Battery cell thickness grading method and system

Abstract

The invention discloses a battery cell thickness grading method and system, and the method comprises the steps: obtaining the thicknesses of a plurality of battery cells in a battery cell module; calculating a thickness mean value and a standard deviation of the battery cell module; taking the thickness mean value and the standard deviation as thickness grading parameters, determining a thickness interval corresponding to each physical gear channel according to a plurality of physical gear channels which are sequentially arranged, and forming a grading program; the battery cells are graded according to the thickness interval, so that the number of the battery cells divided by a plurality of physical gear channels in one batch is distributed in a mode that the number of the battery cells corresponding to the middle physical gear channel is gradually reduced from the number of the battery cells corresponding to the physical gear channels on the two sides and the battery cells are symmetrically distributed, and a grouping program is formed; dividing the battery cells into corresponding physical gear channels according to a grading program; according to the grouping program, the battery cells of different physical gear channels are grabbed and grouped into modules, and the situation that the thickness of the battery cells, the length of the modules and the internal pressure are not matched can be effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of battery cell thickness grading, and in particular to a battery cell thickness grading method and system. Background Art

[0002] Since the battery module is composed of many rings, the probability method is used to design the length dimension and tolerance. The probability method uses the ideal design dimension chain as the design basis, which is inconsistent with the actual battery cell thickness process level.

[0003] The charge and discharge cycle of the battery cell is accompanied by the expansion and contraction of the battery cell. During the PACK manufacturing process, excessive pressure inside the battery module is not conducive to the battery cell cycle, and too little pressure is not conducive to the structural strength of the battery module. When meeting the length dimension and tolerance requirements of the battery module, the pressure of the battery cell inside the battery module is related to the thickness of the battery cell.

[0004] The thickness of the battery cell meets the normal distribution during the manufacturing process. If the battery cell of a module is taken as a sub-sample, the thickness data distribution of the sub-sample is difficult to meet the parent distribution during the manufacturing process. A thin battery cell will cause the pressure inside the battery module to exceed the lower limit, and a thick battery cell will cause the pressure inside the battery module to exceed the upper limit. Therefore, the appropriate thickness grading method can effectively solve the contradiction between battery cell thickness and internal pressure.

[0005] In the prior art, the invention patent with the patent publication number CN118218274A discloses a battery cell grading method, electronic device, storage medium and electrical equipment. In the patent, the battery cell capacity difference is obtained according to the initial capacity of the battery cell, the discharge battery cell capacity and the charge battery cell capacity; the battery cell capacity difference is weighted to obtain the weighted capacity value; the voltage change value is weighted to obtain the weighted voltage value; the battery cell is graded according to the weighted capacity value and the weighted voltage value to obtain the battery cell performance parameter grading. However, this patent is applied to the capacity and thickness grading of the battery cell manufacturing end, and the purpose is to grade and group the retired batteries in combination with the battery cell thickness grading. Summary of the invention

[0006] The technical problem to be solved by the present invention is to solve the contradiction between the thickness of the battery cell and the internal pressure in the module manufacturing process at the PACK end.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] A method for grading the thickness of a battery cell, comprising:

[0009] Obtain the thickness of multiple cells in a cell module;

[0010] Calculate the thickness mean and standard deviation of the battery module;

[0011] Using the thickness mean and standard deviation as thickness grading parameters, determining the thickness interval corresponding to each physical gear channel according to the multiple physical gear channels set in sequence, and forming a grading program; and grading the battery cells according to the thickness intervals, so that the number of battery cells divided by the multiple physical gear channels in a batch is distributed in a decreasing and symmetrical manner from the number of battery cells corresponding to the middle physical gear channel to the number of battery cells corresponding to the physical gear channels on both sides, forming a grouping program;

[0012] According to the binning procedure, the cells are divided into corresponding physical bin channels;

[0013] According to the grouping procedure, the battery cells of different physical gear channels are grouped into modules.

[0014] Beneficial effect: The present invention is based on the principle of mathematical statistics and provides a cell buffer to prevent cells with extremely large or extremely small thicknesses from being stacked in the same module, causing excessive or insufficient pressure in the module.

[0015] In one embodiment of the present invention, calculating the thickness mean and standard deviation of the battery cell module includes:

[0016] Calculate the average thickness X of the first group of battery modules 1 , and the standard deviation S 1 , and the thickness mean X 1 As an estimate of the mean thickness of this batch of cells, and the standard deviation S 1 As an estimate of the standard deviation of the thickness of this batch of cells, and store it;

[0017] When calculating the estimated value of the mean value of the cell thickness and the estimated value of the standard deviation of the cell thickness of the mth group of cell modules:

[0018] Then the average thickness of the mth group of battery modules is X M The sum of the average thickness of the first m groups of battery modules is then added to the average thickness of the battery modules in this group, and then the average is calculated;

[0019] The standard deviation S of the mth group of cell modules M The sum of the thickness standard deviations of the first m groups of battery modules is then summed with the standard deviation of the group of battery modules, and then the average is calculated;

[0020] The thickness mean X M As an estimate of the mean thickness of this batch of cells, the standard deviation S M This is used as an estimate of the standard deviation of the thickness of this batch of cells and is stored; and so on.

[0021] Beneficial effect: By applying the recursive method, the next round of iteration uses the calculation results of the previous round. As the sample size increases, its mean and standard deviation are closer to the true value.

[0022] In one embodiment of the present invention, seven physical gear channels are sequentially arranged, the middle physical gear channel is the fourth physical gear channel; and the thickness interval corresponding to the fourth physical gear channel is [X k -S k / 2,X k +S k / 2]; where X k represents the estimated value of the mean cell thickness of the kth group of cell modules, S k Expressed as an estimate of the standard deviation of cell thickness for k groups of cell modules.

[0023] Beneficial effect: According to the mean and standard deviation of the distribution of the matrix data of the battery cell thickness, the battery cells are divided into 7 gears so that the battery cells can be distributed more evenly and symmetrically in a decreasing manner from the middle to both sides.

[0024] In one embodiment of the present invention, the number of battery cells divided into a batch in the third physical gear channel and the fifth physical gear channel, the second physical gear channel and the sixth physical gear channel, and the first physical gear channel and the seventh physical gear channel is equal.

[0025] In one embodiment of the present invention, the thickness interval corresponding to the third physical gear channel is [X k -3S k / 2,X k -S k / 2], the thickness range corresponding to the fifth physical gear channel is [X k +S k / 2,X k +3S k / 2]; the thickness range corresponding to the second physical gear channel is [X k -5S k / 2,X k -3S k / 2], the thickness range corresponding to the sixth physical gear channel is [X k +3S k / 2,X k +5S k / 2]; the thickness range corresponding to the first physical gear channel is [X k -7S k / 2,X k -5S k / 2] and the thickness range corresponding to the seventh physical gear channel is [X k +5S k / 2,X k +7S k / 2].

[0026] In one embodiment of the present invention, the estimated value of the mean value of the thickness of the cells and the estimated value of the standard deviation of the thickness of the cells of the mth group of cell modules are obtained by the following formula:

[0027]

[0028] S M =(R 1 +R 2 +...+R m ) / d 2 (n) / m;

[0029] In the formula, R m It is expressed as the range of cell thickness in the mth group of cell modules, d 2 (n) is a constant factor obtained by looking up the table, and n is the number of cells in a group of cell modules.

[0030] In one embodiment of the present invention, according to the grouping procedure, the battery cells of different physical gear channels are grabbed and grouped into modules, including: checking in turn whether there are battery cells at the front end of the fourth physical gear channel, the third physical gear channel and the fifth physical gear channel, the second physical gear channel and the sixth physical gear channel, the first physical gear channel and the seventh physical gear channel; if there are battery cells, they are clamped into groups; if there are no battery cells in a physical gear channel, they are supplemented from the fourth physical gear channel closest to the upper layer, and then clamped into groups.

[0031] In one embodiment of the present invention, obtaining the thickness of multiple battery cells in a battery cell module includes: applying a certain force to two opposite largest surfaces of the battery cells, and measuring a vertical distance between the two opposite largest surfaces of the battery cells as the thickness of the battery cells.

[0032] In one embodiment of the present invention, the two physical gear channels at the outermost edges are also used as the battery cell channel that does not meet the thickness range and the NG battery cell channel whose thickness does not meet the design specifications.

[0033] The present invention also provides a system using the above-mentioned battery cell thickness grading method, comprising:

[0034] A thickness measurement module is used to obtain the thickness of multiple cells in the cell module;

[0035] A calculation module is used to calculate the thickness mean and standard deviation of the battery cell module; and use the thickness mean and standard deviation as thickness grading parameters, determine the thickness interval corresponding to each physical gear channel according to the multiple physical gear channels set in sequence, and form a grading program; and grade the battery cells according to the thickness interval, so that the number of battery cells divided by multiple physical gear channels in a batch is distributed in a decreasing and symmetrical manner from the number of battery cells corresponding to the middle physical gear channel to the number of battery cells corresponding to the physical gear channels on both sides, forming a grouping program;

[0036] A binning module, used to divide the cells into corresponding physical bin channels according to the binning procedure;

[0037] The grouping module is used to grab the battery cells of different physical gear channels and group them into modules according to the grouping program.

[0038] Compared with the prior art, the beneficial effects of the present invention are: the thickness range of each physical gear channel in the present invention is dynamic, and the recursive method or the principle of mathematical statistics is applied. The next round of iteration uses the calculation results of the previous round, and each iteration is fine-tuned and corrected once. As the sample size increases, the mean and standard deviation are infinitely close to the true value.

[0039] The current grading method is relatively simple, with manual grading of the grade standards, and the formulated grades have countless statistical support. The present invention provides real-time online thickness grading, feedback correction, and combines the principles of mathematical statistics to provide statistical support for thickness grading. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The present invention is a flow chart of a method for grading the thickness of a battery cell according to an embodiment of the present invention.

[0041] Figure 2 It is a schematic diagram of thickness ranges corresponding to multiple physical gear channels in an embodiment of the present invention.

[0042] Figure 3 The present invention is a block diagram of a battery cell thickness grading system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is further described in conjunction with the accompanying drawings of the specification.

[0044] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0045] See also Figure 1 As shown, the present invention provides a method for grading the thickness of a battery cell, comprising:

[0046] S10, obtaining thicknesses of multiple battery cells in a battery cell module.

[0047] In one embodiment of the present invention, a certain force is applied to two opposite largest surfaces of the battery cell, and the vertical distance between the two opposite largest surfaces of the battery cell is measured as the thickness of the battery cell.

[0048] S20, calculating the thickness mean and standard deviation of the battery cell module.

[0049] In one embodiment of the present invention, the average thickness X of the first group of battery cell modules is calculated. 1 , and the standard deviation S 1 , and the thickness mean X 1 As an estimate of the mean thickness of this batch of cells, and the standard deviation S 1 As an estimate of the standard deviation of the thickness of this batch of cells, it is stored. Specifically, the number of cells in a cell module is a group. Assume that a cell module has n cells, and the thicknesses are d 11 , d 12 ...d 1n ,but And store it as an estimate of the mean thickness of a batch of cells. Calculate the standard deviation S 1 =R 1 / d 2 (n) is an estimate of the standard deviation of the thickness of this batch of cells. 1 It is represented by the extreme difference of the thickness of the battery cells in the first group of battery cell modules, and d2(n) is a constant factor, which is obtained by looking up the table, as shown in Table 1.

[0050] Represents a table of constant factor values.

[0051] Sample size n <![CDATA[d 2 (n)]]> Sample size n <![CDATA[d 2 (n)]]> 2 1.128 11 3.173 3 1.693 12 3.258 4 2.059 13 3.336 5 2.426 14 3.407 6 2.534 15 3.472 7 2.704 16 3.532 8 2.847 17 3.588 9 2.970 18 3.640 10 3.078 19 3.698

[0052] In this embodiment, when calculating the estimated value of the mean value of the cell thickness and the estimated value of the standard deviation of the cell thickness of the mth group of cell modules:

[0053] Then the average thickness of the mth group of battery modules is X M The sum of the average thickness of the first m groups of battery modules, and then the average thickness of the battery modules in this group, and finally the average. The specific formula is as follows:

[0054]

[0055] The standard deviation S of the mth group of cell modules M The sum of the thickness standard deviations of the first m groups of battery modules, then the sum of the standard deviations of the group of battery modules, and finally the average. The specific formula is as follows:

[0056] S M =(R 1 +R 2 +...+R m ) / d 2 (n) / m;

[0057] The thickness mean X MAs an estimate of the mean thickness of this batch of cells, the standard deviation S M This is used as an estimate of the standard deviation of the thickness of this batch of cells and is stored, and so on.

[0058] S30, taking the thickness mean and standard deviation as thickness grading parameters, determining the thickness range corresponding to each physical gear channel according to the multiple physical gear channels set in sequence, and forming a grading program; and grading the battery cells according to the thickness range, so that the number of battery cells divided by multiple physical gear channels in a batch is distributed in a decreasing and symmetrical manner from the number of battery cells corresponding to the middle physical gear channel to the number of battery cells corresponding to the physical gear channels on both sides, forming a grouping program.

[0059] See also Figure 1 and Figure 2 As shown, in one embodiment of the present invention, seven physical gear channels are arranged in sequence, namely, the first physical gear channel, the second physical gear channel, the third physical gear channel, the fourth physical gear channel, the fifth physical gear channel, the sixth physical gear channel and the seventh physical gear channel, and the middle physical gear channel is the fourth physical gear channel.

[0060] In this embodiment, when making the kth battery cell module, the binning algorithm stores the estimated value of the mean thickness of a batch of battery cells and the standard deviation S k The estimated value of is used as the parameter for the binning. The five physical gear channels in the middle correspond to five standard deviations S k The width of the grade range, and the thickness range corresponding to the fourth physical gear channel is [X k -S k / 2,X k +S k / 2]. Among them, X k represents the estimated value of the mean cell thickness of the kth group of cell modules, S k It is expressed as the estimated value of the standard deviation of the thickness of the battery cells of the k-group battery cell module. The thickness range corresponding to the third physical gear channel is [X k -3S k / 2,X k -S k / 2], the thickness range corresponding to the fifth physical gear channel is [X k +S k / 2,X k +3S k / 2]; the thickness range corresponding to the second physical gear channel is [X k -5S k / 2,X k -3S k / 2], the thickness range corresponding to the sixth physical gear channel is [X k +3S k / 2,X k +5S k / 2]; the thickness range corresponding to the first physical gear channel is [X k -7S k / 2,X k -5S k / 2] and the thickness range corresponding to the seventh physical gear channel is [X k +5S k / 2,X k +7S k / 2].

[0061] In this embodiment, the number of battery cells divided into a batch in the third physical gear channel and the fifth physical gear channel, the second physical gear channel and the sixth physical gear channel, and the first physical gear channel and the seventh physical gear channel is equal.

[0062] In this embodiment, the two physical gear channels at the outermost edges, namely the first physical gear channel and the seventh physical gear channel, also serve as a cell channel that does not conform to the thickness range and an NG cell channel whose thickness does not conform to the design specification, respectively.

[0063] S40: According to the grading procedure, the battery cells are divided into corresponding physical grading channels.

[0064] S50, according to the grouping procedure, grab the battery cells of different physical gear channels and group them into modules.

[0065] In the embodiment of the present invention, the fourth physical gear channel, the third physical gear channel and the fifth physical gear channel, the second physical gear channel and the sixth physical gear channel, the first physical gear channel and the seventh physical gear channel are sequentially checked for battery cells. If there are battery cells in all of them, they are clamped into groups. If there are no battery cells in a physical gear channel, they are supplemented from the fourth physical gear channel closest to the upper layer and then clamped into groups. If there are no battery cells in the second physical gear channel, but there are more than one battery cells in the third physical gear channel, one battery cell is supplemented from the third physical gear channel to prevent disrupting the production line rhythm.

[0066] See also Figure 3 As shown, the present invention also provides a battery cell thickness grading system, which applies the above-mentioned battery cell thickness grading method, including:

[0067] The thickness measuring module 10 is used to obtain the thickness of multiple battery cells in the battery cell module.

[0068] The calculation module 20 is used to calculate the thickness mean and standard deviation of the battery cell module; and use the thickness mean and standard deviation as thickness grading parameters, determine the thickness interval corresponding to each physical gear channel according to multiple physical gear channels set in sequence, and form a grading program; and grade the battery cells according to the thickness interval, so that the number of battery cells divided by multiple physical gear channels in a batch is distributed in a decreasing and symmetrical manner from the number of battery cells corresponding to the middle physical gear channel to the number of battery cells corresponding to the physical gear channels on both sides, forming a grouping program.

[0069] The binning module 30 is used to divide the battery cells into corresponding physical bin channels according to the binning program.

[0070] The grouping module 40 is used to group the cells of different physical gear channels into modules according to the grouping procedure.

[0071] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0072] The above-described embodiments merely represent implementation methods of the invention. The protection scope of the present invention is not limited to the above-described embodiments. For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for grading the thickness of a battery cell, characterized in that: include: Obtain the thickness of multiple cells in a cell module; Calculate the thickness mean and standard deviation of the battery module; Using the thickness mean and standard deviation as thickness grading parameters, determining the thickness interval corresponding to each physical gear channel according to the multiple physical gear channels set in sequence, and forming a grading program; and grading the battery cells according to the thickness intervals, so that the number of battery cells divided by the multiple physical gear channels in a batch is distributed in a decreasing and symmetrical manner from the number of battery cells corresponding to the middle physical gear channel to the number of battery cells corresponding to the physical gear channels on both sides, forming a grouping program; According to the binning procedure, the cells are divided into corresponding physical bin channels; According to the grouping procedure, the battery cells of different physical gear channels are grouped into modules.

2. The method for grading the thickness of a battery cell according to claim 1, characterized in that: Calculate the mean and standard deviation of the thickness of the battery module, including: Calculate the thickness mean X1 and standard deviation S1 of the first group of battery cell modules, and use the thickness mean X1 as an estimated value of the thickness mean of this batch of battery cells, and use the standard deviation S1 as an estimated value of the thickness standard deviation of this batch of battery cells, and store them; When calculating the estimated value of the mean value of the cell thickness and the estimated value of the standard deviation of the cell thickness of the mth group of cell modules: Then the average thickness of the mth group of battery modules is X M The sum of the average thickness of the first m groups of battery modules is then added to the average thickness of the battery modules in this group, and then the average is calculated; The standard deviation S of the mth group of cell modules M The sum of the thickness standard deviations of the first m groups of battery modules is then summed with the standard deviation of the group of battery modules, and then the average is calculated; The thickness mean X M As an estimate of the mean thickness of this batch of cells, the standard deviation S M This is used as an estimate of the standard deviation of the thickness of this batch of cells and is stored; and so on.

3. The method for grading the thickness of a battery cell according to claim 2, characterized in that: There are seven physical gear channels arranged in sequence, and the middle physical gear channel is the fourth physical gear channel; And the thickness range corresponding to the fourth physical gear channel is [X k -S k / 2,X k +S k / 2]; where X k represents the estimated value of the mean cell thickness of the kth group of cell modules, S k Expressed as an estimate of the standard deviation of cell thickness for k groups of cell modules.

4. The method for grading the thickness of a battery cell according to claim 3, characterized in that: In the third physical gear channel and the fifth physical gear channel, the second physical gear channel and the sixth physical gear channel, and the first physical gear channel and the seventh physical gear channel, the number of battery cells divided into one batch is equal.

5. The method for grading the thickness of a battery cell according to claim 3, characterized in that: The thickness range corresponding to the third physical gear channel is [X k -3S k / 2,X k -S k / 2], the thickness range corresponding to the fifth physical gear channel is [X k +S k / 2,X k +3S k / 2]; the thickness range corresponding to the second physical gear channel is [X k -5S k / 2,X k -3S k / 2], the thickness range corresponding to the sixth physical gear channel is [X k +3S k / 2,X k +5S k / 2]; the thickness range corresponding to the first physical gear channel is [X k -7S k / 2,X k -5S k / 2] and the thickness range corresponding to the seventh physical gear channel is [X k +5S k / 2,X k +7S k / 2].

6. The method for grading the thickness of a battery cell according to claim 2, characterized in that: The estimated value of the mean value of the cell thickness and the estimated value of the standard deviation of the cell thickness of the mth group of cell modules are obtained by the following formula: S M =(R1+R2+...+R m ) / d2(n) / m; In the formula, R m It is represented as the extreme difference of the thickness of the battery cells in the mth group of battery cell modules, d2(n) is represented as a constant factor, which is obtained by looking up the table, and n is represented as the number of battery cells in a group of battery cell modules.

7. The method for grading the thickness of a battery cell according to claim 3, characterized in that: According to the grouping procedure, the battery cells of different physical gear channels are grabbed and grouped into modules, including: checking in turn whether there are battery cells at the front end of the fourth physical gear channel, the third physical gear channel and the fifth physical gear channel, the second physical gear channel and the sixth physical gear channel, the first physical gear channel and the seventh physical gear channel; if there are battery cells, they are clamped into groups; if there are no battery cells in a physical gear channel, they are supplemented from the fourth physical gear channel closest to the upper layer, and then clamped into groups.

8. The method for grading the thickness of a battery cell according to claim 1, characterized in that: Obtaining the thickness of multiple battery cells in the battery cell module includes: applying a certain force to two opposite largest surfaces of the battery cells, and measuring a vertical distance between the two opposite largest surfaces of the battery cells as the thickness of the battery cells.

9. The method for grading the thickness of a battery cell according to claim 1, characterized in that: The two physical gear channels at the outermost edges also serve as channels for battery cells that do not meet the thickness range, and channels for NG battery cells whose thickness does not meet the design specifications.

10. A system using the battery cell thickness grading method according to any one of claims 1 to 9, characterized in that: include: A thickness measurement module is used to obtain the thickness of multiple cells in the cell module; A calculation module, used to calculate the thickness mean and standard deviation of the battery cell module; and taking the thickness mean and standard deviation as thickness grading parameters, determining the thickness interval corresponding to each physical gear channel according to the multiple physical gear channels set in sequence, and forming a grading program; and grading the battery cells according to the thickness intervals, so that the number of battery cells divided by the multiple physical gear channels in a batch is distributed in a decreasing and symmetrical manner from the number of battery cells corresponding to the middle physical gear channel to the number of battery cells corresponding to the physical gear channels on both sides, and forming a grouping program; A binning module, used to divide the cells into corresponding physical bin channels according to the binning procedure; The grouping module is used to grab the battery cells of different physical gear channels and group them into modules according to the grouping program.

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