METHOD AND APPARATUS FOR PRODUCING AN ELECTRODE STACK

Abstract

The invention relates to a method for producing an electrode stack (4) from monocells (5) for a lithium-ion battery, in particular of an electrically powered motor vehicle, wherein the monocells (5) are each formed from an anode (6) and a cathode (8), wherein the monocells (5) are conveyed into receptacles (14) of a rotationally driven or rotationally drivable stacking wheel (12), wherein the monocells (5) accommodated in the receptacles (14) are conveyed by means of a rotation of the stacking wheel (12) to a stacking compartment (24), wherein the monocells (5) are held by means of a stripper arm (22) in the region of the stacking compartment (24), and are transferred due to the rotation of the stacking wheel (12) from the respective receptacles (14) into the stacking compartment (24), wherein the monocells (5) are stacked in the stacking compartment (24), and wherein the stacked monocells (5) are pressed against each other in the stacking compartment (24). The invention also relates to an apparatus (2) for producing such an electrode stack (4).

Claims

1. A method for producing an electrode stack from monocells for a lithium-ion battery, wherein the monocells are each formed from an anode and a cathode, comprising: conveying the monocells into receptacles of a rotationally driven or rotationally drivable stacking wheel, conveying the monocells accommodated in the receptacles to a stacking compartment by means of a rotation of the stacking wheel, and holding the monocells by means of a stripper arm in the region of the stacking compartment, and transferring the monocells due to the rotation of the stacking wheel from the respective receptacles into the stacking compartment, wherein the monocells are stacked in the stacking compartment, and wherein the stacked monocells are pressed against each other in the stacking compartment.

2. The method according to claim 1, wherein at least two of the monocells are conveyed simultaneously into the corresponding receptacles of the stacking wheel.

3. The method according to claim 1, wherein a speed of conveying the monocells into the respective receptacles of the stacking wheel is adjusted in such a way that the monocells, before they are stopped by the stripper arm, are decelerated to a standstill due to friction relative to the given receptacle.

4. An apparatus for producing an electrode stack having monocells, for a lithium-ion battery, comprising a stacking wheel which can be driven to rotate about an axis of rotation, with receptacles for the monocells, wherein the receptacles are formed on a circumference of the stacking wheel and extend in an axial direction, a conveying device for conveying the monocells into the receptacles of the stacking wheel, a stripper arm which can be inserted into a recess that is continuous in a circumferential direction of the stacking wheel, and which forms a stop for the monocells accommodated in the receptacles when the stacking wheel rotates, such that the monocells are transferred from the respective receptacles into a stacking compartment due to rotation of the stacking wheel, or two stripper arms which are arranged in the axial direction on both sides of the stacking wheel, wherein the stacking wheel has a smaller extension in the axial direction than the monocells, such that the stripper arms form a stop for the monocells accommodated in the receptacles and protruding in the axial direction from the receptacles when the stacking wheel rotates, and wherein the monocells are transferred from the respective receptacles into a stacking compartment due to the rotation of the stacking wheel, and wherein the stacking compartment has a compression unit for generating a pressing force on the monocells stacked in the stacking compartment.

5. The apparatus according to claim 4, wherein the receptacles are arcuate, in particular spiral-shaped, in a plane perpendicular to the axis of rotation.

6. The apparatus according to claim 4, wherein the conveying device for conveying the monocells into the receptacles of the stacking wheel has at least two first conveyor belts.

7. The apparatus according to claim 6, wherein each of the first conveyor belts is assigned a second conveyor belt oriented in parallel, with a direction of rotation opposite to the assigned first conveyor belt, such that the monocells are clamped during their conveying process between the first conveyor belt and the second conveyor belt.

8. The apparatus according to claim 7, wherein the first conveyor belts and/or the second conveyor belts protrude into the or a recess of the stacking wheel, such that the monocells are conveyed tangentially into the receptacle.

9. The apparatus according to claim 4, wherein, for removing the electrode stack, the stacking compartment can be moved and/or tilted about a tilting axis parallel to the axis of rotation.

10. The apparatus according to claim 4, wherein each of the slides of the stacking compartment, and/or the stripper arm, provided for orienting the monocells in alignment with each other, has a contacting recess for electrical contacts of the anodes and the cathodes of the monocell.

Description

[0034] Embodiments of the invention are explained in more detail below with reference to the drawings, wherein:

[0035] FIG. 1 schematically shows a first variant of an apparatus for producing an electrode stack, having a stacking wheel that can be driven to rotate about an axis of rotation, with receptacles for monocells, wherein a stripper arm is inserted into a circumferentially continuous recess of the stacking wheel, and by means of this the monocells can be transferred from the receptacles into a stacking compartment,

[0036] FIG. 2a schematically shows the first variant of the apparatus in a side view, viewed perpendicular to the axis of rotation,

[0037] FIG. 2b schematically shows the first variant of the apparatus in a plan view,

[0038] FIG. 3a shows a second variant of the apparatus in a side view, viewed perpendicular to the axis of rotation of its rotationally driven stacking wheel, wherein a stripper arm is arranged in front of the stacking wheel, and another stripper arm is arranged and behind the stacking wheel with respect to a direction parallel to the axis of rotation, and these serve as a stop for the monocells conveyed by means of the receptacles of the stacking wheel,

[0039] FIG. 3b schematically shows the second variant of the apparatus in a plan view,

[0040] FIG. 4 shows a method sequence for producing the electrode stack, in a flowchart, and

[0041] FIG. 5 shows one of the monocells, the monocell being formed from anodes and cathodes.

[0042] Corresponding parts and dimensions are always provided with the same reference signs in all figures.

[0043] In FIG. 1 and FIGS. 2a and 2s, a first variant of an apparatus 2 is shown, which is used to produce an electrode stack 4 from monocells 5. One of the monocells is shown in FIG. 5. The monocell 5 is formed from an anode 6 and a cathode 8, a separator 9 being arranged between the anode 6 and the cathode 8. Furthermore, a further separator 9 is arranged on the side of the cathode 8 facing away from the anode 6. The anode 6, the cathode 8, and the separators 9 are joined to each other by means of lamination. The anodes 6 and the cathodes 8 are sheet-shaped. Furthermore, the anodes 6 and the cathodes 8 each have an electrical contact 10, the same also being referred to as a tab. For the purpose of improved clarity, the monocell 5 is shown in simplified form in FIGS. 1 to 3b.

[0044] The electrode stack 4 is intended for a lithium-ion battery (not shown in further detail), for example for a (traction) battery of an electrically powered motor vehicle. The apparatus 2 has a stacking wheel 12 which can be driven to rotate about an axis of rotation D.

[0045] The stacking wheel 12 has receptacles 14 for the monocell 5 formed on the circumference thereof and extending in the axial direction A, that is to say along the axis of rotation D. The receptacles 14 are formed by means of arms 16, which are also referred to as blades, which extend from the region of the axis of rotation D to the circumferential side of the stacking wheel 12—that is to say, outward. The arms 16, and thus also the receptacles 14, are designed in a spiral shape in a plane perpendicular to the axis of rotation D. The receptacles 14 therefore have a spiral cross-section in this plane. In this case, a curvature of the arcuate receptacle increases from the circumferential side toward the axis of rotation D—that is to say, as the radial distance from the axis of rotation D becomes smaller. Furthermore, the receptacles 14 extend outward opposite the direction of rotation of the stacking wheel 12 represented by a corresponding arrow about the axis of rotation D.

[0046] The stacking wheel 12 has a wall 18 at each end with respect to the axial direction A, which wall delimits the receptacles 14. In this case, the front wall 18 in the viewing direction is not shown in FIG. 1 for the purpose of visibility. The wall 18 prevents an undefined displacement of the monocells 5 in a direction along the axis of rotation D during the rotation of the stacking wheel 12, and during the process of the monocells 5 being received in the receptacles 14.

[0047] As can be seen in particular in FIGS. 2a and 2b, the stacking wheel 12 has a circumferential recess 20 which is continuous in the circumferential direction of the stacking wheel 12. The recess 20 thus extends in a plane perpendicular to the axis of rotation D. The recess 20 also has an extension opposite the radial direction R to the axis of rotation D, which is greater than the extension of the receptacles 14 in this direction. The arms 16 are therefore not continuous in the axial direction A.

[0048] A stripper arm 22 is arranged in the recess 20. The section of the stripper arm 22 which is arranged within the recess 20 is shown with dashed lines in FIG. 1. The stripper arm 22 serves as a stop for the monocells 5 accommodated in the receptacles 14. Upon the rotation of the stacking wheel 12, the monocells 5 arranged in the receptacles 14 are displaced relative to the stripper arm 22, such that they are held against further conveyance by means of the stacking wheel 12. Due to the further rotation of the stacking wheel 12, each of the monocells 5 are transferred from the respective receptacles 14 into a stacking compartment 24 arranged in the region of the stripper arm 22.

[0049] The stacking compartment 24 has a slide 26 for orienting the monocells 5 in alignment with each other. For this purpose, it is able to move in the direction of the stripper arm 22. This movement is shown in FIG. 1 by means of a double arrow. Furthermore, the stacking compartment 24 has a compression unit 28 for generating a pressing force on the monocells 5 stacked in the stacking compartment 24 and aligned with each other. For this purpose, the compression unit 28 can be pivoted through the recess 20. The electrode stack 4 is formed by orienting the monocells 5 in alignment with each other and pressing them together.

[0050] According to a variant of the stacking compartment 24, not shown, the compression unit 28 is adjustable in the axial direction A, such that the compression unit 28 cannot be pivoted through the recess 20, but can be moved between the stacking wheel 12 and a bottom 29 of the stacking compartment 24.

[0051] The stacking compartment 24 can also be tilted, together with the compression unit 28 and with the stripper arm 22, about a tilting axis K oriented parallel to the axis of rotation D, such that the electrode stack 4 can be removed from the stacking compartment and transported away by means of a conveyor belt 30. By means of the conveyor belt 30, the electrode stack 4, that is to say the monocells 5 pressed against each other, can be transported for further production of the battery, or to a magazine or a storage.

[0052] In FIG. 1, the apparatus 2 is shown, with a viewing direction along the axis of rotation D; and in FIGS. 2a and 2b, it is shown with a viewing direction perpendicular to the axis of rotation D and parallel or perpendicular to the bottom of the stacking compartment 29. The stripper arm 22 is shown in simplified form in FIGS. 2a and 2b for the purpose of improved clarity.

[0053] As can be seen in particular in FIG. 2b, the slide 26 and the stripper arm 22 each have a contacting recess 32 for the electrical contacts 10 of the anodes 6 and the cathodes 8 of the monocells 5.

[0054] Furthermore, the apparatus 2 has a conveying device 34 for conveying the monocells 5 into the receptacles 14 of the stacking wheel 12. The conveying device 34 has two first conveyor belts 36, by means of which two of the monocells 5 can be conveyed into the receptacles 14 of the stacking wheel 12 at the same time. Furthermore, each of the first conveyor belts 36 is assigned a second conveyor belt 38, wherein each conveyor belt 38 is arranged parallel to the first conveyor belt 36 it is assigned to. Each of the conveyor belt surfaces 40 of the second conveyor belts 38 has an opposite direction of rotation to the conveyor belt surface 40 of the assigned first conveyor belt 36. The first conveyor belts 36 and the assigned second conveyor belts 38 are each spaced apart from each other in such a way that the monocells 5 are clamped between the first conveyor belt 36 and the corresponding second conveyor belt 38 when they are conveyed.

[0055] The first conveyor belts 36 protrude partially into the recess 20 of the stacking wheel 12, such that the monocells are conveyed tangentially into the receptacle 14. Those portions of the conveyor belts 36 and 38 which protrude into the recess 20 are shown in dashed lines.

[0056] As can be seen in particular in FIG. 2a, the first conveyor belts 36 and the second conveyor belts 38 have a smaller extension than the monocells 5 in a direction which runs perpendicular to the conveying direction and in the planes spanned by their conveyor belt surfaces 40. In other words, the monocells 5 protrude beyond the conveyor belts 38 in the transverse direction of the conveyor belt.

[0057] A second variant of the apparatus 2 is shown in FIGS. 3a and 3b. With the exception of what is discussed below, the explanations given above apply analogously to the second variant, and are not shown in further detail here.

[0058] The apparatus 2 has two stripper arms 22 which are arranged in the axial direction A on both sides of the stacking wheel 12. In other words, one of the two stripper arms is arranged with respect to the axial direction A in front of the stacking wheel 12, and the other stripper arm 22 is arranged behind it. The stacking wheel 12 in this case has a smaller extension in the axial direction A, such that the monocells 5 accommodated in the receptacles 14 protrude in the axial direction A on both sides beyond the stacking wheel 12. When the stacking wheel 12 rotates, the two stripper arms 22 form a stop for the monocells 5 accommodated in the receptacles 14. The monocells 5 are consequently supported against further conveyance due to the rotation of the stacking wheel 12, and are transferred from the given receptacle 14 into the stacking compartment 24.

[0059] In comparison to the first variant, the stacking wheel 12 does not have a wall 18 which closes off the receptacles 14 at the ends with respect to the axial direction A.

[0060] The stripper arms 22 still have no contacting recess 32 for the electrical contacts 10 of the anodes or the cathodes. Rather, the electrical contacts 10 are arranged between the arms 16 of the stacking wheel.

[0061] The flow diagram shown in FIG. 4 illustrates a method for producing an electrode stack 4 from the monocells 5. An apparatus 2 according to FIGS. 1 and 2 is preferably used for this purpose.

[0062] In a first step I, the monocells 5 are conveyed into the receptacles 14 of the stacking wheel 12, which is driven to rotate—in particular continuously. In the process, at least two of the monocells 5 are conveyed into the given receptacle 14 of the stacking wheel 12 at the same time. For this purpose, the apparatus 2, as set out above, has two first conveyor belts 36.

[0063] In this case, only a single monocell is received in each of the receptacles 14, the receptacles 14 being formed in such a way that the anodes 6 and the cathodes 8 of the monocells 5 are arranged alternately in the circumferential direction (direction of rotation) of the stacking wheel 12.

[0064] The electrical contacts 10 of the anodes 6 and the cathodes 8 of the monocells 5 are arranged at the front and rear with respect to their conveying direction into the given receptacle 14 of the stacking wheel 12. In this way, the electrical contacts 10 of the anodes 6 and the cathodes 8 are arranged on opposite sides of the electrode stack 4.

[0065] In a second step II, the monocells 5 accommodated in the receptacles 14 are conveyed to a stacking compartment 24 by means of a rotation of the stacking wheel 12.

[0066] In a third step III of the method, the monocells 5 are held in the region of the stacking compartment 24 by means of the stripper arm 22 or by means of the stripper arms 22. As such, the monocells 5 are held (supported) against the rotation of the stacking wheel 12 by means of the stripper arm 22 or by means of the stripper arms 22, such that the given receptacle 14 is displaced relative to the associated monocell 5 due to the rotation of the stacking wheel 12, and the monocell 5 is accordingly transferred out of the given receptacle 14 into the stacking compartment 24. The monocells are alternately stacked in the stacking compartment 24.

[0067] Furthermore, the conveying speed of the monocells 5 into each of the receptacles 14 of the stacking wheel 12 is adjusted in such a way that the monocells 5, before they are stopped by the stripper arm 22 or the stripper arms 22, are decelerated to a standstill relative to the given receptacle, due to friction between the monocells 5 and the given receptacle 14. The conveying speed is adjusted as a function of the shape of the receptacles 14. Due to the spiral shape of the receptacles 14, a frictional force between each receptacle 14 and the monocell 5 becomes greater toward the end (at the axis of rotation) of the receptacle 14 facing the axis of rotation D.

[0068] In a fourth step IV, the stacked monocells 5 in the stacking compartment 24 are aligned with each other by means of the slide 26, and are pressed against each other by means of the compression unit 28, forming the electrode stack 4. For this purpose, the compression unit 28 acts with a pressing force on the monocells 5 stacked in the stacking compartment 24 and aligned with each other.

[0069] The invention is not limited to the embodiment described above. Rather, other variants of the invention can also be derived therefrom by a person skilled in the art without departing from the subject matter of the invention. In particular, all of the individual features described in connection with the embodiments can also be combined with each other in other ways without departing from the subject matter of the invention.

LIST OF REFERENCE SIGNS

[0070] 2 apparatus [0071] 4 electrode stack [0072] 5 monocell [0073] 6 anode [0074] 8 cathode [0075] 9 separator [0076] 10 electrical contact of the electrode [0077] 12 stacking wheel [0078] 14 receptacle [0079] 16 arm [0080] 18 wall [0081] 20 recess [0082] 22 stripper arm [0083] 24 stacking compartment [0084] 26 slide [0085] 28 compression unit [0086] 29 bottom of the stacking compartment [0087] 30 conveyor belt [0088] 32 contacting recess [0089] 34 conveying direction [0090] 36 first conveyor belt [0091] 38 second conveyor belt [0092] 40 conveyor belt surface [0093] I conveying the monocells into the receptacles of the stacking wheel [0094] II conveying the monocells to the stacking compartment by means of the stacking wheel [0095] III transferring the monocells from the receptacle into the stacking compartment [0096] IV pressing the monocells against each other [0097] A axial direction [0098] D axis of rotation [0099] K tilting axis