DE102022111706A1 - Method for producing an accumulator and accumulator - Google Patents

Abstract

The invention relates to a method for producing an accumulator, wherein the metal foils (3), which contact the electrodes of the accumulator, are wound together with the electrodes of the accumulator to form an, at least essentially, circular-cylindrical electrode coil (1) that on one of the A first edge region of a first metal foil (3) protrudes from both opposite end faces of the electrode winding (1) for contacting a first electrode relative to the other layer-shaped components of the electrode winding (1). The electrode coil (1) is inserted into a cup-shaped housing part (21) and in order to contact the first electrode of the accumulator, the first edge region of the first metal foil (3) of the first electrode is brought into contact with the bottom (22) of the housing part (21) and welded to the floor by applying a laser beam to the outside of the bottom (22) of the housing part (21).

Description

The invention relates to a method for producing an accumulator, in particular a method for producing an electrode lead of an accumulator, and an accumulator that can be produced using the method according to the invention.

In the case of accumulators of the type in question, the metal foils, which in particular contact the anode and/or the cathode of the accumulator, are wound together with other flat components of the accumulator, such as in particular the electrodes of the accumulator, preferably spirally, to form an electrode coil.

Such accumulators can be manufactured by inserting the electrode coils into cup-shaped housing parts. The cup-shaped housing part can be closed with a lid, which can be electrically insulated from the housing part. A pole is passed through the cover and is electrically contacted with one of the metal foils of the electrode coil. The other metal foil of the electrode wrap is electrically contacted with the cup, which thus forms the second pole of the resulting accumulator. Here, flags are used with which the metal foils are contacted with the cup-shaped housing part or the pole passed through the lid. On the one hand, the type of contacting is comparatively complex, and on the other hand, it regularly results in comparatively long current paths. Such accumulators are therefore less suitable for applications in which the accumulators are intended to deliver high electrical power.

From the DE 10 2017 006 229 A1 a method for producing an accumulator and an accumulator are known in which edge regions of the metal foils for contacting the electrodes on the two opposite end faces of the electrode coil protrude from the other layer-shaped components of the electrode coil. The edge areas are welded to contact elements, which in turn are welded to poles, which are passed through corresponding insulating covers on both end faces of the circular cylindrical battery. The contacting enables short current paths and such accumulators are significantly more suitable for applications in which the accumulators have to deliver high electrical power. The disadvantage, however, is that such accumulators require more space and are more expensive to manufacture, since corresponding contact elements with poles attached to them must be installed on both end faces of the circular cylindrical housing.

The object of the invention is therefore to provide a method for producing an accumulator and an accumulator in which the aforementioned disadvantages do not occur or at least occur to a reduced extent.

The task is solved by a method using an accumulator with the features of the independent claims. The features of the dependent claims relate to advantageous embodiments.

The method for producing the accumulator provides that the metal foils, which contact the electrodes of the accumulator, are wound together with the electrodes of the accumulator to form an, at least essentially, circular cylindrical electrode coil that on one of the two opposite end faces of the electrode coil first edge region of a first metal foil for contacting a first electrode protrudes from the other layer-shaped components of the electrode coil. The end faces are to be understood as meaning the sides of the electrode coil which correspond to the base surfaces of the circular cylinder describing the geometric shape of the electrode coil.

The electrode coil is introduced into a cup-shaped housing part and in order to contact the first electrode of the accumulator, the first edge region of the first metal foil of the first electrode is brought into contact with the bottom of the housing part and by applying a laser beam to the outside of the bottom of the housing part with the floor welded. In this case, the electrode coil with the protruding first edge region of the first metal foil is pressed, in particular, onto the bottom of the housing part.

The first electrode can in particular be the cathode. The metal foil that is used to contact the first electrode is preferably made of aluminum or an aluminum alloy. This can be advantageously welded to the housing part, especially if the housing part and in particular the bottom of the housing part is also made of aluminum or an aluminum alloy. It is particularly advantageous if the floor is made of the same material as the metal foil.

The housing part can in particular be deep-drawn. It has been shown that deep drawing, which is preferably carried out in several stages, ensures sufficient dimensional stability of the floor can be achieved in order to carry out the welding in a reproducible manner.

It has surprisingly been shown that a reliable weld between the metal foil and the floor can be achieved in this way.

The accumulator is preferably a lithium-ion battery. Lithium-ion batteries enable the storage of comparatively large amounts of energy with low weight and space requirements. The method according to the invention therefore offers high added value, particularly in the production of these accumulators.

The accumulator preferably has an, at least essentially, cylindrical geometry. An at least essentially cylindrical geometry is to be understood in particular as a geometry in which the main dimensions of the accumulator form a cylindrical geometry. Individual elements of the accumulator, for example the poles, can have a design that deviates from a strict cylindrical shape. Accumulators with cylindrical geometry are already standardized as a design, which is why the accumulators can be easily replaced on a regular basis.

Due to the spiral winding, the accumulator takes on an, at least essentially, circular cylindrical shape. The axis of the spiral winding preferably corresponds to the central axis of the cylinder. The axis here is to be understood in particular as the linear center of the spiral winding. A physical axis in the sense of a corresponding component can be present, but is not absolutely necessary.

The method can provide that in order to contact a second electrode of the accumulator, a second metal foil is welded to a contact element for contacting the second electrode. Here, the contact element is oriented in particular flat and at right angles to the axis of the electrode coil.

It is advantageous if the metal foil, in particular the area of the metal foil to be connected to the base and/or the contact element, is in the direction of the other flat or layered components of the accumulator, such as the cathode, the anode or another metal foil Bottom and / or the contact element, preferably in the direction of the axis of the electrode winding, protrudes. It is advantageous here if the metal foil protrudes by at least 1 mm, preferably at least 2 mm, and/or at most 8 mm, preferably at most 6 mm, relative to the other layered components of the battery. This protruding area of the metal foil makes it possible to contact the metal foil using the method according to the invention, whereby the risk of impairing and/or damaging other layered components of the accumulator as a result of the welding is excluded or at least reduced.

It is advantageous if an area of the metal foil is bent over. The area of the metal foil can expediently be bent over before and/or during the winding of the metal foil. A variety of bending processes can be used, preferably a flanging process. The welding of the metal foil to the base and/or the contact element then preferably takes place in the area of the bend created. This increases the contact surface of the metal foil on the floor and/or on the contact element, which has a positive effect on the welding. The bend can be, for example, a bend of 180°. However, other configurations of the bend are also conceivable, in particular multiple bending can also take place. In this context, it is understood that the edge area that is connected to the contact element is, in case of doubt, not to be understood as the edge area of the original metal foil before the bending, but rather the part of the metal foil which, after the metal foil has been bent, is through the Bending creates a new edge of the metal foil.

The thickness of the flat contact element is preferably at least 0.05 mm, particularly preferably at least 0.15 mm, and/or preferably at most 1.5 mm, particularly preferably at most 0.6 mm.

It is advantageous if the first and/or second metal foil is welded to a projecting region of the inside of the base and/or the first surface of the contact element. Such a projecting area on the base and/or the contact element makes it possible to produce a defined local contact between the metal foil and the base and/or the contact element on which the welding takes place. The base and/or the contact element preferably has a recessed area on its surface opposite the projecting area. This is preferably designed to be complementary to the projecting area in terms of its shape. The projecting area and the recessed area can expediently be designed together as a bead in the base and/or the contact element. This This design has the advantage that it can be manufactured in a simple manner and means that the thickness of the base and/or the contact element in the affected area remains at least approximately constant.

The projecting area on the inside of the base is created in particular during deep drawing and/or after deep drawing. For example, a corresponding area can be impressed into the ground during deep drawing and/or after deep drawing. This can be done in particular by forming, in particular embossing, a depression on the outside of the base, which then forms a corresponding projection on the inside of the base. By means of the projecting areas, unevenness in the floor that results from the deep-drawing process can be compensated for, thereby ensuring contact.

The projecting region preferably jumps by at least 0.3 mm, particularly preferably by at least 0.5 mm, and/or preferably by at most 2 mm, particularly preferably by at most 1.5 mm, relative to the surrounding inside of the base and/or the first Surface of the contact element.

The projecting area or the bead is preferably designed in a linear manner and has a width of preferably at least 0.5 mm, particularly preferably at least 1 mm, and/or preferably at most 5 mm, particularly preferably at most 3 mm. In this case, in the plane in which the metal foil comes into contact with the projecting area, the projecting area preferably intersects with the metal foil. When the battery is folded and/or wound up, there are a number of individual points of contact between the edge region of the metal foil and the base and/or the contact element, which leads to reliable welding at these points.

The metal foil preferably has a thickness of at least 0.001 mm, particularly preferably at least 0.005 mm, and/or preferably at most 0.02 mm, particularly preferably at most 0.012 mm.

It is advantageous if a pole element is connected, in particular welded, to the contact element to form the pole of the accumulator. In this way, the geometry of the contact element, which is preferably flat or platelet-shaped, can be designed independently of the shape of the pole. This is particularly advantageous because the shape of the pole is subject to restrictions which regularly depend on the intended use of the battery produced and/or technical standards.

The connection of the pole element to the contact element can be carried out, for example, by an overlap weld or a fillet weld.

Advantageously, the connection of the pole element to the contact element can be carried out using the same laser as the welding of the metal foil to the contact element. This makes it possible, for example, to carry out the welding of the metal foil to the contact element and the welding of the pole element to the contact element in the same device, which simplifies the production of the accumulator.

The pole element can, for example, have a thread to form the pole of the accumulator. With such a thread, the accumulator can be reliably electrically connected to the device supplied by the accumulator.

It is advantageous if the pole element has a sealing surface. The sealing surface serves in particular to connect the pole element to the housing of the battery. In this way, a sealed and preferably electrically insulated accumulator can be created, with the pole element remaining accessible for the purpose of electrically contacting the accumulator. The electrical insulation of the accumulator can be arranged between the housing part and a cover of the housing and/or the pole element and a cover of the housing.

The pole element preferably covers - at least partially - weld seams for connecting the metal foil to the contact element. Such a design of the accumulator can be produced in particular by first welding the metal foil to the contact element and then welding the contact element to the pole element. In this way, the pole element and in particular the sealing surface of the pole element can be arranged in an area on the second surface of the contact element, which is also used for welding the contact element to the metal foil.

It is advantageous if the pole element is pressed against the contact element when welding to the contact element. It has been shown that in this way the formation of gaps that can occur between the pole element and the contact element can be effectively prevented.

The laser is preferably a fiber laser. Fiber lasers, also known as fibers, use the doped core of an optical fiber as the active medium. The advantage of fiber lasers is that high amplification is possible due to the large length of the laser-active fiber.

The laser is preferably operated continuously, i.e. as a continuous wave laser. In particular, the laser beam is not pulsed during this operation. It has been shown that particularly good welding results can be achieved with continuous operation of the laser.

Preferably, the average power, in particular the constant power, of the laser in continuous operation of the laser when welding the metal foil to the base and/or the contact element is at least 100 W, particularly preferably at least 200 W and/or at most 700 W, particularly preferably at most 500 W With these services, particularly good results were achieved in terms of welding.

If the pole element is also welded to the contact element with the laser, it makes sense to increase the laser power for this purpose. When welding the pole element to the contact element, the average power, in particular the constant power of the laser in continuous operation, is preferably at least 500 W, particularly preferably at least 700 W, and/or preferably at most 1500 W, particularly preferably at most 1000 W.

The wavelength of the laser is preferably 1070 nm. Good results can be achieved with a laser of this wavelength, and lasers of this wavelength are also commercially available.

A single-mode laser is preferably used. With these lasers, only waves of a single desired mode are amplified, while other modes are suppressed. Ideally, such lasers only have a single, narrow spectral line. As a result, the laser beam achieves a high optical quality, which has a particular impact on its good focusability.

The laser is preferably focused using focusing optics. Such focusing optics enable the laser beam to be focused. It has been shown that for the method according to the invention, focusing optics with a focal length of at least 10 mm, preferably at least 100 mm and/or at most 5000 mm, preferably at most 500 mm, lead to particularly good results. This applies both to the welding of the metal foil to the base and/or the contact element, as well as to the welding of the contact element to the pole element.

The laser beam used preferably has a focus diameter of at least 1 µm, preferably at least 10 µm and/or at most 500 µm, preferably at most 50 µm. It has been shown that particularly good welding of the metal foil to the contact element can be achieved with these focus diameters. This applies both to the welding of the metal foil to the base and/or the contact element, as well as to the welding of the contact element to the pole element.

Preferably, the point of impact of the laser on the ground and/or the contact element, which is preferably the focus of the laser beam, is moved along a movement path which results from the superimposition of a feed movement and an oscillating movement. When welding the contact element to the pole element, this may apply to the point of impact of the laser beam on the pole element.

The feed movement is the movement with which the point of impact of the laser follows the course of the weld seam to be produced. The speed at which the point of impact moves along the weld seam on the surface of the ground and/or the contact element or possibly the pole element is referred to in this context as the feed speed. The feed speed is preferably at least 10 mm/s, preferably at least 70 mm/s, and/or at most 200 mm/s, preferably at most 150 mm/s. It has been shown that these feed speeds enable the weld seams to be produced comparatively quickly and at the same time to be of high quality. It is understood that - in the case of superimposition of the feed movement with an oscillating movement - not the absolute speed of the resulting movement in the feed direction, but rather an average movement speed in the feed direction is to be viewed as the feed speed.

The oscillating movement, which is preferably superimposed by the feed movement, preferably has a frequency of at least 100 Hz, preferably at least 500 Hz and/or at most 5000 Hz, preferably at most 1500 Hz. The amplitude of the oscillating movement is preferably at least 0.02 mm, preferably at least 0.1 mm, and/or at most 0.5 mm, preferably at most 1 mm. It has been shown that local power modulation rea can be lized, which enables particularly good melt pool control.

It can preferably be a circular oscillating movement. In this case, the radius of the circle described by the oscillating movement corresponds to the amplitude with respect to the values given above. In the case of complex oscillating movements, such as an elliptical oscillating movement, an average amplitude is to be regarded as the amplitude.

The method can in particular provide that the power of the laser beam is varied during the welding of the metal foil to the ground and/or the contact element. In particular, the power of the laser beam can be increased at the beginning of the production of a weld seam and/or reduced at the end of the production of a weld seam. The power can be increased and/or decreased continuously, for example in the form of a ramp. It has been shown that in particular the formation of holes in the base and/or in the contact element during welding can be avoided.

• 1 zeigt eine schematische perspektivische Darstellung eines Elektrodenwickels eines beispielhaften, mit dem erfindungsgemäßen Verfahren hergestellten Akkumulators.
• 2 zeigt eine schematische Darstellung eines beispielhaften Kontaktelements in einer Draufsicht.
• 3 zeigt eine Detaildarstellung einer beispielhaften erfindungsgemäßen Verschweißung der Metallfolie mit dem Kontaktelement.
• 4 zeigt eine schematische Darstellung einer beispielhaften Bewegungsbahn des Lasers beim Verschweißen.
• 5 zeigt eine Seitenansicht eines beispielhaften Polelements.
• 6 zeigt das Polelement in eine Schnittdarstellung.
• 7 zeigt das Polelement in einer Draufsicht.
• 8 zeigt das Polelement in einer perspektivischen Darstellung,
• 9 zeigt eine Schnittdarstellung eines Beispielhaften Akkumulators,
• 10 eine Draufsicht auf den Boden des Akkumulators aus 9.

The invention is explained below using the 1 until 8th and explained schematically in more detail using exemplary embodiments.

• 1 shows a schematic perspective view of an electrode coil of an exemplary battery produced using the method according to the invention.
• 2 shows a schematic representation of an exemplary contact element in a top view.
• 3 shows a detailed representation of an exemplary welding according to the invention of the metal foil with the contact element.
• 4 shows a schematic representation of an exemplary trajectory of the laser during welding.
• 5 shows a side view of an exemplary pole element.
• 6 shows the pole element in a sectional view.
• 7 shows the pole element in a top view.
• 8th shows the pole element in a perspective view,
• 9 shows a sectional view of an exemplary accumulator,
• 10 a top view of the bottom of the accumulator 9 .

The exemplary battery advantageously has a contact element 2, which is welded to a metal foil 3 of an electrode coil 1. To produce the in 1 Electrode winding 1 shown, an edge region of the metal foil 3 is brought into contact with a first surface 4 of the contact element 2. By applying a laser beam 6 to a second surface 5 of the contact element 2 facing away from the first surface 4 of the contact element 2, the contact element 2 is welded to the metal foil 3.

In the example shown, the metal foil 3 is wound together with other flat components of the accumulator, in particular the electrodes, to form a spiral winding. This results in a circular cylindrical structure of the electrode coil 1. In the example shown, the metal foil 3 is arranged at right angles to the first surface 4 of the contact element 2.

According to an advantageous embodiment, the contact element 2 in the example shown has an opening 7, preferably a plurality of openings 7.

As in 3 is shown, the first surface 4 of the contact element 2 in the example shown has a plurality of projecting areas 8. The projecting areas 8 are advantageously designed as beads 9. The metal foil 2 and the projecting areas 8 are advantageously oriented towards one another in such a way that they cross each other.

In the example shown, the contact element 2 has a thickness of 0.3 mm. The projecting areas 8 protrude by 0.4 mm compared to the first surface.

In the example shown, the metal foil 3 has a bent area 10. The metal foil 2 lies in the area of the bend 11 on the projecting area 9 of the first surface 4 of the contact element 2. The thickness of the metal foil 3 is preferably 0.01 mm.

For better clarity, the 3 corresponding cutting line 12 in 2 shown schematically.

Preferably, the metal foil 3 and the contact element 2 are each welded using a single-mode fiber laser with a wavelength of 1070 nm. This results in the in 4 Schematically shown movement band 13 of the laser beam from the superposition of a feed movement 14 and a circular oscillating movement 15.

Advantageously, the laser can also be used as part of the method according to the invention to weld a pole element 17 to the contact element 2. In the example shown, the pole element 17 has a sealing surface 18. It serves to provide a pole of the accumulator 1, which in the example shown expediently has a thread 19. As can be seen in particular from the comparison of 1 and the 2 results, the pole element 17 with its sealing surface 18 partially covers the beads 9, along which the weld seams between the contact element 2 and the metal foil 3 are carried out.

The pole element 17 can be welded on, for example, in the area of a connection area 20 of the pole element. In the example shown, the connection area 20 surrounds the sealing surface 18.

To weld the pole element 17 to the contact element 2, the laser power is expediently increased to, for example, 800 W. The focal length of the focusing optics used is 330 mm in the exemplary embodiment. The feed movement 14 of the laser beam is also superimposed by an oscillating movement 15 during the exemplary welding of the pole element. The frequency of the circular oscillating movement is, for example, 800 Hz and the amplitude is 0.2 mm. The feed speed can be, for example, 100 mm/s. In the example shown, the pole element 17 advantageously consists of the same material as the contact element 2, preferably copper.

The unit produced in this way consisting of the electrode winding 1 and the contact element 2 with the welded-on pole element 17 can now be introduced into a cup-shaped housing part 21. The first edge region of the first metal foil 3 of the first electrode is brought into contact with the bottom 22 of the housing part 21. By applying a laser beam to the outside of the bottom 22 of the housing part 21, the first edge region of the first metal foil 3 is welded to the bottom 22.

Here, the floor 22 can be in the example 9 and 10 shown have beads 9 on its outside, which form corresponding projections 8 on the inside of the base. The weld seams 23 preferably run in the beads 9 or on the projections 8.

List of reference symbols:

1

Electrode wrap

2

Contact element

3

metal foil

4

first surface

5

second area

6

laser beam

7

opening

8th

protruding area

9

Beading

10

bent area

11

Area of bend

12

cutting line

13

trajectory

14

feed movement

15

oscillating movement

16

amplitude

17

Pole element

18

sealing surface

19

thread

20

Connection area

21

Cup-shaped housing part

22

Floor

23

Weld

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102017006229 A1 [0004]

Claims (15)

Method for producing an accumulator, wherein the metal foils (3), which contact the electrodes of the accumulator, are wound together with the electrodes of the accumulator to form an, at least essentially, circular cylindrical electrode coil (1) that on one of the two opposite end faces of the electrode winding (1) a first edge region of a first metal foil (3) protrudes for contacting a first electrode relative to the other layer-shaped components of the electrode winding (1), characterized in that the electrode winding (1) is inserted into a cup-shaped housing part (21) and is used Contacting the first electrode of the accumulator, the first edge region of the first metal foil (3) of the first electrode is brought into contact with the bottom (22) of the housing part (21) and by applying a laser beam to the outside of the bottom (22 of the housing part (21). is welded to the base (22). Procedure according to Claim 1 , characterized in that the first electrode is the cathode. Procedure according to Claim 1 or 2 , characterized in that the housing part (21) is made of aluminum or an aluminum alloy. Method according to one of the preceding claims, characterized in that the housing part (21) is deep-drawn. Method according to one of the preceding claims, characterized in that in order to contact a second electrode of the accumulator, a second metal foil (3) is welded to a contact element (2) for contacting the second electrode. Procedure according to Claim 5 , characterized in that a second edge region of the second metal foil (3) for contacting the second electrode protrudes relative to the other layer-shaped components of the electrode coil (1) and with a first surface (4) of the contact element (2) oriented at right angles to the second metal foil (3). ) is brought into contact and welded to the contact element (2) by applying a laser beam (6) to a second surface (5) of the contact element (2) facing away from the first surface (4) of the contact element (2). Procedure according to Claim 1 or 2 , characterized in that a region (10) of the first or second metal foil (3), preferably before winding, is bent over, in particular bent through 180 °, the first metal foil (3) being in the area of the bend (11) with the Base (22) or the second metal foil (3) is welded to the contact element (2) in the area of the bend (11). Method according to one of the preceding claims, characterized in that the first edge region and/or the second edge region is at least 1 mm, preferably at least 3 mm, and/or at most 8 mm, preferably at most 6 mm, compared to other layer-shaped components of the electrode coil (1). presides. Method according to one of the preceding claims, characterized in that the first metal foil (3) is welded to a projecting region (8) of the base (22), the projecting region (8) preferably being formed by a bead (9), in particular wherein the metal foil (3) intersects with the projecting area (8). Method according to one of the preceding claims, characterized in that the second metal foil (3) is welded to a projecting region (8) of the first surface (4) of the contact element (2), the projecting region (8) preferably being protected by a bead ( 9) is formed, in particular wherein the metal foil (3) intersects with the projecting region (8). Procedure according to one of the Claims 9 or 10 , characterized in that the projecting area (8) is at least 0.3 mm, in particular by at least 0.5 mm, and / or by a maximum of 2 mm, in particular by a maximum of 1.5 mm, compared to the surrounding inside of the base (22 ) and/or the first surface (4) of the contact element (2). Procedure according to one of the Claims 9 until 11 , characterized in that the projecting area (8) and/or the bead (9) is linear and has a width of at least 0.5 mm, in particular at least 1 mm, and/or at most 5 mm, in particular at most 3 mm. Method according to one of the preceding claims, characterized in that a pole element (17), preferably designed as a contact bolt, is welded to the contact element (2), in particular wherein the welding of the contact element (2) to the pole element (17) and the welding of the Metal foil (3) with the contact element takes place with the same laser (6). Procedure according to one of the Claims 5 until 13 , characterized in that the welding of the second metal foil (3) to the contact element (2) and in particular the welding of the pole element (17) to the contact element (2) takes place before the electrode winding (1) is introduced into the housing part. Method according to one of the preceding claims, characterized in that the power of the laser beam is varied during the welding of the metal foil (3) to the base (22) and/or the contact element (2), in particular wherein the power of the laser beam at the beginning of Production of a weld seam is increased and / or lowered at the end of production of a weld seam.

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