A method and device for selecting consistency of lithium titanate batteries

Abstract

The present invention relates to a method and device for selecting the consistency of lithium titanate batteries, and relates to the field of lithium battery technology. It includes: S1: controlling lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, and collecting the battery state of charge and the corresponding static voltage after being at rest; the N / P ratio is ≤1; S2: constructing a first fitting curve to determine a first battery state of charge interval that distinguishes different N / P ratios of the lithium titanate battery; S3: constructing a second fitting curve to determine a second battery state of charge interval of the lithium titanate battery; S4: taking the intersection value of the first battery state of charge interval and the second battery state of charge interval as the target battery state of charge interval. The present invention adopts a strategy of combining the battery state of charge and SOC‑OCV fitting curves with different N / P ratio charging curves to achieve dual-standard selection of battery cell k value and OCV, thereby extending the service life of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a method and device for selecting the consistency of lithium titanate batteries. Background Art

[0002] Currently, the more common lithium iron phosphate and ternary batteries on the market use carbon-based negative electrodes, such as graphite and hard carbon. These negative electrode materials have a low lithium insertion potential of around 0.1V, which easily forms lithium metal deposits. Therefore, the battery design adopts an excess negative electrode design to avoid the formation of lithium dendrites. Lithium titanate batteries are lithium-ion batteries with a lithium titanate negative electrode material. The lithium insertion potential of lithium titanate material is 1.55V. Due to its high potential, there is no problem of lithium dendrites. Therefore, lithium titanate battery design generally adopts an excess positive electrode design to improve cycle life.

[0003] However, the design of lithium titanate battery with excess positive electrode will cause the charge and discharge curve to fluctuate significantly with different N / P ratios (N / P ratio refers to the ratio of the single-surface area capacity of the negative electrode to the unit area capacity of the positive electrode in lithium-ion batteries). Figure 1 ), as the charge and discharge curve with fluctuating N / P ratios can affect the selection of self-discharge OCV. Especially with the widespread application of lithium titanate batteries in large-scale energy storage projects, the existing selection system for lithium titanate battery modules and packs is inappropriate. Although seemingly reasonable testing and selection methods, such as k-value control and OCV range control, can lead to serious deviations in OCV after a period of use, affecting the service life of the lithium titanate battery module or pack. A scientific and reasonable selection method for lithium titanate batteries is urgently needed to ensure stable product operation.

[0004] In view of the above problems, the present invention provides a method and device for selecting the consistency of lithium titanate batteries. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method and device for selecting lithium titanate battery consistency. This method combines the battery state of charge (SOC) with different N / P charging curves and SOC and dQ / dV analysis methods to accurately select the SOC, OCV, and k-value selection ranges for the final step after the lithium titanate battery is capacitated. This allows for accurate selection of cells with consistent charge / discharge curves and self-discharge, avoiding the weak link effect of cells in the system and thus extending the system life.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] In a first aspect, a method for selecting consistency of a lithium titanate battery comprises the following steps:

[0008] S1: Controlling lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, and collecting the battery state of charge and corresponding static voltage of the lithium titanate batteries after they are at rest; the N / P ratio is ≤1;

[0009] S2: constructing a first fitting curve (SOC-OCV fitting curve) based on the collected battery states of charge and corresponding static voltages of the lithium titanate battery with different N / P ratios; the first fitting curve is used to characterize the relationship between the battery state of charge and the static voltage under different N / P ratios; and determining a first battery state of charge range for different N / P ratios of the lithium titanate battery based on the first fitting curve;

[0010] S3: constructing a second fitting curve (static SOC and dQ / dV curve) based on any one of the collected first fitting curves and the corresponding battery state of charge of the lithium titanate battery; the second fitting curve is used to represent the relationship between the battery state of charge and the ratio of the battery state of charge change to the static voltage change; determining a second battery state of charge range of the lithium titanate battery based on the second fitting curve;

[0011] S4: Taking the intersection value of the first battery state of charge interval and the second battery state of charge interval as the target battery state of charge interval.

[0012] The beneficial effect of the present invention is as follows: based on a first fitting curve for characterizing the relationship between the battery state of charge and the static voltage of lithium titanate batteries with different N / P ratios and a second fitting curve for characterizing the relationship between the battery state of charge and the ratio of the battery state of charge change to the static voltage change, the present invention adopts a strategy combining the battery state of charge (SOC) with different N / P charging curves and the SOC with dQ / dV analysis method to accurately select the target battery state of charge range for the last step after the lithium titanate battery is capacitated, so that when the SOC of the battery to be selected is within the target battery state of charge range, the battery cell k (self-discharge rate) value and OCV (static voltage) are selected by dual standards, thereby accurately positioning each battery cell in the corresponding gear, achieving a reduction in the charge and discharge electrode difference from the original 300mV to 80mV under the full SOC, thereby extending the service life of the system.

[0013] On the basis of the above technical solution, the present invention can also be improved as follows.

[0014] Furthermore, step S1 includes the following specific steps:

[0015] Controlling lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, wherein the battery state of charge of the lithium titanate battery increases or decreases in a gradient;

[0016] After being at rest, the battery state of charge and the corresponding static voltage of the lithium titanate battery are collected.

[0017] The battery state of charge of the lithium titanate battery to be selected increases or decreases with a gradient of 2 to 10 between adjacent gradient values.

[0018] Furthermore, the construction of the first fitting curve in step S2 includes the following specific steps:

[0019] According to the collected battery state of charge and corresponding static voltage of the lithium titanate battery, a first fitting curve is constructed with the battery state of charge as the abscissa and the corresponding static voltage as the ordinate.

[0020] Furthermore, determining the first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery in step S2 includes the following specific steps:

[0021] Comparing the trends of the first fitting curves of the lithium titanate batteries, and screening and distinguishing the starting points and end points of the trends of the first fitting curves;

[0022] According to the different starting points and end points of the trend of the first fitting curve, the corresponding battery state of charge interval is determined, that is, the first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery.

[0023] The beneficial effect of adopting the above further scheme is that monomers with different N / P ratios can be distinguished by different OCV values, and monomers with the same or similar N / P ratios can be placed in the same gear. The performance of monomers with the same or similar N / P ratios is similar, avoiding the system life being affected by the inconsistency of monomers. This sorting strategy of increasing N / P ratio helps to extend the service life of the system.

[0024] Furthermore, the construction of the second fitting curve in step S3 includes the following specific steps:

[0025] A second fitting curve is constructed with the collected battery state of charge of the lithium titanate battery as the horizontal coordinate and the ratio of the battery state of charge change to the static voltage change in the corresponding first fitting curve as the vertical coordinate (differential).

[0026] Furthermore, determining the second battery state of charge interval of the lithium titanate battery in step S3 includes the following steps:

[0027] Calculate the slope of each point of the second fitting curve; determine the second battery state of charge interval based on the target point whose slope belongs to the preset slope interval

[0028] Furthermore, the target battery state of charge range is 65% to 95%, preferably 65% ​​to 75%.

[0029] In a second aspect, a device for constructing a selection model for consistency of a lithium titanate battery is provided, the device comprising:

[0030] An acquisition module is used to control lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, and to collect the battery state of charge and the corresponding static voltage of the lithium titanate battery after it comes to rest;

[0031] A first construction module is configured to construct a first fitting curve based on the collected battery states of charge and corresponding static voltages of the lithium titanate battery with different N / P ratios; the first fitting curve is configured to characterize the relationship between the battery state of charge and the static voltage under different N / P ratios; and determine a first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery based on the first fitting curve;

[0032] a second construction module, configured to construct a second fitting curve based on any one of the collected first fitting curves and the corresponding battery state of charge of the lithium titanate battery; the second fitting curve is configured to characterize the relationship between the battery state of charge and the ratio of the battery state of charge change to the static voltage change; and determine a second battery state of charge range of the lithium titanate battery based on the second fitting curve;

[0033] The determination module is configured to take an intersection value of the first battery state of charge interval and the second battery state of charge interval as a target battery state of charge interval.

[0034] In a third aspect, an electronic device comprises: a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor and the memory communicate through the bus, and the machine-readable instructions are executed by the processor when running according to the steps of the method for selecting the consistency of lithium titanate batteries.

[0035] In a fourth aspect, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for selecting the consistency of a lithium titanate battery are executed.

[0036] The process of selecting the consistency of a lithium titanate battery is as follows:

[0037] According to the target battery state of charge range in the method for selecting consistency of lithium titanate batteries, and the limitations on the self-discharge rate k value and OCV range value of the lithium titanate batteries to be selected, the lithium titanate batteries to be selected are divided into grades, and each grade has requirements; the self-discharge rate k value is 0.2 mV / day (7-day self-discharge selection); the OCV range value is ≤10 mV. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a static SOC-OCV fitting curve diagram of the lithium titanate battery of the present invention;

[0039] Figure 2 This is a static SOC-OCV fitting curve diagram under different N / P conditions of the present invention;

[0040] Figure 3 This is a diagram showing the relationship between static OC and dQ / dV of the present invention;

[0041] Figure 4 The present invention is a flowchart of a method for constructing a selection model for lithium titanate battery consistency. DETAILED DESCRIPTION

[0042] The principles and features of the present invention are described below. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or the product instructions are used. Where the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased through regular channels.

[0043] In the existing technology, the selection system for lithium titanate battery modules or lithium titanate battery packs is not properly formulated. Although the test selection methods seem reasonable on the surface, such as k-value control and OCV range control, serious deviations in OCV will occur after a period of use, affecting the service life of the lithium titanate battery module or lithium titanate battery pack.

[0044] Based on this, the present invention provides a method and device for selecting the consistency of lithium titanate batteries. The present invention adopts a strategy that combines the battery state of charge (SOC) with different N / P charging curves and the SOC and dQ / dV analysis methods to accurately select the SOC of the lithium titanate battery in the last step after capacity setting, and realize the dual-standard selection of the battery cell k (self-discharge rate) value and OCV (quiescent voltage), accurately positioning each battery cell in the corresponding gear, and reducing the charge and discharge electrode difference from the original 300mV to 80mV under the full SOC, thereby extending the service life of the system.

[0045] like Figure 4 This embodiment provides a method for selecting the consistency of lithium titanate batteries, comprising the following steps:

[0046] S1: Controlling lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, and collecting the battery state of charge and corresponding static voltage of the lithium titanate batteries after they are at rest; the N / P ratio is ≤1;

[0047] S2: constructing a first fitting curve (SOC-OCV fitting curve) based on the collected battery states of charge and corresponding static voltages of the lithium titanate battery with different N / P ratios; the first fitting curve is used to characterize the relationship between the battery state of charge and the static voltage under different N / P ratios; and determining a first battery state of charge range for different N / P ratios of the lithium titanate battery based on the first fitting curve;

[0048] S3: constructing a second fitting curve (static SOC and dQ / dV curve) based on any one of the collected first fitting curves and the corresponding battery state of charge of the lithium titanate battery; the second fitting curve is used to represent the relationship between the battery state of charge and the ratio of the battery state of charge change to the static voltage change; determining a second battery state of charge range of the lithium titanate battery based on the second fitting curve;

[0049] S4: Taking the intersection value of the first battery state of charge interval and the second battery state of charge interval as the target battery state of charge interval.

[0050] Based on the first fitting curve for characterizing the relationship between the battery state of charge and the static voltage of lithium titanate batteries with different N / P ratios, and the second fitting curve for characterizing the relationship between the battery state of charge and the ratio of the battery state of charge change to the static voltage change, a strategy combining the battery state of charge (SOC) with different N / P charging curves and the SOC with dQ / dV analysis method is adopted to accurately select the target battery state of charge range for the last step after the lithium titanate battery is capacitated. When the SOC of the battery to be selected is within the target battery state of charge range, the battery cell k (self-discharge rate) value and OCV (static voltage) are used for dual-standard selection, thereby accurately positioning each battery cell in the corresponding gear, reducing the charge and discharge electrode difference from the original 300mV to 80mV at the full SOC, thereby extending the service life of the system.

[0051] In this embodiment, step S1 preferably includes the following specific steps:

[0052] Controlling lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, wherein the battery state of charge of the lithium titanate battery increases or decreases in a gradient;

[0053] After being at rest, the battery state of charge and the corresponding static voltage of the lithium titanate battery are collected.

[0054] The battery state of charge of the lithium titanate battery to be selected increases or decreases with a gradient of 2 to 10 between adjacent gradient values.

[0055] In this embodiment, preferably, the construction of the first fitting curve in step S2 includes the following specific steps:

[0056] According to the collected battery state of charge and corresponding static voltage of the lithium titanate battery, a first fitting curve is constructed with the battery state of charge as the abscissa and the corresponding static voltage as the ordinate.

[0057] Specifically, the SOC-OCV fitting curve is obtained by discharging the battery cell to 1.5V with a current of 0.01C, and collecting the voltage OCV1 at 0% SOC after standing for 3 hours. Then, the battery cell is charged with a current of 0.01C for 3 minutes, and after standing for 3 hours, the voltage OCV2 is collected at 5% SOC. Then, the battery cell is charged for 3 minutes, and the static voltage is collected until the static voltage OCV20 at 100% SOC is obtained. The SOC is used as the horizontal axis and the OCV is used as the vertical axis to construct the SOC-OCV fitting curve ( Figure 1 );

[0058] In this embodiment, preferably, determining the first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery in step S2 includes the following specific steps:

[0059] Comparing the trends of the first fitting curves of the lithium titanate batteries, and selecting starting points and end points with different trends of the first fitting curves;

[0060] According to the different starting points and end points of the trend of the first fitting curve, the corresponding battery state of charge interval is determined, that is, the first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery.

[0061] In this embodiment, preferably, the second fitting curve construction in step S3 includes the following specific steps:

[0062] A second fitting curve is constructed with the collected battery state of charge of the lithium titanate battery as the horizontal coordinate and the ratio of the battery state of charge change to the static voltage change in the corresponding first fitting curve as the vertical coordinate (differential).

[0063] Furthermore, determining the second battery state of charge interval of the lithium titanate battery in step S3 includes the following steps:

[0064] Calculate the slope of each point of the second fitting curve; determine the second battery state of charge interval based on the target point whose slope belongs to the preset slope interval

[0065] In this embodiment, the target battery state of charge range is preferably 65% ​​to 95%, preferably 65% ​​to 75%.

[0066] N / P refers to the ratio of the negative electrode's per-area capacity to the positive electrode's per-area capacity in a lithium-ion battery. Different N / P ratios will result in different SOC-OCV curves. During the manufacturing process, especially during the coating process, fluctuations in the coating density directly impact the N / P ratio. In the lithium-ion manufacturing industry, this fluctuation is inherent and cannot be eliminated. Precisely controlling the coating density fluctuations can narrow the N / P fluctuation range and produce more consistent batteries. For lithium titanate batteries, the high charge and discharge potentials prevent lithium plating. To maximize cycle life, the positive electrode is generally chosen to have a greater per-area capacity than the negative electrode. In this case, because N / P ≤ 1, fluctuations in the charge and discharge curves directly reflect differences in N / P. Cells with different N / P ratios exhibit varying performance. To maximize system life by grouping cells with consistent performance characteristics, such as capacity and degradation trends, into the same bin, N / P ratios must be factored into the binning strategy.

[0067] Therefore, the present invention establishes the relationship between the SOC-OCV fitting curve and different N / P ratios for grading. Figure 2 The static SOC-OCV fitting curves are shown in the figure below when N / P is 1.0, 0.98, and 0.95. Figure 2 It can be seen that the charging curves under different N / P ratios are quite different. The differences between these different curves are due to the fluctuations in the production process and need to be selected and classified separately. Figure 2 It can be seen that when the SOC is below 50%, it is difficult to distinguish different N / P ratios, but when the SOC is greater than 50%, especially in the SOC range of 60%~95%, the curves are obviously different, and the grading is suitable to be selected in this range.

[0068] The SOC and dQ / dV analysis method refers to taking the slope at each SOC in the static SOC-OCV fitting curve. The size of the slope represents the change of the curve in the SOC-OCV fitting curve, that is, the size of the rate of change. The larger the rate of change, the steeper the curve. At this SOC, OCV can be used to characterize different N / P cells. At the same time, at this SOC, the k value changes more significantly, which is also conducive to the selection of battery cell self-discharge. Figure 3 This is the SOC and dQ / dV curve. From this curve, we can see that the dQ / dV values ​​under different SOCs fluctuate greatly, in the low SOC area (0% SOC ~10% SOC) and high SOC (65% SOC~100% SOC). In the low SOC area, because the charge is too low, the battery cell is prone to power failure for a long time storage, so it is not suitable. In the high SOC area, the higher the SOC, the higher the risk. Therefore, it is generally chosen under the appropriate k value and OCV selection conditions to select a low SOC.

[0069] In summary, by combining the SOC-OCV fitting curve with different N / P charging curves, and analyzing the SOC and dQ / dV curves, we can obtain an optimal selection strategy, that is, the SOC interval is selected between 65% and 95%. Under this SOC range, the OCV and k value of each monomer can be accurately sorted, and each monomer can be finely graded to improve consistency and increase the service life of the system.

[0070] Based on the same inventive concept, this embodiment also provides a device for constructing a selection model for consistency of lithium titanate batteries, the device comprising:

[0071] An acquisition module is used to control lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, and to collect the battery state of charge and the corresponding static voltage of the lithium titanate battery after it comes to rest;

[0072] A first construction module is configured to construct a first fitting curve based on the collected battery states of charge and corresponding static voltages of the lithium titanate battery with different N / P ratios; the first fitting curve is configured to characterize the relationship between the battery state of charge and the static voltage under different N / P ratios; and determine a first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery based on the first fitting curve;

[0073] a second construction module, configured to construct a second fitting curve based on any one of the collected first fitting curves and the corresponding battery state of charge of the lithium titanate battery; the second fitting curve is configured to characterize the relationship between the battery state of charge and the ratio of the battery state of charge change to the static voltage change; and determine a second battery state of charge range of the lithium titanate battery based on the second fitting curve;

[0074] The determination module is configured to take an intersection value of the first battery state of charge interval and the second battery state of charge interval as a target battery state of charge interval.

[0075] Based on the same inventive concept, this embodiment also provides an electronic device, including: a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor and the memory communicate through the bus, and the machine-readable instructions are executed by the processor when running, such as the steps of the method for selecting the consistency of lithium titanate batteries.

[0076] Based on the same inventive concept, this embodiment also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for selecting the consistency of a lithium titanate battery as described above are executed.

[0077] Specifically, in this embodiment, the storage medium can be a general storage medium, such as a mobile disk, a hard disk, etc. When the computer program on the storage medium is run, the above-mentioned battery consistency selection method can be executed.

[0078] The following examples further illustrate this concept. The following examples utilize prefabricated positive and negative electrode sheets with N / P ratios of 1.0, 0.98, and 0.95, respectively. The positive electrode is a ternary material, and the negative electrode is a lithium titanate material. Assembly and capacity testing are performed using an 18650 platform model. After the capacity testing, comparative analysis is performed using the following examples.

[0079] Example 1:

[0080] Ten cells of each of three different N / P ratios were taken and charged to 70% SOC with a constant current of 1C. After standing for 12 hours, the voltage at 70% SOC was tested for the first time (70% OCV1). Then, after standing at room temperature for 7 days, the voltage was tested for the second time (70% OCV2).

[0081] Example 2:

[0082] Ten cells of each type of N / P battery were taken and charged to 10% SOC with a constant current of 1C. After standing for 12 hours, the voltage at 10% SOC was tested for the first time (10% OCV1). After standing at room temperature for 7 days, the voltage was tested for the second time (10% OCV2).

[0083] Example 3:

[0084] Ten cells of each type of N / P battery were taken and charged to 40% SOC with a constant current of 1C. After standing for 12 hours, the voltage at 40% SOC was tested for the first time (40% OCV1). After standing at room temperature for 7 days, the voltage at 40% OCV2 was tested for the second time.

[0085] Example 4:

[0086] Ten cells of each of the three types of N / P batteries were taken and charged to 95% SOC with a constant current of 1C. After standing for 12 hours, the voltage at 95% SOC was tested for the first time (95% OCV1). After standing at room temperature for 7 days, the voltage was tested for the second time (95% OCV2).

[0087] The self-discharge data statistics of Examples 1 to 4 are shown in Table 1 below:

[0088] Table 1 Self-discharge data

[0089]

[0090] From the data in Table 1, we can see that when the SOC is 95%, the difference in k value and OCV is large, and the difference between different N / P is more obvious. The monomers with different N / P can be selected according to the k value and OCV; similarly, at 70% SOC, although the k value, OCV and the difference are relatively obvious under different N / P, it is easy to identify the battery cells with different N / P; at 10% SOC and 40% SOC, although the k value difference of 10% SOC is more obvious, the OCV difference is not obvious; and at 40% SOC, the OCV difference is larger than 10%, but the k value difference is not obvious, so it is not easy to select the battery cells with different N / P.

[0091] Therefore, combining the above embodiments and theoretical analysis, the present invention adopts a strategy combining SOC with different N / P charging curves and an analysis method of SOC and dQ / dV. For lithium titanate batteries, the SOC selection range is 65% SOC~95% SOC, preferably within the range of 65%~75%. The consistency of the single cells is improved, and the system can exert more energy during the charge and discharge process, and will not cause insufficient charge and discharge due to inconsistent cell voltages, thereby extending the service life of the system. Improved consistency of battery cells will greatly extend the service life of the system.

[0092] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for selecting consistency of lithium titanate batteries, characterized in that: The steps include: S1: Controlling lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, and collecting the battery state of charge and corresponding static voltage of the lithium titanate battery after it comes to rest; The N / P ratio is ≤1; S2: constructing a first fitting curve based on the collected battery states of charge and corresponding static voltages of the lithium titanate battery with different N / P ratios; the first fitting curve is used to characterize the relationship between the battery state of charge and the static voltage under different N / P ratios; and determining a first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery based on the first fitting curve; S3: constructing a second fitting curve based on any one of the collected first fitting curves and the corresponding battery state of charge of the lithium titanate battery; the second fitting curve is used to represent the relationship between the battery state of charge and the ratio of the battery state of charge change to the static voltage change; and determining a second battery state of charge range of the lithium titanate battery based on the second fitting curve; S4: Taking the intersection value of the first battery state of charge interval and the second battery state of charge interval as the target battery state of charge interval.

2. The method for selecting consistency of lithium titanate batteries according to claim 1, characterized in that: Step S1 includes the following specific steps: Controlling lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, wherein the battery state of charge of the lithium titanate battery increases or decreases in a gradient; After being at rest, the battery state of charge and the corresponding static voltage of the lithium titanate battery are collected.

3. The method for selecting consistency of lithium titanate batteries according to claim 1, characterized in that: The construction of the first fitting curve in step S2 includes the following specific steps: According to the collected battery state of charge and corresponding static voltage of the lithium titanate battery, a first fitting curve is constructed with the battery state of charge as the abscissa and the corresponding static voltage as the ordinate.

4. The method for selecting consistency of lithium titanate batteries according to claim 1, characterized in that: Determining the first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery in step S2 includes the following specific steps: Comparing the trends of the first fitting curves of the lithium titanate batteries, and screening and distinguishing the starting points and end points of the trends of the first fitting curves; According to the different starting points and end points of the trend of the first fitting curve, the corresponding battery state of charge interval is determined, that is, the first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery.

5. The method for selecting consistency of lithium titanate batteries according to claim 1, characterized in that: The construction of the second fitting curve in step S3 includes the following specific steps: A second fitting curve is constructed with the collected battery state of charge of the lithium titanate battery as the horizontal coordinate and the ratio of the battery state of charge change to the static voltage change in the corresponding first fitting curve as the vertical coordinate.

6. The method for selecting consistency of lithium titanate batteries according to claim 1, characterized in that: Determining the second battery state of charge interval of the lithium titanate battery in step S3 includes the following steps: Calculating the slope of each point of the second fitting curve; and determining the second battery state of charge range based on the target point whose slope belongs to a preset slope range.

7. A method for selecting consistency of lithium titanate batteries according to claim 6, characterized in that: The target battery state of charge range is 65% to 95%.

8. A device for selecting consistency of lithium titanate batteries, characterized in that: The device comprises: An acquisition module is used to control lithium titanate batteries with different N / P ratios to charge or discharge according to a preset current, and to collect the battery state of charge and the corresponding static voltage of the lithium titanate battery after it comes to rest; A first construction module is configured to construct a first fitting curve based on the collected battery states of charge and corresponding static voltages of the lithium titanate battery with different N / P ratios; the first fitting curve is configured to characterize the relationship between the battery state of charge and the static voltage under different N / P ratios; and determine a first battery state of charge interval for distinguishing different N / P ratios of the lithium titanate battery based on the first fitting curve; a second construction module, configured to construct a second fitting curve based on any one of the collected first fitting curves and the corresponding battery state of charge of the lithium titanate battery; the second fitting curve is configured to characterize the relationship between the battery state of charge and the ratio of the battery state of charge change to the static voltage change; and determine a second battery state of charge range of the lithium titanate battery based on the second fitting curve; The determination module is configured to take an intersection value of the first battery state of charge interval and the second battery state of charge interval as a target battery state of charge interval.

9. An electronic device, characterized in that: include: A processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor and the memory communicate through the bus, and the machine-readable instructions are executed by the processor to execute the steps of a method for selecting the consistency of a lithium titanate battery as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for selecting consistency of a lithium titanate battery according to any one of claims 1 to 7 are executed.

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