DE102012018128A1 - Single cell e.g. lithium ion cell, for use in elliptic column-type non-aqueous electrolyte battery for electric car, has electrode film arrangement pressed against wall of cell housing by elastic element that is designed as hollow body - Google Patents

Abstract

The cell (1) has an electrode film arrangement (3) and an elastic element (2) arranged in a cell housing (5). The electrode film arrangement is pressed against a housing wall (5.1) of the cell housing by the elastic element that is designed as a fluid-tight gas filled hollow body (6). The elastic element is made of a plastic material and a closed-pore foam material, where the elastic element corresponds to the planar expansion anodes and/or cathodes of the electrode film arrangement. The elastic element is arranged in the electrode film arrangement. Independent claims are also included for the following: (1) a battery (2) a method for manufacturing a single cell.

Description

The invention relates to a single cell for a battery according to the features of the preamble of claim 1, a battery according to the features of the preamble of claim 8 and a method for producing a single cell according to the features of the preamble of claim 10.

From the prior art, as in the DE 33 21 129 A1 described a non-aqueous electrolyte cell of the elliptical column type. The battery includes an elliptical column type spiral electrode assembly which is formed by winding positive and negative electrode plates separated by a separator. Further, the battery comprises an elastic member positioned in the center of the electrode assembly and normally unclamps this electrode assembly from the center to the outward directions of the larger and smaller radius parts by elastically compressing it as the helical electrode assembly winds, such that the latter after winding by its elastic restoring force to all radial directions of the spiral cross-section pushes outward.

In the DE 30 00 469 C2 a cylindrical electrochemical element will be described. The positive electrode of this electrochemical element communicates with the outer wall and is separated from the negative electrode by a porous separator. The negative electrode consists of a metal foil wound around a current collector with a strong negative potential. The collector has the shape of a tube which is cut parallel to the axis and elastically deformable. At least the two tubular parts of the collector lying in the vicinity of the cut line are cut out in a complementary manner, so that they engage with one another, in that the projecting regions of one pipe part come to rest in the notch regions of the other pipe part. The metal foil, which forms the negative electrode, is subdivided into at least two parts by at least one cut extending parallel to the cylinder axis.

The invention has for its object to provide an improved single cell for a battery, an improved battery and an improved method for producing a single cell for a battery.

The object is achieved by a single cell for a battery having the features of claim 1, a battery having the features of claim 8 and a method for producing a single cell for a battery having the features of claim 10.

Advantageous embodiments of the invention are the subject of the dependent claims.

A single cell for a battery, i. H. for an electrochemical energy store and / or energy converter, comprises a cell housing in which an electrode foil arrangement and at least one elastic element are arranged, wherein the electrode foil arrangement is pressed against at least one housing wall of the cell housing by the at least one elastic element.

According to the invention, the at least one elastic element is designed as a fluid-tight gas-filled hollow body or has at least one fluid-tight gas-filled hollow body.

The electrode foil assembly is formed by layers of cathode foils and anode foils, i. H. in lithium-ion cell chemistry, layers of coated aluminum foils and copper foils are formed, each separated by layers of a separator. In this example, individual sheets of cathode sheets, anode foils and separators are stacked or tapes are wound from these, preferably flat wound, or a strip-shaped separator is folded in Z-shape and the cathode foil sheets or anode foil sheets are laterally in itself by the Z-forming Pockets inserted. The anode foils and cathode foils are uncoated at at least one edge and protrude out of the electrode foil assembly in the form of current collector tabs which are connected to respective components for current delivery to an outside of the housing.

For proper operation of the single cell, the electrode foil assembly is to be pressed with a predetermined force so that, for example, a required distance of the cathode foils, anode foils and separators to one another in the electrode foil arrangement is set. When the individual cell is filled with an electrolyte, when a single cell is formed and as a function of a state of charge and an aging state of the individual cell, as well as in dependence on a temperature of the single cell, a thickness of the electrode foil arrangement changes.

By means of the at least one elastic element which is designed as a fluid-tight gas-filled hollow body or at least has a fluid-tight gas-filled hollow body, such changes in thickness of the electrode foil arrangement can be compensated in a simple and cost-effective manner. The elastic element compresses the electrode foil arrangement in the individual cell in a predetermined manner according to the principle of a gas spring or air spring. In this case, a spring rate and a thickness of the elastic element and thereby a pressing action on the electrode foil arrangement by a corresponding design of the elastic element and / or by a filling of the elastic element with a predetermined amount of a gas, for example air, dried air or an inert gas, for example nitrogen or argon, pretending and thereby sufficient in a simple manner to adjust exactly. In this case, only a very small space in the single cell is required for the thus formed elastic element, so that the single cell is more compact than other solutions known from the prior art.

The elastic element makes it possible, in comparison to other solutions known from the prior art, for example elastic cell housings, which can be used only with relatively small changes in thickness of the electrode foil arrangement and only in the case of flat individual cells, to compensate for larger changes in thickness of the electrode foil arrangement in the single cell. Another solution known from the prior art is the use of a fleece. However, these webs lead to a much higher space requirement than in the inventive solution, since only a portion of a thickness of the web to compensate for changes in thickness of the electrode foil arrangement is available, because a possible compensation path of the web corresponds to the difference of a thickness of the web in a non-compressed Condition and a thickness of the web in a fully compressed state. Such nonwovens also tend to set under the action of a compressive force, d. H. resulting in a plastic deformation, resulting in a reduction of a pressing force acting from the nonwoven to the electrode foil assembly. This is not the case with the inventive solution with the elastic element, which has at least one fluid-tight gas-filled hollow body or is designed as such a fluid-tight gas-filled hollow body. Furthermore, such known from the prior art nonwovens suck with electrolyte full, so that a larger amount of electrolyte in the single cell is required. This leads to a higher weight of the single cell known from the prior art compared to the single cell designed according to the invention.

The described disadvantages of the prior art with respect to the plastic deformation of the elastic element over a lifetime of the single cell with a resulting loss of pressing force on the electrode foil assembly, with respect to the entry of electrolyte into an enclosed by the elastic element interior, which then not effective from the single cell is to be used for electrochemical energy storage and / or conversion and a higher weight of the single cell means, and with respect to a large required space to meet also known from the prior art, designed as a bent metal part elastic element.

The single cell is advantageously designed as a flat cell, for example as a so-called hardcase cell, in which an electrochemically active content, d. H. in particular, the electrode foil arrangement and an electrolyte is surrounded by a substantially rigid and mostly metallic cell housing. These hardcase cells can be designed, for example, as bipolar frame flat cells or as so-called prismatic hardcase cells.

Conveniently, the at least one elastic element is made of plastic, in particular of an electrolyte-resistant plastic, for example of polypropylene (PP) or polyethylene terephthalate (PET). As a result, damage to the elastic element by the electrolyte is avoided, so that the force acting on the electrode foil assembly by the elastic member pressing force is ensured over a lifetime of the single cell.

The elastic element is formed in a particularly advantageous embodiment as a pillow-like hollow body. This is a particularly space-saving solution. The elastic element is formed in this embodiment, for example, from a hose which has a small wall thickness. After filling with the gas ends of the tube material, form and / or non-positively close, preferably to be welded. In this way, the elastic element is formed in one piece and has only two closure points, which are preferably closed by welding. This allows a particularly stable and fluid-tight elastic element. Alternatively, the elastic element in this embodiment, for example, by two mutually superimposed and on peripheral side edges material, form and / or non-positively interconnected, preferably welded together form a complete closure of course only after filling with the gas. Another possibility of forming the elastic element of this embodiment is a targeted folding of a film such that it encloses a cavity. This folded film is then material, form and / or non-positively close on three sides, for example by welding. A fourth page is already closed by the folding of the film. The complete closing of course also takes place here first after filling with the gas. Also, this elastic element is integrally formed, so that a particularly stable and fluid-tight elastic element is made possible.

In a further advantageous embodiment, the at least one elastic element is formed from a closed-cell foam. In this foam whose closed pores or bubbles, in each of which a gas is enclosed, each form a fluid-tight gas-filled hollow body, that is, the elastic element then has a plurality of fluid-tight gas-filled hollow body. The closed-cell foam is expediently a foamed and therefore elastic plastic, for example polypropylene (PP), polyethylene terephthalate (PET), polyethylene (PE), polyurethane (PU) or polystyrene (PS). The gas in the pores or bubbles of the foam already forms during manufacture of the foam, ie during foaming of the plastic, by a chemical reaction and / or is added to the plastic during manufacture of the foam to foam the plastic.

Preferably, a planar expansion of the at least one elastic element substantially corresponds to a planar expansion of at least one of anodes and / or cathodes of the electrode foil arrangement or a planar extension of the entire electrode foil arrangement, i. H. also of areas which are not used as anodes or cathodes. In this way, the elastic element covers an entire area of the electrode foil arrangement or at least an entire area of the anodes and / or cathodes, so that a uniform full-surface pressing action of the elastic element on the electrode foil arrangement is achieved. In this way, it is ensured that predetermined distances between the layers of the anode foils, cathode foils and separators can be maintained during a lifetime of the individual cell and are constant over a total areal extent of the electrode foil arrangement. This allows optimal functioning of the single cell.

Preferably, the at least one elastic element is arranged in the electrode foil arrangement. Although it is also possible to arrange the at least one elastic element between the cell housing and the electrode foil arrangement, in particular in single cells, in which the cell housing or at least parts of the cell housing are metallic and serve due to a resulting good thermal conductivity of a temperature of the single cell, d. H. a cooling and / or heating of the single cell, the embodiment in which the at least one elastic element is arranged in the electrode foil arrangement, but particularly advantageous because in this embodiment, the electrode foil arrangement as large as possible by means of the elastic element against the cell housing, d. H. is pressed against one or more housing walls of the cell housing, thereby optimizing heat transfer from the electrode foil assembly to the cell housing to dissipate heat from the single cell or from the cell housing to the electrode foil assembly to absorb heat.

Since the elastic member is disposed in the electrode foil assembly and not between the electrode foil assembly and the cell case, no portions of the cell case are hidden by the elastic member, i. H. no area of the cell housing is thermally insulated from the electrode foil arrangement by the elastic element. In order to exert an optimally distributed pressing force on the electrode foil arrangement by means of the at least one elastic element, the at least one elastic element is preferably arranged centrally in the electrode foil arrangement, so that in all directions or at least in the directions of normal vectors of surfaces defined by the anodes and cathodes, d. H. perpendicular to these surfaces and in the direction of the cell housing, the same pressing force acts on the anode foils, cathode foils and separators and presses them evenly in the direction of the cell housing.

A shell of the at least one elastic element preferably has a diffusion barrier layer. The diffusion barrier layer is expediently formed of metal, for example as a metal coating or a metal foil, for example of aluminum, which is introduced into the shell or applied to the shell, d. H. on an inside and / or outside of the shell. In the embodiment of the elastic element formed as a pillow-like hollow body, for example, the metal foil, for example aluminum foil, laminated in a plastic film to form the pillow-like hollow body and / or laminated to an inside or outside of the plastic film or the plastic film is on the inside and / or outside coated with metal. In the embodiment of the elastic member formed of the closed-cell foam, for example, an outer surface of the elastic member may be metal-coated or wrapped with a metal foil. Diffusion barrier layers of another material are also possible.

Advantageously, an internal pressure in the cell housing is lower than an ambient pressure of the single cell. Ie. a cell interior of the single cell has a negative pressure. This can be achieved for example by a so-called evacuation of the individual cell before a fluid-tight, in particular gas-tight sealing of the cell housing. Here, gases, for example air, to be sucked out of cavities of the single cell, which after filling the Housing with all components, ie in particular with the electrode foil assembly and the electrolyte, initially still remain in the single cell. By this negative pressure or by an overpressure in the outer environment of the single cell, a back pressure through the cell housing is made possible, which counteracts the pressure exerted by the at least one elastic element pressure or the pressing force of the at least one elastic element on the electrode foil arrangement, so that the electrode foil arrangement is pressed in a predetermined manner.

The negative pressure in the cell housing or the overpressure in the vicinity of the cell housing relative to an interior in the cell housing pulls or presses housing walls of the cell housing inwards, in the direction of the electrode foil arrangement, and thus increases their rigidity. This evacuation of the single cell is particularly advantageous if the cell housing is not sufficiently rigid, so that it would deform plastically and / or elastically by the pressing force of the at least one elastic element, d. H. the press force would give and would deform outward. Such an outward deformation counteracts the negative pressure in the cell housing and the resulting overpressure of an external environment of the cell housing, which acts on the cell housing, so that the cell housing does not deform or deform inwardly in the direction of the electrode foil arrangement.

A battery according to the invention, d. H. an inventive electrochemical energy storage and / or energy converter comprises at least one cell network with a plurality of electrically connected in series and / or parallel to each other such individual cells. The battery is preferably a vehicle battery, in particular a battery for a hybrid vehicle, for a fuel cell vehicle or for an electric vehicle. The battery is expediently a so-called high-voltage battery. The advantages described for the single cell according to the invention, since the battery has a plurality of such individual cells, also apply to the battery. In particular, a weight reduction and size reduction of the battery as well as an improved function of the battery is achieved by the individual cells, which each have at least one such elastic element.

Preferably, the individual cells in the cell assembly are clamped or pressed together. This can be done for example by means of tension bands, tie rods and / or other tensioning devices. For optimum clamping, the cell composite has pressure gauges on its end faces, for example, which are then to be braced against one another by means of tensioning straps, tie rods and / or other tensioning means, whereby the individual cells of the cell composite arranged therebetween are pressed together. In this case, the individual cells are based, for example, either directly or via partitions and / or spacers, so-called spacers, on adjacent individual cells. In this way, analogous to the negative pressure in the single cell and the resulting pressure of an external environment on the single cell, a support of the cell housing of the individual cells against a plastic and / or elastic deformation is achieved to the outside, so that the cell housing of the pressing force of at least do not yield an elastic element in the respective single cell and an optimal pressing action is achieved on the electrode foil assembly.

In a method according to the invention for producing such a single cell, an electrode foil arrangement and at least one elastic element which is designed as a fluid-tight, gas-filled hollow body or at least has a fluid-tight gas-filled hollow body are arranged in a cell housing in such a way that the electrode foil arrangement opposes the at least one elastic element at least one housing wall of the cell housing is pressed.

The electrode foil assembly is formed by layers of cathode foils and anode foils, i. H. formed in a lithium-ion cell chemistry of layers of coated aluminum foils and copper foils, which are each separated by layers of a separator. In this case, for example, individual sheets of cathode foils, anode foils and separators are stacked or tapes are wound from these, preferably flat wound, or a ribbon-shaped separator is folded in Z-shape and the cathode foil sheets or anode foil sheets are laterally in itself by the Z-forming Pockets inserted. The anode foils and cathode foils are left uncoated on at least one edge and formed and / or arranged so that they protrude from the electrode foil arrangement in the form of current discharge lugs, which are connected to corresponding components for the current output on a housing outside.

For proper operation of the single cell, the electrode foil assembly is pressed with a predetermined force, so that, for example, a required distance of the cathode foils, anode foils and separators to each other in the electrode foil arrangement is set. In a filling of the single cell with an electrolyte, in a formation of the single cell and in dependence on a state of charge and an aging state of the single cell and in dependence on a Temperature of the single cell, a thickness of the electrode foil arrangement changes.

By means of the at least one elastic element which is designed as a fluid-tight gas-filled hollow body or at least has a fluid-tight gas-filled hollow body, such changes in thickness of the electrode foil arrangement can be compensated in a simple and cost-effective manner. The elastic element compresses the electrode foil arrangement in the individual cell in a predetermined manner according to the principle of a gas spring or air spring. In this case, a spring rate and a thickness of the elastic element and thereby a pressing action on the electrode foil assembly by a corresponding design of the elastic member and / or by filling the elastic member with a predetermined amount of a gas, for example air, dried air or an inert gas to Example nitrogen or argon, given and thus adjusted in a simple manner with sufficient accuracy. This filling of the elastic element with the gas must be carried out with a suitable device in order to predetermine with sufficient accuracy the amount of gas trapped in the at least one hollow body of the elastic element and thereby the spring rate and thickness of the elastic element. The device, for example a compressor or a compressed gas container, must have at least one filling quantity and / or pressure determining unit for determining an amount and / or a pressure of the gas in the hollow body. For the thus formed elastic element only a very small space in the single cell is required, so that the single cell can be made more compact compared to other solutions known from the prior art.

The elastic element makes it possible, in comparison to other solutions known from the prior art, for example elastic cell housings, which can be used only with relatively small changes in thickness of the electrode foil arrangement and only in the case of flat individual cells, to compensate for larger changes in thickness of the electrode foil arrangement in the single cell. Another solution known from the prior art is the use of a fleece. However, these webs lead to a much higher space requirement than in the inventive solution, since only a portion of a thickness of the web to compensate for changes in thickness of the electrode foil arrangement is available, because a possible compensation path of the web corresponds to the difference of a thickness of the web in a non-compressed Condition and a thickness of the web in a fully compressed state. Such nonwovens also tend to set under the action of a compressive force, d. H. resulting in a plastic deformation, resulting in a reduction of a pressing force acting from the nonwoven to the electrode foil assembly. This is not the case with the inventive solution with the elastic element, which has at least one fluid-tight gas-filled hollow body or is designed as such a fluid-tight gas-filled hollow body. Furthermore, such known from the prior art nonwovens suck with electrolyte full, so that a larger amount of electrolyte in the single cell is required. This leads to a higher weight of the single cell known from the prior art compared with the single cell formed by means of the method according to the invention.

The described disadvantages of the prior art with respect to the plastic deformation of the elastic element over a lifetime of the single cell with a resulting loss of pressing force on the electrode foil assembly, with respect to the entry of electrolyte into an enclosed by the elastic element interior, which then not effective from the single cell is to be used for electrochemical energy storage and / or conversion and a higher weight of the single cell means, and with respect to a large required space to meet also known from the prior art, designed as a bent metal part elastic element.

Conveniently, the at least one elastic element is formed prior to placement in the cell housing made of plastic, in particular of an electrolyte-resistant plastic, for example of polypropylene (PP) or polyethylene terephthalate (PET). Thereby, damage to the elastic member by the electrolyte is avoided, so that the pressing force acting on the electrode foil assembly by the elastic member is ensured over a lifetime of the single cell.

The elastic element is formed in a particularly advantageous embodiment as a pillow-like hollow body. This is a particularly space-saving solution. The elastic element is formed in this embodiment, for example, from a hose which has a small wall thickness. After filling with the gas ends of the tube are closed material, positive and / or non-positive, preferably welded. In this way, the elastic element is formed in one piece and has only two closure sites, which are preferably closed by welding. This allows a particularly stable and fluid-tight elastic element. Alternatively, the elastic element in this embodiment is formed, for example, by two films arranged on top of one another, which are connected to one another at peripheral side edges in a material, positive and / or non-positive manner, are preferably welded together, with a complete closure of course only after filling with the gas. Another possibility of forming the elastic element of this embodiment is to fold a film so targeted that it encloses a cavity. This folded film is then closed material, positive and / or non-positive on three sides, for example, welded. A fourth page is already closed by folding the film. The complete closing course, of course, only after filling with the gas. This elastic element is also formed in one piece, so that a particularly stable and fluid-tight elastic element is made possible.

In a further advantageous embodiment, the at least one elastic element is formed from a closed-cell foam. In this foam, its closed pores or bubbles, in each of which a gas is enclosed, each form a fluid-tight gas-filled hollow body, d. H. the elastic element then has a plurality of fluid-tight gas-filled hollow bodies. The closed-cell foam is expediently a foamed plastic, for example polypropylene (PP), polyethylene terephthalate (PET), polyethylene (PE), polyurethane (PU) or polystyrene (PS). The gas in the pores or bubbles of the foam already forms during manufacture of the foam, i. H. during foaming of the plastic, by a chemical reaction and / or is added to the plastic during the manufacture of the foam to foam the plastic.

Preferably, the at least one elastic element is arranged in the electrode foil arrangement. Although it is also possible to arrange the at least one elastic element between the cell housing and the electrode foil arrangement, in particular in single cells, in which the cell housing or at least parts of the cell housing are metallic and serve due to a resulting good thermal conductivity of a temperature of the single cell, d. H. a cooling and / or heating of the single cell, the embodiment in which the at least one elastic element in the electrode foil assembly is arranged, but particularly advantageous because in this embodiment, the electrode foil arrangement as large as possible by means of the elastic element against the cell housing, d. H. is pressed against one or more housing walls of the cell housing, thereby optimizing heat transfer from the electrode foil assembly to the cell housing to dissipate heat from the single cell or from the cell housing to the electrode foil assembly to absorb heat.

Since the elastic member is disposed in the electrode foil assembly and not between the electrode foil assembly and the cell case, no portions of the cell case are hidden by the elastic member, i. H. no area of the cell housing is thermally insulated from the electrode foil arrangement by the elastic element. In order to exert an optimally distributed pressing force on the electrode foil arrangement by means of the at least one elastic element, the at least one elastic element is preferably arranged centrally in the electrode foil arrangement, so that in all directions or at least in the directions of normal vectors of surfaces defined by the anodes and cathodes, d. H. perpendicular to these surfaces and in the direction of the cell housing, the same pressing force acts on the anode foils, cathode foils and separators and presses them evenly in the direction of the cell housing.

Preferably, a diffusion barrier layer is arranged on and / or in a shell of the at least one elastic element or formed. The diffusion barrier layer is expediently formed of metal, for example as a metal coating or a metal foil, for example of aluminum, which is introduced into the envelope or applied to the envelope, i. H. on an inside and / or outside of the shell. In the embodiment of the elastic element formed as a pillow-like hollow body, for example, the metal foil, for example aluminum foil, is laminated into a plastic film to form the pillow-like hollow body and / or laminated onto an inside or outside of the plastic film, or the plastic film becomes on the inside and / or outside coated with metal. In the embodiment of the elastic member formed of the closed-cell foam, for example, an outer surface of the elastic member may be coated with metal or covered with a metal foil. Diffusion barrier layers of another material are also possible.

Advantageously, the single cell is evacuated prior to a fluid-tight, in particular gas-tight, closing of the cell housing, so that an internal pressure in the cell housing is less than an ambient pressure of the single cell. Ie. a cell interior of the single cell then has a negative pressure. In this case, gases, for example air, are sucked out of cavities of the individual cell, which after filling the housing with all constituents, ie in particular with the electrode foil arrangement and the electrolyte, initially remain in the single cell. By this negative pressure or by an overpressure in the outer environment of the single cell is a back pressure through the cell housing which counteracts the pressure exerted by the at least one elastic element or the pressing force of the at least one elastic element on the electrode foil arrangement, so that the electrode foil arrangement is pressed in a predefined manner. The negative pressure in the cell housing or the overpressure in the vicinity of the cell housing relative to an interior in the cell housing pulls or presses housing walls of the cell housing inwards, in the direction of the electrode foil arrangement, and thus increases their rigidity. This evacuation of the single cell is particularly advantageous if the cell housing is not sufficiently rigid, so that it would deform plastically and / or elastically by the pressing force of the at least one elastic element, ie would yield to the pressing force and deform outwards. Such an outward deformation counteracts the negative pressure in the cell housing and the resulting overpressure of an external environment of the cell housing, which acts on the cell housing, so that the cell housing does not deform or deform inwards, in the direction of the electrode foil arrangement.

Embodiments of the invention are explained in more detail below with reference to drawings.

Showing:

1 1 is an exploded view of a first embodiment of a single cell for a battery;

2 FIG. 2 schematically a perspective view of a first embodiment of a single cell for a battery, FIG.

3 FIG. 2 schematically a perspective view of an electrode foil arrangement of a first embodiment of a single cell for a battery, FIG.

4 schematically a cross-sectional view of a first embodiment of a single cell for a battery,

5 FIG. 2 schematically a longitudinal section of a first embodiment of a single cell for a battery, FIG.

6 1 is a schematic enlargement of a longitudinal section of a first embodiment of a single cell for a battery in the region of current collector tabs of one polarity,

7 schematically a perspective view of an elastic element,

8th schematically a cross-sectional view of an elastic element,

9 FIG. 2 schematically a longitudinal section of a second embodiment of a single cell for a battery, FIG.

10 1 is a schematic enlargement of a longitudinal section of a second embodiment of a single cell for a battery in the region of current collector tabs of one polarity,

11 FIG. 2 schematically a perspective view of an electrode foil arrangement and an elastic element, FIG.

12 FIG. 2 schematically a perspective view of an electrode foil arrangement and an elastic element arranged therein, FIG.

13 FIG. 2 schematically a longitudinal sectional view of an electrode foil arrangement and an elastic element arranged therein, FIG.

14 FIG. 2 schematically a cross-sectional view of an electrode foil arrangement and an elastic element arranged therein, FIG.

15 schematically a detail enlargement of a longitudinal sectional view of an electrode foil arrangement and an elastic element arranged therein in the region of Stromableiterfahnen one polarity, and

16 schematically a battery.

Corresponding parts are provided in all figures with the same reference numerals.

The 1 and 2 . 4 to 6 such as 9 and 10 each show a schematic representation of a single cell 1 a battery B, ie an electrochemical energy storage and / or energy converter. The 7 and 8th show an elastic element 2 for such single cells 1 the battery B, the 11 shows such an elastic element 2 prior to placement in an electrode foil assembly 3 such a single cell 1 and the 3 such as 12 to 15 show electrode foil assemblies 3 , in each of which an elastic element 2 is arranged. A battery B with a cell network Z of a plurality of electrically series and / or parallel interconnected single cells 1 is schematic in 16 shown.

The battery B, in which such single cells 1 In particular, a vehicle battery, such as a battery B for a hybrid vehicle, is a fuel cell vehicle or an electric vehicle. Such vehicle batteries, which serve in particular driving purposes of the vehicle, are also referred to as high-voltage batteries.

Such high-voltage batteries for vehicle applications have a plurality of electrically connected in series and / or parallel single cells 1 on, which are located with an associated electronics and cooling in a common housing. The single cells 1 For example, they are designed as so-called hardcase cells in which an electrochemically active content is surrounded by a substantially rigid and mostly metallic shell. These single cells 1 are, for example, as in the 1 and 2 . 4 to 6 such as 9 and 10 represented formed as so-called bipolar frame flat cells, in which electrical poles are formed by cell walls, or formed as so-called prismatic hard case cells with poles. The prismatic hardcase cells, not shown here, consist of a metal housing with a rectangular cross-section, through which the current-carrying electrical poles are passed in isolation. Furthermore, an embodiment is also possible in which one electrical pole is formed directly through the metallic housing and the other electrical pole is led out of the housing in isolation, ie a so-called polar cell.

The single cell 1 has the electrode foil arrangement 3 on, also referred to as electrode stack or electrode winding. The electrode foil arrangement 3 is formed by layers of cathode foils and anode foils, ie in a lithium-ion cell chemistry of layers of coated aluminum foils and copper foils, which are each separated by layers of a separator. Here are, for example, as in the 1 to 6 such as 9 and 10 shown, individual sheets of cathode foils, anode foils and separators stacked or a band-shaped separator is folded in Z-shape and the cathode foil sheets or anode foil sheets are laterally inserted into itself by the Z-forming pockets or it, as in 11 to 15 shown, tapes of the anode foils, cathode foils and separators arranged therebetween wound, preferably flat wound.

The anode foils and cathode foils are uncoated on at least one edge and protrude from the electrode foil assembly 3 in the form of current collector flags 4 out with the appropriate components for power delivery to a housing outside of a cell housing 5 the single cell 1 are electrically connected.

The cell case 5 the single cell 1 is how in 1 shown in detail from two metallic shell-shaped housing walls 5.1 formed, each by an insulating shell 5.2 made of plastic from the electrode foil assembly 3 are electrically isolated. The two housing walls 5.1 simultaneously serve as cell poles of the single cell 1 for electrically contacting the single cell 1 , ie for the introduction or removal of electrical power, and are through the insulation shells 5.2 extending into a flange area of the housing walls 5.1 extend, electrically isolated from each other. The electrical connection of the electrode foil arrangement 3 to the housing walls 5.1 done by welding the current collector lugs 4 the anode foils or cathode foils with inner sides of the housing walls 5.1 , The means of insulation shells 5.2 made of plastic electrically insulated housing walls 5.1 are in the range of welds where the current collector flags 4 each with a housing wall 5.1 are electrically and mechanically connected by welding, provided with openings. A waste heat of the single cell 1 is about the corresponding thickened housing walls 5.1 on narrow sides of the single cell 1 derivable and there deliver to at least one cooling plate not shown in detail of the battery B. Preferably, in the battery B on opposite narrow sides of the individual cells 1 each arranged a cooling plate. The cooling plates have channels and are flowed through by a tempering medium, for example by an air-conditioning coolant or a cooling liquid.

For electrical isolation of the cell case 5 of the single cells 1 in the battery B opposite the respective metallic cooling plate is between the single cells 1 and the respective cooling plate expediently arranged a heat-conducting foil. To improve the heat transfer are the housing walls 5.1 of the single cells 1 in the region of the cooling plate parallel to this bent by substantially 90 °. This is also called a cooling flag 5.3 designated. If necessary, heating of the single cell is also possible via a heat conduction path formed thereby 1 possible, for example at low outside temperatures. For this purpose, the respective metallic cooling plate, for example, flows through a warm fluid.

For closing the single cell 1 is used in a process for producing the single cells 1 preferably a hot pressing method used, also referred to as a seal. Here, the thermoplastic located in the flange area of the insulation shells 5.2 partially melted in a hot press. By solidification of the plastic at falling temperature and under pressure, the two with the insulation shells 5.2 made of plastic electrically insulated housing walls 5.1 connected with each other.

For proper operation of the single cell 1 is the electrode foil arrangement 3 to press with a predetermined force, so for example, a required distance of the cathode foils, anode foils and separators to each other in the electrode foil assembly 3 is set. When filling the single cell 1 with an electrolyte, in a formation of the single cell 1 and depending on a state of charge and an aging state of the single cell 1 as well as in dependence on a temperature of the single cell 1 a thickness of the electrode foil arrangement changes 3 ,

To achieve a compensation of these changes in thickness, the single cell indicates 1 the elastic element 2 through which the electrode foil assembly 3 against at least one housing wall 5.1 of the cell housing 5 is pressed, in the illustrated embodiments against both housing walls 5.1 of the cell housing 5 , This pressing action, ie one by the elastic element 2 on the electrode foil assembly 3 acting press force, is in the 4 to 6 such as 10 and 15 represented by arrows P. This elastic element 2 is like in the 1 to 8th and 11 to 15 represented as a fluid-tight, in particular gas-tight, and gas-filled hollow body 6 trained or has, as in the 9 and 10 represented, at least one fluid-tight, in particular gas-tight, and gas-filled hollow body 6 on. In the in 9 and 10 illustrated embodiment, the elastic element 2 a plurality of such fluid-tight gas-filled hollow body 6 on, as will be described later.

The elastic element 2 compresses the electrode foil assembly 3 in the single cell 1 in a predetermined manner according to the principle of a gas spring or air spring. The force effect of the elastic element 2 is additionally reinforced when the cell case 5 is set under negative pressure, that is evacuated. Ie. to improve the effect of the elastic element 2 and to build up a counterforce is an interior of the single cell 1 evacuated. This creates a necessary back pressure. The negative pressure pulls the housing walls 5.1 inward and thus increases their rigidity.

The elastic element 2 covers a complete area of the electrode foil assembly 3 or at least one surface of the anodes and / or cathodes, so that a uniform full-surface pressing action of the elastic element 2 on the electrode foil assembly 3 is reached. In this way, it is ensured that predetermined distances between the layers of anode foils, cathode foils and separators during a lifetime of the single cell 1 can be maintained and over an entire areal extent of the electrode foil arrangement 3 are constant. This allows optimal functioning of the single cell 1 ,

Furthermore, the single cells 1 in the cell assembly Z in the battery B preferably clamped or pressed together. This can be done for example by means not shown here tension bands, tie rods and / or other clamping devices. For optimal bracing, the cell assembly Z, for example, pressure goggles on the front sides, which are then to be clamped against each other by means of such straps, tie rods and / or other tensioning means, whereby the individual cells arranged therebetween 1 of the cell composite Z are pressed together. The individual cells are based on this 1 for example, either directly or via partitions and / or spacers, so-called spacers, on adjacent individual cells 1 from. In this way, analogous to the negative pressure in the single cell 1 , a support of the cell case 5 of the single cells 1 achieved against a plastic and / or elastic deformation to the outside, so that the cell housing 5 the pressing force of the at least one elastic element 2 in the respective single cell 1 can not yield and an optimal pressing action on the electrode foil assembly 3 is reached.

Because the metallic cell case 5 usually by its good thermal conductivity of the temperature of the single cell 1 serves, as already described, is the elastic element 2 preferably within the electrode foil assembly 3 arranged, preferably in the middle, as in the illustrated embodiments, and presses their halves to the housing walls 5.1 , so that a good thermal connection of the electrode foil arrangement 3 to the cell case 5 the single cell 1 and thereby a good heat transfer is possible.

That in the 1 to 8th and 11 to 15 illustrated elastic element 2 , ie the fluid-tight gas-filled hollow body shown here 6 , consists of a fluid-tight, in particular gas-tight enclosure with gas filling. Such pillow-shaped hollow body 6 are particularly space-saving. This embodiment of the elastic element 2 is in the process for the preparation of the single cell 1 For example, from a plastic tube of small wall thickness welded ends, made of two circumferentially welded films or from a folded and welded on three sides film. A wall of the hollow body 6 preferably consists of an electrolyte-resistant plastic, for example of polypropylene (PP) or polyethylene terephthalate (PET), in which as a diffusion barrier, for example, a metal insert, for example, a thin aluminum foil is laminated or laminated. The closure of the thus formed elastic element 2 done by a Foil welding process. The hollow body is filled 6 for example with a given amount of air, dried air or an inert gas, for example nitrogen or argon. Since the enclosed amount of gas a spring rate and thickness of the hollow body 6 pretend, this must be set by a suitable device with sufficient accuracy.

Instead of the pillow-like hollow body 6 can also, as in the 9 and 10 shown, a closed-cell foam can be used, which has similar properties by the gas enclosed in the pores or bubbles. Ie. in this in the 9 and 10 illustrated embodiment is the elastic element 2 formed from a closed-cell foam, ie from a mat of a closed-cell foam. In this foam, its closed pores or bubbles, in each of which a gas is enclosed, each form a fluid-tight gas-filled hollow body 6 ie the elastic element 2 then has a plurality of fluid-tight gas-filled hollow body 6 on. The closed-cell foam is expediently a foamed and cured plastic which is elastic due to the foaming, for example polypropylene (PP), polyethylene terephthalate (PET), polyethylene (PE), polyurethane (PU) or polystyrene (PS). The gas in the pores or bubbles of the foam already forms during manufacture of the foam, ie during foaming of the plastic, by a chemical reaction and / or is added to the plastic during manufacture of the foam to foam the plastic.

LIST OF REFERENCE NUMBERS

1

single cell

2

elastic element

3

Electrode foil arrangement

4

discharge lug

5

cell case

5.1

housing wall

5.2

insulation shell

5.3

cooling fin

6

hollow body

B

battery

P

arrow

Z

cell assembly

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 3321129 A1 [0002]
• DE 3000469 C2 [0003]

Claims (10)

Single cell ( 1 ) for a battery (B), comprising a cell housing ( 5 ) in which an electrode foil arrangement ( 3 ) and at least one elastic element ( 2 ) are arranged, wherein by the at least one elastic element ( 2 ) the electrode foil arrangement ( 3 ) against at least one housing wall ( 5.1 ) of the cell housing ( 5 ) is pressed, characterized in that the at least one elastic element ( 2 ) as a fluid-tight gas-filled hollow body ( 6 ) is formed or at least one fluid-tight gas-filled hollow body ( 6 ) having. Single cell ( 1 ) according to claim 1, characterized in that the at least one elastic element ( 2 ) is formed of plastic. Single cell ( 1 ) according to claim 1 or 2, characterized in that the at least one elastic element ( 2 ) is formed of a closed-cell foam. Single cell ( 1 ) according to one of claims 1 to 3, characterized in that a flat extension of the at least one elastic element ( 2 ) substantially a flat extension of at least anodes and / or cathodes of the electrode foil arrangement ( 3 ) corresponds. Single cell ( 1 ) according to one of the preceding claims, characterized in that the at least one elastic element ( 2 ) in the electrode foil assembly ( 3 ) is arranged. Single cell ( 1 ) according to one of the preceding claims, characterized in that a sheath of the at least one elastic element ( 2 ) has a diffusion barrier layer. Single cell ( 1 ) according to one of the preceding claims, characterized in that an internal pressure in the cell housing ( 5 ) is less than an ambient pressure of the single cell ( 1 ). Battery (B) comprising at least one cell network (Z) with a plurality of electrically series-connected and / or parallel interconnected individual cells ( 1 ) according to one of claims 1 to 7. Battery (B) according to claim 8, characterized in that the individual cells ( 1 ) in the cell composite (Z) are clamped together. Method for producing a single cell ( 1 ) according to one of claims 1 to 7, wherein an electrode foil arrangement ( 3 ) and at least one elastic element ( 2 ), which serves as a fluid-tight gas-filled hollow body ( 6 ) is formed or at least one fluid-tight gas-filled hollow body ( 6 ), in a cell housing ( 5 ) are arranged such that by the at least one elastic element ( 2 ) the electrode foil arrangement ( 3 ) against at least one housing wall ( 5.1 ) of the cell housing ( 5 ) is pressed.

Images