Battery cells for vehicle batteries

Abstract

The invention relates to a battery cell (2) for a vehicle battery, comprising an electrode assembly (4) which is accommodated in an encapsulated casing (8), wherein the electrode assembly (4) has two terminals (6) for electrical contact, wherein the casing (8) is formed by a surrounding frame (10) and two films (12) arranged on the frame at the end sides, wherein the frame (10) consists of two electrically conductive conductive frames (16) and a non-conductive insulating frame (18), which are arranged one on top of the other as frame layers (16, 18), wherein the insulating frame (18) is arranged between the two conductive frames (16), wherein the conductive frames (16) each have a recess (14) for accommodating one of the terminals (6), and wherein the terminal (6) is located in the recess (14) and is electrically conductively connected to the respective conductive frame (16).

Description

Technical Field

[0001] The invention relates to a battery cell in which an electrode assembly is accommodated in an encapsulating casing and also to a vehicle battery having such a battery cell. Background Art

[0002] Electrically or electrically driven motor vehicles or motor vehicles that can be electrically or electrically driven, such as electric vehicles, hybrid vehicles, plug-in vehicles or fuel cell vehicles, usually include an electric motor, which can drive one or two axles. To supply electrical energy, the electric motor is usually connected to a (high-voltage) battery inside the vehicle as an electrical energy store.

[0003] In particular, electrochemical cells are to be understood here and hereinafter to be so-called secondary batteries (secondary batteries) of motor vehicles. In such (secondary) vehicle batteries, the consumed chemical energy can be restored by means of an electrical (re)charging process. Such vehicle batteries are designed, for example, as electrochemical accumulators, in particular lithium-ion accumulators.

[0004] In order to generate or provide a sufficiently high operating voltage, such vehicle batteries typically have at least one battery module (cell module) in which a plurality of individual battery cells are connected in a modular manner. Alternatively, a so-called Cell2Pack design is possible in which the battery cells are directly connected together, in particular connected in parallel, to form a vehicle battery and are not pre-assembled into modules.

[0005] The battery cell has, for example, an electrode assembly configured as an electrode stack or a flat coil, which is accommodated in a cell housing as an outer cover or jacket. The cell housing is configured, for example, as a casing having an aluminum composite film or an aluminum laminate film, wherein such a flexible or film-like casing is also referred to as a soft bag or a soft film jacket, and a battery cell having such a cell housing is also referred to as a soft cell (pouch cell) or a soft packaging cell.

[0006] Such soft packaging bags are produced, for example, from a single folded bag sheet or from two joined bag halves, which are usually designed as deep-drawn soft packaging films, which are joined circumferentially in a material-locking manner to form a tight soft packaging bag, for example by means of a heat-sealing process.

[0007] For electrical contact, the electrode assembly has (connection) tabs leading from the soft bag as terminals, or as anodes and cathodes. Here, the terminals are usually sealed relative to the soft bag by means of so-called pre-sealing tapes.

[0008] In the case of soft-pack bags for relatively high (space-intensive) electrode assemblies, the soft-pack film must be deep-drawn accordingly, whereby there is the risk that the soft-pack film becomes too thin or even tears (during operation of the battery cell), i.e. does not seal. Furthermore, in order to seal the soft-pack bag, outwardly protruding joining sections (flange sections) are required, which disadvantageously take up space and make (thermal) contact with the cooling device more difficult. Furthermore, when the battery cells are connected in a battery module, the protruding tabs or terminals are relatively space-intensive, thereby disadvantageously reducing the energy density of the battery module or vehicle battery. Summary of the invention

[0009] The object of the present invention is to specify a particularly suitable battery cell. In particular, a battery cell which is as space-efficient as possible should be specified, which utilizes the available installation space as best as possible. The object of the present invention is also to specify a particularly suitable vehicle battery.

[0010] According to the invention, this object is achieved in terms of a battery cell by a battery cell for a vehicle battery, wherein the battery cell has an electrode assembly which is accommodated in an encapsulated casing, wherein the electrode assembly has two terminals for electrical contacting, wherein the casing is formed by a surrounding frame and two films arranged on the end sides of the frame, wherein the frame consists of two electrically conductive conducting frames and a non-conductive insulating frame which are arranged one above the other as frame layers, wherein the insulating frame is arranged between the two conducting frames, wherein the conducting frames each have a recess for accommodating one of the terminals, and wherein the terminal is located in the recess and is electrically conductively connected to the respective conducting frame.

[0011] This object is achieved with respect to a vehicle battery by a vehicle battery, wherein the vehicle battery has a battery cell as described above.

[0012] The advantages and embodiments listed with respect to the battery cells can also be appropriately transferred to the vehicle battery, and vice versa.

[0013] The battery cell according to the invention is arranged and suitable for this purpose and is designed for a vehicle battery, in particular for a traction battery of an electrically driven or electrically drivable motor vehicle. The battery cell is particularly preferably designed as a lithium-ion battery cell. The battery cell is also preferably arranged and is designed for a battery module of a vehicle battery. In principle, it is possible for the battery cell to be a primary battery cell (primary cell), but the battery cell is expediently designed as a secondary battery cell (secondary cell).

[0014] A battery cell comprises an electrode assembly, which in turn has at least one anode and at least one cathode as (connection) terminals. The terminals or anodes and cathodes of the electrode assembly are implemented, for example, as (discharger) tabs or discharger tabs (discharger tabs). The electrode assembly is configured, for example, as an electrode winding (flat winding), in which an anode layer in contact with the anode and a cathode layer in contact with the cathode and a separator (separator layer) arranged between the anode layer and the cathode layer are wound around a flat winding mandrel. Alternatively to this, the electrode assembly is configured as an electrode stack (single cell stack) having a plurality of anode layers and a plurality of cathode layers. Here, the anode layers and the cathode layers are alternately stacked on each other in a stacking direction, wherein a separator or a separator layer is respectively arranged between the anode layer and the cathode layer.

[0015] The battery cell also has a housing in which the electrode assembly is accommodated. In other words, the electrode assembly is surrounded by the housing in a fluid-tight manner. The housing is formed by means of two films and a surrounding frame. The frame is arranged between the two films, wherein the frame forms a side wall of the housing. The frame is arranged in particular at the end side, i.e. at the periphery of the respective film. Thus, substantially parallel films are arranged at the end side at opposite end sides of the frame.

[0016] The two films are suitably joined to the frame in a fluid-tight manner. Particularly preferably, the bottom of the housing of the battery cell and the cover oriented parallel thereto are formed by means of the two films, which are arranged on the frame upper side and the frame lower side. The films are joined to the frame element on the peripheral side in a suitable manner. In particular, the two films are welded to the frame element and the battery cell is thus sealed. The films are particularly preferably designed as soft packaging films, in particular as plastic-aluminum composite films. They have an electrically insulating plastic layer on the side facing the electrode assembly, so that short circuits of the electrode assembly by means of the aluminum component of the film are avoided.

[0017] For example, a rectangular, cylindrical or prismatic frame is preferably implemented to be mechanically stable or rigid. This means that the frame has sufficient thickness, in other words wall thickness. For example, the thickness of the frame is between 1 mm (millimeter) and 15 mm, preferably between 4 mm and 7 mm.

[0018] According to the invention, the frame consists of two electrically conductive (i.e. electrically conducting) conducting frames and a non-conductive (i.e. electrically insulating) insulating frame. The conducting frames and the insulating frame are arranged one on top of the other in an axial stacking direction. Here and hereinafter, "axial" or "axial direction" is understood in particular to be a direction parallel (coaxial) to the longitudinal direction or height direction of the housing, i.e. a direction perpendicular to the end-face film. The insulating frame is arranged between the two conducting frames. In other words, the conducting frames are electrically insulated or separated from one another by means of the insulating frame (intermediate frame).

[0019] Each conductive frame has a recess for receiving or passing one of the lead terminals. The terminal is located in the associated recess and is electrically conductively connected to the corresponding conductive frame. In this way, a particularly suitable battery cell is achieved.

[0020] The frame structure of the battery cell according to the present invention is a suitable alternative to the conventional battery cell in the form of a soft pack. In particular, due to the frame, the deep drawing process for the film is omitted, thereby advantageously and simply avoiding the deep drawing problem, especially the risk of tearing of the film in the case of a space-intensive electrode assembly. According to the present invention, the frame does not only have an encapsulation effect. Instead, due to the conductive frame electrically connected to the terminal, the frame also has a voltage potential. Therefore, the conductive frame effectively replaces the space-intensive discharger tabs or tabs. In other words, the conductive frame forms the terminals of the battery cell or the housing. It is thus not necessary for the terminals of the electrode winding to protrude from the housing. As a result, a housing or battery cell with a particularly tight structure space is achieved, which utilizes the existing structure space as optimally and effectively as possible.

[0021] For the best possible contact, the conductive frame has a recess in which the terminal to be contacted is at least partially located. This allows for a less laborious contact from outside the frame or housing, making the assembly and manufacture of the battery cell particularly simple and cost-effective.

[0022] The conductive frame is made of metal or conductive plastic, for example. Alternatively, the conductive frame is made of non-conductive material, for example, and is provided with a conductive coating. The material (or coating) of the conductive frame is preferably adapted to the respective terminal, so that a reliable and operationally safe connection, in particular a welded connection, can be achieved between the conductive frame and the respective terminal. For example, the conductive frame for the anode is made of the material of the anode tab, for example a copper material such as C1020 or CU-OF, and the conductive frame for the cathode is made of the material of the cathode tab, for example an aluminum material such as EN AW-3003.

[0023] In an advantageous embodiment, the frame layers of the frame (i.e. the conductive frame and the insulating frame) are mechanically firmly joined to one another. In other words, in the frame construction according to the invention, a plurality of frame layers made of different materials are used, which are mechanically firmly joined to one another by a joining process. The frame layers are joined to one another in a form-fitting and / or force-fitting and / or materially fitting manner, for example by means of screwing, gluing, welding, stamping, riveting, clinching or a combination thereof.

[0024] The conjunction “and / or” is to be understood here and below in such a way that the features connected by means of this conjunction can be configured not only together but also as alternatives to one another.

[0025] A "positive fit" or a "positive connection" between at least two interconnected components is understood here and below to mean that the interconnected components are held together at least in one direction by the direct engagement of the contours of the components themselves or by indirect engagement via additional connecting components. The "impediment" of mutual movement in this direction is thus achieved in a form-dependent manner.

[0026] A "force fit" or "force-fit connection" between at least two parts connected to one another is to be understood here and hereinafter in particular as meaning that the parts connected to one another are prevented from sliding against one another due to friction forces acting between them. If a "connecting force" causing such friction forces is absent (this means a force which presses the parts against one another, such as threading forces or gravity itself), the force-fit connection cannot be maintained and can therefore be released.

[0027] “Material fit” or “material fit connection” between at least two interconnected components is understood here and hereinafter to mean in particular that the interconnected components are held together at their contact surfaces by material bonding or crosslinking (e.g. due to atomic or molecular bonding forces), optionally with the action of additives.

[0028] In a preferred embodiment, the terminal is materially engaged with the corresponding conductive frame. In particular, the terminal is fluid-tightly engaged with the conductive frame, so that the recess is sealed relative to the terminal. For example, the recess filled with the terminal is fluid-tightly sealed by means of a welding process, so that the battery cell is sealed and the (electrical) contact resistance is reduced by connecting the tab to the frame.

[0029] In a suitable development, the terminals do not substantially protrude beyond the outer periphery of the frame. This means that the frame or the housing has substantially flat sides. For example, before the terminals are connected to the conductive frame, the terminals are guided through the recesses and the outwardly protruding parts are cut off or separated. Alternatively, the joining process can be carried out with the protruding terminals and these terminals are separated only at the end. In the case of this sequence, polishing can be integrated directly in the course of the separation step to obtain a smooth surface of the frame.

[0030] In one possible embodiment, the frame has an approximately rectangular cross-sectional shape, wherein the terminals and the recesses are arranged on opposite sides of the frame. This means that the recesses for the anode and the recesses for the cathode are arranged on opposite sides of the frame. As a result, the terminals are arranged on different sides of the housing, which simplifies the automated production of the battery cell, in particular with regard to the contacting of the terminals with the conductive frame. Alternatively, if this is required due to the application or installation situation of the battery cell, the terminals and the recesses of the conductive frame can also be arranged on the same frame side or on frame sides oriented perpendicular to each other.

[0031] The recess is arranged, for example, at the frame edges facing each other towards the insulating frame. In other words, the recess is, for example, closed on three sides and open towards the insulating frame. Due to the presence of the recess at the edge of the respective conductive frame, the terminal can be clamped between the conductive frame and the insulating frame when assembling the frame layers. The clamping fastening or clamping fixation of the terminal simplifies the subsequent contacting and / or separation of the terminal.

[0032] Alternatively, the recess is introduced into the conductive frame as a cutout-like through-hole. This means that the recess is introduced into the conductive frame surface as an opening or (long) hole that is closed on all sides. For example, the recess is arranged here at approximately half the height of the respective conductive frame.

[0033] An additional or further aspect of the invention provides that the conductive frame is designed in two parts with an upper frame and a lower frame, which are arranged one above the other in the joined state. In particular, the upper frame and the lower frame have a contour as a partial recess closed on three sides at their frame edges facing each other, so that a recess for the terminal is formed in the joined state.

[0034] As a result, a central arrangement of the terminal is achieved, in which the terminal is essentially surrounded by the conductive frame on all sides, wherein the advantages of a (partial) recess open on three sides for clamping (pre)fixed terminals can be achieved at the same time. In other words, this variant enables an assembly in which the terminal is inserted into a partial recess of the lower frame before the upper frame is placed on the lower frame and joined to it. On the one hand, an additional joining step is required in this variant for joining the upper frame and the lower frame. On the other hand, it is relatively simple to introduce the terminal into the (partial) recess, thereby reducing the risk of damage to the terminal during the process of passing through the recess closed on all sides. In particular, the housing or the recess can be sealed particularly simply in terms of process technology by means of a welding process.

[0035] In one conceivable embodiment, the conductive frame is flanked at the end by a further insulating frame. In other words, the frame of the housing has, for example, five layers, in which insulating frames and conductive frames are arranged alternately. Due to the additional insulating frames arranged at the end or on the outside of the frame, the conductive frame is insulated at the end or on the outside, whereby the film fastened to the frame is connected to the insulating frame and is therefore electrically isolated from the conductive frame.

[0036] The vehicle battery according to the invention is particularly designed and suitable for and is provided for an electrically driven or electrically drivable motor vehicle, for example for an electric vehicle or a hybrid vehicle. The vehicle battery has at least one battery cell as described above. The vehicle battery has, for example, at least one battery module (battery cell module), in which a plurality of individual battery cells are connected in a modular manner. Alternatively, a so-called Cell2Pack design is possible, in which the battery cells are directly connected together, in particular connected in parallel, to form a vehicle battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Next, an embodiment of the present invention will be explained in more detail with the aid of the accompanying drawings. In which:

[0038] Figure 1 Shows a battery cell,

[0039] Figure 2 shows a frame of a battery cell in a first embodiment,

[0040] Figure 3 shows a frame of a battery cell in a second embodiment,

[0041] Figure 4 shows a frame of a battery cell in a third embodiment,

[0042] Figure 5 shows a frame of a battery cell in a fourth embodiment, and

[0043] Figure 6 The frame of a battery cell is shown in a fifth embodiment.

[0044] In all the figures, corresponding parts and dimensions are always provided with the same reference symbols. DETAILED DESCRIPTION

[0045] Figure 1 A battery cell 2 of a vehicle battery (not shown in detail) is shown. The battery cell 2 is designed as a lithium-ion battery cell in the form of a cell similar to a soft bag. The battery cell 2 has an electrode assembly 4, which is Figure 1 6. The electrode assembly 4 has two terminals 6 as electrode dischargers (i.e. as anode connection and cathode connection) for electrical contacting. The battery cell 2 also has a housing 8 as a cell housing, which surrounds the electrode assembly 4 in an encapsulating manner.

[0046] The housing 8 has a rigid frame 10 which is arranged circumferentially around the electrode assembly 4. The end sides of the frame 10, i.e. the frame top and the frame bottom, are each closed in a fluid-tight manner by means of a film 12, so that a closed and in particular fluid-tight housing 8 for the electrode assembly 4 is achieved. The film 12 is here circumferentially joined to the corresponding edge of the frame 10 in a materially fitting manner, for example welded or sealed.

[0047] The frame 10 has two recesses 14 for the terminals 6. Figure 1 In the embodiment shown, the terminals 6 slightly protrude from the outer periphery of the frame 10, but preferably, the terminals 6 are separated flush on the outside of the frame 10, so as to achieve a flat or smooth (outer) surface of the housing 8. The protruding terminals 6 or tabs are omitted by connecting the electrode dischargers to the frame 10 which is partially or partially conductive.

[0048] Next, with the help of Figures 2 to 6 Different embodiments of the frame 10 are explained in more detail. Here, the frame 10 has two conductive frames 16 made of an electrically conductive material or having an electrically conductive coating, and at least one insulating frame 18 made of an electrically non-conductive or insulating material. The conductive frames 16 and the insulating frames 18 are arranged one on top of the other as frame layers or frame plies along a stacking direction not indicated in more detail, wherein the insulating frames 18 are arranged between the conductive frames 16. Here, the conductive frames 16 each have a recess 14 for accommodating the respectively associated terminal 6.

[0049] The frame layers 16, 18 of the frame 10 are mechanically fixed or rigidly joined to one another in the assembled state. In particular, the frame layers 16, 18 are connected to one another in a force-fitting and / or form-fitting and / or materially fitting manner. In particular, the frame layers 16, 18 are joined to one another in a fluid-tight manner.

[0050] In the embodiment shown, the frame 10 and thus the conductive frame 16 and the insulating frame 18 each have an approximately rectangular basic shape or cross-sectional shape. However, the frame 10 can also have other cross-sectional shapes, such as a polygonal cross-sectional shape. In this embodiment, the recesses 14 of the conductive frame 16 are arranged at opposite sides.

[0051] exist Figure 2In the embodiment of the present invention, the recess 14 is implemented as a contour closed on three sides at the frame edge facing the insulating frame 18. Since the recess 14 is arranged at the edge of the conductive frame 16, the terminal 6 can be clamped between the conductive frame 16 and the insulating frame 18 respectively when assembling or stacking the frame layers 16, 18. This means that the insulating frame 18 closes the recess 14 open on one side, so that the terminal 6 located therein is surrounded by the corresponding conductive frame 16 and the insulating frame 18 in a form-fitting manner. Here, the recess 14 corresponds to the (outer) contour of the terminal 6. In particular, the extension of the recess 14 in the vertical direction or stacking direction corresponds to the extension of the terminal 6, including (not further shown) joining or sealing elements surrounding the terminal 6 on the peripheral side. After the terminal 6 is clamped in the recess 14, the part of the terminal 6 protruding from the frame body 10 is cut off, and the recess 14, which is basically completely filled with the terminal 6, is closed in a fluid-tight manner by means of a welding process. The integral connection seals the housing 8 on the one hand and electrically connects or contacts the terminals to the associated conductive frame 16 on the other hand, so that the outer surfaces of the conductive frame 16 effectively form the anode and cathode connections of the battery cell 2 .

[0052] Alternatively, the joining process of the frame 10 with the protruding terminals 6 can be carried out and these terminals are separated only at the end. In the case of this sequence, polishing can be directly integrated into this step to obtain a smooth surface of the frame 10 or the housing 8.

[0053] Figure 3 The embodiment corresponds essentially to Figure 2 The above-described embodiment, in which the frame 10 has two additional insulating frames 18, which are placed on the end side as the outermost frame layer on the conductive frame 16. Therefore, the frame 10 has five stacked frame layers 16, 18, in which two conductive frames 16 and three insulating frames 18 are arranged alternately stacked. Further electrical insulation for the film 12 is achieved by the additional insulating frames 18.

[0054] Figure 4 The embodiment of FIG. 1 shows a frame 10 having five frame layers 16, 18. Compared to the above-described embodiments, the recess 14 is not provided at the frame edge 14, but rather is implemented as a through-hole, for example a cutout or slot-like through-hole, which is closed on all sides, at the frame surface of the conductive frame 16. As a result, the terminal 6 is held in place more reliably.

[0055] Framework 10 Figure 5 The embodiment shown in FIG. 1 has a conductive frame 16 that is designed in two parts. The conductive frame 16 consists of two identical frame parts, which are also referred to below as upper frame 20 and lower frame 22, regardless of the actual orientation in space. The frame parts 20, 22 are basically the same as above. Figure 2 and 3The frame parts 20, 22 are designed like the conductive frame 16 of FIG. 1 and each have a contour not indicated in more detail as a partial recess introduced at the frame edges facing each other. The frame parts 20, 22 are arranged in the joined state so that the partial recesses realize a recess 14 that is closed on all sides, such as Figure 4 As in the embodiment of .

[0056] Figure 5 The variant thus enables the following battery cell assembly, in which the terminal 6 is inserted into the partial recess in the lower frame 22 before the upper frame 20 is placed on the lower frame 22 and joined to it. On the one hand, in this variant, an additional joining step is required for joining the frame parts 20, 22. On the other hand, it is relatively simple to introduce the terminal 6 into the (partial) recess, thereby reducing the risk of damage to the terminal 6 during the process of passing through the recess 14 closed on all sides.

[0057] Figure 6 The frame 10 shown in FIG. 1 corresponds substantially to Figure 5 The above-described embodiment is similar to that of FIG. 1 , in which a further insulating frame 18 is respectively attached to the conductive frame 16 at the end faces.

[0058] The claimed invention is not limited to the above-described embodiments. Instead, other variants of the invention may be derived by a person skilled in the art within the scope of the disclosed claims without departing from the subject matter of the claimed invention. In particular, all individual features described in conjunction with the different embodiments may also be combined in other ways within the scope of the disclosed claims without departing from the subject matter of the claimed invention.

[0059] Reference numerals list

[0060] 2 battery cells

[0061] 4 Electrode assembly

[0062] 6 terminals

[0063] 8. Cover

[0064] 10 Framework

[0065] 12 films

[0066] 14 recess

[0067] 16 Conductive frame, frame layer

[0068] 18 Insulation frame, frame layer

[0069] 20 Upper frame, frame parts

[0070] 22 Lower frame, frame part.

Claims

1. A battery cell (2) for a vehicle battery, comprising an electrode assembly (4) which is accommodated in an encapsulating casing (8), -in, The electrode assembly (4) has two terminals (6) for electrical contact. wherein the housing (8) is formed by a surrounding frame (10) and two films (12) arranged on the end sides of the frame, wherein the frame (10) consists of two electrically conductive conductive frames (16) and a non-conductive insulating frame (18), the conductive frames and the insulating frame being arranged one on top of the other as frame layers (16, 18), - wherein the insulating frame (18) is arranged between two of the conductive frames (16), - wherein the conductive frames (16) each have a recess (14) for accommodating one of the terminals (6), and - wherein the terminals (6) are located in the recesses (14) and are electrically conductively connected to the corresponding conductive frames (16).

2. The battery cell (2) according to claim 1, It is characterized in that The frame layers (16, 18) of the frame (10) are mechanically firmly joined to one another.

3. The battery cell (2) according to claim 1 or 2, It is characterized in that The terminals (6) are materially engaged with the corresponding conductive frames (16).

4. The battery cell (2) according to claim 1 or 2, It is characterized in that The terminal (6) substantially does not protrude beyond the outer periphery of the frame (10).

5. The battery cell (2) according to claim 1 or 2, It is characterized in that The frame (10) has an approximately rectangular cross-sectional shape, wherein the terminal (6) and the recess (14) are arranged on opposite sides of the frame (10).

6. The battery cell (2) according to claim 1 or 2, It is characterized in that The recess (14) is introduced into the conductive frame (16) as a cutout-shaped through-hole.

7. The battery cell (2) according to claim 1 or 2, It is characterized in that The conducting frame (16) is designed in two parts, comprising an upper frame (20) and a lower frame (22), which are arranged one above the other in a joined state.

8. The battery cell (2) according to claim 7, It is characterized in that The upper frame (20) and the lower frame (22) each have a partial recess at frame edges facing each other, and the partial recess forms a recess (14) of the conductive frame (16) in a joined state.

9. The battery cell (2) according to claim 1 or 2, It is characterized in that The conductive frame (16) is flanked on the end sides by insulating frames (18).

10. A vehicle battery for an electrically driven motor vehicle, comprising a battery cell (2) according to any one of claims 1 to 9.

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