METHOD FOR DETERMINING THE PLACEMENT ACCURACY OF A PLURALITY OF ELECTRODE SHEETS IN A STACK

Abstract

A method for determining the placement accuracy of a plurality of electrode sheets, wherein the electrode sheets extend on mutually parallel planes and are stacked on top of one another and form a stack; wherein the placement accuracy describes positions of the edges of all of the electrode sheets relative to one another in the stack; wherein the method is carried out using a measuring device having a two-dimensionally resolving X-ray system with at least one beam source for X-ray radiation and a detector.

Claims

1. A method for determining the placement accuracy of a plurality of electrode sheets, wherein the electrode sheets extend on mutually parallel planes and are stacked on top of one another and form a stack; wherein the placement accuracy describes positions of the edges of all of the electrode sheets relative to one another in the stack; wherein the method is carried out using a measuring device having a two-dimensionally resolving X-ray system with at least one beam source for X-ray radiation and a detector, and comprises at least the following steps: a) providing the stack and arranging the stack in the measuring device between the at least one beam source and the detector; b) irradiating the stack with the at least one beam source from a first spatial coordinate, with the beam direction extending at least transversely to the planes and toward the detector, and with a beam from the beam source detecting the edges of the electrode sheets that are arranged one above the other and projecting a two-dimensional first contour of the edges of the stack onto the detector; c) irradiating the stack with the at least one beam source from at least one second spatial coordinate that differs from the first spatial coordinate, the beam detecting the stacked edges of the electrode sheets and projecting a two-dimensional second contour of the edges of the stack onto the detector; d) detecting the first contour using the detector; e) detecting the at least one second contour using the detector; and f) evaluating the first contour and the at least one second contour and determining the positions of the edges of the electrode sheets.

2. The method as set forth in claim 1, wherein the first spatial coordinate and the at least one second spatial coordinate differ from one another by a mutually different separation from the stack, in which case the separation extends along a first direction which is transverse to the planes, or by a mutually different distance from the edges, in which case the distance extends along second direction which is parallel to the planes and is transverse to the edges.

3. The method as set forth in claim 1, wherein in step f) the individual edges in the respective contour are correlated with the respective spatial coordinates using linear equations.

4. The method as set forth in claim 1, further comprising: g) performing an assessment of the placement accuracy; wherein a limit value for a maximum deviation of the contour from a desired position of an edge is specified for the stack; and wherein it is assumed for the maximum deviation that the electrode sheet closest to the detector produces the maximum deviation.

5. The method as set forth in claim 4, wherein only steps a), b), d), f), and g) are initially carried out in order to determine the placement accuracy, and steps c) and e) are carried out only if it is determined in step g) that the limit value has been exceeded.

6. The method as set forth in claim 5, if it is determined that the limit value has been exceeded, steps c) and e) are carried out exactly twice with mutually different spatial coordinates, whereupon steps f) and g) are carried out again.

7. The method as set forth in claim 6, wherein, if it is repeatedly determined in step g) that the limit value has been exceeded, steps c) and e) are carried out with a number of repetitions that are required for the unambiguous determination of the positions of all edges.

8. The method as set forth in claim 1, wherein artificial intelligence is used at least for step f).

9. The method as set forth in claim 8, wherein the contours are evaluated using a convolutional neural network; wherein the convolutional neural network learns from a synthetic data set for a stack with known positions of the edges of the electrode sheets in order to then determine the position of the edge of each electrode sheet from the contours of the stack detected in step d).

10. The method as set forth in claim 1, wherein at least one process parameter from the evaluation of the placement accuracy according to step g) used to produce the respective stack is determined and altered in a further step h), thereby improving the placement accuracy for further stacks.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0084] The invention and the technical environment will be explained in greater detail with reference to the enclosed figures. It should be noted that the invention is not intended to be limited by the specified embodiments. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the features explained in the figures and to combine them with other components and insights from the present description. In particular, it should be pointed out that the figures and, in particular, the illustrated proportions are only schematic. In the drawings:

[0085] FIG. 1 shows a first embodiment of the method;

[0086] FIG. 2 shows a second embodiment of the method;

[0087] FIG. 3 shows step f) of the method according to the first variant;

[0088] FIG. 4 shows steps b), d), and g) of the method for a first stack;

[0089] FIG. 5 shows steps b), d), and g) of the method for a second stack;

[0090] FIG. 6 shows steps c) and e) of the method for the first stack;

[0091] FIG. 7 shows repeated execution of steps c) and e) of the method for the first stack;

[0092] FIG. 8 shows steps c) and e) of the method for the second stack; and

[0093] FIG. 9 shows repeated execution of steps c) and e) of the method for the second stack.

DETAILED DESCRIPTION OF THE INVENTION

[0094] FIG. 1 shows a first variant of the method. The method is used as part of a method for manufacturing battery cells. Appropriately cut electrode sheets 1, 2, 3—i.e., anode sheets, cathode sheets, and possibly separator sheets—are arranged in a predetermined order to form a stack 5 and aligned with one another. In the stack 5 created in this manner, the individual electrode sheets 1, 2, 3 should be arranged in the most aligned position relative to one another.

[0095] The electrode sheets 1, 2, 3 extend on mutually parallel planes 4 and, when stacked on top of one another, form a stack 5. The stack 5 comprises a plurality of electrode sheets 1, 2, 3.

[0096] The electrode sheets 1, 2, 3 each have a substantially rectangular shape. Conductor lugs extend beyond this rectangular shape at an edge 9 of the electrode foils 1, 2, 3.

[0097] The placement accuracy describes the positions 6, 7, 8 of the edges 9 of all of the electrode sheets 1, 2, 3 relative to one another in the stack 5. The electrode sheets 1, 2, 3 should be arranged in a predetermined position relative to one another. Since the size of anode sheets and cathode sheets as well as of any separator sheets that may be present can differ from one another, the placement accuracy is determined at the edges 9 of the electrode sheets 1, 2, 3, which are aligned with one another along a first direction 21 extending transversely to the planes. The placement accuracy of the electrode sheets 1, 2, 3 is only determined at one edge 9 of an electrode sheet 1, 2, 3.

[0098] The method is carried out using a measuring device 10 that has a two-dimensionally resolving X-ray system 11 with a beam source 12 for X-ray radiation and a detector 13. The beam source 12 is used to emit X-rays along a beam direction 15. A detector 13 is used to record the X-ray radiation in order to display an X-ray image.

[0099] The detector 13 makes it possible to display a two-dimensional image (hereinafter referred to as contour 17, 19) of the X-ray radiation. The proposed method enables the electrode sheets 1, 2, 3 to be placed accurately from these two-dimensional images taken by the detector 13.

[0100] According to step a), the stack 5 is provided, and the stack 5 is arranged in the measuring device 10 between the one beam source 12 and the detector 13. According to step b), the stack 5 is irradiated with the beam source 12 from a first spatial coordinate 14, the beam direction 15 extending transversely to the planes 4 and toward the detector 13 (substantially along a first direction 21). A beam 16 from the beam source 12 detects the stacked edges 9 of the electrode sheets 1, 2, 3 and projects a two-dimensional first contour 17 of the edges 9 of the stack 5 onto the detector 13. The beam source 12 is arranged precisely above the edges 9, i.e., without a lateral offset relative to the edges 9.

[0101] In arranging the stack 5, it is assumed that the edges 9 of the electrodes 1, 2, 3 are in a predetermined desired position. The actual position 6, 7, 8 of the edges 9 deviating therefrom is determined as part of the method.

[0102] According to step d), the first contour 17 is detected using the detector 13.

[0103] According to step c), the stack 5 is irradiated with the beam source 12 from at least one second spatial coordinate 18 that differs from the first spatial coordinate 14, the beam 16 detecting the stacked edges 9 of the electrode sheets 1, 2, 3 and projecting a two-dimensional second contour 19 of the edges 0 of the stack 5 onto the detector 13.

[0104] According to step e), the second contour 19 is detected using the detector 13.

[0105] It is shown that steps c) and e) are carried out repeatedly, with the second spatial coordinates 18 of each step c) differing from the respective previous second spatial coordinates 18 of the previous steps c). The further spatial coordinates of this repetition of steps c) and e) are referred to as third spatial coordinates 25, and the contour detected in this manner as the third contour 26.

[0106] According to step f), the various contours 17, 19, 26 are evaluated and the positions 6, 7, 8 of the edges 9 of the electrode sheets 1, 2, 3 are determined. The evaluation is carried out by the system 27 for data processing.

[0107] The measuring device 10 comprises a system 27 for data processing, having means which are suitably equipped, configured, or programmed to carry out the method, more particularly which carry out the method. The means comprise, for example, a processor and a memory in which instructions to be executed by the processor are stored, as well as data lines or transmission devices which enable instructions, measured values, data, or the like to be transmitted between the listed elements.

[0108] A contour 17, 19, 26 detected by the detector 13 comprises a two-dimensional image in which the edges 9 of the electrode sheets 1, 2, 3 can be identified based on the transitions between color intensities. It is not readily possible to correlate the edges 9 present in the contour 17, 19, 26 to individual electrode sheets 1, 2, 3. The method described represents one way of achieving this correlation.

[0109] In the framework of the method, multiple contours 17, 19, 26 of one stack 5 are generated by the beam source 12 and detected by the detector 13. Due to the different arrangement of the beam source 12 relative to the stack 5 or the edges 9, different contours 17, 19, 26 are generated. These contours 17, 19, 26 are evaluated using linear equations, which means that, by virtue of the known arrangement of beam source 12 and detector 13 and the linear, i.e., rectilinear course of the beam 12 generated by the beam source 12, the position of the edges 9 in the respective contour 17, 19, 26 can be used to infer the position 6, 7, 8 of the respective edge 9 in the stack 5.

[0110] The first spatial coordinate 14 and the at least one second spatial coordinate 18, 25 (i.e., the second and third spatial coordinates) differ from one another by a different distance 22 to the edges 9, with the distance 22 extending along a second direction 23 that extends parallel to the planes 4 and transversely to the edges 9. A third direction 28 extends parallel to the edges 9 that are measured using the measuring device 10.

[0111] The individual contours 17, 19, 26 are correlated with the respective spatial coordinates 14, 18, 25 by arrows.

[0112] FIG. 2 shows a second variant of the method. Reference is made to the remarks in relation to FIG. 1.

[0113] In contrast to the first variant, in which the beam source 12 is moved between steps b) and d) parallel to the planes 4 toward the second spatial coordinate 18, in the second variant the beam source 12 is moved between steps b) and d) transversely to the planes 4 toward the second spatial coordinate 18 or toward the third spatial coordinate 25. The different contours 17, 19, 26 generated in this manner also enable the unambiguous determination of the edge 9 of each electrode sheet 1, 2, 3.

[0114] The first spatial coordinate 14 and the at least one second spatial coordinate 18, 25 (i.e., the second and third spatial coordinates) differ from one another by a different separation 20 from the stack 5. The separation 20 extends along a first direction 21 extending transversely to the planes 4.

[0115] The individual contours 17, 19, 26 are correlated with the respective spatial coordinates 14, 18, 25 by arrows.

[0116] FIG. 3 shows step f) of the method according to the first variant. Reference is made to the remarks in relation to FIG. 1.

[0117] According to step f), the various contours 17, 19, 26 are evaluated and the positions 6, 7, 8 of the edges 9 of the electrode sheets 1, 2, 3 are determined. The evaluation is carried out by the system 27 for data processing.

[0118] The stack 5, the beam source 12, and the detector 13 are viewed on a common plane. A spatial coordinate z is therefore identical for all components 1, 2, 3, 5, 12, 13. The first direction 21, i.e., transverse to the planes 4, extends along a y axis (here the vertical axis in the upper diagram of FIG. 3). The second direction 23, i.e., parallel to the planes 4, extends along the x axis (here the horizontal axis in the upper diagram of FIG. 3). A third direction 28 extends along a z axis (here the backward-pointing axis in the upper diagram of FIG. 3).

[0119] The first spatial coordinates 14 are (x.sub.q1|y.sub.q1), and the second spatial coordinates 18 are (x.sub.q2|y.sub.q2). The spatial coordinates of the edge 9 of the first electrode sheet 1 that is to be determined are denoted as (x.sub.e|y.sub.e). The positions of the edge 9 of this electrode sheet 1 in the first contour 13 detected by the detector 13 are (x.sub.d1|y.sub.d1) for the first spatial coordinates 14 of the beam source 12 and, in the second contour 19, (x.sub.d2|y.sub.d2) for the second spatial coordinates 18 of the beam source 12.

[0120] The following applies to the linear equation for the first spatial coordinates 14 of the beam source 12:

[00004] $\begin{matrix} m_{1} = \frac{Δ y_{1}}{Δ x_{1}} = \frac{y_{d 1} - y_{q 1}}{x_{d 1} - x_{q 1}} & (1) \end{matrix}$ $\begin{matrix} y = m_{1} .Math. (x - x_{q 1}) + y_{q 1} & (2) \end{matrix}$ $\begin{matrix} y = m_{1} x + b_{1} & (3) \end{matrix}$

[0121] For the linear equation of the second spatial coordinates 18 of the beam source 12, the following applies:

[00005] $\begin{matrix} m_{2} = \frac{Δ y_{2}}{Δ x_{2}} = \frac{y_{d 2} - y_{q 2}}{x_{d 2} - x_{q 2}} & (1) \end{matrix}$ $\begin{matrix} y = m_{2} .Math. (x - x_{q 2}) + y_{q 2} & (2) \end{matrix}$ $\begin{matrix} y = m_{2} x + b_{2} & (3) \end{matrix}$

[0122] These equations are equated, so that:

[00006] $\begin{matrix} m_{1} .Math. x + b_{1} = m_{2} .Math. x + b_{2} & (4) \end{matrix}$ $\begin{matrix} .fwdarw. (m_{1} - m_{2}) .Math. x = b_{2} - b_{1} & (5) \end{matrix}$ $\begin{matrix} .fwdarw. x_{e} = \frac{b_{2} - b_{1}}{(m_{1} - m_{2})} & (6) \end{matrix}$ $\begin{matrix} .fwdarw. y_{e} = m_{1} .Math. \frac{b_{2} - b_{1}}{(m_{1} - m_{2})} + b_{1} & (7) \end{matrix}$

[0123] The spatial coordinates of (x.sub.e|y.sub.e) indicate the first position 6 of the edge 9 of the first electrode sheet 1.

[0124] FIG. 4 shows steps b), d), and g) of the method for a first stack 5. Reference is made to the remarks in relation to FIG. 1.

[0125] In the first stack 5, the bottom first electrode sheet 1 has the greatest deviation 24 from a desired position. The placement accuracy is evaluated in a step g). A limit value for a maximum deviation 24 of the contour 17, 19, 26 (or of the position of the edge 9 identified in the contour) from a desired position of an edge 9 is specified for the stack 5. For the maximum deviation 24, it is assumed that the electrode sheet 1, 2, 3 closest to the detector 13 produces the maximum deviation 24.

[0126] The maximum deviation 24 is the maximum permissible difference between the desired position of an edge 9 in the stack 5 and an actual position 6, 7, 8 of the edge 9. The maximum deviation 24 is determined on the first contour 17, by taking into account the first spatial coordinates 14 compared to the desired position of the edges 9.

[0127] Only steps a), b), d), f), and g) are initially carried out in order to determine the placement accuracy, and steps c) and e) (see FIGS. 8 and 9) are carried out only if it is determined in step g) (see FIG. 4) that the limit value has been exceeded.

[0128] Each stack 5 is thus checked in the context of the present method with regard to placement accuracy, but a determination of the positions 6, 7, 8 of the edges of 9 all of the electrode sheets 1, 2, 3 in the stack 5 is only made if the limit value is exceeded, for example. Otherwise, each stack 5 is only checked for an overshoot of the limit value.

[0129] If it is determined that the limit value has been exceeded, steps c) and e) are carried out exactly twice with different (second) spatial coordinates 18, 25, whereupon steps f) and g) are carried out again (see FIGS. 8 and 9).

[0130] The first spatial coordinates 14 are selected such that the radiation source 12 is arranged precisely above, i.e., so as to be aligned in the first direction 21 with the desired position of the edges 9 of the stack 5 (see FIG. 4). The two second spatial coordinates 18, 25 (i.e., second and third spatial coordinates) are then selected such that the radiation source 12 is arranged so as to be offset relative to the first spatial coordinates 14 in the second direction 23, once toward the stack 5, so that the radiation source 12 is aligned with the stack 5 and offset once away from the stack 5, so that the radiation source 12 is located laterally adjacent to the stack 5 (see FIGS. 8 and 9).

[0131] If it is repeatedly determined in step g) that the limit value has been exceeded, steps c) and e) are carried out with a number of repetitions that are required for the unambiguous determination of the positions 6, 7, 8 of all edges 9.

[0132] By virtue of this step-by-step method, not every stack has to be fully measured (i.e., not all of the positions 6, 7, 8 of the edges 9 of all of the electrode sheets 1, 2, 3 have to be determined) during the production of the stacks 5. The maximum deviation 24 in the stack 5 can be detected or estimated on the basis of fewer contours 17, 19, 26, i.e., fewer images taken by the detector 13. If the limit value is exceeded, further measurements can be used to determine the respective positions 6, 7, 8 of the electrode sheets 1, 2, 3.

[0133] FIG. 5 shows steps b), d), and g) of the method for a second stack 5. Reference is made to the remarks in relation to FIG. 4.

[0134] In the second stack 5, the uppermost first electrode sheet 1 has the greatest deviation 24 from a desired position. The placement accuracy is evaluated in a step g). A limit value for a maximum deviation 24 of the contour 17, 19, 26 (or of the position of the edge 9 identified in the contour) from a desired position of an edge 9 is specified for the stack 5. For the maximum deviation 24, it is assumed that the electrode sheet 1, 2, 3 closest to the detector 13 produces the maximum deviation 24. For the second stack 5 that is shown, the greatest deviation 24 that can be recognized in the first contour 17 would then be much smaller (that is, if the first electrode sheet 1 were arranged at the very bottom of the stack 5). In this case impermissibly large deviations 24 could not be recognized.

[0135] If it is determined that the limit value has been exceeded, steps c) and e) are carried out exactly twice with different (second) spatial coordinates 18, 25, whereupon steps f) and g) are carried out again (see FIGS. 6 and 7).

[0136] The first spatial coordinates 14 are selected such that the radiation source 12 is arranged precisely above, i.e., so as to be aligned in the first direction 21 with the desired position of the edges 9 of the stack 5 (see FIG. 5). The two second spatial coordinates 18, 25 (i.e., second and third spatial coordinates) are then selected such that the radiation source 12 is arranged so as to be offset relative to the first spatial coordinates 14 in the second direction 23, once toward the stack 5, so that the radiation source 12 is aligned with the stack 5 and offset once away from the stack 5, so that the radiation source 12 is located laterally adjacent to the stack 5 (see FIGS. 6 and 7).

LIST OF REFERENCE SYMBOLS

[0137] 1 first electrode sheet
2 second electrode sheet
3 third electrode sheet
4 plane
5 stack
6 first position
7 second position
8 third position
9 edge
10 measuring device
11 X-ray system
12 beam source
13 detector
14 first spatial coordinate
15 beam direction
16 beam
17 first contour
18 second spatial coordinate
19 second contour
20 separation
21 first direction (y axis)
22 distance
23 second direction (z axis)
24 deviation
25 third spatial coordinate
26 third contour
27 system
28 third direction (x axis)

METHOD FOR DETERMINING THE PLACEMENT ACCURACY OF A PLURALITY OF ELECTRODE SHEETS IN A STACK

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H01M10/0585

ELECTRICITY

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G01N23/04

PHYSICS

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Y02E60/10

GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

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H01M10/0463

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G01N23/083

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H01M10/0525

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G01N2223/40

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G01N23/044

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International classification

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G01N23/04

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G01N23/083

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Abstract

Claims

Description