temperature conditions, and voltage and capacity data are collected; the low-temperature conditions refer to temperatures below zero degrees Celsius, such as -10°C or -20°C. The sampling interval for collecting voltage and capacity data is 1 to 10 seconds, for example, 1 second, 5 seconds, or 10 seconds.

[0043] S2. Process the collected cycle performance test data and plot the dQ / dV-V curve; this mainly involves processing the cycle data from the first, middle, and last cycles of the entire cycle and plotting the dQ / dV-V curves for each cycle. The single-cycle dQ / dV-V curve of a lithium-ion battery is shown below. Figure 2 As shown, the dQ / dV-V curves for the first cycle, the intermediate cycles, and the last cycle are as follows: Figure 3 As shown, specifically, the dQ / dV-V curves for the 1st, 11th, and 21st weeks of a 21-cycle condition at -10℃ are displayed.

[0044] S3. Based on the changes in the redox peaks of the dQ / dV-V curves during each cycle, determine whether the factor affecting the battery's low-temperature charge-discharge performance is the positive or negative electrode. The specific process is as follows:

[0045] As the number of low-temperature cycles increases, if the oxidation peak of the dQ / dV-V curve remains unchanged while the reduction peak shifts successively, it indicates that the chemical behavior during charging is consistent across the above cycles, while the polarization during discharging gradually intensifies. This suggests that the factor affecting the battery's low-temperature charge-discharge performance is the positive electrode of the battery. Conversely, if the oxidation peak of the dQ / dV-V curve shifts successively while the reduction peak remains unchanged, it indicates that the polarization during charging gradually intensifies across the above cycles, while the chemical behavior during discharging remains consistent. This suggests that the factor affecting the battery's low-temperature charge-discharge performance is the negative electrode of the battery.

[0046] In this embodiment, a square 150AH lithium-ion battery was used, with lithium iron phosphate as the main positive electrode material and artificial graphite as the main negative electrode material. A 21-week cycle test was conducted at -10℃, and voltage and capacity data were collected. The collected cycle data were processed, and dQ / dV-V curves were plotted for the data from weeks 1, 11, and 21, as shown in the figure. Figure 3 .Depend on Figure 3 It can be seen that with the increase of low-temperature cycle number, the oxidation peak did not change significantly, while the position of the reduction peak shifted successively. This indicates that the chemical behavior during the charging process was basically the same in the above cycle number, while the polarization during the discharging process gradually intensified. This suggests that the low-temperature charge-discharge performance of the cathode material is relatively poor, and the low-temperature performance of the cathode material needs to be optimized.

[0047] Through the above technical solutions, the lithium battery of the present invention is subjected to cycle testing under low temperature conditions. The voltage and capacity data obtained from the test are plotted as dQ / dV-V curves. The position and peak intensity of the charge-discharge redox peaks change, indicating that polarization occurs during the charge-discharge process. That is, the low temperature performance of the negative or positive electrode is relatively poor, and this electrode needs to be optimized, providing a direction for optimizing the low temperature performance of the battery.

[0048] Example 2

[0049] Based on Example 1, Example 2 of the present invention also provides a battery charging and discharging performance influencing factor testing system, including:

[0050] The data acquisition module is used to perform cycle performance tests on batteries under low-temperature conditions and collect voltage and capacity data.

[0051] The data processing module is used to process the collected cyclic performance test data and generate dQ / dV-V curves.

[0052] The results analysis module is used to determine whether the factor affecting the low-temperature charge and discharge performance of the battery is the positive or negative electrode, based on the changes in the redox peaks of the dQ / dV-V curves each cycle.

[0053] Specifically, the low-temperature condition refers to a temperature below zero degrees Celsius.

[0054] More specifically, the low temperature condition is -10° or -20°.

[0055] Specifically, the sampling interval for collecting voltage capacity data is 1 to 10 seconds.

[0056] More specifically, the sampling interval is 1 second, 5 seconds, or 10 seconds.

[0057] Specifically, the data processing module is also used for:

[0058] The cyclic data of the first, middle, and last cycles in the entire cycle are processed, and dQ / dV-V curves are plotted for each cycle.

[0059] More specifically, the data processing module is also used for:

[0060] The system was subjected to cyclic testing at -10℃ for 21 weeks, and voltage and capacity data were collected. dQ / dV-V curves were plotted for the data from weeks 1, 11, and 21.

[0061] Specifically, the result analysis module is also used for:

[0062] As the number of low-temperature cycles increases, if the oxidation peak of the dQ / dV-V curve remains unchanged while the reduction peak shifts successively, it indicates that the chemical behavior during charging is consistent across the above cycles, while the polarization during discharging gradually intensifies. This suggests that the factor affecting the battery's low-temperature charge-discharge performance is the positive electrode of the battery. Conversely, if the oxidation peak of the dQ / dV-V curve shifts successively while the reduction peak remains unchanged, it indicates that the polarization during charging gradually intensifies across the above cycles, while the chemical behavior during discharging remains consistent. This suggests that the factor affecting the battery's low-temperature charge-discharge performance is the negative electrode of the battery.

[0063] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing factors affecting battery charge and discharge performance, characterized in that, Includes the following steps: Step 1: Perform cycle performance testing on the battery under low temperature conditions and collect voltage and capacity data; Step 2: Process the collected cyclic performance test data and plot the dQ / dV-V curve; Step 3: Based on the changes in the redox peaks of the dQ / dV-V curves during each cycle, determine whether the factor affecting the battery's low-temperature charge-discharge performance is the positive or negative electrode. Step 3 includes: As the number of low-temperature cycles increases, if the oxidation peak of the dQ / dV-V curve remains unchanged while the reduction peak shifts successively, it indicates that the factor affecting the low-temperature charge-discharge performance of the battery is the positive electrode of the battery; conversely, if the oxidation peak of the dQ / dV-V curve shifts successively while the reduction peak remains unchanged, it indicates that the factor affecting the low-temperature charge-discharge performance of the battery is the negative electrode of the battery.

2. The method for testing factors affecting battery charge and discharge performance according to claim 1, characterized in that, The low-temperature condition refers to a temperature below zero degrees Celsius.

3. The method for testing factors affecting battery charge and discharge performance according to claim 2, characterized in that, The low temperature conditions are -10° or -20°.

4. The method for testing factors affecting battery charge and discharge performance according to claim 1, characterized in that, The sampling interval for collecting voltage capacity data is 1 to 10 seconds.

5. The method for testing factors affecting battery charge and discharge performance according to claim 4, characterized in that, The sampling interval is 1 second, 5 seconds, or 10 seconds.

6. The method for testing factors affecting battery charge and discharge performance according to claim 1, characterized in that, Step two includes: The cyclic data of the first, middle, and last cycles in the entire cycle are processed, and dQ / dV-V curves are plotted for each cycle.

7. The method for testing factors affecting battery charge and discharge performance according to claim 6, characterized in that, Step two also includes: The system was subjected to cyclic testing at -10℃ for 21 weeks, and voltage and capacity data were collected. dQ / dV-V curves were plotted for the data from weeks 1, 11, and 21.

8. A test system for factors affecting battery charge and discharge performance, characterized in that, include: The data acquisition module is used to perform cycle performance tests on batteries under low-temperature conditions and collect voltage and capacity data. The data processing module is used to process the collected cyclic performance test data and generate dQ / dV-V curves. The results analysis module is used to determine whether the factor affecting the low-temperature charge-discharge performance of the battery is the positive or negative electrode based on the changes in the redox peaks of the dQ / dV-V curves per cycle; the results analysis module is also used for: As the number of low-temperature cycles increases, if the oxidation peak of the dQ / dV-V curve remains unchanged while the reduction peak shifts successively, it indicates that the factor affecting the low-temperature charge-discharge performance of the battery is the positive electrode of the battery; conversely, if the oxidation peak of the dQ / dV-V curve shifts successively while the reduction peak remains unchanged, it indicates that the factor affecting the low-temperature charge-discharge performance of the battery is the negative electrode of the battery.

9. A battery charge / discharge performance influencing factor testing system according to claim 8, characterized in that, The low-temperature condition refers to a temperature below zero degrees Celsius.

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