Method for correcting cell capacity of production line of cells

Abstract

The invention provides a method for correcting the capacity of a production line battery cell of a battery cell, and the method comprises the following steps: a first obtaining step: obtaining a temperature correction equation of the capacity of the battery cell; a second obtaining step: obtaining the maximum temperature and the capacity of the battery cell of the production line, which are measured in the production line measurement, and the capacity of the battery cell of the laboratory, which is measured in the laboratory at the preset environment temperature; a temperature correction step: correcting the measured production line cell capacity based on a temperature correction equation to obtain a corrected cell capacity at a preset environment temperature; and an equation determination step in which a capacity fitting equation is obtained through fitting based on the obtained corrected battery cell capacity and the measured laboratory battery cell capacity, and a correction equation is determined based on the temperature correction equation and the capacity fitting equation. The method has the advantages that the corrected battery cell capacity has higher accuracy, so that the capacity calculation accuracy of battery pack software can be improved.

Description

Technical Field

[0001] The present application relates to a method for correcting the capacity of battery cells in a production line of battery cells. Background Art

[0002] Cells are usually measured on the production line to obtain the production line cell capacity of the cell. However, due to the large fluctuations in the ambient temperature of the production line, the strategy for battery pack software is not directly based on the production line cell capacity, but on the laboratory cell capacity measured in the laboratory at a preset ambient temperature. Compared with production line measurement, the ambient temperature in the laboratory is more stable and the measurement equipment is more accurate.

[0003] Due to time and cost considerations, only a small number of cells can be measured in the laboratory, while the cell capacity of a large number of cells is still obtained based on production line measurements. If the production line cell capacity is directly used as the input of the battery pack software, the battery pack software will estimate the capacity inaccurately. Summary of the invention

[0004] The purpose of the present application is to provide a method for correcting the production line cell capacity of a battery cell. Compared with the original production line cell capacity, the corrected cell capacity has higher accuracy, which helps to improve the capacity calculation accuracy of the battery pack software.

[0005] According to a first aspect of the present application, a method for correcting the capacity of a production line battery cell of a battery cell is provided, the method comprising the following steps:

[0006] The first acquisition step, in the first acquisition step, obtains the temperature correction equation K=f1(T) of the battery cell capacity Y, wherein T is the maximum temperature of the battery cell, and K is used to correct the battery cell capacity Y at the maximum temperature T of the battery cell to the preset ambient temperature T h0 Correction parameters of

[0007] The second acquisition step, in the second acquisition step, obtains the maximum temperature Tn and the capacity Yn of the production line cells measured in the production line measurement and the temperature at the preset ambient temperature T h0 The laboratory cell capacity Ym measured in the laboratory is as follows;

[0008] A temperature correction step, in which a corresponding correction parameter Kn=f1(Tn) is obtained based on the measured maximum temperature Tn of the production line battery cells and the temperature correction equation, and the measured production line battery cell capacity Yn is corrected to the preset ambient temperature Tn based on the obtained correction parameter Kn. h0 Corrected cell capacity Yx = f2(Yn, Kn) = f2(Yn, f1(Tn));

[0009] An equation determination step, in which a capacity fitting equation Ym=f3(Yx) is fitted based on the obtained corrected battery cell capacity Yx and the measured laboratory battery cell capacity Ym, and a correction equation f3(f2(Yn,f1(Tn))) for capacity correction based on the maximum temperature Tn of the production line battery cell is determined based on the temperature correction equation and the capacity fitting equation.

[0010] According to an optional embodiment of the present application, in the first acquisition step, the battery cells at different ambient temperatures T h The maximum cell temperature T and cell capacity Y measured in the laboratory are used to fit the temperature correction equation based on the measured maximum cell temperature T and cell capacity Y. The temperature correction equation is obtained by fitting the temperature correction equation for different ambient temperatures T. h In particular, it includes at least the preset ambient temperature T h0 , the different ambient temperatures T h Especially in the temperature range of 25°C to 40°C.

[0011] According to an optional embodiment of the present application, in the first acquisition step, the temperature correction equation is obtained by polynomial fitting, and the polynomial fitting in the first acquisition step is especially a first-order polynomial fitting or a second-order polynomial fitting.

[0012] According to an optional embodiment of the present application, in the equation determination step, the capacity fitting equation is obtained by polynomial fitting, and the polynomial fitting in the equation determination step is especially a first-order polynomial fitting.

[0013] According to an optional embodiment of the present application, K represents the capacity ratio,

[0014] Corrected cell capacity Yx = f2(Yn, Kn) = Yn / Kn = Yn / f1(Tn),

[0015] The correction equation is f3(Yn / f1(Tn)).

[0016] According to an optional embodiment of the present application, K represents the capacity ratio,

[0017] In the first acquisition step, the temperature correction equation is obtained by quadratic polynomial fitting:

[0018] K=f1(T)=a+bT+cT 2 ,

[0019] Among them, a, b, and c are constants.

[0020] Corrected cell capacity Yx = Yn / f1(Tn) = Yn / (a+bTn+cTn 2 ),

[0021] In the equation determination step, the capacity fitting equation is obtained by first-order polynomial fitting:

[0022] Ym=f3(Yx)=d+eYx, where d and e are constants.

[0023] The correction equation is f3(Yn / f1(Tn))=d+eYn / (a+bTn+cTn 2 ).

[0024] According to an optional embodiment of the present application, K represents the capacity difference,

[0025] Corrected cell capacity Yx = f2(Yn, Kn) = Yn-Kn = Yn-f1(Tn),

[0026] The correction equation is f3(Yn-f1(Tn)).

[0027] According to an optional embodiment of the present application, the preset ambient temperature T h0 It is 25℃.

[0028] According to an optional embodiment of the present application, in the first acquisition step, a plurality of battery cells are extracted from different production batches for measurement, and in particular, seven battery cells are extracted from two production batches for measurement.

[0029] According to an optional embodiment of the present application, in the second acquisition step, multiple battery cells are extracted for multiple production line measurements and at least one measurement is performed in a laboratory, especially sixty battery cells are extracted for three production line measurements and one measurement is performed in the laboratory.

[0030] According to an optional embodiment of the present application, the method includes a correction step, in which the maximum temperature Tn of the production line battery cell and the production line battery cell capacity Yn measured in the production line measurement of the battery cell to be corrected are substituted into the correction equation for correction.

[0031] The positive effect of the present application is that by establishing a correction equation, the capacity of the production line cells can be corrected or compensated, and the compensated production line cell capacity has a higher accuracy, which can improve the capacity estimation accuracy of the battery pack software when input into the battery pack software. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present application will be described in more detail below with reference to the accompanying drawings, so that the principles, features and advantages of the present application can be better understood. The accompanying drawings include:

[0033] Figure 1 An example of production line measurement of a battery cell under production line conditions and measurement in a laboratory is shown;

[0034] Figure 2 An example of the process of the method of the present application is schematically shown;

[0035] Figure 3 An example of the maximum temperature and capacity of seven cells sampled and calculated under different ambient temperatures in a laboratory and correction parameters thereof is schematically shown;

[0036] Figure 4 Schematically shows Figure 3 A scatter plot of the data. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial technical effects to be solved by the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and multiple exemplary embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the scope of protection of the present application.

[0038] Figure 1 An example of production line measurement and laboratory measurement of a battery cell 1 under production line conditions is shown in the figure. The left side shows the production line measurement, and the right side shows the laboratory measurement.

[0039] Cell 1 is usually measured on the production line to obtain the production line cell capacity Yc of cell 1. However, due to the large fluctuations in the ambient temperature of the production line, when formulating the strategy for the battery pack software, it is not directly based on the production line cell capacity Yc, but on the laboratory cell capacity Ym measured in the laboratory at a preset ambient temperature. Compared with production line measurement, the ambient temperature in the laboratory is more stable and the accuracy of the measurement equipment is higher.

[0040] Due to time and cost considerations, only a small number of cells 1 can be measured in the laboratory, while the cell capacity of a large number of cells 1 is still obtained based on production line measurements. If the production line cell capacity is directly used as the input of the battery pack software, the battery pack software will estimate the capacity inaccurately.

[0041] In this regard, the present application proposes a method for correcting the production line cell capacity of a battery cell. Through the method, the corrected production line cell capacity is at least close to the cell capacity measured in the laboratory or more accurate, so that it is more suitable as an input for the battery pack software than the original production line cell capacity.

[0042] Figure 2 An example of the process of the method of the present application is schematically shown.

[0043] like Figure 2 As shown, the method comprises the following steps:

[0044] In the first acquisition step 200, a temperature correction equation K=f1(T) of the cell capacity Y is obtained, wherein T is the maximum temperature of the cell, and K is used to correct the cell capacity Y at the maximum temperature T to the preset ambient temperature T. h0 Correction parameters of

[0045] The second acquisition step 202, in which the maximum temperature Tn and the capacity Yn of the production line cells measured in the production line measurement are obtained, as well as the temperature at the preset ambient temperature T h0 The laboratory cell capacity Ym measured in the laboratory is as follows;

[0046] In the temperature correction step 204, based on the measured maximum temperature Tn of the production line battery cell and the temperature correction equation, a corresponding correction parameter Kn=f1(Tn) is obtained, and based on the obtained correction parameter Kn, the measured production line battery cell capacity Yn is corrected to the preset ambient temperature T h0 Corrected cell capacity Yx = f2(Yn, Kn) = f2(Yn, f1(Tn));

[0047] Equation determination step 206. In equation determination step 206, based on the obtained corrected battery cell capacity Yx and the measured laboratory battery cell capacity Ym, a capacity fitting equation Ym=f3(Yx) is fitted, and based on the temperature correction equation and the capacity fitting equation, a correction equation f3(f2(Yn,f1(Tn))) for capacity correction of the production line battery cell capacity Yn based on the maximum temperature Tn of the production line battery cell is determined.

[0048] Here, f1 is known, and f2 can be directly determined based on what capacity relationship K represents, and f3 is known, so the correction equation can be directly determined based on the temperature correction equation and the capacity fitting equation. In addition, in the measurement, the battery cell has the highest battery cell temperature, for example, near the two poles.

[0049] According to an exemplary embodiment of the present application, K represents the capacity ratio,

[0050] Corrected cell capacity Yx = f2(Yn, Kn) = Yn / Kn = Yn / f1(Tn),

[0051] The correction equation is f3(Yn / f1(Tn)).

[0052] According to an exemplary embodiment of the present application, K represents the capacity difference,

[0053] Corrected cell capacity Yx = f2(Yn, Kn) = Yn-Kn = Yn-f1(Tn),

[0054] The correction equation is f3(Yn-f1(Tn)).

[0055] According to an exemplary embodiment of the present application, in the first acquisition step 200, the battery cells at different ambient temperatures T h The maximum cell temperature T and cell capacity Y measured in the laboratory are used to fit the temperature correction equation based on the measured maximum cell temperature T and cell capacity Y. The temperature correction equation is obtained by fitting the temperature correction equation for different ambient temperatures T. h In particular, it includes at least the preset ambient temperature T h0 , the different ambient temperatures T h Especially in the temperature range of 25°C to 40°C.

[0056] According to an exemplary embodiment of the present application, in the first acquisition step 200, a plurality of battery cells are extracted from different production batches for measurement, and in particular, seven battery cells are extracted from two production batches for measurement.

[0057] Figure 3 The diagram schematically shows an example of the maximum cell temperature T and cell capacity Y of seven cells sampled in a laboratory at different ambient temperatures and a correction parameter K calculated therefrom. Here, the correction parameter K is exemplarily a capacity ratio.

[0058] Figure 4 Schematically shows Figure 3 A scatter plot of the data.

[0059] exist Figure 3 The first column lists multiple ambient temperatures T in the temperature range of 25°C to 40°C. h The second column lists the corresponding ambient temperature T h The maximum cell temperature T measured under the condition of . The third column lists the measured cell capacity Y. The fourth column lists the correction parameters obtained based on the third column.

[0060] exist Figure 3 In the example, the preset ambient temperature T h0 The exemplary temperature is 25°C, but it is obvious that the preset ambient temperature T h0 For the preset ambient temperature T h0 Obviously, no correction is needed (or in other words, the preset ambient temperature T h0 As a benchmark), if the correction parameter K represents the capacity ratio, then at T h When =25℃, K=1.

[0061] See the second row, at T h =27℃, K=240.984 / 240=1.0041. At other ambient temperatures T hThe K value below is deduced accordingly.

[0062] Based on the ambient temperature T h The correction itself is compared with the corresponding ambient temperature T h It will be more accurate to correct the cell capacity Y based on the maximum cell temperature T under normal conditions.

[0063] According to an exemplary embodiment of the present application, in the first acquisition step 200, the temperature correction equation is obtained by polynomial fitting, and the polynomial fitting in the first acquisition step 200 is especially a first-order polynomial fitting or a second-order polynomial fitting.

[0064] according to Figure 3 For data, see Figure 4 The dashed line in the figure, in the case of a first-order polynomial fitting, obtains the first temperature correction equation K = 0.9492 + 0.001646T. In the case of a second-order polynomial fitting, see Figure 4 The dot-dash line in the figure gives the second temperature correction equation

[0065] K=0.8401+0.007396T-0.000075T 2 .

[0066] According to an exemplary embodiment of the present application, in the second acquisition step 202, multiple battery cells are extracted for multiple production line measurements and at least one measurement is performed in the laboratory, in particular, sixty battery cells are extracted for three production line measurements and one measurement is performed in the laboratory. The production line battery cell capacity used for fitting can be the average value of the battery cell capacity of multiple production line measurements. It is conceivable that the battery cell extracted in the first acquisition step 200 is different from the battery cell extracted in the second acquisition step 200. Alternatively, it is also conceivable that the measurement data in the first acquisition step 200 can be at least partially used in the second acquisition step 202.

[0067] According to an exemplary embodiment of the present application, in the equation determination step 206, the capacity fitting equation is obtained by polynomial fitting, and the polynomial fitting in the equation determination step 206 is especially a first-order polynomial fitting.

[0068] For example, when the production line cell capacity Yn of the sixty cells extracted is corrected by Yx=Yn / Kn based on the first temperature correction equation to obtain the corrected cell capacity Yx, based on the corrected cell capacity Yx and the measured laboratory cell capacity Ym of the sixty cells, a first capacity fitting equation is obtained through a first-order polynomial fitting:

[0069] Ym=f3(Yx)=20.48+0.7239Yx.

[0070] Correspondingly, the first correction equation is

[0071] f3(Yn / f1(Tn))=20.48+0.7239Yn / (0.9492+0.001646Tn).

[0072] When the production line cell capacity Yn of the sixty cells extracted is corrected by Yx=Yn / Kn based on the second temperature correction equation to obtain the corrected cell capacity Yx, the second capacity fitting equation is obtained by first-order polynomial fitting based on the corrected cell capacity Yx and the measured laboratory cell capacity Ym of the sixty cells:

[0073] Ym=f3(Yx)=20.92+0.7188Yx.

[0074] Correspondingly, the second correction equation is

[0075] f3(Yn / f1(Tn))=20.92+0.7188Yn / (0.8401+0.007396Tn-0.000075Tn 2 ).

[0076] In the above embodiments, fitting is performed twice successively.

[0077] In addition, when the measured data of the sixty cells sucked are directly fitted by a two-variable first-order polynomial, for example, the third correction equation can be obtained:

[0078] f3(Yn,Tn)=23.5-0.114Tn+0.731Yn

[0079] When the credibility of the first correction equation, the second correction equation and the third correction equation was verified based on the measurement data of the extracted sixty battery cells, it was found that the second correction equation had better repeatability.

[0080] Generally, for example, if K represents the capacity ratio,

[0081] In the first acquisition step 200, a temperature correction equation is obtained by fitting a quadratic polynomial:

[0082] K=f1(T)=a+bT+cT 2 ,

[0083] Among them, a, b, and c are constants.

[0084] Corrected cell capacity Yx = Yn / f1(Tn) = Yn / (a+bTn+cTn 2 ),

[0085] In the equation determination step 206, the capacity fitting equation is obtained by first-order polynomial fitting:

[0086] Ym=f3(Yx)=d+eYx, where d and e are constants.

[0087] The correction equation is f3(Yn / f1(Tn))=d+eYn / (a+bTn+cTn 2 ).

[0088] If K represents the capacity difference, if in the first acquisition step 202, the temperature correction equation is obtained by quadratic polynomial fitting:

[0089] K=f1(T)=a+bT+cT 2 ,

[0090] Corrected cell capacity Yx = Yn-f1(Tn) = Yn-a-bTn-cTn 2 ,

[0091] In the equation determination step 206, the capacity fitting equation is obtained by first-order polynomial fitting:

[0092] Ym=f3(Yx)=d+eYx

[0093] Then the correction equation is f3(Yn-f1(Tn))=d+e(Yn-a-bTn-cTn 2 ).

[0094] More variations can be inferred accordingly, which are not listed here in detail for the sake of brevity.

[0095] According to an exemplary embodiment of the present application, see Figure 2 The method includes a correction step 208, in which the maximum temperature Tn of the production line battery cell and the capacity Yn of the production line battery cell measured in the production line measurement of the battery cell to be corrected are substituted into the correction equation for correction.

[0096] It should be pointed out that measurement "in the laboratory" in the sense of the present application can be broadly understood as measurement with more stable ambient temperature and / or higher accuracy of the measuring equipment compared to production line measurement, and should not be narrowly understood as the location being in the laboratory.

[0097] In the present application, the multiple steps of the method may be presented in a specific order, but this does not represent a mandatory sequence of these steps. In principle, these steps may also be in other sequences and / or performed simultaneously. These variations should all be considered to be within the scope of the disclosure of the present application.

[0098] Some specific data and constant values ​​are given in this application, but these should be understood as examples only, rather than absolute limitations to this application.

[0099] Although the specific embodiments of the present application are described in detail herein, they are provided for the purpose of explanation only and should not be considered to limit the scope of the present application. Various substitutions, changes and modifications may be conceived without departing from the spirit and scope of the present application.

[0100] Reference numerals list

[0101] 1 battery cell

[0102] 200 First acquisition step

[0103] 202 Second acquisition step

[0104] 204 Temperature Correction Steps

[0105] 206 Equation Determination Steps

[0106] 208 Correction Steps

[0107] K correction parameter

[0108] T Maximum cell temperature

[0109] Y cell capacity

[0110] T h0 Preset ambient temperature

[0111] Maximum temperature of battery cells in Tn production line

[0112] Yn production line battery capacity

[0113] Ym at the preset ambient temperature T h0 Laboratory cell capacity measured under

[0114] Yx is corrected to the preset ambient temperature T h0 Corrected cell capacity

Claims

1. A method for correcting the capacity of a cell in a production line of a cell, characterized in that: The method comprises the following steps: A first acquisition step (200), in which a temperature correction equation K=f1(T) of the cell capacity Y is obtained, wherein T is the maximum temperature of the cell, and K is used to correct the cell capacity Y of the cell (1) at the maximum temperature T of the cell to a preset ambient temperature T. h0 Correction parameters of The second acquisition step (202) is to obtain the maximum temperature Tn and the capacity Yn of the production line cells of the cell (1) measured in the production line measurement and the temperature at the preset ambient temperature T h0 The laboratory cell capacity Ym measured in the laboratory is as follows; A temperature correction step (204), in which a corresponding correction parameter Kn=f1(Tn) is obtained based on the measured maximum temperature Tn of the production line battery cells and the temperature correction equation, and the measured production line battery cell capacity Yn is corrected to a preset ambient temperature T based on the obtained correction parameter Kn. h0 Corrected cell capacity Yx = f2(Yn, Kn) = f2(Yn, f1(Tn)); An equation determination step (206), in which a capacity fitting equation Ym=f3(Yx) is fitted based on the obtained corrected cell capacity Yx and the measured laboratory cell capacity Ym, and a correction equation f3(f2(Yn,f1(Tn))) for correcting the capacity of the production line cell Yn based on the maximum temperature Tn of the production line cell is determined based on the temperature correction equation and the capacity fitting equation.

2. The method for correcting the capacity of a production line battery cell according to claim 1, characterized in that: In the first obtaining step (200), the battery cell (1) is obtained at different ambient temperatures T h The maximum cell temperature T and cell capacity Y measured in the laboratory are used to fit the temperature correction equation based on the measured maximum cell temperature T and cell capacity Y. The temperature correction equation is obtained by fitting the temperature correction equation for different ambient temperatures T. h In particular, it includes at least the preset ambient temperature T h0 , the different ambient temperatures T h Especially in the temperature range of 25°C to 40°C.

3. The method for correcting the capacity of a production line battery cell according to any one of the preceding claims, characterized in that: In the first acquisition step (200), a temperature correction equation is obtained by polynomial fitting, and the polynomial fitting in the first acquisition step (200) is especially a first-order polynomial fitting or a second-order polynomial fitting.

4. The method for correcting the capacity of a production line battery cell according to any one of the preceding claims, characterized in that: In the equation determination step (206), the capacity fitting equation is obtained by polynomial fitting, and the polynomial fitting in the equation determination step (206) is especially a first-order polynomial fitting.

5. The method for correcting the capacity of a production line battery cell according to any one of the preceding claims, characterized in that: K represents the capacity ratio, Corrected cell capacity Yx = f2(Yn, Kn) = Yn / Kn = Yn / f1(Tn), The correction equation is f3(Yn / f1(Tn)).

6. The method for correcting the capacity of a production line battery cell according to claim 5, characterized in that: K represents the capacity ratio, In the first acquisition step (200), the temperature correction equation is obtained by quadratic polynomial fitting: K=f1(T)=a+bT+cT 2 , Among them, a, b, and c are constants. Corrected cell capacity Yx = Yn / f1(Tn) = Yn / (a+bTn+cTn 2 ), In the equation determination step (206), the capacity fitting equation is obtained by first-order polynomial fitting: Ym=f3(Yx)=d+eYx, where d and e are constants. The correction equation is f3(Yn / f1(Tn))=d+eYn / (a+bTn+cTn 2 ).

7. The method for correcting the capacity of a production line battery cell according to any one of claims 1 to 4, characterized in that: K represents the capacity difference, Corrected cell capacity Yx = f2(Yn, Kn) = Yn-Kn = Yn-f1(Tn), The correction equation is f3(Yn-f1(Tn)).

8. The method for correcting the capacity of a production line battery cell according to any one of the preceding claims, characterized in that: The preset ambient temperature T h0 It is 25℃.

9. The method for correcting the capacity of a production line battery cell according to any one of the preceding claims, characterized in that: In the first acquisition step (200), a plurality of battery cells are selected from different production batches for measurement, in particular, seven battery cells are selected from two production batches for measurement; In the second acquisition step (202), a plurality of battery cells are selected for multiple production line measurements and at least one measurement in a laboratory, in particular, sixty battery cells are selected for three production line measurements and one measurement in a laboratory.

10. The method for correcting the capacity of a production line battery cell according to any one of the preceding claims, characterized in that: The method comprises a correction step, in which the maximum temperature Tn of the production line battery cell and the capacity Yn of the production line battery cell measured in the production line measurement of the battery cell (1) to be corrected are substituted into the correction equation for correction.

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