Battery cell group for a battery module of a motor vehicle battery intended for the purely electric propulsion of a motor vehicle

Abstract

Battery cell group (14, 40) for a battery module (12) of a motor vehicle battery (10) provided for the purely electric drive of a motor vehicle, with a first battery cell (16) for generating electrical energy, a first heat-conducting heat transfer layer (22) adjacent to the first battery cell (16), a second battery cell (24) adjacent to the first heat transfer layer (22) for generating electrical energy, a second heat-conducting heat transfer layer (30) adjacent to the second battery cell (24), a cooling body (32) thermally coupled to the first heat transfer layer (22) and the second heat transfer layer (30) for cooling the first battery cell (16) via the first heat transfer layer (22) and for cooling the second battery cell (24) via the second heat transfer layer (30) and a heating element (34) thermally coupled to the second heat-conducting layer (30) for heating the second battery cell (24) via the second heat-conducting layer (30).

Description

[0001] The invention relates to a battery cell group for a battery module of a motor vehicle battery intended for the purely electric drive of a motor vehicle, with the aid of which electrical energy can be stored and released in order to be able to drive a motor vehicle purely electrically.

[0002] From DE 10 2009 016 868 A1 a battery cell group for a battery designed as a pouch cell is known, in which conductors of a first battery cell and a second battery cell are thermally coupled to one another via a heat sink, so that one heat sink can cool both battery cells.

[0003] From DE 10 2010 001 430 A1, a motor vehicle battery is known with a plurality of battery cells which are each thermally coupled to one another via heat transport bodies, wherein the respective heat transport body has a heating wire for heating the battery cells and can passively dissipate heat via its free side surfaces when the heating wire is switched off.

[0004] There is a constant need to temperature control battery cells of a motor vehicle battery with little design effort.

[0005] The object of the invention is to demonstrate measures that enable temperature control of battery cells of a motor vehicle battery with little design effort.

[0006] The object is achieved according to the invention by a battery cell group having the features of claim 1. Preferred embodiments of the invention are specified in the subclaims, which can each individually or in combination represent an aspect of the invention.

[0007] According to the invention, a battery cell group for a battery module of a motor vehicle battery intended for the purely electric drive of a motor vehicle is provided with a first battery cell for generating electrical energy, a heat-conducting first heat-conducting layer adjacent to the first battery cell, a second battery cell for generating electrical energy adjacent to the first heat-conducting layer, a heat-conducting second heat-conducting layer adjacent to the second battery cell, a heat-conducting heat-conducting layer thermally coupled to the first heat-conducting layer and the second heat-conducting layer for cooling the first battery cell via the first heat-conducting layer and for cooling the second battery cell via the second heat-conducting layer, and a heating element thermally coupled to the second heat-conducting layer for heating the second battery cell via the second heat-conducting layer.

[0008] This takes advantage of the knowledge that, particularly in the case of a motor vehicle battery designed as a pouch cell, the battery cells require a certain predetermined temperature range for the best possible operation. In order to operate the battery cells in this temperature range, it is not only necessary to prevent overheating by cooling, but also to heat the battery cells, for example during a cold start of a motor vehicle with a motor vehicle battery comprising the battery group according to the invention. In this case, however, the heat sink is not also used for heating purposes; rather, a heater is provided in addition to the heat sink. The heat sink and the heater can be operated independently of one another as needed, so that a temperature can be regulated for the respective battery cell within a temperature range intended for optimal operation with little effort.This exploits the fact that the battery cells arranged in layers one behind the other in a pouch cell essentially have the same temperature, and that either cooling or heating occurs when a target temperature is reached. Therefore, the second thermally conductive layer can be functionalized for both cold and heat transfer.

[0009] If heating is required, the heating element can heat the second battery cell indirectly via the second heat-conducting layer. Furthermore, the heating element can indirectly heat the second battery cell and / or directly the first battery cell of a layered, similarly constructed battery cell group, so that essentially all of the battery cells of a battery module comprising multiple battery cell groups can be heated to a desired temperature. Furthermore, the finding is exploited that, during operation of the battery module comprising multiple battery cell groups, a higher cooling power is generally required than heating power. If cooling is required, the heat sink can cool both the first battery cell and the second battery cell via the first heat-conducting layer, so that both battery cells of the battery cell group can be cooled.At the same time, the heat sink can also cool the second battery cell and the first battery cell of a similarly structured battery cell group layered in successive layers via the second thermally conductive layer. This allows almost all battery cells of the battery module comprising multiple battery cell groups to be cooled on both ends via a thermally conductive layer. This allows a space-saving layered structure of the battery cells to be maintained, which, in particular, enables a large heat transfer area between the respective thermally conductive layers and the battery cells.With the help of the heat conducting layers thermally coupled via the heat sink, the battery cells can be cooled on both sides and several battery cell groups can be heated on one side via the second heat conducting layer thermally coupled to the radiator in a layered composition, so that the temperature of the battery cells of a motor vehicle battery can be controlled with little design effort.

[0010] The first battery cell has two first end faces, each facing adjacent second battery cells, spaced apart from one another by a thickness and connected to one another via first side surfaces. The second battery cell has two second end faces, each facing adjacent first battery cells, spaced apart from one another by a thickness and connected to one another via second side surfaces. The first battery cell and the second battery cell are designed in particular symmetrically, preferably identically. The battery cells in particular have a substantially rectangular battery body which forms the respective end faces and side surfaces, wherein conductors can protrude from the battery body, each forming a pole, in particular a negative pole or positive pole, of the battery cell. The respective heat-conducting layer in particular has a higher thermal conductivity than the battery cells.The respective thermally conductive layer is preferably designed as an electrical insulator, so that subsequent battery cells are electrically insulated from one another layer by layer via the thermally conductive layer. The thermally conductive layers form, in particular, a heat transfer surface to the battery cells, which in particular essentially covers the entire end face of the respective battery cell and, if appropriate, additionally at least partially covers the end faces of the conductors. The cold of the heat sink and / or the heat of the heater can be generated, for example, by a gaseous and / or liquid fluid flowing through it and / or by electrothermal processes in the material of the heat sink or heater.

[0011] In particular, the heating element rests against a front side of the second heat-conducting layer facing away from the second battery cell. The heating element can thus directly contact the second heat-conducting layer over a large area. This allows a correspondingly large heat flow to be quickly introduced into the second battery cell and / or the first battery cell of a subsequent battery cell group.

[0012] Preferably, the heat sink is thermally coupled indirectly to the first battery cell via the first heat conducting layer, wherein in particular the heat sink bears against the second battery cell. For example, the first heat conducting layer can contact the first battery cell on one end face and the heat sink on an opposite end face. The heat sink can contact the first heat conducting layer on one end face and the second battery cell on an opposite end face. As a result, for example, a short circuit between the first battery cell and the second battery cell via the heat sink can be prevented by electrically insulating the first heat conducting layer. Furthermore, the heat sink can be thermally coupled indirectly to the second battery cell via the heat sink or directly to the second heat conducting layer.

[0013] It is particularly preferably provided that the first battery cell has a first battery body and first conductors protruding from the first battery body, and the second battery cell has a second battery body and second conductors protruding from the second battery body, wherein the heat sink is arranged laterally at a distance from the first battery body and the second battery body, wherein the heat sink runs in particular between the first conductor and the second conductor. The heat sink can thus be arranged essentially parallel to the battery body, so that the extension in the longitudinal direction of the battery cell group with the battery bodies and heat-conducting layers arranged one behind the other in layers is not increased by the thickness of the heat sink. Instead, an installation space already provided for the arrangement of the conductors can be used for the heat sink.Furthermore, the heat sink can introduce cold into the battery body not only via the first heat conductor and the second heat conductor but also, in particular directly, via the conductors.

[0014] In particular, the heating element is arranged at the end face of the first battery body and the second battery body. The heating element can thus be integrated as an additional layer into a layered structure of the battery cells separated from one another by the heat-conducting layers. The heating element forms, in particular, a heat transfer surface that essentially covers the entire end face of the respective battery cell and, if appropriate, also at least partially covers the end faces of the conductors.

[0015] Preferably, the heater is designed as a PTC element. This allows the heater to be easily operated with electrical energy to generate heat. Furthermore, the heater can be easily configured as a thin layer compared to the thickness of the battery cells, thus keeping the space requirement of the battery cell array small.

[0016] Particularly preferably, the first thermally conductive layer and / or the second thermally conductive layer are made of graphite foil. This allows the respective thermally conductive layer to provide good thermal conductivity and / or form a sufficient electrical insulation layer.

[0017] In particular, the first thermally conductive layer and / or the second thermally conductive layer comprises an insulating layer for electrically insulating the first battery cell from the second battery cell. The insulating layer can be formed, for example, from the material of the thermally conductive layer itself, for example, by the basal planes of the graphite of a thermally conductive layer configured as a graphite foil running substantially parallel to the end faces of the battery cells. The thermally conductive layer is preferably provided with a layer of an electrically insulating material, in particular by coating.

[0018] The invention further relates to a battery module for a motor vehicle battery intended for the purely electric drive of a motor vehicle, comprising a first battery cell group, which can be designed and developed as described above, and a second battery cell group, which can be designed and developed as described above, wherein the heating element of the first battery cell group is thermally coupled to the first battery cell of the second battery cell group. With the aid of the heat-conducting layers thermally coupled via the heat sink, the battery cells can be cooled on both sides, and several battery cell groups in the battery module can be heated on one side via the second heat-conducting layer thermally coupled to the heating element in a layered composition, so that the temperature of the battery cells of the battery module for the motor vehicle battery can be controlled with little design effort.

[0019] In particular, the heating element of the first battery cell group is in contact with the second thermally conductive layer of the first battery cell group and with the first battery cell of the second battery cell group. The heating element thus enables a layered thermal contact between the first battery cell group and the second battery cell group. The heating element thus assumes a heating function for both the first battery cell group and the second battery cell group.

[0020] The invention will now be explained by way of example with reference to the accompanying drawings using preferred embodiments, wherein the features presented below may represent an aspect of the invention both individually and in combination. They show: Fig. 1: a schematic perspective view of a motor vehicle battery and Fig. 2: a schematic side view of a part of a battery module for the motor vehicle battery of Fig. 1.

[0021] The Fig. The motor vehicle battery 10 shown in Figure 1 comprises, for example, three battery modules 12 arranged one above the other. Several battery modules 12 can also be arranged side by side or one behind the other at a common height.

[0022] As in Fig.As shown in Figure 2, the battery module 12 can have a plurality of battery cell groups 14 arranged one behind the other in the longitudinal direction in layers, which repeat as a recurring unit in the longitudinal direction of the battery module 12. The battery cell group 14 has a first battery cell 16 with a substantially rectangular first battery body 18, from which first conductors 20 protrude upwards to form a negative pole and a positive pole. A first heat-conducting layer 22 is located on the first battery cell 16, in particular substantially over the entire height of the first battery cell 16. The first heat-conducting layer 22 can in particular contact both the first battery body 18 and the first conductor 20.

[0023] On the side of the first heat-conducting layer 22 facing away from the first battery cell 16, a second battery cell 24 rests with its second battery body 26. Second conductors 28 protrude upward from the second battery body 26 at a distance from the first conductors 20. A second heat-conducting layer 30 rests on the second battery cell 24, in particular substantially over the entire height of the second battery cell 24. The second heat-conducting layer 30 can in particular contact both the second battery body 26 and the second conductor 28. A heat sink 32 is provided above the battery bodies 18, 26, which heat sink is in particular directly thermally contacted with the first heat-conducting layer 22 and the second heat-conducting layer 30 at the level of the conductors 20, 28.In particular, the heat sink 32 and / or the first heat conducting layer 22 of the first battery body 18 is designed to be substantially flush with an outer side of the discharge lines 20, 28 facing away from the associated battery body 18, 26. In particular, the heat sink 32 and / or the first heat conducting layer 22 and / or the second heat conducting layer 30 do not protrude beyond the outer sides of the discharge lines 20, 28 facing away from the associated battery body 18, 26.

[0024] On the side of the second heat-conducting layer 30 facing away from the second battery cell 24 is a heater 34 designed as a PTC element. The heater 34 covers an area corresponding to the end faces of the battery bodies 18, 26. The heater 34 can be supplied with electrical energy via electrical lines 36 to generate heat. A further first battery cell 38 of a second battery cell group 40 constructed correspondingly to the first battery cell group 14 can be connected to the heater 34, so that the heater 34 can indirectly heat the second battery cell 24 of the battery cell group 14 via the second heat-conducting layer 30 and directly heat the first battery cell 38 of the second battery cell group 40 on one side. The heat sink 32 can indirectly cool the second battery cell 24 on both sides via the first heat-conducting layer 22 and the second heat-conducting layer 30.The first battery cell 16 can be cooled by the heat sink 32 of the same battery cell group 14 on one end face via the first heat conducting layer 22 and preferably on the other end face by a heat sink of an upstream battery cell group via its second heat conducting layer and its heating element, which is not heated in this situation.

Claims

[1] Battery cell group (14, 40) for a battery module (12) of a motor vehicle battery (10) intended for the purely electric drive of a motor vehicle, with a first battery cell (16) for generating electrical energy, a heat-conducting first heat-conducting layer (22) adjacent to the first battery cell (16), a second battery cell (24) adjacent to the first heat-conducting layer (22) for generating electrical energy, a heat-conducting second heat-conducting layer (30) adjacent to the second battery cell (24), a heat sink (32) thermally coupled to the first heat conducting layer (22) and the second heat conducting layer (30) for cooling the first battery cell (16) via the first heat conducting layer (22) and for cooling the second battery cell (24) via the second heat conducting layer (30) and a heating element (34) thermally coupled to the second heat-conducting layer (30) for heating the second battery cell (24) via the second heat-conducting layer (30). [2] Battery cell group (14, 40) according to claim 1, characterized by that the heating element (34) rests against an end face of the second heat-conducting layer (30) facing away from the second battery cell (24). [3] Battery cell group (14, 40) according to claim 1 or 2, characterized by that the heat sink (32) is thermally coupled indirectly to the first battery cell (16) via the first heat conducting layer (22), wherein in particular the heat sink (32) rests against the second battery cell (24). [4] Battery cell group (14, 40) according to one of claims 1 to 3, characterized byin that the first battery cell (16) has a first battery body (18) and first conductors (20) projecting from the first battery body (18), and the second battery cell (24) has a second battery body (26) and second conductors (28) projecting from the second battery body (26), wherein the heat sink (32) is arranged laterally spaced from the first battery body (18) and the second battery body (26), wherein the heat sink (32) runs in particular between the first conductor (20) and the second conductor (28). [5] Battery cell group (14, 40) according to claim 4, characterized by that the heating element (34) is arranged on the end face of the first battery body (18) and the second battery body (26). [6] Battery cell group (14, 40) according to one of claims 1 to 5, characterized by that the heating element (34) is designed as a PTC element. [7] Battery cell group (14, 40) according to one of claims 1 to 6, characterized bythat the first heat-conducting layer (22) and / or the second heat-conducting layer (30) is made of graphite foil. [8] Battery cell group (14, 40) according to one of claims 1 to 7, characterized by that the first heat-conducting layer (22) and / or the second heat-conducting layer (30) has an insulator layer for electrically insulating the first battery cell (16) from the second battery cell (24). [9] Battery module (12) for a motor vehicle battery (10) provided for the purely electric drive of a motor vehicle, comprising a first battery cell group (14) according to one of claims 1 to 8 and a second battery cell group (40) according to one of claims 1 to 8, wherein the heating element (34) of the first battery cell group (14) is thermally coupled to the first battery cell (38) of the second battery cell group (40). [10] Battery module (12) according to claim 9, characterized bythat the heating element (34) of the first battery cell group (14) rests against the second heat-conducting layer (30) of the first battery cell group (14) and against the first battery cell (38) of the second battery cell group (40).

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