DE102019109501A1 - Battery cell pack - Google Patents

Abstract

A battery cell pack 20 comprises at least one contact 15 between individual battery cells 10, wherein pressure pulses are exerted on the contact 15 via a shell 30 which at least partially encloses the battery cell pack 20. About the pressure forces a mechanical contact contacts 16, 17 of the contact 15 is ensured.

Description

The present invention relates to a battery cell pack and a method of manufacturing the same.

In the manufacture of batteries, in particular for use in electric vehicles, individual (in particular rechargeable) battery cells are combined into battery cell packages. In this case, the task of a simple and while permanently secure contacting the battery cells to each other. A contacting is understood in the context of this document as at least two electrical conductors which are in electrical contact with each other. A known embodiment of battery cells is the so-called "pouch cell". In this cell type, the actual battery is in a kind of bag and on one or two sides electrical conductors are led out. These pages can be opposite each other. The conductors are often flat conductor tracks which, for example, can be soldered, welded or screwed to make contact and thus to form a battery cell packet.

In addition to use in an (electric) automobile, the invention also relates in particular to applications for bicycles, stationary energy storage or power tools or similar mobile or stationary applications in which electrical energy is to be stored. The object of the present invention is to enable a simple connection of individual battery cells, which permanently ensures safe electrical contact. This object is achieved by the means of the independent claims. Preferred developments are the subject of the dependent claims

In a battery cell package with at least one contact between individual battery cells of the battery cell packet and / or to connecting conductors are applied via an at least partially enveloping shell pressure forces on the contact. The pressure forces ensure a mechanical contact between contacts of the contact. The contacting preferably serves to allow the most resistance-free contact possible of two conductors. Conventional design measures have been taken to ensure contact using separate, dedicated components. However, it has been recognized that an envelope, which is usually necessary anyway, can generate forces that can permanently ensure mechanical and thus electrical contact between the contacts. The casing may, for example, be a plastic film which, for reasons of safety, has to be clamped around the battery cell packet against short circuits. In this case, it must have a certain minimum thickness of, for example, greater than 0.5 mm or greater than 1.0 mm. About this material thickness sufficiently high forces can be effected on the contact.

Alternatively or additionally, in a battery cell package with at least one contact between individual battery cells of the battery cell packet and / or connection leads via a battery cell package at least partially enveloping envelope pressure forces are exerted on the contact. In this case, neither form-fitting, non-positive nor cohesive joining means for ensuring the mechanical contact of preferably at least two contacts of the contacting are provided in the contacting on the pressure forces caused by the shell addition. As a positive joining means are understood in particular mechanical latching hooks, crimping, flanging, screwing or undercuts. As non-positive joining means in particular spring-elastic means such as spring contacts or an elastic tension of a holder or carrier of the contacts are understood. In particular, soldering, bonding or welding are understood as cohesive joining means. The above-mentioned means are merely illustrative and are means of construction. They differ from the present inventive embodiment, in which during assembly, the individual battery cells are aligned only with respect to their location, or are arranged side by side or one above the other and taken in this arrangement, no further measures to allow a current flow. Generally speaking, no connecting means is used, which serves exclusively for the purpose of contacting. Thus, the construction according to the invention is inexpensive and fast to implement. The casing, which is usually required anyway, causes forces (for example, by spring forces) directly or indirectly (for example, via a negative pressure) on the contacts to effect the contacting.

It is particularly advantageous if the enveloping envelope comprises or consists of a film. An air-tight or at least a liquid-tight seal around the battery cells of the battery cell packet is thereby preferably effected. A liquid-tight design is advantageous if liquid cooling is to be provided around the battery cell pack. An airtight seal is necessary in particular in the following use of a negative pressure to produce the contact.

It is also advantageous if in the contacting contacts of the battery cells and / or the connecting conductor are in a planar contact with each other. The contact surface should be at least 1 cm ² to ensure a secure contact even in poor positioning. Alternatively may be required that the contact surface is at least 10% of the area of the associated surface of the battery cell.

In particular, the sheath may be designed as a shrink film. Alternatively, one (or more) winding (s) with an elastic film (in particular stretch film) can be applied under longitudinal tension forces. In these ways permanently elastic tensioning forces can be effected.

Alternatively or additionally, the sheath may comprise a vacuum suction point. Also, the shell may be an airtight shell and within the shell there is a negative pressure relative to the environment. In these cases, a negative pressure within the battery cell packet can cause permanent forces to ensure the contacts.

Alternatively or additionally, a resilient element such as in particular a foam or a spring may also be provided within the envelope, in order to effect the pressure forces of the contacting effecting forces on the envelope. This is particularly advantageous if the elasticity of the sheath is considered not sufficiently high for the permanent maintenance of the pressure forces. Thus, the pressure forces are generated at least in addition to the additional resilient element.

It is also advantageous if individual battery cells of the battery cell package lie flat against each other and thereby define a contact surface. At least a portion of the contacting is at a distance of at least 35% from the edge of the contact surface spaced preferably at least 20%, with respect to the total length and / or width of the contact surface. Since battery cells, especially in the case of the pouch type, tend to become bumpy when they age, it is thus possible to ensure that the contacting takes place where the bumpiness occurs. Thus, the bulging deformation of the battery cells supports the formation of forces that support the contact (s).

In preferred embodiments, contacts are each led out on end sides of the battery cell and are bent in a U-shape. Such battery cells are usually manufactured in large numbers, are therefore readily available, so that these standard components are advantageously used.

In a corresponding method for producing a battery cell packet, a plurality of battery cells is positioned relative to each other so that electrical contacts of the battery cells are adjacent to one another. In this case, however, no constructive measures are taken to ensure a permanent electrical contact of the contacts and subsequently a shell is applied to the mutually aligned battery cells, so that over the shell pressure forces are effected on the battery cells and thereby the contacts in a mechanical and electrical contact held each other.

• 1 eine schematische Seitenansicht einer Batteriezelle,
• 2 eine Seitenansicht eines Batteriezellpakets als einem Stapel entsprechender Batteriezellen,
• 3 eine Batteriezelle gemäß einer alternativen Ausführungsform,
• 4 eine Seitenansicht einer veränderten Art der Bildung eines Batteriezellpakets,
• 5 eine alternative Ausführungsform des Batteriezellpakets mit einem elastischen Element,
• 6 eine schematische Draufsicht auf eine Batteriezelle und
• 7 ein schematisches Diagramm zur Erläuterung des Effekts der Dickenänderung einer Batteriezelle in Abhängigkeit des Ladezustands und der Alterung.

Hereinafter, preferred embodiments of the invention will be described by way of example with reference to the figures. Show it:

• 1 a schematic side view of a battery cell,
• 2 a side view of a battery cell pack as a stack of corresponding battery cells,
• 3 a battery cell according to an alternative embodiment,
• 4 a side view of a modified way of forming a battery cell packet,
• 5 an alternative embodiment of the battery cell packet with an elastic element,
• 6 a schematic plan view of a battery cell and
• 7 a schematic diagram for explaining the effect of the change in thickness of a battery cell as a function of the state of charge and aging.

1 shows a schematic side view of a battery cell 10 which is designed as a pouch cell. Pouch cells are pocket-shaped battery elements in which the individual layers of the battery are aligned in a "pocket" parallel to each other. For the contact lead two contacts 16 and 17 from the battery cell 10 out. In the side view of 1 they are only shown as a line. However, shows 6 a rotated view of the 1 is, from above, that the contacts are flat. These can be, for example, metal-coated flexible conductor tracks. The contacts 16 and 17 leave the body of the battery cell 10 on opposite sides, however, any other embodiments are the arrangement of the contacts 16 and 17 possible. The contacts 16 . 17 each have U-shaped bends, so that the free ends in parallel and, for example, above or below the body of the battery cell 10 lie. For better visibility is a distance from the contacts 16 and 17 to the body of the battery cell 10 shown, wherein in the concrete embodiments, due to the forces, which will be explained below, there is no corresponding distance. The same applies to the shown distances of contacts of different battery cells in the following figures.

2 shows a battery cell pack 20 from eight individual battery cells 10 that are stacked directly on top of each other. By an appropriate orientation of the battery cells 10 will ensure that the contacts 16 . 17 from neighboring battery cells 10 to each other in an electrically conductive contact. The external battery cells 10 are in direct contact with connection conductors 18 that the battery cell pack 20 that from the battery cells shown 10 is formed, contact electrically. Consequently, here is a series connection of the battery cells 10 shown, but also a parallel circuit or a combined parallel and series circuit is possible, so as to obtain a desired power or voltage profile. To the individual battery cells 10 around is a shell 30 shown. Through this shell 30 defines the battery cell package 20 ,

In a first preferred embodiment, the shell 30 be executed as a shrink film. In a first variant of this embodiment, a shrink tube of length l (please refer 6 ) around the battery cell pack 20 be laid and shrunk by heat so that it fits tightly. So the in 1 shown distances between the shell 30 and the battery cells 10 disappear. In addition, the contacts are 16 . 17 different battery cells 10 (other than shown) directly to each other, so that an electric current flow is made possible. In conventionally known battery cell packages, the individual battery cells have been securely fastened to each other by connecting means such as welding or screwing. In order to reduce the production costs here is based on a constructive connection, which has a force-based connection, which over the envelope 30 is effected, goes out, renounces. It has been recognized that in particular large-area contacts, the only through the shell 30 be compressed, are sufficient for a secure power transmission. Because the battery cell pack 20 anyway, usually by a (foil-like) shell against the environment must be protected, the shell 30 take over the contacting task immediately.

It is a characteristic of battery cells that they increase in volume over the life of the battery and on the other hand, the volume increases slightly with each charge and decreases as it discharges. This connection is in 7 shown. From a small volume at the beginning of the life, which in the 7 is referred to as the cell thickness, a band of thickness changes is shown that is linearly increasing over the life and thereby, as already described, at each charge cycle has a certain thickness variation of the battery cell. The case 30 is preferably made of a plastic material and has a certain elasticity, which is sufficiently large, that even with the charging cycle-dependent different thicknesses of the battery cells 10 always a sufficient pressure force exists, so that a secure flow of current is ensured. There is also the physical effect of aging, that the elasticity of the shell 30 can lose some of their lifespan. This can be expressed as a plastic, ie permanent stretching of the shell. This effect, which is in principle negative, is compensated by the thickness of the battery cells 10 over the life increases (see 7 ). Thus, until the end of the life sufficient pressure force for contacting 15 allows.

In a second variant of the first preferred embodiment according to 1 can the serving 30 as a foil hermetically or airtight around the battery cell pack 20 be placed and over a vacuum suction 35 can in the manufacture of the battery cell pack 20 the air contained there are sucked off. So ensures the in the battery cell pack 20 generated negative pressure for the sheath directly to the battery cells 10 puts and compresses them to each other and thereby a pressure on the contact 15 generated. In the second variant, any air-impermeable film can be used. Also, the two variants mentioned are connected to each other, so that in a shrink film, a vacuum / negative pressure generated, or permanently ensured.

In a third variant (not shown), the shell 30 be created by wrapping with a stretch film. That is, a film having a high elasticity becomes under application of axial forces around the packet of the battery cells 10 wound and over this permanent high forces are effected on the contacts. The stretch film can also be used in addition with an additional shrink film.

3 shows an alternative embodiment of the battery cell 10 in which the contacts 16 and 17 on the large outer sides of the battery cell 10 are integrated. These can (as shown schematically) also be a direct or integral part of the surface of the battery cell. The battery cell 10 can be designed to be conductive at these points accordingly. This facilitates stacking, as it does not affect the orientation of the free ends of contacts 16 . 17 (according to 1 ) must be respected.

4 shows an alternative to the formation of a battery cell packet in which the battery cells 10 arranged one behind the other. Also, combined arrangements of a parallel and a series arrangement are possible. Also, additional measuring conductors 19 be used on one or more contacts to ensure that inside the battery cell pack 20 the voltage potentials are correct. These measuring conductors 19 can also be held in place only by pressure forces. Alternatively, these measuring leads can be fastened separately, eg welded, so that they can be applied during the subsequent application of the cover 30 do not move.

5 shows a further alternative of the battery cell package 20 , which can also be combined with the variants described above. It is in the battery cell pack 20 a springy element 40 integrated. This can be, for example, a foam. In the manufacture of the battery cell pack, the foam is compressed by external forces, such as a clamping, and retains its elasticity over its lifetime, so that there is always an internal tension in the battery cell pack 20 that is the battery cells 10 against the shell 30 suppressed. The elastic element 40 so makes the contact (s) 15 for sure. In a preferred variant, the resilient element is in an inner layer of the battery cell packet 20 arranged so that the low thermal conductivity of a foam dissipates heat loss from the battery cells 10 not disabled. Alternatively, as a springy element 40 Any elements are used which can store at least locally, but preferably flat, permanently mechanical deformation energy, such as a wavy metallic (or other non-metallic) metal sheet or a corresponding molding.

6 explains a preferred location of the contact. In the aging or state of charge-dependent increase in volume, the pouch of the battery cell 10 is due to the large surface area in 6 is shown, a bulge arise. This is preferably in the middle. That is, only where the rectangular hatched area is shown, with a certain aging of the battery cells 10 a mechanical contact (ie, lying on each other) of the battery cells to each other. At the areas in 6 To the left and to the right of the hatched area, a certain lift may occur. That means the contacts 16 and 17 be so long that they come in the hatched area. It has been recognized that for safe, permanent contact, the contacts should (also) be within a range of at least 35% of the length l the battery cell from the respective end of the battery cell 10 away. In other words, in a middle area of about 40% of the length of the battery cell 10 need the contacts 16 . 17 adjacent battery cells are located. In other embodiments may be required that said distance instead of 20% is at least 30%, so as to ensure a higher security of the contact.

In the method of manufacturing the battery cell package 20 First, a plurality of battery cells 10 relative to each other so aligned that contacts 16 . 17 aligned with each other for the transmission of a current. This may possibly be a bending of the contacts 16 . 17 to be required. But no action is taken, that the contacts 16 . 17 permanently attached to each other or permanently positioned. Below is a shell 30 applied, which can be a foil. In the case of a shrink film can be softened by thermal heating, the film so that mechanical tension of the film are released, the film can contract and the film also with clamping forces around the package of battery cells 10 is applied. Alternatively or additionally, the shell 30 be airtight and in it a negative pressure / vacuum can be generated and kept permanently over the life, so that over the negative pressure forces to ensure the contacting 15 are guaranteed. Alternatively or additionally, in the package of battery cells 10 a springy element 40 integrated in the production of the battery cell package 20 is compressed so that it is within the envelope 30 permanently causes a mechanical tension.

While the invention has been described above for pouch-shaped cells, it is also applicable to other cell shapes, such as cylindrical or prismatic cells. As already mentioned above, features which have been explained in only one embodiment (or variant) are also considered usable for other embodiments, provided that no constructive obstacles prevent this.

LIST OF REFERENCE NUMBERS

10

battery cell

15

contact

16, 17

Contact

18

connecting conductors

19

measuring Head

20

Battery cell pack

30

shell

35

Vakuumsaugstelle

40

elastic element

Claims (10)

Battery cell package (20) with at least one contact (15) between individual battery cells (10) of the battery cell package (20) and / or connection conductors (18), wherein over a battery cell package (20) at least partially enveloping shell (30) pressure forces on the contact (15) are exercised, characterized in that on the pressing forces a mechanical contact of contacts (16, 17) of the contact (15) is ensured. Battery cell package (20) with at least one contact (15) between individual battery cells (10) of the battery cell package (20) and / or connection conductors (18), wherein over a battery cell packet (20) at least partially enveloping shell (30) pressing forces on the contact (15) are exercised, characterized in that in the contact (15) on the by the sheath (30) caused Andruckkräfte neither form-fitting, non-positive or cohesive connection means for ensuring the mechanical contact of preferably at least two contacts of the contact are provided be understood in particular as a positive joining means mechanical latching hooks, crimping, flanging, screwing or undercuts, and / or in particular as non-positive joining means resilient means such as spring contacts or elastic tension of a holder or carrier of the contacts are understood and / or in particular al s cohesive joining means soldering or welding are understood. Battery cell package (20) according to Claim 1 or 2 wherein the enveloping sheath (30) comprises or consists of a foil; and in particular causes an airtight or at least a liquid-tight seal around the battery cells (10) of the battery cell pack (20). Battery cell package according to one of the preceding claims, wherein in the contact (15) contacts (16, 17) of the battery cells (10) and / or the connecting conductor (18) are in a planar contact with each other. A battery cell package (20) according to any one of the preceding claims, wherein the envelope (30) is implemented as a shrink film. A battery cell package (20) according to any one of the preceding claims, wherein the sheath (30) comprises a vacuum suction pad (35) and / or the sheath (30) is an airtight sheath and there is a negative pressure to the environment within the sheath. Battery cell package (20) according to one of the preceding claims, wherein within the envelope (30) a resilient element (40), such as in particular a foam or a spring is provided to the effect of forces on the sheath (30), the pressing forces of contacting ( 15) to effect. Battery cell package (20) according to one of the preceding claims, wherein individual battery cells (10) of the battery cell package (20) abut each other flat and thereby define a contact surface, and at least a portion of the contact (15) at a distance of at least 20% from the edge of the contact surface with respect to the total length (l) and / or width (b) of the abutment surface. Battery cell package (20) according to one of the preceding claims, wherein the contacts (16, 17) are each led out on end sides of the battery cell (10) and bent in a U-shape. A method of manufacturing a battery cell package (20) in which a plurality of battery cells (10) are positioned relative to each other so that electrical contacts (16, 17) of the battery cells (10) are relative to each other and no constructive measures are taken to avoid them To ensure permanent electrical contact of the contacts (16, 17) and subsequently, a sheath (30) is applied to the aligned battery cells (10) that on the shell (30) forces on the battery cells (10) are effected and thereby the contacts ( 16, 17) are held in mechanical and electrical contact with each other.

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