Energy storage arrangement with a pouch cell and motor vehicle with such an energy storage arrangement

Abstract

An energy storage arrangement (28) comprising one or more pouch cells (1) arranged in a housing and interconnected, each of which comprises a plurality of cell layers (14, 15) designed for electrochemical energy conversion, which are arranged inside a closed casing (2), and at least two contacting elements (17, 18) electrically conductively connected to at least one cell layer (14, 15) and which extend from the interior of the casing (2) through a sealing seam (7) closing the casing (2), wherein at least one heat collector (19) designed for heat dissipation is arranged inside the casing (2), which heat collector is thermally coupled to at least one heat dissipator (20, 21) extending from the interior of the casing (2) through the sealing seam (7), wherein the energy storage arrangement (28) has at least one heat conductor (29) designed to dissipate heat from the interior of the pouch cells (1),which is thermally coupled to the at least one heat dissipator (20, 21) of at least one pouch cell (1), characterized in that the at least one heat dissipator (20, 21) is guided through the sealing seam (7) at a section located between the contacting elements (17, 18) which is located on the same side of the energy storage arrangement (28) as the contacting elements (17, 18).

Description

[0001] The invention relates to an energy storage arrangement according to the preamble of claim 1.

[0002] Pouch cells have recently become the focus of industrial development efforts as the basis for traction batteries. In a pouch cell, the electrodes involved in electrochemical energy conversion are designed as foils and referred to as cell layers. The cell layers forming a galvanic cell, in particular a lithium-ion cell, are separated by separators and arranged in a closed, electrolyte-filled casing. This also typically consists of one or more foil elements that are joined together to form a sealed seam, for which ultrasonic welding processes are often used. The contacting elements are connected to the electrodes inside the casing and are passed through the sealed seam to the outside, thus also being welded to the casing. Within a pouch cell, several galvanic cells can also be realized using at least one pair of cell layers each.

[0003] Because pouch cells have a high power density, cooling them during operation, especially during energy extraction, presents a particular challenge. This is even more true when a pouch cell contains multiple parallel galvanic elements, and the associated increase in the number of cell layers also increases the thickness of the pouch cell. This can result in the need for several thinner pouch cells separated by cooling elements within an energy storage arrangement, instead of a particularly efficient but difficult-to-cool pouch cell with multiple cell layers. Contacting elements are known to be used to dissipate heat from the interior of a pouch cell.

[0004] DE 10 2010 021 908 A1 discloses a pouch cell comprising an electrical energy storage structure, a housing that accommodates and tightly encloses the electrical energy storage structure, and at least two contact elements accessible outside the housing for electrically connecting to electrode regions of the electrical energy storage structure. A heat-conducting element is arranged within the housing, by means of which heat can be absorbed from the electrical energy storage structure and dissipated outside the housing.

[0005] US 2012 / 0 231 313 A1 discloses a battery cell assembly comprising a battery cell and a casing made of an insulating material enclosing the battery cell. A cooling element is also provided, with an internal portion of the cooling element being arranged within the casing and in thermal contact with the battery cell. An external portion of the cooling element is arranged outside the casing. Heat can be dissipated from the battery cell by means of the cooling element.

[0006] Another energy storage arrangement is known from JP 2014 - 203 792 A. This comprises cell layers arranged in a casing. Contacting elements extend from the casing and penetrate a seam in the casing. Furthermore, a heat collector with three flat sections is provided inside the energy storage arrangement and a heat sink arranged between the contacting elements.

[0007] Furthermore, US 2015 / 0 072 191 A1 also discloses an energy storage arrangement. This arrangement comprises a plurality of battery cells, wherein a heat collector arranged between cell layers of the respective battery cell is connected to a heat sink that extends out of a battery casing of the energy storage arrangement. The heat sink is connected to a heat sink. Electrical contact elements are arranged on the side of the energy storage arrangement opposite the heat sink.

[0008] DE 10 2013 201 457 A1 discloses an energy storage element comprising at least one energy storage cell and an electrical discharge contact. For heat dissipation, the discharge contacts are arranged on at least one holding element comprising a thermally conductive material, which in turn is connected to a heat conduction channel by means of a clamp.

[0009] However, pouch cells of this type, which utilize contact elements for heat dissipation, have the disadvantage that the thermal contact must be electrically insulated with a heat sink outside the pouch cell, which requires considerable effort. Furthermore, only the cross-section of the contact elements is available for heat flow, which significantly limits the efficiency of heat dissipation, since the contact elements are typically relatively narrow.

[0010] The invention is therefore based on the object of providing an energy storage arrangement with improved cooling properties.

[0011] To achieve this object, the invention provides an energy storage arrangement having the features of claim 1 and a motor vehicle having the features of claim 9.

[0012] The invention is based on the idea of ​​providing, in addition to the electrical contacting elements, one or more non-current-conducting heat sinks extending through the sealed seam, which are thermally connected inside the casing to a heat collector that absorbs the heat generated there. One or more heat sinks can be assigned to a heat collector, which are passed through the sealed seam at different points. Suitable sections of the sealed seam can be located between the contacting elements, but can also be arranged on sides of the pouch cell that do not have contacting elements. The heat sinks, like the contacting elements, are joined to the casing during production of the pouch cell.According to the invention, the at least one heat conductor is guided through the sealing seam at a section of the sealing seam located between the contacting elements.

[0013] The heat collectors located inside the shell must be electrically insulated from the cell layers to ensure that they do not influence the electrochemical processes within the pouch cell. The same applies to the arrangement of the heat collectors relative to the cell layers, whereby the arrangement must be chosen so that the impact on the energy conversion processes is as minimal as possible.

[0014] Since heat dissipation is particularly important for particularly thick pouch cells comprising a large number of cell layers, it is preferred that several heat collectors be arranged inside the shell, each of which is thermally coupled to at least one heat dissipator and arranged such that at least one cell layer is located between each two heat collectors. The heat collectors are therefore arranged at different levels of the pouch cell and can thus absorb heat from several volume sections of the pouch cell. The heat collectors and the heat dissipators thermally coupled to them can be of identical design, so that heat dissipators assigned to different heat collectors are led out at one point along the sealing seam.It is also conceivable, however, that at one point of the sealing seam, heat dissipators thermally coupled to only some of the heat collectors are led out and separate points are provided for the heat dissipators of other heat collectors to pass through the sealing seam.

[0015] In a pouch cell of the energy storage arrangement according to the invention, it is particularly advantageous if the at least one or each heat collector is flat and arranged parallel to the cell layers. The at least one or each heat collector is then arranged in a stack with the cell layers, wherein it is particularly expedient if the base area of ​​the heat collectors corresponds to that of the individual cell layers. In this respect, flat is understood to mean that the height of the at least one or each heat collector is significantly less than its length and width. In particular, it is expedient if the at least one or each heat collector is designed as a sheet metal or foil layer. The at least one or each heat collector then fits into the structure of the pouch cell and can advantageously be arranged parallel to the cell layers easily using known manufacturing processes for pouch cells.

[0016] In a pouch cell of the energy storage arrangement according to the invention, it is further particularly advantageous if two of the cell layers form an electrode pair of a galvanic cell, and the at least one or each heat collector is arranged outside the at least one electrode pair. It is therefore proposed that heat collectors not be arranged between two cell layers forming an electrode pair. This largely eliminates any influence of the at least one or each heat collector on the electrochemical energy conversion processes within the pouch cell.

[0017] To advantageously enable particularly simple production of pouch cells for the energy storage arrangement according to the invention, it can also be provided that the at least one or each heat collector is formed as a single piece with the at least one heat dissipator thermally coupled to it. The heat collector and the associated heat dissipator then form a single component for the production of the pouch cell. In particular, the at least one or each heat collector with the at least one heat dissipator thermally coupled to it can be cut from a single piece of sheet metal or foil.

[0018] Within the scope of the invention, it is particularly preferred if the at least one or each heat sink and / or the at least one or each heat collector consists of a thermally conductive material. In this way, particularly efficient heat dissipation from the interior of the pouch cell can be achieved. In particular, if the material, in addition to its thermal conductivity, also has a non-negligible electrical conductivity, for example in the case of a metal such as aluminum or copper, it is particularly expedient if it is coated with an electrically insulating surface layer at least in an area located inside the casing. Influences on the electrochemical processes within the pouch cell and, above all, a current flow on the heat collector or the heat sink can be prevented in this way.The surface layer can preferably consist of a plastic, whereby when at least one or each heat collector is realized as a film layer, it is particularly preferred if it is laminated.

[0019] The invention relates to an energy storage arrangement comprising one or more pouch cells arranged in a housing and interconnected as described above. The housing is designed to accommodate the one pouch cell or the multiple pouch cells. By interconnecting multiple pouch cells, the output voltage and / or the capacity of the energy storage arrangement can be determined to suit their respective intended use. Such an energy storage arrangement has the particular advantage that, due to the improved heat dissipation of pouch cells according to the invention, fewer of them are required to implement the energy storage arrangement, resulting in a more compact design.

[0020] An energy storage arrangement according to the invention is provided with at least one heat conductor designed to dissipate heat from the interior of the pouch cells, which heat conductor is thermally coupled to the at least one heat dissipator of at least one pouch cell. Such an energy storage arrangement can thus make the heat dissipation improved by means of the pouch cells as described above even more efficient in that the heat dissipators transfer their heat to a heat conductor of the energy storage arrangement and this is thermally coupled, for example, to a cooling device known from the prior art. Such an energy storage arrangement therefore has a more efficient cooling capacity and / or a heat conductor design that can be implemented with less effort than conventional energy storage arrangements.

[0021] Finally, the invention also relates to a motor vehicle comprising at least one energy storage arrangement according to the invention.

[0022] All statements regarding the pouch cell as described above can be transferred analogously to the energy storage arrangement according to the invention and the motor vehicle according to the invention, so that the advantages already mentioned can also be achieved with these.

[0023] Further advantages and details of the invention will become apparent from the exemplary embodiments described below and from the drawings. These show: Fig. 1 a plan view of an embodiment of a pouch cell, Fig. 2 a cross-section through the Fig. 1 pouch cell shown, Fig. 3 a longitudinal section through the Fig. 1 shown pouch cell and Fig. 4 an embodiment of a motor vehicle according to the invention with an energy storage arrangement according to the invention.

[0024] Fig. Figure 1 is a plan view of a pouch cell 1, which, for example, has several lithium-ion cells inside a casing 2. These cells are each electrically connected to a positive contact tab 3 and a negative contact tab 4. Furthermore, the pouch cell 1 has two heat dissipation tabs 5, 6 arranged on opposite sides, with the heat dissipation tab 5 being arranged between the contact tabs 3, 4. The contact tabs 3, 4 and the heat dissipation tabs 5, 6 extend from the interior of the casing 2 through a sealing seam 7, thereby sealing the casing 2 in a liquid-tight manner to the outside. The sealing seam 7 was formed using an ultrasonic welding process.

[0025] The contact lugs 3, 4 are made of a highly electrically conductive material. The heat dissipation lugs 5, 6 are made of aluminum, which can be directly thermally contacted from the outside in the hatched areas 10, 11. However, in the non-hatched areas 12, 13, they have an electrically insulating layer made of plastic.

[0026] Fig. Figure 2 shows a cross-section through the pouch cell 1 with, by way of example, three lithium-ion cells. The three lithium-ion cells each comprise a cell layer 14 assigned to the positive contact tab 3, a cell layer 15 assigned to the negative contact tab 4, and a separator 16 separating these cell layers 14, 15. Each cell layer 14 has a contact element 17 electrically connected to it, and the cell layers 15 each have a contact element 18 electrically connected to them. The contact elements 17 are led out of the interior of the casing 2, penetrating the sealed seam 7, and when joined together, form the positive contact tab 3. Likewise, the contact elements 18 are led out of the casing 2 and form the negative contact tab 4.

[0027] In each of the two areas between the electron pairs, a heat collector 19 is arranged with two heat sinks 20, 21 arranged on opposite sides (heat sinks 21 not visible in the cross-sectional view). The heat collectors 19 are formed in one piece with their heat sinks 20, 21 and are thus thermally coupled. They consist of a thin, rolled foil layer 22 made of aluminum, which is covered with a surface layer 23 made of an electrically insulating plastic. The heat sinks 20 are led out of the interior of the casing 2, penetrating the sealing seam 7, where they form the heat sink tab 5. Likewise, the Fig. 2 invisible heat sinks 21 are led out of the interior of the casing 2 and, when joined together, form the heat sink lug 6.

[0028] During operation of the pouch cell 1, the heat collectors 19 absorb the heat generated inside the casing 2 and dissipate it to the outside of the casing 2 via the heat sinks 20, 21. Due to their arrangement between the electron pairs, they have no influence on the electrochemical processes of the three lithium-ion cells. Being made of aluminum, they exhibit good thermal conductivity, with particularly efficient heat dissipation achieved by their wide cross-section. This is particularly larger than that of the contact elements 17, 18, so that a larger amount of heat can be dissipated by the heat sinks 20, 21 than in a pouch cell, which uses its contact elements for heat dissipation.

[0029] Fig. Figure 3 shows a longitudinal section through the pouch cell 1 at the level of a heat collector 19. As can be seen, the heat collector 19 has the same length and width as the cell layers 14, 15 and thus has the largest possible surface area for absorbing the heat generated inside the casing 2. The heat sinks 20, 21, like the contacting elements 17, 18, are led out of the interior of the casing 2 through the sealing seam 7 so that they can be joined to form the heat sink tabs 5, 6 and the contacting elements 17, 18, respectively. Due to the welding process used to create the sealing seam 7, the pouch cell 1 is sealed liquid-tight from the exterior of the casing 2. The surface layer 23 ends behind the areas 12, 13 of the heat dissipation tabs 5, 6, so that direct thermal contact is possible in the areas 10, 11 of the heat dissipation tabs 5, 6 or the heat dissipators 20, 21.

[0030] Furthermore, further embodiments of pouch cells 1 are conceivable, which have only one pair of electrodes. In this case, either a heat collector 19 is provided parallel to a cell layer 14, 15 of the electrode pair, or two heat collectors 19 are arranged on either side of the electrode pair. The remaining statements regarding the previously described embodiment can be applied analogously to such pouch cells 1.

[0031] Fig.Figure 4 is a schematic diagram of an embodiment of a motor vehicle 24 whose front wheels 26, arranged on a front axle 25, are driven by a drive device 27. The drive device 27 is supplied with electrical energy by an energy storage arrangement 28. This arrangement comprises a plurality of pouch cells 1 that are interconnected and thermally coupled to a heat conductor 29 by means of their heat dissipation tabs 5, 6. A cooling device 30 is arranged on the heat conductor, which realizes heat exchange between the pouch cells 1 and the ambient air.

Claims

[1] An energy storage arrangement (28) comprising one or more pouch cells (1) arranged in a housing and interconnected, each of which comprises a plurality of cell layers (14, 15) designed for electrochemical energy conversion, which are arranged inside a closed casing (2), and at least two contacting elements (17, 18) electrically conductively connected to at least one cell layer (14, 15) and which extend from the interior of the casing (2) through a sealing seam (7) closing the casing (2), wherein at least one heat collector (19) designed for heat dissipation is arranged inside the casing (2), which heat collector is thermally coupled to at least one heat dissipator (20, 21) extending from the interior of the casing (2) through the sealing seam (7), wherein the energy storage arrangement (28) has at least one heat conductor (29) designed for dissipating heat from the interior of the pouch cells (1),which is thermally coupled to the at least one heat sink (20, 21) of at least one pouch cell (1), characterized by that the at least one heat dissipator (20, 21) is guided through the sealing seam (7) at a section located between the contacting elements (17, 18) which is located on the same side of the energy storage arrangement (28) as the contacting elements (17, 18). [2] Energy storage arrangement (28) according to claim 1, characterized by in that a plurality of heat collectors (19) are arranged inside the casing (2), each of which is thermally coupled to at least one heat dissipator (20, 21) and is arranged such that at least one cell layer (14, 15) is located between each two heat collectors (19). [3] Energy storage arrangement (28) according to claim 1 or 2, characterized by that the at least one or each heat collector (19) is flat and arranged parallel to the cell layers (14, 15). [4] Energy storage arrangement (28) according to claim 3, characterized by that the at least one or each heat collector (19) is designed as a sheet metal or foil layer (22). [5] Energy storage arrangement (28) according to one of the preceding claims, characterized by in that two of the cell layers (14, 15) each form an electrode pair of a galvanic cell and the at least one or each heat collector (19) is arranged outside the at least one electrode pair. [6] Energy storage arrangement (28) according to one of the preceding claims, characterized by that the at least one or each heat collector (19) is formed in one piece with the at least one heat dissipator (20, 21) thermally coupled thereto. [7] Energy storage arrangement (28) according to one of the preceding claims, characterized bythat the at least one or each heat dissipator (20, 21) and / or the at least one or each heat collector (19) consists of a thermally conductive material. [8] Energy storage arrangement (28) according to claim 7, characterized by that the thermally conductive material is covered with an electrically insulating surface layer (23) at least in an area located inside the casing (2). [9] Motor vehicle (24) comprising an energy storage arrangement (28) according to one of the preceding claims.

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