WO2014111306A1 - Protective mechanism for battery cells - Google Patents

Abstract

The invention relates to a battery cell (10) comprising an electrode arrangement (12) with an active layer (28) that has at least one coated positive electrode layer (18) and at least one coated negative electrode layer (20), between which at least one separator layer (22) is provided, said electrode arrangement (12) being arranged within a housing (14, 14.1, 14.2, 14.3). The invention is characterized in that the electrode arrangement (12) additionally comprises at least one inactive layer (30). The invention further relates to a battery module with at least two such battery cells and to a vehicle equipped with at least one such battery cell.

Description

 Description title

 Protection Mechanism for Battery Cells PRIOR ART The invention overcomes a battery cell comprising an electrode arrangement with at least one coated positive electrode layer and at least one

coated negative electrode layer, between which at least one separator layer is arranged. In addition, the invention relates to a battery module with at least two such battery cells and a vehicle equipped with at least one such battery cell.

Rechargeable battery cells, which are also referred to as secondary cells or accumulator cells, are typically designed in the form of galvanic cells, which serve as electrochemical energy storage and energy converters. When loading the

Battery cell is thereby converted by electrochemical reaction of electrical energy into chemical energy. Conversely, when discharging chemical energy is converted into electrical energy. Electrical energy can thus be stored as needed or provided to a consumer.

Such battery cells are used, inter alia, in the form of battery packs or

Battery modules used in hybrid and electric vehicles, which include a number of series-connected or parallel-connected electrochemical battery cells. For the propulsion of vehicles, the use of lithium-ion battery cells is increasingly prevailing, since they have a high capacity, a low volume and a low self-discharge. In general, lithium-ion battery cells comprise at least one positive electrode and at least one negative electrode, which are coated with an active material to reversibly store the lithium ions at intercalation or outsource at deintercalation. In addition to the positive and negative electrode active materials, passive materials such as separators, metal trap films, metallic collectors and metal terminals are also included in such a battery cell. In the prior art, different battery cells are known. US 2008/010796 A1 discloses a battery cell in which the electrodes and the separator layer arranged therebetween are in a wound configuration. For contacting the battery cell, a collector is arranged between the respective electrodes and an external terminal.

In particular, when using lithium-ion battery cells for driving vehicles are different security measures in the event of an accident or other impact on the battery cell to take. One problem is the short-circuit reaction in the battery cell, which can even lead to the ignition of the battery cell. In this case, the separator introduced between the positive and negative electrodes melts, causing the battery cell to deeply discharge and heat up.

In order to prevent such reactions, protective devices such as lithium-ion battery cells are typically used. Diodes, fuse or targeted weak points provided in the housing of the cell, so that at a gas pressure within the cell controlled opening to release the gas takes place. Due to the dangers resulting from this in a motor vehicle, in particular for the driver and the occupants, there is a continuing interest in making such battery cells as safe as possible.

Disclosure of the invention

According to the invention, a battery cell with an electrode arrangement is proposed which comprises an active layer with at least one coated positive electrode layer (cathode) and at least one coated negative electrode layer (anode), between which at least one separator layer is provided, and which is arranged in a housing the electrode assembly additionally comprises at least one inactive layer. A battery cell according to the invention refers to a secondary cell, as

rechargeable electrochemical cell is constructed. Such cells are also known by the term accumulator cells and make it possible to store electrical energy that can be used in particular for driving electric vehicles or hybrid vehicles. Hybrid vehicles, in contrast to purely electrically driven Electric vehicles an additional drive unit based on the combustion of fuel.

 An inactive position in the sense of the invention denotes a layer which comprises at least one electrically conductive material layer and does not store or dispose of lithium ions during operation of the battery cell. The inactive situation is thus not involved in the energy storage or the energy supply, but designed so that at a

Short-circuit reaction within the battery cell, current is dissipated via the inactive layer. Thus, the battery cell can be transferred to a safe state, for example, overheating of the battery cell can be prevented.

The electrode arrangement of the battery cell according to the invention can be designed in different configurations. In particular, the electrode assembly may be wound or stacked. In stack configuration, the electrode layers and the separator layers between them are stacked. In wound cells, also referred to as jelly rolls, the electrode layers and the separator layer arranged therebetween are rolled up into a roll. In this case, the electrode layers and the separator layers are made of a flexible material, for example, in order to realize the winding.

The coated positive electrode layer and the coated negative electrode layer may further comprise a conductive foil or a conductive plate coated with an active material. Films may have a thickness of 75 μηη to 200 μηη, the Cu film has a thickness between 7 μηη and 15 μηη, the Al film between 10 μηη and 20 μηη. These are particularly suitable for wound electrode arrangements. Plates can have a thickness of from 75 μm to 250 μm and are particularly suitable for stacked electrode arrangements. The active material with which the plates or foils are coated, hereby provides the appropriate properties to the

To design electrode layers as an acceptor or donor of a particular ion.

In a preferred embodiment, the battery cell is designed as a lithium-ion battery cell. The active material is acceptor or donor for lithium ions. Thus, the coated positive electrode layer provides a medium into which positively charged lithium ions can be stored when discharging the battery.

The positive electrode layer may comprise, for example, an aluminum foil filled with an active material such as lithium metal oxides, vanadium oxides, olivines and rechargeable lithium oxides, is coated. Such coatings contain, for example, transition metal oxides (LiMO ₂ , M = Co, Ni, E, Mn, Al), lithium cobalt oxide (LiCo ₂ O ₄ ), lithium iron phosphate (LiFePO ₄ ) or lithium manganese oxide (LiMn ₂ O ₄ ). , Lithium-nickel-cobalt-aluminum oxide or lithium-nickel-cobalt-manganese oxide.

In contrast, the negative electrode layer provides the positively charged lithium ions and may comprise, for example, copper foil coated with an active material such as lithium, graphite, soft carbon, hard carbon, silicon, tin alloys, lithium alloyed material or

Intermetallic is coated.

The housing of the battery cell may be at a ground potential, a negative potential or a positive potential. Here, negative potential means the potential corresponding to the negative electrode and positive potential, the potential corresponding to the positive electrode. The housing can also be designed as a hardcase in cylindrical shapes with an angular or round base. Suitable materials for such hard cases are, for example, electrically conductive metals, such as steel, aluminum, aluminum alloys or plastics. In addition to the Hardcaseausführung the housing can also be designed as a soft pack or pouch, which typically consists of films, in particular composite films such. Aluminum composite foil, is made.

In one embodiment, the inactive layer in a housing at ground potential comprises at least one material layer corresponding to an uncoated positive electrode layer, and at least one material layer corresponding to a coated or uncoated negative electrode layer.

In a further embodiment of the electrode arrangement, the inactive layer may comprise at least one material layer which corresponds to the uncoated or coated electrode layer, which lies at the opposite-pole potential in comparison to the housing. In a preferred embodiment, the inactive layer comprises at least one material layer corresponding to a coated or uncoated negative electrode layer in the case of a housing at positive potential. In a further preferred embodiment, the inactive layer in a housing at negative potential comprises at least one material layer which corresponds to an uncoated positive electrode layer. In addition, the electrode assembly with inactive position may comprise at least one insulating layer, which serves for the electrical insulation of the individual electrode layers and / or the housing. According to the invention, a battery module is furthermore proposed which comprises at least two of the battery cells according to the invention. The battery cells can be connected in series or in parallel. Furthermore, a plurality of battery cells can be interconnected in a matrix, wherein the battery cells are connected in series in series or in parallel. Another object of the invention is the use of at least one

Battery cell according to the invention in a vehicle, in particular as a drive unit in a vehicle, and a vehicle comprising at least one battery cell according to the invention in particular as a drive unit. Advantages of the invention

The invention makes it possible to realize battery cells with an easy-to-implement

Provide protection mechanism that prevents in particular overheating of the battery cell. Thus, the inventively proposed battery cell with inactive position within the electrode assembly functions as a current-draining layer when the active layers are short-circuited. In this way, the battery cell can be transferred to the formation of the short circuit in the active position of the electrode assembly in a safe state. As a result, a subsequent reaction, such as overheating, which can lead to the ignition of the battery can be prevented. Such protective measures are of great interest, in particular for applications in the vehicle, in order to protect the driver and the passengers.

Furthermore, the proposed solution according to the invention can be easily integrated into the production of battery cells, since in addition to control engineering changes no additional measures are required. The additional electrode layers and

Separator layers of the inactive layer can be wound in particular in a wound

Electrode assembly can be easily integrated without having to make further production steps or changes to the production line. Brief description of the drawings

Embodiments of the invention are explained in more detail in the drawings. Show it:

1 shows an exploded view of a battery cell according to the invention

 wound electrode arrangement,

FIG. 2 shows a first exemplary embodiment of an electrode arrangement for the

 battery cell according to the invention according to FIG. 1,

Figure 3 shows a second embodiment of the electrode assembly for the

 battery cell according to the invention according to FIG. 1,

Figure 4 shows a third embodiment of the electrode assembly for the

 Battery cell according to FIG. 1 according to the invention.

Embodiments of the invention

Figure 1 shows schematically a battery cell 10 according to the invention with wound

Electrode arrangement 12 in exploded view.

The battery cell 10 includes a housing 14 in which an electrode assembly 12 is received. The housing 14 is further closed by a terminal cover 16 having an electrical connection from outside the housing 14 to the

Electrode arrangement 12 allows. For this purpose, the terminal cover 16 provides collectors (not shown) which are each electrically connected to an uncoated area 15 of a coated positive and a coated negative electrode layer 18, 20. The housing 14 of Figure 1 is designed as a hardcase in cylindrical shapes with an angular base. In other embodiments, the housing 14 may also assume other approximately cylindrical shapes with a round base. The housing 14 may further be made of different materials. For hardcases, for example, electrically conductive metals, such as steel, aluminum, aluminum alloys or plastics are suitable. In addition to the Hardcaseausführung the housing 14 and soft pack versions are possible, for example, made of films, in particular composite films such as aluminum composite film.

The electrode assembly 12 received in the housing 14 includes a

coated negative electrode layer 20 (anode) and a coated positive

 Electrode layer 18 (cathode), between which a separator layer 22 is embedded. In the exemplary electrode assembly 12 of FIG. 1, this is embodied as a winding electrode in which the stacked arrangement of coated negative and positive electrode layers 18, 20 with separator layer 22 therebetween is wound. Furthermore, the electrode arrangement 12 provides uncoated regions 24, which serve for electrical connection of the electrode layers 18, 20 to the terminals.

The electrode layers 18, 20 comprise an electrically conductive film with a corresponding coating. In this case, the coated positive electrode layer 18 (cathode) provides a medium into which positively charged lithium ions (Li ⁺ ) can be stored during discharge. For example, the coated positive electrode layer 18 may comprise an aluminum foil coated with an active material such as lithium metal oxides, vanadium oxides, olivines and lithium rechargeable oxides. Common coatings include transition metal oxides (LiM0 ₂ , M = Co, Ni, E, Mn, Al), lithium cobalt oxide (LiCo ₂ 0 ₄ ), lithium iron phosphate (LiFeP0 ₄ ), or lithium manganese oxide (LiMn ₂ 0 ₄ ). On the other hand, the coated negative electrode layer 20 (anode) provides the positively charged lithium ions and may include, for example, copper foil coated with an active material such as lithium, graphite, soft carbon, hard carbon, silicon, tin alloys, lithium alloyed material or intermetallics.

Between the electrodes 18, 20, a separator layer 22 is further introduced, which is permeable to the lithium ions and at the same time acts as an electrically insulating, in order to prevent direct contact between the electrode layers 18, 20 and thus a short circuit. For the separator layer 22, materials such as polymer membranes, ceramic materials or combinations thereof are suitable. For example, are useful as polymers

Polyethylene (PE), polypropylene (PP), polyimide (PI), polyethylene terephthalate (PTFE) or polyphenylidene fluoride (PVdF) and combinations thereof. Compared with polymers, ceramics such as alumina, barium oxide or titanium oxide have the advantage that they have a better heat resistance with their relatively high melting temperature of up to 700 ° C. The battery cell 10 from FIG. 1 can furthermore be used individually or as a composite of a plurality of battery cells 10 in a battery module. Such battery modules typically comprise at least two battery cells 10. Here, the

Battery cells 10 may be connected in series or in parallel in a battery module. In a further realization, the battery cells 10 of a battery module can be interconnected in a matrix, wherein the individual battery cells 10 are connected in series in series or in parallel. FIG. 2 shows an electrode arrangement 12 for the battery cell 10 according to the invention according to FIG. 1, wherein the electrode arrangement 12 comprises an additional inactive layer 30.

In the embodiment according to FIG. 2, the housing 14. 1 of the battery cell 10 is at ground potential with respect to the electrodes 18, 20. This includes the

Electrode assembly 12 between the active layer 28, which include the electrode layers 18, 20 and the separator layer 22, and the housing 14.1 an inactive layer 30. Das

Housing 14.1, the electrode layers 18, 20 and the separator layer 22 may be configured as described above. In particular, the housing 14.1, the electrode layers 18, 20 and the separator layer 22 may be made of the aforementioned materials.

In the embodiment according to FIG. 2, the inactive layer 30 comprises a material layer 24, which corresponds to the positive electrode layer 18 without coating, and a material layer 23, which corresponds to the negative electrode layer 20 in coated or uncoated form. Because the material layer 24, which corresponds to the positive electrode layer 18, is uncoated, this layer 24 is uncharged and thus inactive. If the battery cell 10 is damaged so that there is a short circuit between the positive and negative electrode layers 18, 20 of the active layer 28, the current flows through this inactive layer 30, in particular via the uncoated material layer 24, which corresponds to the positive electrode layer 18 , The battery cell 10 can thus be transferred to a safe state, and the probability of a subsequent reaction of the battery cell 10 is reduced.

For electrical insulation, between the layers of material 23, 24 of the inactive layer 30 and the active layer 28, an insulating layer 26, for example a separator layer 22, non-conductive foil or adhesive tape is provided. Another insulation layer 26, such as a Separatorlage 22, non-conductive foil or adhesive tape is inserted between the material layers 23 and 24. In addition, depending on the choice of material of the housing, between the housing 14.1 and the inactive layer 30, an insulating layer 26, such as a separator layer 22, non-conductive film or tape, may be provided. In a plastic housing 14.1 about this additional insulation layer 26 can be omitted.

Due to the inactive layer 30 with a material layer 24, which corresponds to the positive electrode 18 without coating with active material, this area is uncharged. If there is a short circuit between the negative electrode and the positive electrode 18, 20, for example, when the separator layer 22 melts by heating, the current flows through the inactive layer 30, in particular via the material layer 24, the material of the positive electrode 18 without active material coating includes. While this may not completely eliminate the effects of a short circuit, the battery cell 10 may be placed in a safer state than without the inactive layer 30. This reduces the likelihood that subsequent reactions will result in a fire or other consequences.

FIG. 3 shows a further embodiment of an electrode arrangement 12 for a

Battery cell 10 according to Figure 1, wherein the housing 14.2 relative to the electrode layers 18, 20 at a positive potential or at the potential of the positive electrode 18 is located.

In the embodiment according to FIG. 3, the housing 14. 2 of the battery cell 10 lies opposite the electrodes 18, 20 at a positive potential. Furthermore, the

Electrode assembly 12 between the active layers 28, which include the electrode layers 18, 20 and the separator layer 22, and the housing 14.2 an inactive layer 30. Das

Housing 14.2, the electrode layers 18, 20 and the separator layer 22 may be configured as described above. In particular, the housing 14.2, the electrode layers 18, 20 and the separator layer 22 may be made of the aforementioned materials.

Between the active layer 28 and the housing 14.2 is located in this

Embodiment an inactive layer 30 with a material layer 24, the negative

Electrode layer 20 corresponds. The material layer 24 in this configuration has no positive electrode as the opposite pole and is therefore inactive. For electrical insulation is between the successive electrodes 20 and 24, an insulating layer 26, in particular a separator layer 22, non-conductive foil or adhesive tape provided. The insulation between the material layer 24 and the housing 14.2 can also be effected by an insulating layer 26, such as a separator layer 22, adhesive tape or non-conductive film.

In the event of a short circuit in the active layer 28, the current flows in the embodiment according to FIG. 3 via the inactive layer 24 and the housing 14. This can be a

Protective device can be provided, which transfers the battery cell 10 in a safe state. Thus, although subsequent reactions, such as overheating, not

but the likelihood of such a reaction can be significantly reduced. In addition, results in a wound design over a stacked design, the advantage that the additional layers 30 can be easily and quickly integrated into the production process, since only control technical changes must be made and no modifications to the

Production facilities are necessary.

FIG. 4 shows a further embodiment of an electrode arrangement 12 for a

Battery cell 10 according to Figure 1, in which the housing 14 with respect to the electrode layers 18, 20 at a negative potential or at the potential of the negative electrode 20 is located.

 The embodiment illustrated in FIG. 4 also comprises a coated negative electrode layer 20 and a coated positive electrode layer 18, between which at least one separator layer 22 is provided. Furthermore, the

Electrode assembly 12 between the active layers 28, which include the electrode layers 18, 20 and the separator layer 22, and the housing 14.3 an inactive layer 30. Das

Housing 14.3, the electrode layers 18, 20 and the separator layer 22 may be configured as described above. In particular, the housing 14.3, the electrode layers 18, 20 and the separator layer 22 may be made of the aforementioned materials.

Between the active electrode structure 28 and the housing 14, in this embodiment, there is an inactive layer 30 with a material layer 24 that corresponds to the uncoated material of the positive electrode layer 18. For electrical insulation, an insulating layer 26 is provided between the successive positive and negative electrodes 20, 24. The insulating layer 26 between the negative electrode layer 24 and the Housing 14.3 can also be done by an insulating layer 26, such as a Separatorlage 22, tape and / or non-conductive film.

In the event of a short circuit in the active layer 28, the current also flows in this

Embodiment about the inactive layer 24 and the housing 14.3. As a result, a protective device can be provided, which transfers the battery cell 10 to a safe state, and the risk of subsequent reactions is significantly reduced.

In addition, the result of a wound design compared to a stacked design is the advantage that the additional layers 30 can be easily and quickly integrated into the production process, since only changes in control technology have to be made and no modifications to the production plants are necessary

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

Claims

Claims 1. A battery cell (10) comprising an electrode assembly (12) having an active layer (28) comprising at least one coated positive electrode layer (18) and at least one coated negative electrode layer (20) between which at least one separator layer (22) is provided the electrode assembly (12) within a housing (14, 14.1, 14.2, 14.3) is arranged, characterized in that the Electrode assembly (12) additionally comprises at least one inactive layer (30). 2. Battery cell (10) according to claim 1, characterized in that the Electrode assembly (12) is wound or stacked. 3. Battery cell (10) according to any one of claims 1 or 2, characterized in that the coated positive electrode layer (18) and the coated negative electrode layer (20) comprise a conductive foil which is coated with an active material. 4. battery cell (10) according to one of claims 1 to 3, characterized in that the housing (14, 14.1, 14.2, 14.3) is at a Massepotenial, a negative potential or a positive potential. 5. battery cell (10) according to one of claims 1 to 4, characterized in that the inactive layer (30) at a housing (14, 14.1, 14.2, 14.3) at ground potential at least one material layer (24), the uncoated positive electrode layer (18), and at least one layer of material (23) coated or coated uncoated negative electrode layer (20) corresponds. 6. battery cell (10) according to one of claims 1 to 5, characterized in that the inactive layer (30) in a housing (14, 14.1, 14.2, 14.3) on positive potential at least one layer of material (24) comprising a coated or uncoated negative electrode layer (20). 7. Battery cell (10) according to any one of claims 1 to 6, characterized in that the inactive layer (30) at a housing (14, 14.1, 14.2, 14.3) at a negative potential at least one material layer (24), which is an uncoated positive Electrode layer (18) corresponds. 8. battery cell (10) according to one of claims 1 to 7, characterized in that the inactive layer (30) comprises at least one insulating layer (26). 9. Battery module comprising at least two battery cells (10) according to one of claims 1 to 8. 10. Use of the battery cell (10) according to one of claims 1 to 8 in a vehicle. 1 1. Vehicle comprising at least one battery cell according to one of claims 1 to 8.