Method, device and equipment for predicting cycle life of battery cell
By measuring the volume expansion change rate of the negative electrode of the battery cell, the cycle test state of charge interval is solved, and a more efficient life prediction is achieved.
Patent Information
- Application Number
- CN202411221910.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-02
- Publication Date
- 2025-01-10
Smart Images
Figure CN119291542A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of battery cell life prediction, and in particular to a method, device and equipment for predicting the cycle life of a battery cell. Background Art
[0002] In recent years, lithium-ion batteries have been widely used in the energy storage field due to their high specific capacity, low cost and mature manufacturing process. At present, large-scale commercial energy storage products on the market basically need to be cycled more than 6,000 times in their entire life cycle, which is a huge challenge for product design. That is, the test cycle will exceed two years, affecting the product development process and iteration cycle.
[0003] Therefore, how to shorten the battery cell cycle test period has become a technical problem that technical personnel in this field urgently need to solve. Summary of the invention
[0004] The present invention provides a method, device and equipment for predicting the cycle life of a battery cell, so as to solve the defect of a long cycle test period of the battery cell life in the prior art.
[0005] In a first aspect, the present invention provides a method for predicting the cycle life of a battery cell, comprising:
[0006] Based on the material properties, system properties and structural properties of the battery cell sample, determining that the test target of the battery cell sample is the battery cell negative electrode;
[0007] Determine the volume expansion change rate of the negative electrode of the battery cell within the full state of charge range, and determine the cycle test state of charge range of the battery cell sample based on the volume expansion change rate;
[0008] The cycle life of the battery cell to be tested is tested within the cycle test state of charge interval to characterize the cycle life of the battery cell to be tested within the full state of charge interval.
[0009] According to a method for predicting the cycle life of a battery cell provided by the present invention, the step of determining the charge state interval of the cycle test of the battery cell sample based on the volume expansion change rate includes:
[0010] Determining the total volume expansion of the battery cell sample within a full state of charge range;
[0011] Based on the total volume expansion, determining a volume change rate within any state of charge interval;
[0012] Determine the interval in which the volume change rate is greater than the preset change rate as the cycle test charge state interval.
[0013] According to a method for predicting the cycle life of a battery cell provided by the present invention, the step of determining the total volume expansion of the battery cell sample within a full charge state interval includes:
[0014] Determine the discharge capacity and charge cut-off voltage at the nominal capacity current of the cell sample;
[0015] Based on the discharge capacity and the charge cut-off voltage, constructing a volume expansion curve of the battery cell sample in a full charge state range;
[0016] The volume corresponding to the highest point of the volume expansion curve is taken as the total volume expansion amount.
[0017] According to a method for predicting the cycle life of a battery cell provided by the present invention, determining the rate of change within any state of charge interval based on the total volume expansion includes:
[0018] Based on the volume expansion curve, determining a volume expansion range corresponding to the battery cell sample in any state of charge range;
[0019] Based on the ratio of any volume expansion range to the corresponding state of charge interval, the volume change rate within any state of charge interval is obtained.
[0020] According to a method for predicting the cycle life of a battery cell provided by the present invention, after determining that the interval in which the change rate is greater than the preset change rate is the cycle test state of charge interval, the method further includes:
[0021] The battery sample is tested for a preset number of cycles under the condition of the cycle test state of charge range to obtain the test capacity retention rate in the test range;
[0022] The battery sample is tested for a preset number of cycles under the condition of a full charge state interval to obtain a full interval test capacity retention rate;
[0023] Compare the consistency of the test capacity retention rate in the test interval with the test capacity retention rate in the full interval.
[0024] A method for predicting the cycle life of a battery cell provided by the present invention further includes:
[0025] The ratio of the discharge capacity at each cycle to the discharge capacity at the first cycle was taken as the discharge capacity retention rate.
[0026] According to a method for predicting the cycle life of a battery cell provided by the present invention, the volume expansion curve also includes: a voltage change curve at a nominal battery capacity and a voltage change curve at a preset multiple of the nominal battery capacity.
[0027] According to a method for predicting a battery cell cycle life provided by the present invention, the cycle test state of charge interval is an interval corresponding to a 70%-100% state of charge.
[0028] In a second aspect, the present invention further provides a battery cell cycle life prediction device, comprising:
[0029] A first determination module is used to determine that the test target of the battery sample is the battery cell negative electrode based on the material properties, system properties and structural properties of the battery cell sample;
[0030] A second determination module is used to determine the volume expansion change rate of the negative electrode of the battery cell within the full state of charge range, and determine the cycle test state of charge range of the battery cell sample based on the volume expansion change rate;
[0031] The characterization module is used to test the cycle life of the battery cell to be tested within the cycle test state of charge interval, and characterize the cycle life of the battery cell to be tested within the full state of charge interval.
[0032] In a third aspect, the present invention further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a method for predicting the cycle life of a battery cell as described above is implemented.
[0033] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for predicting the cycle life of a battery cell.
[0034] In a fifth aspect, the present invention further provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the battery cell cycle life prediction method as described above is implemented.
[0035] The present invention provides a method, device and equipment for predicting the cycle life of a battery cell. The method determines that the test target of the battery cell sample is the negative electrode of the battery cell based on the material properties, system properties and structural properties of the battery cell sample; determines the volume expansion change rate of the negative electrode of the battery cell in a full-charge state range, and determines the cycle test charge state range of the battery cell sample based on the volume expansion change rate; tests the cycle life of the battery cell to be tested in the cycle test charge state range to characterize the cycle life of the battery cell to be tested in the full-charge state range. Since the life prediction of the battery cell to be tested is performed through the cycle test charge state range, compared with the cycle test of the cycle life in the full-charge state range, the discharge and charging time of the battery cell to be tested is effectively shortened, thereby effectively reducing the entire life prediction cycle time of the battery cell to be tested, and improving the life prediction efficiency of the battery cell to be tested. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0037] Figure 1 is a flow chart of a method for predicting the cycle life of a battery cell provided in this embodiment;
[0038] Figure 2 is a schematic diagram of volume expansion and voltage change in a fully charged state provided by this embodiment;
[0039] Figure 3 It is a schematic diagram of the capacity retention rate of the negative electrodes of LL350 and KB-2 provided in this embodiment in the charge state interval of the cycle test;
[0040] Figure 4 is with Figure 3 Schematic diagram of the capacity retention rate of the corresponding negative electrode in the full charge state range;
[0041] Figure 5 It is a schematic diagram of the capacity retention rate of the negative electrodes of LL350 and KT208 provided in this embodiment in the charge state interval of the cycle test;
[0042] Figure 6 is with Figure 5 Schematic diagram of the capacity retention rate of the corresponding negative electrode in the full charge state range;
[0043] Figure 7 is a schematic diagram of the structure of the battery cell cycle life prediction device provided in this embodiment;
[0044] Figure 8 It is a schematic diagram of the structure of the electronic device provided in this embodiment. DETAILED DESCRIPTION
[0045] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0046] Figure 1 It is a flow chart of the method for predicting the cycle life of a battery cell provided in this embodiment.
[0047] like Figure 1As shown, a method for predicting the cycle life of a battery cell provided by an embodiment of the present invention mainly includes the following steps:
[0048] 101. Based on the material properties, system properties and structural properties of the battery cell samples, the test target of the battery cell samples is determined to be the negative electrode of the battery cell.
[0049] In a specific implementation process, lithium iron phosphate cells for energy storage are used as cell samples. The cell samples have the same specifications as the cells to be tested. There are many factors that affect the cycle life of the cells, among which the structural stability of the positive and negative electrode materials themselves is particularly important. During the long-term cycle process, the positive and negative electrodes repeatedly embed and extract lithium ions, which can easily cause the positive electrode lattice to be destroyed and the negative electrode graphite to expand and fall off, resulting in irreversible capacity loss. Therefore, based on the working characteristics and own characteristics of the cell, and the material characteristics, system characteristics and structural characteristics of the cell, the negative electrode of the cell sample is tested to reflect the cycle life of the cell sample. Starting from the perspective of negative electrode volume expansion, cycle life testing can better feedback the accuracy of the cycle life of the cell sample.
[0050] Taking the negative electrode of the battery cell as the test target, the volume change range of the negative electrode during the whole life cycle is larger, the potential is lower, and the damage of the solid electrolyte interphase (SEI) is more obvious. Therefore, based on this characteristic, choosing the negative electrode as the test target can better reflect the life of the battery cell.
[0051] 102. Determine the volume expansion change rate of the negative electrode of the battery cell within the full charge state range, and determine the charge state range of the cycle test of the battery cell sample based on the volume expansion change rate.
[0052] The negative electrode of the battery cell is calibrated and tested. At the preset temperature and capacity, the full life cycle calibration is performed to obtain the volume expansion change rate of the negative electrode of the battery cell in the full charge state range. The volume expansion change rate refers to the volume change range of the negative electrode of the battery cell in the full charge state. When the volume change range exceeds the preset range, it indicates that the battery cell sample has reached the life value.
[0053] Since the volume of the negative electrode of the battery sample has been changing throughout the entire cycle, and the change is nonlinear, it is necessary to determine the rate of change of volume expansion at different times. Then, according to the size of the volume expansion rate of change, the cycle test state of charge interval is determined, wherein the cycle test state of charge interval refers to the state of charge range where the physical examination changes greatly, and this interval accounts for the full state of charge interval and reaches the target value. The cycle test state of charge interval can reflect the cycle life of the complete battery sample, and is smaller than the full state of charge interval. In this embodiment, the preferred cycle test state of charge interval is the interval corresponding to the 70%-100% state of charge. The volume increment of 70%-100% state of charge (state of charge, SOC) is the largest. At this time, the negative electrode potential is lower, the SEI damage is more obvious, it is easier to distinguish the trend, and it can save 60% of the test time compared to the full interval cycle.
[0054] 103. The cycle life of the battery cell to be tested is tested within the charge state range of the cycle test to characterize the cycle life of the battery cell to be tested within the full charge state range.
[0055] After determining the cycle test state of charge range, the life test can be performed on the battery cell to be tested within the cycle test state of charge range. The battery cell to be tested is defined as the battery cell that needs to be tested for life, which is consistent with the battery cell sample. It can be understood that one or more battery cells are selected from the battery cells to be tested as battery cell samples to determine the cycle test state of charge range.
[0056] Among them, since the battery sample is a battery cell with the same specifications as the battery cell to be tested, the charge state interval of the battery cell to be tested is determined by the battery sample, thereby avoiding testing the full charge state interval of each battery cell to be tested, thereby effectively shortening the cycle test time.
[0057] Further, based on the above embodiments, the present embodiment determines the charge state interval of the battery cell sample for a cycle test based on the volume expansion change rate, including: determining the total volume expansion of the battery cell sample within the full charge state interval; based on the total volume expansion, determining the volume change rate within any charge state interval; determining the interval in which the volume change rate is greater than a preset change rate as the charge state interval for the cycle test.
[0058] Specifically, the total volume expansion refers to the volume change of the battery sample during its entire life cycle, including the change in the fully charged state. Therefore, by testing the battery sample, the total volume expansion of the telecommunications sample in the fully charged state can be effectively understood. First, the discharge capacity and the charge cut-off voltage are determined at the nominal capacity current of the battery sample of 1C; then, based on the discharge capacity and the charge cut-off voltage, the volume expansion curve of the battery sample in the full charge state range is constructed, including the voltage change curve under the nominal battery capacity and the voltage change curve under the preset multiple of the nominal battery capacity. For example, the 1C voltage change curve and the 0.5C voltage change curve. Therefore, through the change curve diagram, it is possible to understand the change relationship between the volume expansion of the negative electrode of the battery cell and the state of charge, the change relationship between the 1C voltage and the state of charge, and the change relationship between the 0.5C voltage and the state of charge. The volume corresponding to the highest point of the volume expansion curve is taken as the total volume expansion, and the volume corresponding to the lowest point is 0.
[0059] like Figure 2 As shown in the figure, the relationship between volume expansion change and voltage change and different charge states is shown. Figure 2 , can directly and effectively read the size of the volume change value and the voltage change under different capacities.
[0060] Among them, based on the total amount of volume expansion, the volume change rate within any state of charge interval is determined, including: based on the volume expansion curve, determining the volume expansion range corresponding to the battery cell sample within any state of charge interval; based on the ratio of any volume expansion range to the corresponding state of charge interval, obtaining the volume change rate within any state of charge interval.
[0061] Specifically, first of all, in order to ensure that the state of charge interval of the cycle test is obtained, it is necessary to ensure that the volume expansion within the interval exceeds a certain value, and at the same time, it is necessary to ensure that the final interval has a certain proportion in the full state of charge interval, so as to ensure that the state of the battery cell in the full state of charge interval can be characterized by the local interval, and the cycle test period of the entire battery cell to be tested can be effectively shortened. Any state of charge interval refers to any range between 0%-100% of the state of charge interval, and the battery cell sample has a corresponding volume expansion range in any state of charge interval. Therefore, there is a volume change rate in any state of charge interval, that is, the ratio of the volume expansion range to the corresponding state of charge interval, that is, the slope of the volume expansion curve in any state of charge interval.
[0062] The range of any state of charge interval is not necessarily the same, but the state of charge interval corresponding to the same volume change, thus ensuring that the corresponding volume expansion change rate can be calculated in any state of charge interval. The volume expansion change rate can also better reflect whether it can be used as a state of charge interval for cycle testing.
[0063] Further, on the basis of the above embodiments, after determining that the interval in which the change rate is greater than the preset change rate is the cycle test state of charge interval in this embodiment, it also includes: testing the battery cell samples for a preset number of cycles under the cycle test state of charge interval conditions to obtain the test interval test capacity retention rate; testing the battery cell samples for a preset number of cycles under the full state of charge interval conditions to obtain the full interval test capacity retention rate; comparing the consistency of the test interval test capacity retention rate with the full interval test capacity retention rate.
[0064] Specifically, after obtaining the charge state interval of the cycle test, the cycle test of the battery life can be performed only within this interval, that is, the battery cell is charged to 100%, then discharged to 70%, then charged to 100%, and then discharged to 70%, and the test is repeated. Compared with discharging to 100%, the test cycle is effectively shortened.
[0065] Among them, the process of the cycle test is to calibrate the 1C capacity of the battery cell to be tested at 55°C, calculate the 1P capacity based on the 1C capacity, and calculate the capacity corresponding to 70% SOC as the discharge cut-off capacity. The battery cell to be tested is cycled at 55°C 1P 70-100% SOC interval, and after repeating the preset number of cycles, such as 200 cycles, the test interval test capacity retention rate is determined; at the same time, the battery cell to be tested is cycled at 55°C 0.33C 0-100% SOC in the full interval, and a volume expansion curve is made to determine the consistency between the batteries; the battery cell to be tested is cycled at 55°C 1P 0-100% SOC in the full interval, and compared with the initial 55°C 1P capacity, as the full interval test capacity retention rate after 200 cycles of interval cycling. Among them, the ratio of the cyclic discharge capacity corresponding to each number of cycles to the first cycle discharge capacity is used as the discharge capacity retention rate.
[0066] By comparing the discharge capacity retention rate within the cycle test state of charge range with that within the full state of charge range, the reliability of the cycle test state of charge range in representing the full state of charge range is verified. The test results efficiently reflect that the 70%-100% state of charge range can accurately represent the life status of the full state of charge range.
[0067] In order to further verify the accuracy of the method for predicting the life of a battery cell by determining the state of charge interval of a cycle test adopted by the present invention, the feasibility of the above method is verified by selecting a lithium iron phosphate-graphite system. Figure 3 and Figure 4 As shown, Figure 3 The following is a comparison of the interval cycle performance of the two graphites. The darker black LL350 on the left has a lower discharge capacity retention rate in subsequent cycles except for the initial discharge capacity retention rate of the lighter gray KB-2 on the right. Figure 4 The actual full-range circulation rules of the two are consistent.
[0068] In another set of verification data, keeping other conditions the same, the two negative electrode graphite interval cycles and the actual full interval cycles were also compared. Figure 5 and Figure 6 As shown, the lighter gray LL350 maintains a retention rate advantage over the darker black KT208 in 200-600 cycles, and the discharge capacity retention rates of the two are comparable at 1000 cycles. The full-range cycling results also show that LL350 first outperforms KT208 and then maintains consistent characteristics, once again proving the applicability of the interval cycling method provided by the present invention for predicting the cycling trends of different negative electrodes in the same system.
[0069] The present invention is based on the law of change of the in-situ volume of the lithium iron phosphate battery cell with SOC, and on this basis determines the charge state interval of the cycle test, namely 70%-100% SOC, and only cycles in the area where the volume expansion of the negative electrode material is most serious, so as to characterize the full charge state interval through the local charge state interval, effectively saving testing time, thereby shortening the product development cycle.
[0070] Based on the same general inventive concept, the present invention also protects a battery cell cycle life prediction device. The battery cell cycle life prediction device provided by the present invention is described below. The battery cell cycle life prediction device described below and the battery cell cycle life prediction method described above can be referenced to each other.
[0071] Figure 7 It is a schematic diagram of the structure of the battery cell cycle life prediction device provided in this embodiment.
[0072] like Figure 7 As shown, this embodiment provides a battery cell cycle life prediction device, comprising:
[0073] A first determination module 701 is used to determine that the test target of the battery cell sample is the battery cell negative electrode based on the material properties, system properties and structural properties of the battery cell sample;
[0074] A second determination module 702 is used to determine the volume expansion change rate of the negative electrode of the battery cell within the full state of charge range, and determine the cycle test state of charge range of the battery cell sample based on the volume expansion change rate;
[0075] The characterization module 703 is used to test the cycle life of the battery cell to be tested within the charge state interval of the cycle test, and characterize the cycle life of the battery cell to be tested within the full charge state interval.
[0076] Furthermore, the second determining module 702 in this embodiment is specifically configured to:
[0077] Determine the total volume expansion of the cell sample within the full state of charge range;
[0078] Based on the total volume expansion, determine the volume change rate within any state of charge interval;
[0079] Determine the interval in which the volume change rate is greater than the preset change rate as the cycle test charge state interval.
[0080] Furthermore, the second determining module 702 in this embodiment is specifically configured to:
[0081] Determine the discharge capacity and charge cut-off voltage at the nominal capacity current of the cell sample;
[0082] Based on the discharge capacity and charge cut-off voltage, the volume expansion curve of the battery sample in the full charge state range is constructed;
[0083] The volume corresponding to the highest point of the volume expansion curve is taken as the total volume expansion.
[0084] Furthermore, the second determining module 702 in this embodiment is specifically configured to:
[0085] Based on the volume expansion curve, determining a volume expansion range corresponding to the battery cell sample in any state of charge range;
[0086] Based on the ratio of any volume expansion range to the corresponding state of charge interval, the volume change rate within any state of charge interval is obtained.
[0087] Furthermore, this embodiment also includes a verification module, which is used to:
[0088] The battery sample is tested for a preset number of cycles under the condition of the cycle test state of charge range to obtain the test capacity retention rate in the test range;
[0089] The battery samples are tested for a preset number of cycles under the full charge state range to obtain the full range test capacity retention rate;
[0090] Compare the consistency of the test capacity retention rate in the test interval with that in the full interval.
[0091] Furthermore, in this embodiment, the ratio of the cycle discharge capacity corresponding to each cycle number to the first cycle discharge capacity is taken as the discharge capacity retention rate.
[0092] Furthermore, the volume expansion curve in this embodiment also includes: a voltage change curve at the nominal battery capacity and a voltage change curve at a preset multiple of the nominal battery capacity.
[0093] Furthermore, in this embodiment, the charge state interval of the cycle test is an interval corresponding to the charge state of 70%-100%.
[0094] Figure 8It is a schematic diagram of the structure of the electronic device provided in this embodiment.
[0095] like Figure 8 As shown, the electronic device may include: a processor 810, a communication interface 820, a memory 830 and a communication bus 840, wherein the processor 810, the communication interface 820 and the memory 830 communicate with each other through the communication bus 840. The processor 810 may call the logic instructions in the memory 830 to execute the battery cell cycle life prediction method, which includes: based on the material properties, system properties and structural properties of the battery cell sample, determining that the test target of the battery cell sample is the battery cell negative electrode; determining the volume expansion change rate of the battery cell negative electrode in the full state of charge interval, and determining the cycle test state of charge interval of the battery cell sample based on the volume expansion change rate; testing the cycle life of the battery cell to be tested in the cycle test state of charge interval to characterize the cycle life of the battery cell to be tested in the full state of charge interval.
[0096] In addition, the logic instructions in the above-mentioned memory 830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.
[0097] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the battery cell cycle life prediction method provided by the above-mentioned methods, the method including: based on the material properties, system properties and structural properties of the battery cell sample, determining that the test target of the battery cell sample is the battery cell negative electrode; determining the volume expansion change rate of the battery cell negative electrode in the full charge state range, and determining the cycle test charge state range of the battery cell sample based on the volume expansion change rate; testing the cycle life of the battery cell to be tested in the cycle test charge state range to characterize the cycle life of the battery cell to be tested in the full charge state range.
[0098] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the battery cell cycle life prediction method provided by the above-mentioned methods, the method comprising: determining that the test target of the battery cell sample is the battery cell negative electrode based on the material properties, system properties and structural properties of the battery cell sample; determining the volume expansion change rate of the battery cell negative electrode within the full charge state range, and determining the cycle test charge state range of the battery cell sample based on the volume expansion change rate; testing the cycle life of the battery cell to be tested within the cycle test charge state range, and characterizing the cycle life of the battery cell to be tested within the full charge state range.
[0099] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.
[0100] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.
[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for predicting the cycle life of a battery cell, characterized in that: include: Based on the material properties, system properties and structural properties of the battery cell sample, determining that the test target of the battery cell sample is the battery cell negative electrode; Determine the volume expansion change rate of the negative electrode of the battery cell within the full state of charge range, and determine the cycle test state of charge range of the battery cell sample based on the volume expansion change rate; The cycle life of the battery cell to be tested is tested within the cycle test state of charge interval to characterize the cycle life of the battery cell to be tested within the full state of charge interval.
2. The method for predicting the cycle life of a battery cell according to claim 1, characterized in that: The determining of the charge state interval of the cycle test of the battery sample based on the volume expansion change rate includes: Determining the total volume expansion of the battery cell sample within a full state of charge range; Based on the total volume expansion, determining a volume change rate within any state of charge interval; Determine the interval in which the volume change rate is greater than the preset change rate as the cycle test charge state interval.
3. The method for predicting the cycle life of a battery cell according to claim 2, characterized in that: The determining the total volume expansion of the battery cell sample within the full charge state range includes: Determine the discharge capacity and charge cut-off voltage at the nominal capacity current of the cell sample; Based on the discharge capacity and the charge cut-off voltage, constructing a volume expansion curve of the battery cell sample in a full charge state range; The volume corresponding to the highest point of the volume expansion curve is taken as the total volume expansion amount.
4. The method for predicting the cycle life of a battery cell according to claim 3, characterized in that: The determining, based on the total volume expansion, a volume change rate within any state of charge interval includes: Based on the volume expansion curve, determining a volume expansion range corresponding to the battery cell sample in any state of charge range; Based on the ratio of any volume expansion range to the corresponding state of charge interval, the volume change rate within any state of charge interval is obtained.
5. The method for predicting the cycle life of a battery cell according to claim 2, characterized in that: After determining that the interval in which the change rate is greater than the preset change rate is a cycle test state of charge interval, the method further includes: The battery sample is tested for a preset number of cycles under the condition of the cycle test state of charge range to obtain the test capacity retention rate in the test range; The battery sample is tested for a preset number of cycles under the condition of a full charge state interval to obtain a full interval test capacity retention rate; Compare the consistency of the test capacity retention rate in the test interval with the test capacity retention rate in the full interval.
6. The method for predicting the cycle life of a battery cell according to claim 5, characterized in that: Also includes: The ratio of the discharge capacity at each cycle to the discharge capacity at the first cycle was taken as the discharge capacity retention rate.
7. The method for predicting the cycle life of a battery cell according to claim 3, characterized in that: The volume expansion curve also includes: a voltage change curve at the nominal battery capacity and a voltage change curve at a preset multiple of the nominal battery capacity.
8. The method for predicting the cycle life of a battery cell according to any one of claims 1 to 7, characterized in that: The cycle test state of charge interval is an interval corresponding to a state of charge of 70%-100%.
9. A battery cell cycle life prediction device, characterized in that: include: A first determination module is used to determine that the test target of the battery sample is the battery cell negative electrode based on the material properties, system properties and structural properties of the battery cell sample; A second determination module is used to determine the volume expansion change rate of the negative electrode of the battery cell within the full state of charge range, and determine the cycle test state of charge range of the battery cell sample based on the volume expansion change rate; The characterization module is used to test the cycle life of the battery cell to be tested within the cycle test state of charge interval, and characterize the cycle life of the battery cell to be tested within the full state of charge interval.
10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for predicting the cycle life of a battery cell as described in any one of claims 1 to 8 is implemented.