DE102014219001A1 - Battery cell with cell housing and a cover assembly with battery contacts - Google Patents

Abstract

The invention relates to a battery cell (1) comprising a cell casing (11), two electrodes arranged in an inner region of the cell casing (11) and an electrolyte material disposed in the inner portion of the cell casing (11) and surrounding the electrodes wherein the cell casing (11) comprises a lid assembly (15) having a cover plate (16) and two battery contacts (20) for electrically contacting the battery cell (1), each of the battery contacts (20) including a battery terminal (38) a current conductor (7, 9) arranged in the inner region of the cell housing (11), which is electrically conductively connected to one of the electrodes, and has an external terminal (40) projecting at least partially in an outer region of the cell housing (11), wherein the battery cell (1) between the cell housing (11) and battery terminal (38) sealing elements (44), and the cover plate (16) and the Di Chtelemente (44) are connected together by means of an adhesion-promoting material (32) into a composite.

Description

State of the art

The invention relates to a battery cell with a cell housing and a cover assembly with battery contacts for electrical contacting and to a method for producing such a battery cell.

Battery systems, and particularly lithium-ion batteries, are used for a variety of high-power applications, exemplifying the recent advances in electrification of automobiles and use in the consumer sector, such as laptops and cell phones. Furthermore, applications such as energy storage for electricity from solar cells or wind turbines are known.

In particular, the batteries used in motor vehicles, e.g. Lithium-ion batteries, often have a prismatic shape due to a good volume value, wherein inside a housing at least one flat-pressed winding is added, which is rolled from an aluminum foil, a copper foil, and two acting as diaphragms plastic or ceramic films. The aluminum foil and the copper foil are coated with reactive cathode and anode material. The housing is filled after introduction of the coil and before the pressure-tight closure with a liquid electrolyte. The electrical contacting of the two electrodes is generally carried out via welded strip-shaped sheet metal parts made of copper or aluminum, the so-called current collectors, and a lead-out of the cell case, there to electrically contact a terminal of a cell or even to form these themselves.

The housing usually has a housing container and a housing cover, which are made for example of aluminum, stainless steel or another metal. When carrying out the current paths through the housing outside, various aspects must be taken into account. Thus, the current paths must face the cell case, i. generally with respect to the housing cover, be electrically insulated and the tightness of the current feedthrough through the cell housing must be ensured, especially against moisture.

A battery cell has sealing members along an inner surface and an outer surface of the housing, the connecting components extending through the housing and the sealing members to electrically connect the power-generating battery cell and external terminals. The sealing elements seal corresponding passages, wherein for the production of a corresponding seal often different items made of plastic are used.

In known battery cells of the housing container and the housing cover are connected by means of a weld, in particular a laser weld, wherein the housing cover but also can be crimped, crimped, pressed or glued.

One problem with welding is the associated heat effect which arises during the welding process and which can lead to a deformation of the cell housing but also in the area of the current feedthroughs. Even during the use of such batteries may cause thermal fluctuations, associated with temperature increase or temperature reduction.

Furthermore, scratched or rough surfaces prove problematic when e.g. pressed or pressed-plastic sealing parts are used for the sealing of the current feedthroughs, since there is the possibility that a connection along wells between the interior of a cell housing and the environment is present, which makes one hand, a seal of the interior ineffective and on the other hand, penetration of water and Allows oxygen from the outside, which ultimately leads to damage to the battery cell.

In DE 10 2012 212 256 A1 is described inter alia for a battery cell, a cell housing having a cover assembly with a housing cover, being provided for electrical contacting of the battery cell battery contacts. Each of the battery contacts is in contact with a current collector arranged in the interior of the cell housing. In this case, the current conductor comprises a recess and is electrically coupled to a corresponding electrode. Furthermore, each battery contact has a battery terminal arranged at least partially in an outer region of the cell housing, wherein in each case a section of the battery terminal is guided through the recess of the current conductor, wherein in each case a welded connection is formed on an inner surface of the recess in order to connect the battery terminal and the current conductor ,

Disclosure of the invention

According to the invention, a battery cell with a cell housing with two electrodes, which are arranged in an inner region of the cell housing, and one in the interior of the Cell housing arranged electrolyte material proposed, wherein the cell housing has a cover assembly with a cover plate and two battery contacts for electrically contacting the battery cell. The respective battery contacts comprise a battery terminal, which is in communication with a current collector or current collector located in the interior of the cell housing, and forms an external terminal in an outer area of the cell housing, sealing elements being arranged between cell housing and battery terminal. In addition, the cover plate and the sealing elements are connected together by means of an adhesion-promoting material to form a composite. Furthermore, a method for producing such a battery cell is proposed.

For the purposes of the invention, the term "battery" also refers to a galvanic element, comprising a cell network as well as individual cells, and in particular rechargeable secondary batteries, or secondary cells, e.g. Lithium-ion batteries. In motor vehicles, especially in electric or hybrid vehicles, the battery in addition to the power supply also serves as an energy storage for the electric drive.

For electrical contacting of the battery cell to an electrical periphery terminals or the battery terminals are provided, wherein the battery terminal may be an integral part of the Stromableiters or alternatively represents a separate element which is electrically connected to the current conductor.

The battery cell may exist as a prismatic cell having an outer shape of a rectangular parallelepiped or as a round cell having an outer shape of a round column. Accordingly, the shape of the cell housing may be a rectangular with a rectangular housing cover, wherein a cover assembly comprises a rectangular plate member, or a cover plate. In particular, an opening of the cell housing with the lid assembly is sealed gas and pressure tight. The lid assembly comprises a plurality of components, which on the one hand form battery contacts, wherein in particular battery terminals extend through the lid assembly and which on the other hand, the lid assembly including the openings provided for the battery contacts sufficiently close tightly.

The cover assembly includes, among other things, a cover plate on which openings are provided for the passage of the battery terminals. In one embodiment, at the openings of the cover plate, designed as through-holes, an insulating sleeve for safe passage of the battery connections is arranged, for example pressed in.

In one embodiment, positioning elements are provided on the lid assembly and the cover plate, for example, latching lugs or recesses which are complementary to corresponding counterparts of the battery terminals, to prevent twisting of a battery terminal to be positioned.

Between the battery connection and cover arrangement or cover plate, sealing elements are provided, for example formed as sealing plates with an opening for receiving a battery connection. For example, the sealing element can be embossed in the positioning elements. The sealing elements ensure that even a pressurized electrolyte material can not escape from the cell housing. The sealing elements separate the corresponding elements from each other, wherein the sealing elements take on an insulating function to isolate the current-carrying battery terminal against the cell housing. Furthermore, the forces acting on the battery terminals forces are absorbed elastically by the sealing elements.

The sealing elements can be connected by a thermal Anschmelzprozess at a temperature greater than a glass transition temperature of a polymeric material of the sealing element or by means of an adhesive process with or without additional adhesive aids gas-tight and hermetically sealed with the respective elements. Alternatively, the sealing elements may be made of a solid insulating material which is bonded to the respective elements by means of an adhesive.

The plurality of components that are associated with the lid assembly, such as the cover plate, the sealing plates, the sleeves and the battery terminals are manufactured in a manufacturing process, which due to the processing of the individual components have a more or less pronounced surface roughness. Thus, the surfaces of the individual components in addition to the material-related pores and scratches and / or depressions, which are often in the order of a few nanometers and which arise, inter alia, by a manufacturing process, such as a stamping process. According to the invention, the composite components are coated with an adhesion-promoting material, which is in particular sprayed, and possibly subjected to a thermal treatment, wherein the adhesion-promoting material is at least partially stored in the existing pores and / or depressions and there adheres by adhesion, or melts. Thus it can be provided that the material is applied by melting such a film or by printing a powder layer. A heating under pressure of a corresponding material for pressing into the existing roughness is conceivable. The adhesion-promoting material is a suitable plastic, such as, for example, thermoplastics, thermosets, in particular polyolefins, polypropylene, polyethylene, polyphenylsulfide or other thermoplastic and chemically inactive polymers. It may also be a low-melting glass or other organic or inorganic material having an insulating effect.

In addition to the suitability of the plastics used to fill pores and depressions, the adhesion-promoting material, which is applied at least partially to a lower and upper side of the cover plate, forms a coating which forms an adhesive layer between the components joined to a composite in these areas, in particular between the cover plate and sealing plates. Accordingly, in the region of a battery contact on the underside and the upper side of the cover plate sealing elements, designed as sealing plates, arranged and connected by means of an adhesive layer with this, or glued. The coating applied according to the invention is distinguished by good adhesion properties and high tightness.

Each battery contact, also referred to as a composite of the battery contact, further comprises a battery terminal, which includes, inter alia, a designed as an external terminal for contacting with an electrical peripheral portion which is disposed on the outwardly facing top of the lid assembly. Accordingly, the lid assembly each comprises an external terminal for the positive electrode and an external terminal for the negative electrode. An external connection can be made with different connection geometries, so that a variety of technologies for contacting a battery cell by a consumer or with each other are possible. An example is a contacting by means of screws, welding or clamping.

The battery terminal comprises, in addition to the section formed as an external connection, a pin section which extends through an opening provided in the cover arrangement and can be connected inside the cell housing to a current conductor, which in turn is connected to the energy-generating elements.

To make a battery contact, a battery terminal is inserted into an opening provided on the lid assembly. The battery connection, the sealing elements and the cover plate, as well as the possibly provided sleeve are joined into a composite, which is connected in particular by the adhesion-promoting material. The composite comprising the adhesion-promoting material or, if appropriate, material to be melted is joined by application of temperature, pressure and / or ultrasound in such a way that the joining takes place with a contact force, the bonded composite being hermetically sealed and having elasticity. In the composite, for example, a contact pressure of 5 to 500 N / cm ² , depending on the plasticity and compressive strength of the material used for the sealing elements.

A connection between pin portion and cover assembly can be done by means of pressing, caulking, flanging and / or welding.

In one embodiment, a battery connection is formed in two parts, in which case the battery connection has a first connection section and a second connection section. The first terminal portion includes the portion formed as an external terminal and the pin portion which is passed through the opening of the lid plate. The second connection section is designed, for example, as an annular element which is arranged from the underside of the cover plate on the pin section projecting there. To produce the battery contact, the second connection section is connected to the first connection section with a certain contact force. The connection of the first and second connecting portion can be done by welding, caulking or flanging, wherein a material or non-positive connection is generated.

In a further embodiment of a battery terminal, the portion of the external terminal protruding from the cover plate is designed such that elements are provided which generate a permanent elastic compressive force on the composite of the battery contact. According to the invention, the elements can be designed as spring elements, in particular spring plates, which are supported on the battery connection, for example on an integrally formed collar or collar, wherein a compressive force is exerted on the composite of the battery contact. The spring element can be made in one or more parts, wherein the spring element, for example, designed as a spring cap, exerts a sufficient compressive force in a wide temperature range on the composite. In the case of a multi-part spring element, the individual parts can be welded together, for example. The spring element and the areas on which the spring element is supported, may be designed such that grooves or depressions are provided to To secure the spring element in its position. Thus, a permanent and elastic connection is produced, which is suitable for receiving mechanical loads, which are exerted, for example, from an outer side of the cell housing to the battery contacts.

Advantages of the invention

In the case of the battery cell proposed according to the invention, the components which are required for the electrical contacting of the electrodes are processed in such a way that any existing surface roughness is largely reduced. The components required for the production of the electrical contacting are optimally matched to one another, wherein in particular a hermetically sealed battery contact is made possible.

The battery contact is joined by adhesive processes, wherein the production of the electrical contact leads to a composite in which the individual components are connected to one another with a contact pressure. In addition, an elastic composite is produced, which ensures a hermetic seal even with incoming mechanical loads. Advantageously, an additional force is built up by the spring element.

Advantageously, the preparation of the components to be joined, i. the application of the adhesion-promoting material to the corresponding surfaces and a possible melting at elevated temperature in the recesses and pores, before the joining of the components and in particular before the merging of cell housing and cover assembly. The components are mounted from an outer side of the cover assembly to an inner side, wherein then in one embodiment, a welded connection between the individual connection parts of a battery terminal from the inside. Accordingly, each battery contact has a maximum of a welded connection, so that a battery contact can be made easier and thus more cost-effective.

Usually, the plurality of components are connected for the contacts by means of material connections, in particular by means of rivet, laser welding and Reibschweißverbindungen. Based on the proposed contacting with at least partially pluggable components, changes in the construction of the lid assembly can be easily implemented. Furthermore, a battery contact according to the invention proves to be less error-prone.

In particular, a hermetically sealed connection is ensured even at temperatures which are above the specified operating temperature of an electrochemical cell.

Brief description of the drawings

Further advantages and embodiments of the objects according to the invention are illustrated by the drawings and explained in more detail in the following description.

Show it:

1 an exploded view of a lithium-ion battery cell according to the prior art;

2 a plan view of a lid assembly according to an embodiment of the present invention;

3 a sectional view through a lid assembly according to an embodiment of the present invention.

State of the art

According to the prior art goes from the presentation 1 a conventional lithium-ion battery cell in an exploded view. A battery cell 1 includes a variety of individual components that are assembled during manufacture. In the following, only the components relevant for the understanding of embodiments of the invention and their features will be described.

The battery cell 1 has a winding element 3 on with a wrapped stack 5 of an anode comprising a copper foil coated with an anode material and a cathode comprising an aluminum foil coated with a cathode material and intervening plastic films serving as a diaphragm. For electrical contacting, the copper foil and the aluminum foil are stacked slightly offset one above the other along the winding axis in the opposite direction, so that copper foil and aluminum foil each protrude slightly on opposite narrow sides over the respective edge of the winding element. At a protruding edge area 4 the copper foil becomes a current conductor made of copper 7 welded, so the current conductor 7 with the anode of the winding element 3 electrically connected. At the opposite edge region of the aluminum foil becomes an existing current conductor of aluminum 9 welded to make electrical contact with the cathode of the winding element 3 manufacture.

That with the current conductors 7 . 9 provided winding element 3 becomes a hermetically sealed cell case 11 introduced, in which a liquid electrolyte is introduced. The cuboid cell housing 11 includes an open-topped container 13 and one the upper opening 14 of the container 13 tightly closing lid assembly 15 , The lid arrangement 15 Includes a variety of components, including a cover plate as a main component 16 , Further in 1 illustrated components of the lid assembly 15 serve to carry out an outwardly reaching contact arrangement for electrical contacting, indicated by battery contact 20 ,

embodiments

In 2 is a section of the cover plate 16 reproduced, to which an electrical contact of the battery cell 1 is formed, that is, a contact with a positive electrode, or the cathode and a negative electrode, or the anode. With 22 is a region of an electrical contact, wherein on the cover plate 16 an opening 24 is provided, formed as a through hole 26 , In the through hole 26 is a sleeve 28 inserted, preferably pressed.

For positioning and anti-rotation of the respective contact are on the cover plate 16 Locators 30 provided, designed here as a latching recess or locking lug, which are formed complementary, so as to provide corresponding elements of the contact for an insulating positive connection.

Due to manufacturing and machining processes and the material of the individual components, eg the cover plate 16 , the through holes 26 and the sleeve 28 , as well as sealing elements (not shown) pores, scratches and / or depressions are present on the respective surfaces, which can lead to leaks in the worst case. According to the invention it is now provided to apply at least partially a material on surfaces of the individual components, for example by means of one or more injection molding operations, which reduces the surface roughness of the joined to a composite components. In particular, by a thermal process, the applied material can melt into the existing roughness. In 2 is now such an applied, adhesion-promoting material with 32 which here not only the pores, depressions and the like on a top 34 the cover plate 16 fills, but a layer 36 forms, which acts as an adhesive layer when joining the individual components to a contact.

In 3 is in schematic form an embodiment of a battery contact 20 shown, which in a lid assembly 15 a battery cell, not shown 1 is provided. Each of the battery contacts 20 has a battery connection 38 up, passing through the through hole 26 extends at least partially.

Starting from the top 34 the cover plate 16 , extends as an external connection 40 trained section of the battery connection 38 outward. The external connection 40 Can be used with different connection geometries for contacting with other battery cells 1 or be realized with a consumer, for example as a pin, with a thread or the like. Further, the outwardly projecting portion of the battery terminal comprises 38 a first annular shoulder 42 , which in the assembled battery contact 20 on a sealing element 44 , For example, designed as a sealing plate 46 , comes to rest. For sealing a passage of a battery contact 20 are at the top 34 the cover plate 16 and at a bottom 48 the cover plate 16 one sealing plate each 46 provided, which by means of the applied layer 36 of the adhesion-promoting material 32 with the top and bottom 34 . 48 the cover plate 16 are glued. The sealing elements 44 , preferably made of plastic, not only seal the through hole 26 in which also the sleeve 28 is included, but also isolate the battery contact 20 opposite the lid assembly 15 , Furthermore, the sealing elements serve 44 for the absorption of mechanical stress, which depends on the battery contact 20 Act.

In the in 3 illustrated embodiment of a battery contact 20 is the battery connection 38 executed in several parts, wherein at a pin portion 49 which extends through the through hole 26 inside the cell case 11 extends, a ring-shaped connection part 50 deferred and with the pin section 49 so material or non-positively connected, that the individual components of the battery contact 20 are connected to each other under pressure. In the in 3 illustrated embodiment, the annular connection part 50 with the pin section 49 by means of a welded joint 52 welded.

Further, the upper portion of the battery terminal 38 , in the section of the external connection 40 formed such that at the battery terminal 38 a spring element 54 can support a further compressive force on the assembled of individual components battery contact 20 In particular, the shoulder will exercise 42 against the sealing element 44 pressed. For example, this is a collar 56 on the battery connector 38 educated.

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 102012212256 A1 [0009]

Claims (11)

Battery cell ( 1 ) with a cell housing ( 11 ), two electrodes located in an interior of the cell housing ( 11 ) are arranged and an electrolyte material, which in the interior of the cell housing ( 11 ) and surrounds the electrodes, wherein the cell housing ( 11 ) a lid assembly ( 15 ) with a cover plate ( 16 ) and two battery contacts ( 20 ) for electrically contacting the battery cell ( 1 ), each of the battery contacts ( 20 ) a battery connection ( 38 ) which is connected to a in the interior of the cell housing ( 11 ) arranged current conductor ( 7 . 9 ), which is electrically conductively connected to one of the electrodes, is electrically coupled and at least partially in an outer region of the cell housing ( 11 ) above external connection ( 40 ), wherein the battery cell ( 1 ) between cell housing ( 11 ) and battery connection ( 38 ) Sealing elements ( 44 ), characterized in that the cover plate ( 16 ) and the sealing elements ( 44 ) with each other by means of an adhesion-promoting material ( 32 ) are connected to a composite. Battery cell ( 1 ) according to claim 1, characterized in that the composite further comprises the battery terminal ( 38 ), wherein the adhesion-promoting material ( 32 ) at least in part on surfaces of the cover plate ( 16 ), the sealing elements ( 44 ) and the battery connection ( 38 ) is applied, which to the composite of the battery contact ( 20 ) are joined. Battery cell ( 1 ) According to claim 1 or 2, characterized in that the adhesion-promoting material ( 32 ) is selected from a plastic or a low-melting glass. Battery cell ( 1 ) according to one of the preceding claims, characterized in that the adhesion-promoting material ( 32 ) is thermally treated, so that it at least partially surface roughness of the cover plate ( 16 ), the sealing elements ( 44 ) and the battery connection ( 38 ) reduced by melting. Battery cell ( 1 ) according to one of the preceding claims, characterized in that the battery connection ( 38 ) as an external connection ( 40 ) formed portion which at least partially in an outer region of the cell housing ( 11 ) and a pin portion ( 49 ), which at least partially into the interior of the cell housing ( 11 ). Battery cell ( 1 ) according to claim 5, characterized in that the battery connection ( 38 ) is formed in several parts, wherein an annular connecting part ( 50 ) in the interior of the cell housing ( 11 ) with the pin portion ( 49 ) is connectable. Battery cell ( 1 ) according to claim 2, characterized in that on the external connection ( 40 ) forming section a spring element ( 54 ) is arranged such that the to the composite of the battery contact ( 20 ) attached cover plate ( 16 ), the sealing elements ( 44 ) and the battery connector ( 38 ) are subjected to a compressive force. Battery cell ( 1 ) according to claim 7, characterized in that the spring element ( 54 ) on the one hand on a collar ( 56 ), formed on the external connection ( 40 ) of the battery connector ( 38 ), and on the other hand on an annular shoulder ( 42 ) is supported in such a way that on the composite of the battery contact ( 20 ) a compressive force is applied. Method for producing a battery cell ( 1 ), in particular a lithium-ion battery cell, wherein the battery cell ( 1 ) two electrodes, which in an interior of a cell housing ( 11 ) are arranged, and an electrolyte material, which in the interior of the cell housing ( 11 ) and surrounds the electrodes, and a lid assembly ( 15 ), the method comprising the steps of: - providing a cover plate ( 16 ), which has a top ( 34 ) and a bottom ( 48 ) having; - Provision of a battery connection ( 38 ) for electrically contacting the battery cell ( 1 ); - providing sealing elements ( 44 ) for sealing an opening ( 24 ) for receiving the battery ( 38 ) of the cover plate ( 16 ); - Applying an adhesion-promoting material ( 32 ) in layers at least on a part of the surfaces of the cover plate ( 16 ) and the sealing elements ( 44 ) for reducing existing surface roughness and forming at least one layer ( 36 ) which forms an adhesive layer; - Add the cover plate ( 16 ), the sealing elements ( 44 ) and the battery connection ( 38 ) to a composite of the battery contact ( 20 ), one end of the battery connector ( 38 ) in the interior of the cell housing ( 11 ) with one of the current conductors ( 7 . 9 ) is electrically coupled. A method according to claim 9, characterized in that the application of the adhesion-promoting material ( 32 ) under temperature conditions in which the adhesion-promoting material ( 32 ) melts into surface roughness and the layer ( 36 ) trains. Method according to one of claims 9 and 10, characterized in that the conditions of the joining of the cover plate ( 16 ), the sealing elements ( 44 ) and the battery connector ( 38 ) are selected such that in the composite of the battery contact ( 20 ) the cover plate ( 16 ), the Sealing elements ( 44 ) and the battery connector ( 38 ) are joined together with contact force.

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