KR20190029461A - Method for producing an electrode unit for a battery cell and battery cell - Google Patents

Abstract

The present invention relates to a manufacturing method for an electrode unit for a battery cell, which comprises: a step of providing a separation membrane (50) including a first ion permeable cover layer (51), a second ion permeable cover layer (52), and a conductive ion permeable core layer (53); a step of forming at least one hole (71, 72) inside the separation membrane (50); a step of providing a first connection element (61) on a first surface (55) of the separation membrane (50) so that the at least one hole (71, 72) can be partially covered by the first connection element (61); a step of providing a contact element (60) on a second surface (56) which faces the first surface (55) of the separation membrane (50); a step of welding at least the first connection element (61), the contact element (60), and the core layer (53) in order to form a welding combination between the core layer (53) and the first connection element (61) inside the at least one hole (71, 72); and a step of placing the separation membrane (50) between an anode (21) and a cathode (22). In addition, the present invention relates to a battery cell including at least one electrode unit which is manufactured by the manufacturing method prepared by the present invention. Therefore, the present invention can achieve high mechanical stability and ensure permanently stable electrical contact.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrode unit for a battery cell,

The present invention provides a method of manufacturing an electrode unit for a battery cell, comprising the steps of: providing a separating membrane including a first ion-permeable cover layer, a second ion-permeable cover layer, and a conductive and ion-permeable core layer, the separator being disposed between the anode and the cathode To an electrode unit for a battery cell. The invention also relates to a battery cell comprising at least one electrode unit manufactured according to the method according to the invention.

Electric energy can be stored by the battery. Batteries convert chemical reaction energy into electrical energy. In this case, the primary battery and the secondary battery are distinguished. A primary battery can only be operated once, while a secondary battery, also called an accumulator, is rechargeable. The battery includes one or a plurality of battery cells.

Especially so-called lithium ion battery cells are used in the accumulator. They are characterized by a particularly high energy density, thermal stability and very low self-discharge. Lithium-ion battery cells are used in particular for automobiles, particularly electric vehicles (EVs), hybrid vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs).

Lithium ion battery cells include 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 include one current conductor, and the active material is provided on the current conductor. The electrodes of the battery cell are designed in a foil shape and are rolled under the separator separating the anode from the cathode to form one electrode winding or stacked to form one electrode stack having a plurality of electrode layers.

In known lithium ion battery cells and in other battery cells, there is a problem with the tree dendritic growth on the anode. During the repeated charging and discharging processes of the battery cell, other metals, such as copper, which have been introduced into the battery cell by lithium or fouling, can be deposited on the anode as the tree topographically and then grow to the cathode. Growing dendrites may puncture the separator and cause a local short within the battery cell upon reaching the cathode. Thus, growing dendrites can cause thermal destruction of the battery cell, also referred to as thermal runaway.

JP 5452202 B2 discloses a lithium ion battery including an anode, a cathode, and a separator disposed between the anode and the cathode. A metal layer is disposed in the separator. The metal layer serves to detect the growing dendrites.

WO 2014/179725 A1 discloses a battery including an anode, a cathode, and a separator disposed between the anode and the cathode, the separator including a conductive layer. The conductive layer is connected to the sensor.

US 2015/214582 Al and DE 10 2014 001 260 A1 disclose batteries comprising an anode, a cathode, and a separator disposed between the anode and the cathode. The separator includes a reference electrode to which an impedance measuring device is assigned.

US 2015/056506 A1 discloses a battery with electrodes, wherein contact flags project from the electrodes. To the contact flags of the electrodes, the connection elements are fixed, in particular by ultrasonic welding.

The object of the present invention is to provide a method of manufacturing an electrode unit for a battery cell and a battery cell in which a high mechanical stability is achieved and a permanently stable electrical contact is ensured.

A method of manufacturing an electrode unit for a battery cell is proposed. The electrode unit comprises at least two electrodes, at least one negative electrode, called an anode, and at least one positive electrode, called a cathode, and at least one separator separating the at least one anode from the at least one cathode.

First, a separation membrane comprising a first ion-permeable cover layer, a second ion-permeable cover layer and a conductive and ion-permeable core layer is provided. The core layer is especially made of metal. The cover layers are particularly designed to be electrically insulating.

At least one hole is formed in the separation membrane, preferably in the edge region of the separation membrane. The at least one hole is designed as a through hole and completely penetrates the separation membrane. The at least one hole is preferably formed in a circular shape, but may have another shape.

The first connecting element is then provided on the first surface of the separator such that at least one hole in the separator is at least partially, preferably completely, covered by the first connecting element. The first connecting element is preferably designed to be conductive and made of metal

A contact element is also provided on the second surface facing the first surface of the membrane. The contact element is designed to be conductive and is preferably made of metal.

Then, at least the first connecting element, the contact element and the core layer of the separator are joined together to provide electrical connection between the first connecting element, the contact element and the core layer of the separator.

The electrical connection between the core layer of the separator, the first connecting element and the contact element is particularly caused by welding. The welding is preferably ultrasonic welding. However, other welding methods, such as laser welding, are also possible.

Since the separator is disposed between the anode and the cathode, an electrode unit is formed. In particular, a plurality of plate-shaped anodes and a plurality of plate-shaped cathodes are stacked on each other under the presence of a plurality of plate-shaped separators each having a core layer electrically connected to one contact element to form one electrode stack.

According to a preferred embodiment of the present invention, the contact element is provided on the second surface of the separator such that at least one hole in the separator is at least partially, preferably completely, covered by the contact element.

For example, the first connecting element, the contact element and the core layer of the separator are welded to create a weld bond between the contact element and the core layer within at least one of the holes. Thus, the contact element is directly welded to the core layer of the separator.

According to another preferred embodiment of the invention, the second connecting element is arranged so that at least one hole in the separator is at least partly, preferably completely covered, by the second connecting element, and that the contacting element is partly Is provided on the second surface of the separator. In this case, the core layers of the first connection element, the second connection element, the contact element and the separator are joined together to provide electrical connection between the first connection element, the core layer, the second connection element and the contact element.

The contact element is welded to the core layer of the separator, for example through a second connection element. The individual weld joints may be formed separately or may be joined together.

According to a preferred refinement of the present invention, the first hole and the second hole are formed in the separator, preferably in the edge region of the separator, with a short interval therebetween. The first connecting element is provided on the first surface of the separator such that the first hole and the second hole are at least partially, preferably completely covered by the first connecting element. The second connecting element may also be arranged on the second surface of the separator such that the first hole and the second hole are at least partly, preferably completely covered, by the second connecting element and that the contacting element is partly Respectively.

Preferably the contact element is disposed between the first and second holes, so that it extends in the region between the two holes.

According to a preferred embodiment of the present invention, the contact element is provided directly to the second cover layer of the separator. A second surface of the separator is formed on the second cover layer, away from the core layer.

Preferably the contact element comprises a convex protrusion, for example in the form of a needle holder. The contact element is provided in the second cover layer of the separator such that the protrusion contacts the core layer through the second cover layer. Thus, additional electrical contact of the contact element and the core layer of the separator is formed.

According to another preferred embodiment of the present invention, the second cover layer is partially removed, in the region of the separation membrane, in which at least one hole is formed in the separation membrane. The contact element is provided directly to the core layer. In this case, the second surface of the separator is formed on the core layer, away from the first cover layer.

According to a preferred refinement of the invention, a sealing element in the form of a coating of electrically insulating material is provided in the contact element at a region remote from at least one hole in the separator. The coating is preferably a polymer, especially polypropylene.

Further, a battery cell including at least one electrode unit manufactured according to the method according to the present invention is proposed.

According to the present invention, it is possible for a relatively thin conductive core layer having a thickness of 10 nm to 1000 nm to make permanent electrical contact in the membrane and to guide the membrane electrically from the cell housing to the outside. Thus, for example, the potential of the core layer of the separator, outside the cell housing, can be measured. Errors, particularly growing dendrites, inside the electrode unit can be detected from the potential of the core layer of the separator. In this case, the cell chemistry is not affected and the contact is mechanically stable. The use of a welding method prevents the use of a conductive adhesive that can contaminate the cell chemistry. Conductive adhesives that are permanently stable in current cell chemistry are not known. By the formation of holes in the separator, perforations can be created in which welds can ensure high mechanical stability and hence permanently stable electrical contact. In particular, there is a commercial metal foil with a partial coating of polypropylene. The coating can be used as an electrolyte-encapsulated guide of the contact from the cell housing to the exterior.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a schematic view of a battery cell;
2 is a schematic view of an electrode unit;
3 is a schematic diagram illustrating the fabrication of a separation membrane according to the first embodiment;
4 is a schematic diagram illustrating the fabrication of a separation membrane according to a second embodiment;
5 is a schematic diagram illustrating the fabrication of a separation membrane according to a third embodiment;
6 is a partially transparent plan view of a separation membrane according to the first, second and third embodiments;
7 is a schematic view showing the manufacture of a separation membrane according to the fourth embodiment;
8 is a partially transparent plan view of a separation membrane according to the fourth embodiment;

In the following description of the embodiments of the present invention, the same or similar elements are denoted by the same reference numerals, and repetitive descriptions of the elements are omitted individually. The drawings show only the subject matter of the present invention schematically.

The battery cell 2 is schematically shown in Fig. The battery cell 2 is designed, for example, in the form of a pouch cell, and includes a cell housing 3 formed in the form of a bag made of foil. The battery cell (2) includes a negative terminal (11) and a positive terminal (12). Through the two terminals 11, 12, the voltage provided by the battery cell 2 can be tapped. Also, the battery cell 2 can be charged through the two terminals 11, 12.

An electrode unit 10 is disposed in a cell housing 3 of a battery cell 2 and the electrode unit 10 includes two electrodes: an anode 21 and a cathode 22. The anode 21 and the cathode 22 are each implemented in a foil shape. The electrode unit 10 also includes a separation membrane 50 formed in a foil shape.

The anode 21 includes the anode active material 41 and the current conductor 31 which are in face-to-face contact with each other. The current conductor 31 of the anode 21 is electrically conductive and is made of metal, e.g., copper. The contact flag 35 protrudes from the current conductor 31 of the anode 21 and the contact flag 35 is electrically connected to the negative terminal 11 of the battery cell 2. [

The cathode 22 includes a cathode active material 42 and a current conductor 32 which are in face-to-face contact with each other. The current conductor 32 of the cathode 22 is designed to be conductive and is made of metal, for example, aluminum. The contact flag 36 protrudes from the current conductor 32 of the cathode 22 and the contact flag 36 is electrically connected to the positive terminal 12 of the battery cell 2. [

The anode 21 and the cathode 22 are separated from each other by a separation membrane 50, and the separation membrane 50 is composed of multiple layers. The separator 50 is disposed between the anode active material 41 and the cathode active material 42. The separation membrane 50 is designed to be ion conductive, that is, permeable to lithium ions.

The separator 50 includes a conductive and ion-permeable core layer 53. The core layer 53 is disposed between the first ion-permeable cover layer 51 and the second ion-permeable cover layer 52. The first cover layer 51 and the second cover layer 52 are electrically insulating and designed to be permeable to lithium ions.

Further, the battery cell 2 includes an electrolyte disposed inside the cell housing 3. The electrolyte is in a liquid state, for example, and the cell housing 3 is designed to be liquid-tight, so that the electrolyte can not escape.

The conductive contact element 60 is connected to the core layer 53 of the separator 50. The contact element 60 is guided out of the separator 50 through the cell housing 3 and serves to measure the potential of the core layer 53 of the separator 50, for example. A sealing element 80 is provided between the contact element 60 and the cell housing 3 and the sealing element 80 seals the cell housing 3 on the one hand so that the electrolyte can not escape, (60) is electrically isolated from the cell housing (3) if the cell housing (3) is designed to be conductive.

Fig. 2 shows a schematic view of the electrode unit 10 of the battery cell 2 shown in Fig. The core layer 53 of the separator 50 is made of, for example, porous metal and is conductive and ion permeable. The first cover layer 51 and the second cover layer 52 of the separator 50 are each made of, for example, a polymer. The first cover layer 51 and the second cover layer 52 are designed here at least approximately the same shape. The contact flag 35 of the anode 21 protrudes from the anode 21. [ The contact flag 36 of the cathode 22 protrudes from the cathode 22. The conductive contact element 60 protrudes from the core layer 53 of the separator 50.

Fig. 3 schematically shows the production of the separation membrane 50 according to the first embodiment. The first hole 71 and the second ion permeable cover layer 52 are formed in the separation membrane 50 including the first ion permeable cover layer 51, the second ion permeable cover layer 52 and the conductive and ion permeable core layer 53 interposed therebetween. Two holes 72 are formed.

The first connecting element 61 is provided on the first surface 55 of the separator 50 such that the first hole 71 and the second hole 72 are covered by the first connecting element 61. The first surface 55 of the separator 50 is formed in the first cover layer 51, away from the core layer 53.

The contact element 60 is provided on a second surface 56 opposite the first surface 55 of the separator 50. A second surface 56 of the separator 50 is formed in the second cover layer 52, away from the core layer 53. The contact element 60 is provided directly on the second cover layer 52 of the separator 50. The contact element 60 is here disposed between the first hole 71 and the second hole 72.

The second connecting element 62 is arranged on the second surface 56 of the separator 50 such that the first hole 71 and the second hole 72 are covered by the second connecting element 62, (60) is partially covered by the second connecting element (62).

The stack thus formed is pressed onto the base 92 by a welding head 90, here designed as an ultrasonic welding head. The welding head 90 and the base 92 each here have a rough surface structure.

 The first connecting element 61, the second connecting element 62, the contact element 60 and the core layer 53 of the separator 50 are then welded by the welding head 90. In this case, a welding connection is formed between the first connecting element 61 and the core layer 53 in the holes 71 and 72. In addition, welds are formed between the second connecting element 62 and the core layer 53 inside the holes 71, 72. Additional welding is also provided between the second connecting element 62 and the contact element 60. The contact element 60 is welded to the core layer 53 of the separator 50 via the second connecting element 62.

Fig. 4 schematically shows the manufacture of the separation membrane 50 according to the second embodiment, which corresponds broadly to the production of the separation membrane 50 according to the first embodiment. Contrary to the first embodiment, the contact element 60 includes a convex protrusion 82, for example, in the shape of a needle, facing the second cover layer 52 of the separator 50. The projecting portion 82 penetrates the second cover layer 52 and contacts the core layer 53. That is, additional electrical contact is made between the contact element 60 and the core layer 53 of the separator 50.

Fig. 5 schematically shows the production of the separation membrane 50 according to the third embodiment, which corresponds broadly to the production of the separation membrane 50 according to the first embodiment. Unlike the first embodiment, the second cover layer 52 is partially removed in the region of the separator 50 where the holes 71 and 72 are formed in the separator 50. Thus, the contact element 60 is provided directly on the core layer 53. In this case, the second surface 56 of the separator 50 is formed on the core layer 53, away from the first cover layer 51. [

Figure 6 shows a partially transparent plan view of a separation membrane 50 according to the first, second and third embodiments. In this case, a plan view of the second surface 56 of the separation membrane 50 is shown. A sealing element 80 in the form of a coating made of an electrically insulating material is provided in the contact element 60 in a region remote from the holes 71 and 72 in the separator 50. The sealing element 80 serves to seal and insulate the contact element 60 when the contact element 60 is later guided through the cell housing 3 of the battery cell 2.

FIG. 7 schematically shows the manufacture of the separation membrane 50 according to the fourth embodiment, which corresponds broadly to the production of the separation membrane 50 according to the first embodiment. Unlike the first embodiment, only one first hole 71 is formed in the separation membrane 50.

The first connecting element 61 is provided on the first surface 55 of the separator 50 such that the first hole 71 is covered by the first connecting element 61. The contact element 60 is provided on the second surface 56 of the separator 50 such that the first hole 71 in the separator 50 is covered by the contact element 60. The second connecting element 62 is not required.

In addition, the second cover layer 52 is partially removed in the region of the separation membrane 50 in which the holes 71 are formed in the separation membrane 50. Thus, the contact element 60 is provided directly on the core layer 53. In this case, the second surface 56 of the separator 50 is formed on the core layer 53, away from the first cover layer 51. [

The second cover layer 52 remains completely on the core layer 53 so that the second surface 56 of the separator 50 is formed on the second cover layer 52 from the core layer 53 Can be formed. Likewise, the contact element 60 may include convex protrusions 82, for example, needle-shaped, directed toward the second cover layer 52 of the separator 50. In this case, the protrusions 82 penetrate the second cover layer 52 and come into contact with the core layer 53.

The first connecting element 61, the contact element 60 and the core layer 53 of the separator 50 are then welded by the welding head 90. In this case, the weld between the core layer 53 and the first connecting element 61 is generated inside the hole 71. In addition, a welded connection occurs between the core layer 53 and the contact element 60 within the hole 71. [ Thus, the contact element 60 is directly welded to the core layer 53 of the separator 50.

FIG. 8 shows a partially transparent plan view of the separation membrane 50 according to the fourth embodiment. In this case, a plan view of the second surface 56 of the separation membrane 50 is shown. A sealing element 80 in the form of a coating made of an electrically insulating material is provided in the contact element 60 in a region remote from the hole 71 in the separator 50. The sealing element 80 serves to seal and insulate the contact element 60 when the contact element 60 is later guided through the cell housing 3 of the battery cell 2.

The invention is not limited to the embodiments described herein and to the aspects shown therein. Rather, many variations that are within the purview of those skilled in the art are possible without departing from the scope of the claims.

2: battery cell 10: electrode unit
21: anode 22: cathode
50: separator 51, 52: cover layer
53: core layer 60: contact element
61, 62: connecting element 71, 72: hole
80: sealing element 82: protrusion

Claims (10)

A method of manufacturing an electrode unit (10) for a battery cell (2)

There is provided a separation membrane (50) comprising a first ion permeable cover layer (51), a second ion permeable cover layer (52) and a conductive and ion permeable core layer (53);

At least one hole (71, 72) is formed in the separation membrane (50);

The first connecting element 61 is provided on the first surface 55 of the separating membrane 50 such that the at least one hole 71,72 is at least partly covered by the first connecting element 61 ;

A contact element 60 is provided on a second surface 56 opposite the first surface 55 of the separator 50;

At least the first connecting element (61), the contact element (60) and the core layer (53) are electrically connected between the first connecting element (61), the contact element (60) Are connected to each other;

Wherein the separator (50) is disposed between the anode (21) and the cathode (22). The method according to claim 1,
Wherein the contact element is provided on the second surface such that the at least one hole is at least partially covered by the contact element. The method according to claim 1,
The second connecting element 62 is configured such that the at least one hole 71, 72 is at least partly covered by the second connecting element 62 and the contacting element 60 is connected to the second connecting element 62, Is provided on the second surface (56) to be partially covered by the second surface (56);
Wherein the first connecting element (61), the second connecting element (62), the contact element (60) and the core layer (53) 2 connection element (62) and the contact element (60). The method of claim 3,
A first hole (71) and a second hole (72) are formed in the separation membrane (50);
The first connecting element 61 is configured to allow the first hole 71 and the second hole 72 to be at least partly covered by the first connecting element 61. [ (55);
The second connecting element 62 is positioned such that the first hole 71 and the second hole 72 are at least partially covered by the second connecting element 62 and the contacting element 60 Is provided on the second surface (56) of the separator (50) so as to be partially covered by the second connection element (62). 5. The method of claim 4,
Wherein the contact element (60) is disposed between the first hole (71) and the second hole (72). 6. The method according to any one of claims 1 to 5,
Wherein the contact element 60 is provided directly to the second cover layer 52 and the second surface 56 of the separator 50 is formed in the second cover layer 52, ≪ / RTI > The method according to claim 6,
The contact element 60 includes a convex protrusion 82 that is configured to contact the core layer 53 through the second cover layer 52 Is provided on the second cover layer (52). 6. The method according to any one of claims 1 to 5,
The second cover layer 52 is partially removed in the region of the separator 50 where the at least one hole 71, 72 is formed in the separator 50;
Wherein the contact element 60 is provided directly to the core layer 53 and the second surface 56 of the separator 50 is formed in the core layer 53. 9. The method according to any one of claims 1 to 8,
A method of manufacturing an electrode unit for a battery cell, wherein a coating-type sealing element (80) of an electrically insulating material is provided in the contact element (60) in a region remote from the at least one hole (71, 72). A battery cell (2) comprising at least one electrode unit (10) manufactured according to the method according to any one of claims 1 to 9.

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