DE102017216131A1 - Method for producing an electrode stack for a battery cell and battery cell - Google Patents

Abstract

The invention relates to a method for producing an electrode stack for a battery cell, comprising the following steps: providing a band-shaped first separator element (16); Providing a plurality of plate-shaped electrode segments (56); Producing a band-shaped composite element (50) by depositing the electrode segments (55) on the first separator element (16); Applying at least one adhesive film (131) to the first separator element (16) of the composite element (50), wherein a height (H) of the adhesive film (131) is greater than a thickness (S) of the electrode segments (56); Applying a band-shaped second separator element to the composite element (50) such that the electrode segments (56) are at least largely enclosed between the two separator elements (16) and that the height (H) of the adhesive film (131) is reduced. The invention also relates to a battery cell comprising at least one electrode stack, which is produced by the process according to the invention.

Description

The invention relates to a method for producing an electrode stack for a battery cell from plate-shaped electrode segments and stacking of the segments. The invention also relates to a battery cell having an electrode stack, which is produced by the method according to the invention.

State of the art

Electrical energy can be stored by means of batteries. Batteries convert chemical reaction energy into electrical energy. Here, a distinction is made between primary batteries and secondary batteries. Primary batteries are only functional once, while secondary batteries, also referred to as accumulators, are rechargeable. In particular, so-called lithium-ion battery cells are used in an accumulator. These are characterized among other things by high energy densities, thermal stability and extremely low self-discharge.

Lithium-ion battery cells have a positive electrode, also referred to as a cathode, and a negative electrode, also referred to as an anode. The cathode and the anode each comprise a current conductor, on which an active material is applied. The electrodes of the battery cell are formed like a foil and stacked, for example, to form an electrode stack with the interposition of a separator which separates the anode from the cathode. The electrodes can also be wound into an electrode winding or in some other way form an electrode unit.

The two electrodes of the electrode unit are electrically connected to poles of the battery cell, which are also referred to as terminals. The electrodes and separator are surrounded by a generally liquid electrolyte. The battery cell further comprises a cell housing, which is made of aluminum, for example. The cell housing is usually prismatic, in particular cuboid, designed and pressure-resistant. But other forms of housing, such as circular cylindrical, or flexible pouch cells are known.

An essential goal in the development of new battery cells is to increase the electrochemical useful volume in the cell. The electrode stack has proven to be the most suitable design of an electrode unit for maximizing the useful volume, since it can be produced both prismatically and in any other geometry.

From the DE 10 2015 202 894 A1 For example, a battery cell is known which has an electrode stack with an anode and a cathode. The anode and the cathode in this case comprise a plurality of plate-shaped segments, which are stacked with the interposition of plate-shaped separators to the electrode stack one above the other.

From the JP 2015-197977 A For example, a method for connecting a separator and an electrode is known. The separator comprises a layer of polypropylene and a layer of ceramic, ie of a heat-resistant material.

From the DE 10 2009 013 345 A1 For example, an electrode stack for a galvanic cell is known. The electrode stack comprises plate-shaped cathodes, anodes and separators, which are connected to one another by means of adhesive.

The DE 10 2006 054 308 A1 discloses an electrode assembly for a battery. The electrode arrangement comprises a flat first electrode element, a flat second electrode element and a flat separator element. The electrode elements are connected by means of adhesive to the separator.

Disclosure of the invention

A method for producing an electrode stack for a battery cell is proposed. The method comprises at least the steps listed below.

First, a band-shaped first separator element is provided. In the present case, the first separator element is flat and band-shaped. In this context, this means that an expansion of the first separator element in a longitudinal direction is much greater, in particular at least ten times greater, than an extension of the first separator element in a transverse direction, which is oriented at right angles to the longitudinal direction.

Furthermore, a plurality of plate-shaped electrode segments are provided. The electrode segments are flat and plate-shaped. In this context, this means that an extension of the electrode segments in the longitudinal direction is approximately the same size, in particular at least half as large and at most twice as large, as an extension of the said segments in the transverse direction.

The electrode segments can be, for example, anode segments which comprise an anodic current conductor to which an anodic active material is applied. Likewise, it can be at the electrode segments to be cathode segments, which comprise a cathodic current collector, on which a cathodic active material is applied.

By depositing the plate-shaped electrode segments on the band-shaped first separator element, a band-shaped composite element is then produced.

Subsequently, at least one adhesive film is applied to the first separator element of the composite element. In this case, a height of the adhesive film is greater than a thickness of the electrode segments. The height of the adhesive film is an extension of the adhesive film in a stacking direction which is oriented perpendicular to the longitudinal direction and perpendicular to the transverse direction. The thickness of the electrode segments is an extension of the electrode segments in the stacking direction.

Thereafter, a band-shaped second separator is applied to the composite element such that the electrode segments are at least largely enclosed between the two separator elements. In particular, the electrode segments are arranged between the two separator elements such that only contact lugs of the electrode segments protrude outward between the separator elements. In this case, the second separator element is applied to the composite element in such a way that the second separator element compresses the adhesive film in the stacking direction, as a result of which the height of the adhesive film is reduced.

In this case, the second separator element is preferably applied to the composite element such that the height of the adhesive film is reduced by the compression at least approximately to the thickness of the electrode segments. The height of the adhesive film thus corresponds to the thickness of the electrode segments and the two separator elements are evenly spaced from each other.

According to an advantageous embodiment of the invention, the second separator is pressed by means of a cylindrical roller on the composite element.

Preferably, the band-shaped composite element is moved by a transport device in a transport direction, while the second separator is applied to the composite element. Preferably, the roller rotates about a roller axis which extends in the transverse direction. The transverse direction is oriented at right angles to the transport direction. The transport direction is parallel to the longitudinal direction.

According to a preferred embodiment of the invention, the at least one adhesive film is applied to the first separator such that a first distance from a center of the adhesive film to the nearest electrode segment is smaller than a second distance from the center of the adhesive film to a longitudinal edge of the first separator. The longitudinal edge extends in the longitudinal direction and the distances extend in the transverse direction.

According to an advantageous development of the invention, the at least one adhesive film is precured, in particular by UV radiation, before the second separator element is applied to the composite element. By UV radiation is meant electromagnetic radiation in the ultraviolet range.

According to a further advantageous development of the invention, the at least one adhesive film is cured, in particular by UV radiation, while the second separator element is applied to the composite element.

According to yet another advantageous development of the invention, the at least one adhesive film is hardened, in particular by UV radiation, after the second separator element has been applied to the composite element.

The ribbon-shaped second separator element and the composite element are preferably cut between the electrode segments, preferably in the transverse direction. Then plate-shaped stack segments are produced by applying further plate-shaped electrode segments. If the composite element has anode segments, cathode segments are now applied. If the composite element has cathode segments, anode segments are now applied.

Each stack segment thus comprises an anode segment, a cathode segment and two separator segments. The stack segments are then stacked to the electrode stack.

It is also proposed a battery cell comprising at least one electrode stack, which is produced by the process according to the invention.

A battery cell according to the invention advantageously finds use in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or in a consumer electronics product. Consumer electronics products are in particular mobile phones, tablet PCs or notebooks.

Advantages of the invention

The inventive method allows a reduction of the required process time when stacking the electrodes and the separator to the electrode stack. Advantageously, the two separator elements are at least approximately flat and not bent after application of the second separator element to the composite element. This avoids the risk of damaging the separator elements, in particular at the corners of the electrode segments. Furthermore, the stack segments are designed to be homogeneous and with uniform thickness, and cavities are avoided in the electrode stack. The arrangement of the adhesive film closer to the electrode segment than to the longitudinal edge of the separator element prevents adhesive from exiting laterally between the two separator elements when the adhesive film is compressed.

list of figures

Embodiments of the invention will be explained in more detail with reference to the drawings and the description below.

• 1 eine schematische Darstellung einer Batteriezelle,
• 2 eine schematische Darstellung einer Anlage zur Herstellung von Elektrodenstapeln für Batteriezellen,
• 3 eine Draufsicht auf ein bandförmiges Verbundelement während ein Klebefilm aufgebracht wird,
• 4 einen Schnitt durch das Verbundelement mit Klebefilm entlang der Schnittlinie A - A in 3,
• 5 das Verbundelement mit Klebefilm nach 4, während ein zweites Separatorelement aufgebracht wird,
• 6 das Verbundelement mit Klebefilm nach 4, nachdem ein zweites Separatorelement aufgebracht wurde, und
• 7 eine schematische Darstellung eines aus mehreren Stapelsegmenten gebildeten Elektrodenstapels.

Show it:

• 1 a schematic representation of a battery cell,
• 2 a schematic representation of a plant for the production of electrode stacks for battery cells,
• 3 a plan view of a band-shaped composite element while an adhesive film is applied,
• 4 a section through the composite element with adhesive film along the cutting line A - A in 3 .
• 5 the composite element with adhesive film after 4 while applying a second separator element,
• 6 the composite element with adhesive film after 4 after a second separator element has been applied, and
• 7 a schematic representation of an electrode stack formed from a plurality of stack segments.

Embodiments of the invention

In the following description of the embodiments of the invention, the same or similar elements are denoted by the same reference numerals, wherein a repeated description of these elements is dispensed with in individual cases. The figures illustrate the subject matter of the invention only schematically.

1 shows a schematic representation of a battery cell 2 , The battery cell 2 includes a housing 3 , which is prismatic, in the present cuboid, is formed. The housing 3 In the present case, it is designed to be electrically conductive and, for example, made of aluminum. The housing 3 can also be designed in the form of a flexible pouch film.

The battery cell 2 includes a negative terminal 11 and a positive terminal 12 , About the terminals 11 . 12 can one from the battery cell 2 provided voltage can be tapped. Furthermore, the battery cell 2 over the terminals 11 . 12 also be loaded.

Inside the case 3 the battery cell 2 an electrode unit is arranged, which in the present case as an electrode stack 10 is executed. The electrode stack 10 has two electrodes, namely an anode 21 and a cathode 22 , on. The anode 21 and the cathode 22 are each carried out like a foil and by a separator 18 separated from each other. The separator 18 is ionic conductive, so permeable to lithium ions.

The anode 21 includes an anodic active material 41 and an anodic current collector 31 , The anodic current conductor 31 is made electrically conductive and made of a metal, such as copper. The anodic current conductor 31 is electric with the negative terminal 11 the battery cell 2 connected.

The cathode 22 comprises a cathodic active material 42 and a cathodic current collector 32 , The cathodic current conductor 32 is made electrically conductive and made of a metal, such as aluminum. The cathodic current conductor 32 is electric with the positive terminal 12 the battery cell 2 connected.

2 shows a schematic representation of a plant 60 for the production of electrode stacks 10 for battery cells 2 , From a first separator roll 71 becomes a belt-shaped first separator element 16 a transport device 110 fed. At the transport device 110 it may be a circulating belt or a linear mover system or the like. On the transport device 110 becomes the first separator element 16 in a transport direction 64 transported.

From a cathode roll 62 the supply of a ribbon-shaped cathode element takes place 46 , The supply of the ribbon-shaped cathode element 46 takes place via a plurality of pulleys, not shown here, to one in a conveying direction 68 circulating conveyor unit 100 , The conveyor unit 100 is with a drive 90 provided, which comprises an encoder and a drive control.

The conveyor unit 100 is a laser 96 or associated with another, in particular knife-like cutting device. By the laser 96 or the cutting device is cut through the band-shaped cathode element 46 , whereby plate-shaped cathode segments 56 be generated. The cathode segments 56 are cut in particular in a transverse direction y, which is perpendicular to the conveying direction 68 runs and in this case is oriented perpendicular to the plane of the drawing. In addition, contour cuts are made to contact lugs 36 the cathode 22 at the cathode segments 56 to create.

The cathode segments 56 be at the conveyor unit 100 For example, fixed by means of a vacuum before the cathode segments 56 on the first separator element 16 on the transport device 110 be filed. This creates a band-like composite element 50 , wherein between the individual cathode segments 56 in the transport direction 64 Gaps 51 be generated. The cathode segments 56 are then in the transport direction 64 regularly spaced from each other on the first separator 16 arranged. Thus, adjacent cathode segments 56 in the composite element 50 through corresponding gaps 51 separated from each other. The composite element 50 is doing by the transport device 110 further in the transport direction 64 transported.

In the transport device 110 a vacuum is generated by means of which the cathode segments 56 through the first separator element 16 be sucked through. So are the cathode segments 56 on the first separator element 16 additionally held.

On the composite element 50 become adhesive films 131 . 132 . 133 applied. Thereafter, the supply of a band-shaped second separator takes place 17 from a second separator roll 72 , This will be on the composite element 50 on the transport device 110 transferred and by means of a roller 119 on the composite element 50 pressed. The band-shaped first separator element 16 and the regularly spaced cathode segments 56 are thus of the second separator 17 covered. Here are the cathode segments 56 largely between the first separator 16 and the second separator element 17 locked in.

Subsequently, within a transfer area 74 the transfer of the composite element 50 with the second separator element 17 to a linear movers system 76 , The linear movers system 76 For example, includes individual acted upon with negative pressure slide, wherein 2 shows that the linear mover system 76 arranged on the underside of individual discrete stacking devices 78 assigned.

After passage of the transfer area 74 is preferably carried out by means of a laser 96 a laser cut 80 the to the linear mover system 76 given arrangement of composite element 50 and second separator element 17 , The result is three-ply stack, which two Separatorsegmente 53 and an intermediate cathode segment 56 include. These three-layered stacks are laterally gripped or vacuum on each separate vacuum-loadable carriage of the linear mover system 76 fixed.

Out 2 it turns out that the linear mover system 76 a powered wheel 92 assigned. This is done with a band-shaped anode element 45 from an anode roll 61 which is on the wheel 92 preferably by a laser 96 to anode segments 55 is cut. The of the band-shaped anode element 45 separated anode segments 55 be within a vacuum range 86 on the driven wheel 92 fixed and to those of the individual carriages of the linear mover system 76 transported three-layered stack of two Separatorsegmenten 53 as well as intervening cathode segment 56 applied.

So obtained, for example, grippers of the linear mover system 76 fixed, four-ply stack segments 58 be in a run-out area of the linear mover system 76 turned by 180 ° and on the individual stacking devices 78 stored. The stack segments 58 are plate-shaped and comprise two separator segments 53 , an anode segment 55 and a cathode segment 56 ,

For completeness, it should be mentioned that the driven wheel 92 , which is above the linear mover system 76 is arranged next to the vacuum area 86 also a blow-off area 88 having. On the bike 92 the laser cut of the anode element takes place 45 preferably by means of the laser 96 , Alternative to the laser 96 also a knife-like cutting device can be used to the plate-shaped anode segments 55 to create. The driven wheel 92 is with a drive 90 Mistake.

3 shows a plan view of a band-shaped composite element 50 while a first adhesive film 131 , a second adhesive film 132 and a third adhesive film 133 be applied. The plate-shaped cathode segments 56 lie in a longitudinal direction x which is perpendicular to the transverse direction y runs, spaced from each other on the band-shaped first separator element 16 , The cathode segments 56 are in the longitudinal direction x through the gaps 51 separated from each other. The longitudinal direction x runs parallel to the transport direction 64 into which the composite element 50 is transported.

The first separator element 16 has two longitudinal edges 125 on, which are parallel to each other in the longitudinal direction x run. The cathode segments 56 are approximately completely on the first separator 16 and are almost completely off the longitudinal edges 125 spaced. The cathode segments 56 have contact flags 36 the cathode 22 on which are in the transverse direction y extend. Only the contact flags 36 the cathode 22 protrude in the transverse direction y over one of the two longitudinal edges 125 of the first separator element 16 sideways out.

By means of a first nozzle, not shown, the first adhesive film 131 between one of the longitudinal edges 125 and one cathode segment each 56 on the first separator element 16 applied. By means of a second nozzle, not shown, the second adhesive film 132 between the other longitudinal edge 125 and the cathode segment 56 on the first separator element 16 applied. The second adhesive film 132 will be close to the longitudinal edge 125 applied over which the tabs 36 the cathode 22 stick out. By means of a third nozzle, not shown, the third adhesive film 133 between every two adjacent cathode segments 56 on the first separator element 16 applied.

The first adhesive film 131 and the second adhesive film 132 extend in the longitudinal direction x , The third adhesive film 133 extends in the transverse direction y , The adhesive films 131 . 132 . 133 are of the cathode segments 56 spaced. In particular, the second adhesive film 132 from the contact flags 36 the cathode 22 spaced.

4 shows a section through the composite element 50 with the first adhesive film 131 along the cutting line A - A in 3 , The first adhesive film 131 points in a stacking direction z a height H on. The cathode segment 56 points in the stacking direction z a strength S on. The said stacking direction z is perpendicular to the longitudinal direction x and perpendicular to the transverse direction y , The height H of the first adhesive film 131 is greater than the strength S of the cathode segment 56 ,

The first adhesive film 131 has an extension in the transverse direction y on. A central location of the first adhesive film 131 at which, for example, the geometric center of gravity of the cross section of the first adhesive film 131 is located below as the middle M of the first adhesive film 131 designated.

The first adhesive film 131 is so on the first separator 16 applied that a first distance D1 from the middle M of the first adhesive film 131 to the nearest cathode segment 56 less than a second distance D2 from the middle M of the first adhesive film 131 to the nearest longitudinal edge 125 of the first separator element 16 , The distances D1 . D2 extend in the transverse direction y ,

In the present case, the first adhesive film 131 through a UV radiation 135 from a UV lamp 136 precured before the second separator element 17 on the composite element 50 is applied.

5 shows the composite element 50 with the first adhesive film 131 to 4 while the second separator element 17 is applied. The second separator element 17 is by means of a cylindrical roller 119 on the composite element 50 pressed. The roller rotates 119 around a roll axis 117 in the transverse direction y runs.

The roller 119 applies a pressure in the stacking direction z to the second separator element 17 from what is indicated by corresponding arrows in the 5 becomes clear. In this case, the second separator element compresses 17 the first adhesive film 131 in the stacking direction z , causing the height H of the first adhesive film 131 is reduced.

In particular, the height H of the first adhesive film 131 thereby approximately on the strength S of the nearest cathode segment 56 reduced. The height H of the first adhesive film 131 thus corresponds to the application of the second separator 17 the strength S of the nearest cathode segment 56 , The first distance D1 from the middle M of the first adhesive film 131 to the nearest cathode segment 56 stays smaller than the second distance D2 from the middle M of the first adhesive film 131 to the nearest longitudinal edge 125 of the first separator element 16 ,

In the present case, the first adhesive film 131 through a UV radiation 135 from a UV lamp 136 hardened during the second separator 17 on the composite element 50 is applied.

6 shows the composite element 50 with the first adhesive film 131 to 4 after the second separator element 17 was applied. The first distance D1 from the middle M of the first adhesive film 131 to the nearest cathode segment 56 stays smaller than the second distance D2 from the middle M of the adhesive film 131 to the nearest longitudinal edge 125 of the first separator element 16 ,

In the present case, the first adhesive film 131 through a UV radiation 135 from a UV lamp 136 hardened after the second separator element 17 on the composite element 50 was applied. In particular, the UV lamp 136 arranged such that the UV radiation 135 the second separator element 17 penetrates.

7 shows a schematic representation of one of several stack segments 58 formed electrode stack 10 , The stack segments 58 are doing in the stacking direction z to the electrode stack 10 stacked. Each stack segment 58 has, as already mentioned, an anode segment 55 , a cathode segment 56 and two separator segments 53 on. One of the separator segments 53 between the cathode segment 56 and the anode segment 55 arranged, wherein present the cathode segment 56 between the two separator segments 53 is arranged.

The anode segments 55 together form the anode 21 of the electrode stack 10 , The cathode segments 56 together form the cathode 22 of the electrode stack 10 , The separator segments 53 together form the separator 18 of the electrode stack 10 , The contact flags, not shown here 35 the anode 21 are welded together and electrically connected to the negative terminal 11 the battery cell 2 connected. The contact flags, not shown here 36 the cathode 22 are also welded together and electrically connected to the positive terminal 12 the battery cell 2 connected.

The invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of expert action.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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 102015202894 A1 [0006]
• JP 2015197977 A [0007]
• DE 102009013345 A1 [0008]
• DE 102006054308 A1 [0009]

Claims (11)

Method for producing an electrode stack (10) for a battery cell (2), comprising the following steps: - Providing a band-shaped first separator element (16); - Providing multiple plate-shaped electrode segments (55, 56); - Producing a band-shaped composite element (50) by depositing the electrode segments (55, 56) on the first separator element (16); - applying at least one adhesive film (131, 132, 133) to the first separator element (16) of the composite element (50), wherein a height (H) of the adhesive film (131, 132, 133) is greater than a thickness (S) of the electrode segments (55, 56); - Applying a band-shaped second separator element (17) on the composite element (50) such that the electrode segments (55, 56) at least substantially between the two separator elements (16, 17) are included, and that the height (H) of the adhesive film (131 , 132, 133) is reduced. Method according to Claim 1 in that the second separator element (17) is applied to the composite element (50) such that the height (H) of the adhesive film (131, 132, 133) is reduced at least approximately to the thickness (S) of the electrode segments (55, 56) , Method according to one of the preceding claims, wherein the second separator element (17) by means of a cylindrical roller (119) is pressed onto the composite element (50). Method according to Claim 3 in that the composite element (50) is moved by a transport device (110) in a transport direction (64) while the second separator element (17) is applied to the composite element (50), and wherein the roller (119) is mounted about a roller axis (117 ) which extends in a transverse direction (y) which is oriented at right angles to the transporting direction (64). Method according to one of the preceding claims, wherein the at least one adhesive film (131, 132, 133) is applied to the first separator element (16) such that a first distance (D1) from a center (M) of the adhesive film (131, 132, 133) to the electrode segment (55, 56) is smaller than a second distance (D2) from the center (M) of the adhesive film (131, 132, 133) to a longitudinal edge (125) of the first separator element (16). Method according to one of the preceding claims, wherein the at least one adhesive film (131, 132, 133) is precured, in particular by a UV radiation (135), before the second separator element (17) is applied to the composite element (50). Method according to one of the preceding claims, wherein the at least one adhesive film (131, 132, 133) is cured, in particular by a UV radiation (135), while the second separator element (17) is applied to the composite element (50). Method according to one of the preceding claims, wherein the at least one adhesive film (131, 132, 133) is cured, in particular by a UV radiation (135), after the second separator element (17) has been applied to the composite element (50). Method according to one of the preceding claims, wherein the band-shaped second separator element (17) and the composite element (50) are cut between the electrode segments (55, 56), plate-shaped stack segments (58) are produced by applying further plate-shaped electrode segments (55, 56) and the stack segments (58) are stacked to the electrode stack (10). Battery cell (2) comprising at least one electrode stack (10) produced by a method according to any one of the preceding claims. Use of a battery cell (2) after Claim 10 in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or in a consumer electronics product.

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