DE102013218248A1 - Electrochemical energy storage - Google Patents

Abstract

The present invention relates to an electrochemical energy store (10) comprising at least two electrochemical cell units (12, 14), the electrochemical cell units (12, 14) each having at least one electrochemical cell (13, 15), at least two cell units (12, 14) by means of a respective cell unit (12, 14) with a connection point (16) connecting electrical line (18, 20) are interconnected, wherein at least one electrical line (18, 20) upstream of the connection point (16) has a fuse (3 ) having. An energy store (10) according to the invention makes it possible, in the case of a particularly cost-effective manufacturability, that in the event of a fault, which in particular is accompanied by an increased flowing current, intact cell units (12, 14) can continue to operate and the system need not be switched off completely immediately.

Description

The present invention relates to an electrochemical energy store. In particular, the present invention relates to an electrochemical energy storage, such as a lithium-ion battery, with improved protection against damage from high currents.

State of the art

Electrochemical energy storage devices, such as lithium-ion batteries, are widely used in many daily applications. They are used, for example, in computers such as laptops, cell phones, smart phones, and other applications such as wind turbines. Even with the currently highly advanced electrification of vehicles, such as motor vehicles, such batteries offer advantages.

From the document US 6,335,114 B1 a battery is known which has coil-like electrodes of different polarity, between which electrodes separator layers are arranged. In this case, insulating layers should protect against a short circuit.

The document US 2009/0035658 A1 describes a battery assembly in which a laminated electrode group is provided. In this case, the electrode group can be connected to current conductors and these current conductors extend from the interior of a housing out of the housing.

Disclosure of the invention

The present invention is an electrochemical energy storage, comprising at least two electrochemical cell units, wherein the electrochemical cell units each comprise at least one electrochemical cell, wherein at least two cell units are interconnected by means of an electrical line connecting the respective cell unit with a connection point, wherein at least one electrical line upstream of the connection point has a fuse.

The above-described electrochemical energy storage allows in a simple and cost-effective manner to cause a fuse effect in the event of a short circuit and to be able to continue working safely at least in an emergency operation.

For this purpose, the electrochemical energy store comprises at least two electrochemical cell units. In this case, each of the electrochemical cell units has at least one electrochemical cell. In other words, one or a plurality of the electrochemical cell units may for example consist of only one electrochemical cell, or one or more of the electrochemical time units may have a plurality of electrochemical cells. The electrochemical cells of an electrochemical time unit can be connected in parallel or in series depending on the desired electrical specifications of the energy store.

An electrochemical cell may be substantially configured as known in the art, including an anode, a cathode, a separator, and an electrolyte. For example, for the exemplary case of a lithium-ion battery, the anode may be comprised of metallic lithium or a material that can intercalate lithium ions. For example, such an anode material may be applied to a current collector, such as scored. Exemplary anode materials include graphite or lithium titanate. The cathode can accordingly, likewise for the purely exemplary case of a lithium-ion battery, have nickel-manganese-cobalt-oxide (NMC) or lithium-cobalt-oxide (LiCoO ₂ ) or be configured therefrom and likewise be applied to a current conductor , Optionally, the cathode material as well as the anode material may be present in a binder, such as polyvinylidene fluoride (PVDF), for example, along with a conductive additive, such as an electrically conductive carbon compound, such as graphite.

The electrolyte can likewise be, for example, a solid electrolyte in a manner known per se or comprise a solvent in which one or more electrically conductive salts are dissolved. For example, aprotic solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate or diethyl carbonate can be used. Furthermore, as the electrically conductive salt lithium hexafluorophosphate (LiPF ₆ ) can be used. For example, the electrolyte may be located in pores of the separator. The separator may for example be a particular porous plastic film, such as formed from polypropylene.

In this case, such an electrochemical cell may be, for example, a so-called jelly roll prismatic cell and thus an arrangement of electrodes which are provided in a wound, for example rolled or folded configuration and wherein a separator layer is provided between the electrodes. Such a configuration can be realized, for example, by applying a correspondingly described electrode layer on both sides to a metal collector. The metal collector can thereby depending on the polarity of the electrode Aluminum or copper. Furthermore, a separator layer can separate the outermost electrode layer from a housing or an insulating layer surrounding the cell.

Furthermore, it is provided that at least two cell units are connected to one another by means of an electrical line connecting the respective cell unit to a connection point. In this case, the different cell units can be connected, for example, in series and or in parallel, wherein the exact circuit can be dependent on the desired electrical power provided or on the specification of the electrochemical energy store.

A connection of the different cell units can thus be realized by an electrical line, which can basically be designed freely. In particular, the electrical line should be designed such that it can easily perform the current occurring in a normal operation of the electrochemical energy storage in dependence on the provided power of the energy storage, without overheating, for example. For example, the line may be designed as a cable or as a busbar. In this case, only one electrical line can be provided, or a plurality of electrical lines can connect the different cell units together. Furthermore, the electrical lines, starting from the cell unit, can in particular lead to a connection point to which electrical lines of a plurality, that is, at least two, of cell units are connected, wherein the electrical lines can be separate components or components of the cell unit or of the cell. For example, the electrical wires may be welded at the connection point. The connection point thus serves to electrically connect the various cell units.

Furthermore, according to the above-described embodiment of the electrochemical energy storage device, at least one electrical line has a fuse upstream of the connection point. In other words, the fuse is arranged such that it may be part of the cell or the cell unit depending on the configuration of the electrical line or is arranged between the cell or the cell unit and the connection point. Such a fuse can serve, in particular, to interrupt the electrical conduction when too high a current flows, which in particular can cause damage to the energy store. Thus, in the occurrence of a fault associated with a high flowing current such as a short circuit, thermal runaway of the battery or other potential hazards to the energy store itself and / or components or people located in the vicinity of the energy store may be significantly reduced or completely eliminated be prevented. Thus, the fuse is particularly a security gain for people in the environment of the energy storage, and also serves to minimize the risk potential, which emanates from an error case.

Furthermore, because the fuse is arranged, for example, between a cell unit and the connection point, it becomes possible to protect the individual cell units individually. In other words, each cell unit, which may comprise only one cell, for example, can be disconnected from the system separately in the event of an error, so that it remains possible to continue using the other, non-corrupt cell units. As a result, only the power of the damaged cell unit can be lost, but the system equipped with such an energy store can continue to operate, at least in an emergency operation. This can be of great advantage, for example, for electrically driven vehicles, since an error situation in a cell unit according to the invention does not necessarily lead to discomfort, but, for example, it can still be easily possible to control a workshop.

In addition, the isolated fuse can prevent the current of the intact cells from flowing through the faulty cell in the event of an internal short circuit, for example. The fuses can thus be designed weak, which can save significant costs.

In summary, an energy store according to the invention thus makes it possible, with a particularly cost-effective manufacturability, to continue working in an error case, which in particular involves an increased flowing current, and the system does not need to be switched off completely immediately.

As part of an embodiment, the fuse may be configured as a fuse. In such an embodiment, in particular a fuse can be used, which operates without the provision of further control mechanisms solely by the heat occurring due to excessive current and interrupts the electrical line. Thus, a particularly reliable interruption of the electrical line can be made possible in this embodiment. Furthermore, in the case of such a fuse, it has a comparatively weak design, as explained above, owing to the arrangement of the fuse or can be dimensioned small. For when melting a fuse, the heat generation in an energy storage device according to the invention is significantly lower than when a larger current flows through the fuse, as would be the case for the positioning behind the connection points. As a result of the lower heat development, the safety of the cell or of the energy store can thus be further increased, in particular by preventing adjacent components and, for example, the housing from being damaged by the heat generation.

In this case, the fuse can be configured in particular by a cross-sectional reduction of the electrical line. In particular, in this embodiment, a particularly simple and inexpensive design of the fuse is possible. Because there are no additional materials or components are introduced into the line, but the line can be provided only by a targeted reduction of the cross section or the diameter of the line with a fuse, the area with reduced cross section or the fuse area in the occurrence of a high current melts and breaks the electrical line so. A Querschnittreduzierung can be realized directly in a manufacturing process of the line, or about by material-removed machining processes. Thus, this embodiment allow a particularly cost-effective embodiment of the fuse.

In the context of a further embodiment, the electrical conduction can be a cross-section reduction to a cross section with a size in a range from greater than or equal to 6% to less than or equal to 75%, in particular greater than or equal to 20% to less than or equal to 50%, compared to the cross section outside the range of reduced cross-section. For example, the normal cross section of the electric wire may be in a range of greater than or equal to 5 mm ² to less than or equal to 8 mm ² , whereas the cross section in the region of the fuse may be in a range of greater than or equal to 0.5 mm ² to smaller or equal equal to 5 mm ² , for example greater than or equal to 1.5 mm ² to less than or equal to 3.5 mm ² , in particular 1.75 mm ² can be. In particular, in this embodiment, it can be ensured that a reliable opening of the electrical line can occur in case of failure, since a melting of the entire line can take place after the occurrence of a fault or after the beginning of flow of an increased current in a suitable time window. In addition, however, sufficient material thickness may be present to allow flow of current without the occurrence of excessive electrical resistance in normal operation. In this case, the specific selected cross-section in the fuse may depend in particular on the selected material of the electrical line as well as on the normal operation of the energy storage current and about a limit at which the fuse should open the line.

In a further embodiment, the fuse may be surrounded by a plastic cover. By a plastic sheath or plastic sheath of the fuse portion of the electrical line can be made possible in particular in the provision of a fuse that melted in the occurrence of a fault and concomitant with a melting of the fuse area molten material from the electrical line and thus pollute the electrochemical energy storage from the inside and prevent the execution of an emergency operation, for example by occurring short circuits. Non-limiting examples of useful plastics include, for example, polypropylene (PP), polyethylene (PE), perfluoroalkoxyalkane (PFA), polyphenylene sulfide (PPS), or polyethylene terephthalate (PTFE).

In the context of a further embodiment, the electrical line can be a current conductor of a cell unit. In particular, the electrical line may be a current conductor of an electrochemical cell provided in the cell unit, wherein, in particular in this embodiment, the fuse may be part of the cell or of the cell unit. This embodiment may allow a particularly simple manufacturing process, since no additional electrical lines need to be inserted. Thus, manufacturing steps can be dispensed with. In addition, in particular current conductors can often be constructed of a material which is suitable, for example, to be able to form a fuse by means of a cross-sectional reduction. Thus, in this embodiment, the advantageous properties of the current conductor can be used, with a particularly cost-effective production is possible.

In the context of a further embodiment, the electrical line can be made of aluminum. In particular, aluminum can be particularly advantageously suitable as an electric line in the context of the present invention. For on the one hand aluminum has a good electrical conductivity in order to allow the flow of a desired current without problems during normal operation of the electrochemical energy store. In addition, the melting point of aluminum is low enough, for example, in a Querschnittreduction of the electrical line in the Occurrence of an increased current to allow the melting of the material easily and thus to realize an opening of the line. In addition, aluminum offers the further advantage that this material has a low weight and thus is particularly suitable for mobile applications, such as when using the energy store in an at least partially electrically powered vehicle. Furthermore, aluminum may therefore be suitable because it can also be used, in particular, as a current conductor material, for example for the cathode.

In the context of a further embodiment, an electrochemical cell unit can have only one electrochemical cell. In other words, in this embodiment, in one or a plurality, for example in all, of the provided electrochemical cell units, only one electrochemical cell is present. For example, the cell unit may consist of the electrochemical cell. In this embodiment, therefore, essentially each electrochemical cell can be secured individually by a fuse. It can thus be made possible that, when an error occurs in an electrochemical cell, all error-free electrochemical cells or cell units can continue to work without problems. Thereby, an emergency operation when the fuse of the defective cell unit has opened the electric wire can be performed with a particularly high performance. As a result, normal operation of the electrochemical energy store can be continued with only slightly reduced power, so that an exchange of the cell unit can be carried out, for example, at a scheduled service appointment.

In a further embodiment, a cell unit may have at least two electrochemical cells. In this embodiment, more than one electrochemical cell is provided in at least one or more, for example in all, of the provided cell units. For example, in individual or in several, for example in all, of the cell units, two cells can be combined into a cell unit in pairs. In this embodiment, a separate hedging of the individual cell units is still possible, but this is the fact that not every single cell is secured, a reduced amount of fuses necessary. Thus, in this embodiment, an emergency operation continue to be possible, however, a particularly cost-effective manufacturing process will be possible, since in a waiver of fuses the cost of production can be reduced.

Examples and drawings

Further advantages and advantageous embodiments of the subject invention are illustrated by the drawings and explained in the following description. It should be noted that the drawings have only descriptive character and are not intended to limit the invention in any way. Show it

1 a schematic representation of a partial view of an embodiment of an electrochemical energy storage device; and

2 an enlarged view of the representation 1 ,

In 1 is a schematic representation of a partial view of an embodiment of an electrochemical energy storage device 10 shown. The energy storage 10 For example, it can be a lithium-ion battery and be arranged approximately in an at least partially electrically driven vehicle.

The electrochemical energy storage 10 comprises at least two electrochemical cell units 12 . 14 , wherein the electrochemical cell units 12 . 14 in each case at least one electrochemical cell 13 . 15 exhibit. In the embodiment according to 1 indicates each of the electrochemical cell units 12 . 14 an electrochemical cell 13 . 15 on. Here are according to 1 the two cell units 12 . 14 for example by means of at least one between the cell unit 12 . 14 and a connection point 16 extending electrical line 18 . 20 at the connection point 16 connected with each other. The wires 18 . 20 are thus at the connection point 16 merged and connected there, for example, welded. The cells 13 . 15 the cell units 12 . 14 For example, they may be formed as a prismatic cell and thus a cell coil 22 . 24 exhibit. Continue to show the cells 13 . 15 the cell units 12 . 14 a current collector 26 . 28 on, which can go beyond the dimensions of the wound electrodes and, for example, with the electrical line 18 . 20 can be connected or form this.

For lithium-ion cells, for example, the electrode material is applied to aluminum or copper foil. These are superimposed and wound up, with a Separatorfolie is arranged as a release layer between the individual windings. One side of each of the metal foils is equipped with an arrester 26 . 28 from the corresponding material combined to form an electrode.

cell units 12 . 14 with high power are doing of several of the above-described also called Jelly Rolls cell wraps 22 . 24 or cells 13 . 15 composed. A cell unit 12 . 14 which supplies 21 or 24 ampere hours, for example, comprises two cell wraps 22 . 24 Cell units with a capacity of 40 or 60 ampere hours can even have three or four cell wraps 22 . 24 The above values are intended to be illustrative only and not restrictive in any way.

Furthermore, at least one electrical line 18 . 20 upstream of the connection point 16 a fuse 3 on, which can be configured for example as a fuse. In a non-limiting example, the fuse can be replaced by a cross-section reduction of the electrical line 18 . 20 be configured, the electrical line 18 . 20 in the cross-cut reduction or in the region of the fuse may have a cross section in a range of greater than or equal to 6% to less than or equal to 75%, compared to the cross section outside the range of reduced cross-section. Furthermore, the fuse 30 , respectively, can the line 18 . 20 in the field of security 30 surrounded by a plastic cover, such as jacketed be.

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

• US 6335114 B1 [0003]
• US 2009/0035658 A1 [0004]

Claims (10)

Electrochemical energy store, comprising at least two electrochemical cell units ( 12 . 14 ), the electrochemical cell units ( 12 . 14 ) at least one electrochemical cell ( 13 . 15 ), wherein at least two cell units ( 12 . 14 ) by means of a respective cell unit ( 12 . 14 ) with a connection point ( 16 ) connecting electrical line ( 18 . 20 ), at least one electrical line ( 18 . 20 ) upstream of the connection point ( 16 ) a fuse ( 30 ) having. Energy storage according to claim 1, wherein the fuse ( 30 ) is designed as a fuse Energy store according to claim 2, wherein the fuse by a cross-sectional reduction of the electrical line ( 18 . 20 ) is configured. Energy store according to claim 3, wherein the electrical line ( 18 . 20 ) has a cross-sectional reduction to a cross-section having a size in a range from greater than or equal to 6% to less than or equal to 75%, in particular greater than or equal to 20% to less than or equal to 50%, compared to the cross-section outside the range of reduced cross-section , Energy store according to one of claims 1 to 4, wherein the fuse ( 30 ) is surrounded by a plastic shell. Energy store according to one of claims 1 to 5, wherein the electrical line ( 18 . 20 ) a current conductor ( 26 . 28 ) of a cell unit ( 12 . 14 ). Energy store according to one of claims 1 to 6, wherein the line ( 18 . 20 ) is made of aluminum. Energy store according to one of claims 1 to 7 wherein at least one cell unit ( 12 . 14 ) only one electrochemical cell ( 13 . 15 ) having. Energy store according to one of claims 1 to 7, wherein at least one cell unit ( 12 . 14 ) at least two electrochemical cells ( 13 . 15 ) having. Energy store according to one of claims 1 to 9, wherein the energy store ( 10 ) is a lithium-ion battery.

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