Battery module with pouch cells

Abstract

Battery module (1) comprising several pouch cells (10) and a housing (20) enclosing the pouch cells (10), wherein the pouch cells (10) are at least partially embedded in a fire-resistant foam (51), preferably PU foam, within the housing (20).

Description

Technical area

[0001] The present invention relates to a battery module comprising a plurality of pouch cells and a housing enclosing the pouch cells, preferably for use in a vehicle. State of the art

[0002] Battery systems are the subject of current research and development in various fields, including electric and hybrid vehicles, as well as fuel cell vehicles. To construct a battery system, several battery cells are typically combined into a battery module. The battery cells are mechanically held together and electrically connected at the positive and negative terminals.

[0003] Different cell formats are known, for example, cylindrical or prismatic battery cells with a hard shell. The comparatively thin and usually flexible pouch format allows for high packing density and offers a favorable weight-to-capacity ratio. Battery modules made of pouch cells are described, for example, in DE 10 2020 216 383 A1, US 2020 / 0350531 A1, and EP 4 007 043 A1.

[0004] Creating and maintaining a well-defined environment is crucial for the reliable operation of a battery system. Furthermore, the individual battery cells must be protected and wired. For these and other reasons, a battery enclosure is provided to house the battery cells and protect them from external influences.

[0005] At the same time, the battery housing serves as a safety device in the event of a defect, such as thermal runaway, which can lead to the explosive release of media such as hot gases, combustion products, and battery cell components from a battery cell. The goal is to ensure controlled removal of these media from the battery housing to minimize damage to the battery system and the vehicle. Thermal runaway, also known as thermal propagation, is an exothermic reaction in a cell caused by internal or external abnormalities that result in the sudden destruction of the cell.

[0006] In the event of a thermal runaway, battery modules made of pouch cells generally do not have a defined outgassing direction, as the pouch cells do not have a burst disc, which means that the cell seal can rupture and outgas at any weak point.

[0007] The random and undirected degassing in the event of a thermal runaway can damage nearby components, accelerating propagation within the battery, for example, through short circuits, arcing, etc. For this reason, all critical components installed near the modules must be carefully protected from high heat and mechanical influences. Description of the invention

[0008] An object of the invention is to provide an improved battery module with pouch cells, in particular to improve safety in the event of a malfunction.

[0009] The object is achieved by a battery module having the features of claim 1. Advantageous further developments follow from the subclaims, the following presentation of the invention and the description of preferred embodiments.

[0010] The battery module is particularly designed for use in a vehicle, preferably an electric or hybrid vehicle or a vehicle with a fuel cell.

[0011] The battery module contains several pouch cells. Pouch cells are battery cells in which the active layers are enclosed in a flexible, usually aluminum-based outer foil. The outer foil may be welded on the open sides, creating sealed seams.

[0012] The battery module further comprises a housing enclosing the pouch cells, wherein the housing is preferably closed on all sides (except for any venting openings).

[0013] According to the invention, the pouch cells in the housing are at least partially encased in a fire-protection foam, preferably PU foam. The fire-protection foam is thus in mechanical contact with the pouch cells and at least partially encloses or surrounds them. In other words, the fire-protection foam is in surface contact with the pouch cells, at least partially forming a negative of the outer contour of the pouch cells.

[0014] By encapsulating the pouch cells with fire-resistant foam, the outer shell of the pouch cells is reinforced in combination with the housing, making the behavior of the battery module more controllable in the event of a thermal runaway. The fire-resistant foam also thermally insulates the pouch cells from each other, slowing propagation between the pouch cells.

[0015] The housing can have a cover plate with a plurality of vents, which create weak points in the housing in the area of ​​the cover plate. In this way, in the event of thermal runaway, venting occurs along a defined preferred direction. The battery module can be installed according to the preferred direction, which allows for better protection of nearby components from thermal and mechanical stress. The vents can be designed as elongated holes, aligned in particular along a longitudinal direction of the housing.

[0016] The pouch cells can each have at least one sealing seam cast into the fire-protection foam, with the sealing seams preferably located on the cover plate side. By encapsulating the pouch cells with the fire-protection foam, the sealing seams, in combination with the housing, are reinforced so that the pouch cell affected by thermal runaway can rupture and degas toward the targeted weak point.

[0017] The housing can be filled (e.g., poured) with a gap filler, which can be a thermally conductive adhesive, on the underside between a base plate of the housing and the pouch cells. This reinforces the housing and the pouch cells on the underside so that uncontrolled destruction or damage to the housing and pouch cells in this section is unlikely in the event of a thermal runaway. The reinforcement on the underside of the housing also helps prevent the pouch cells from rupturing in this area.

[0018] The pouch cells are equipped with connecting electrodes for electrical connection. The battery module can have at least one connecting element that contacts the connecting electrodes of the pouch cells in such a way that the pouch cells of the module are electrically interconnected.

[0019] The connection electrodes can be at least partially encapsulated in the fire protection foam in the area where they contact the connection element, thereby reinforcing the pouch cells in the area of ​​the connection electrodes. This further reduces the likelihood of uncontrolled destruction or damage to the housing in these areas in the event of a thermal runaway.

[0020] The connecting element can be comb-shaped, comprising several parallel grooves into which the connecting electrodes engage as connecting tabs protruding from the pouch cells. That is, each tab-like connecting electrode engages a groove. In this case, the grooves can be at least partially filled with the fire protection foam for the reason stated above.

[0021] Each of the pouch cells can have two terminal electrodes, which are arranged on opposite narrow sides of the pouch cell. Accordingly, in this case, the battery module comprises two terminal elements arranged on opposite end faces of the housing for contacting the corresponding terminal electrodes.

[0022] Heat shields can be installed between the pouch cells to reduce heat transfer between the pouch cells. Alternatively or additionally, such heat shields can also be provided between the side panels of the housing and the corresponding edge-side pouch cells of the pouch cell stack.

[0023] The housing may be partially or completely coated or bonded on the inside with an insulating material to improve the electrical safety of the battery module.

[0024] The insulating material can be designed without any vents in the cover plate area, so that the insulating material effectively spans the cover plate's vents. This allows for the aforementioned weak points for directed venting without leaving the pouch cells exposed.

[0025] The housing can be made of aluminum or comprised of aluminum, thus achieving a good compromise between mechanical stability and the weight of the battery module. Sheet steel is also suitable for the housing.

[0026] Further advantages and features of the present invention will become apparent from the following description of preferred embodiments. The features described therein can be implemented alone or in combination with one or more of the features presented above, provided the features do not contradict each other. The following description of preferred embodiments is made with reference to the accompanying drawings. Short description of the characters

[0027] Preferred further embodiments of the invention are explained in more detail in the following description of the figures. In the figures: Fig. 1 an exploded view of a battery module with a plurality of pouch cells arranged in parallel in a housing; Fig. 2 the battery module in a side sectional view; Fig. 3 the battery module in a sectional plan view; and Fig. 4 an isometric view of the battery module in the assembled state. Detailed description of preferred embodiments

[0028] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements are provided with identical reference numerals in the figures, and a repeated description of these elements is partially omitted to avoid redundancy.

[0029] The Fig. 1 is an exploded view of a battery module 1 with a plurality of pouch cells 10 arranged in parallel and a housing 20. The Fig. 2 shows the battery module 1 in a side sectional view. Fig. 3 shows the battery module 1 in a sectional plan view, and the Fig. 4 is an isometric view of the battery module 1 in the assembled state.

[0030] Pouch cells 10 are battery cells in which the active layers are enclosed by a flexible, usually aluminum-based outer foil. The outer foil can be welded on the open sides, creating sealing seams 11 (see Fig. 2). According to the present structure of the pouch cells 10, flag-like connecting electrodes 12 (cf. Fig. 3) for the electrical connection, the bag-shaped outer film of the pouch cells 10 on opposite narrow sides.

[0031] The pouch cells 10 are stacked to save space and installed in a closed, cuboid-shaped housing 20. The housing 20 comprises a base plate 21, two opposing side plates 22, two opposing end plates 23, and a cover plate 24, which are preferably made of aluminum. The plates 21, 22, 23, 24 forming the housing 20 can each be coated or bonded with an insulating material 25.

[0032] The plates 21, 22, 23, 24 forming the housing 20 can have a thickness of 0.5 mm to 6 mm. The base plate 21 and the cover plate 24 preferably have a thickness of approximately 1 mm. The side plates 22 preferably have a thickness of 5 mm to 6 mm, in particular approximately 5.4 mm. The end plates 23 preferably have a thickness of approximately 3 mm. The insulating material 25 can have a thickness of 0.1 mm to 0.3 mm, preferably 0.2 mm.

[0033] Heat shields 30 are provided between the pouch cells 10 and between the side plates 22 and the corresponding edge pouch cells 10 of the pouch cell stack in order to reduce heat transfer between the cells.

[0034] The battery module 1 has a comb-like connection element 40 on each of the two end faces, where the connection electrodes 12 protrude from the pouch cells 10 as connection lugs. The connection elements 40 are designed to contact the connection electrodes 12 of the pouch cells 10 in such a way that the pouch cells 10 are electrically connected. The two connection elements 40 have parallel grooves 41, formed by adjacent projections 42, into which the connection electrodes 12 engage (see FIG. Fig. 3.

[0035] The battery module 1 has a battery management system (BMS) 70, which serves as an electronic circuit for monitoring and controlling the battery module 1. The BMS 70 can communicate with corresponding sensors. The BMS 70 typically has a communication interface to a higher-level entity, such as the vehicle, and can thus provide information about the status of the battery module 1.

[0036] The battery module 1 is designed in such a way that any degassing, for example in the event of a thermal runaway, can preferably or, if possible, only take place in one direction, here in the direction of the cover plate 24. For this purpose, various design measures are provided which act individually and in combination.

[0037] The underside of the housing 20 is filled (e.g., poured) with a gap filler 50, which is preferably a thermally conductive adhesive. The gap filler 50 can have a thickness of 1 mm to 2 mm, preferably approximately 1.5 mm.

[0038] In addition, the pouch cells 10 are encased in a fire protection foam 51 in the cell contact area and on the top side. The fire protection foam is preferably a PU foam (polyurethane). Fig.3 shows that the encapsulation of the pouch cells 10 into the fire-protection foam 51 particularly encompasses the contact area between the connection electrodes 12 and the connection elements 40. In other words, the grooves 41 of the connection elements 40 are filled with fire-protection foam 51.

[0039] By encapsulating the pouch cells 10 with the fire-protection foam 51 and the gap filler 50, the sealing seams 11, in combination with the housing 20, are reinforced such that the pouch cell 10 affected by thermal runaway can tear open and vent toward a targeted weak point. This targeted weak point is realized by venting openings 24a, preferably elongated holes, in the cover plate 24, with the venting openings 24a being arranged above the sealing seams 11 in the longitudinal direction of the cell.

[0040] In this way, degassing occurs along a preferred direction, allowing for better control of the behavior of battery module 1 in the event of a thermal runaway. Battery module 1 can be installed according to the preferred direction, allowing for better protection of nearby components from thermal and mechanical stress.

[0041] The fire protection foam 51 thermally insulates the cell tops from each other, thereby slowing down the propagation between the pouch cells 10.

[0042] Where applicable, all individual features presented in the embodiments may be combined and / or exchanged without departing from the scope of the invention. List of reference symbols 1 battery module 10 pouch cells 11 Sealing seam 12 Connection electrode 20 housings 21 Base plate 22 Side plate 23 Front plate 24 Cover plate 24a Degassing opening 25 Insulating material 30 Heat shielding 40 connecting element 41 groove 42 lead 50 gap fillers 51 Fire protection foam 70 Battery Management System QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] DE 10 2020 216 383 A1

[0003] US 2020 / 0350531 A1

[0003] EP 4 007 043 A1

[0003]

Claims

[1] Battery module (1) comprising a plurality of pouch cells (10) and a housing (20) enclosing the pouch cells (10), wherein the pouch cells (10) in the housing (20) are at least partially cast into a fire protection foam (51), preferably PU foam. [2] Battery module (1) according to claim 1, characterized by that the housing (20) has a cover plate (24) with a plurality of degassing openings (24a), preferably designed as elongated holes. [3] Battery module (1) according to claim 1 or 2, characterized by that the pouch cells (10) each have at least one sealing seam (11) which is cast into the fire protection foam (51), wherein the sealing seams (11) are preferably located on the side of the cover plate (24). [4] Battery module (1) according to one of the preceding claims, characterized bythat the housing (20) is filled on the underside, between a base plate (21) and the pouch cells (10) with a gap filler 50, which can be a thermally conductive adhesive. [5] Battery module (1) according to one of the preceding claims, characterized by in that the pouch cells (10) are equipped with connecting electrodes (12) and the battery module (1) has at least one connecting element (40) which contacts the connecting electrodes (12) of the pouch cells (10) in such a way that the pouch cells (10) are electrically connected together, wherein the connecting electrodes (12) are at least partially cast into the fire protection foam (51) in the region of the contact with the connecting element (40). [6] Battery module (1) according to claim 5, characterized bythat the connection element (40) has parallel grooves (41) into which the connection electrodes (12) engage as connection lugs projecting from the pouch cells (10), wherein the grooves (41) of the connection element (40) are at least partially filled with the fire protection foam (51). [7] Battery module (1) according to claim 5 or 6, characterized by that each pouch cell (10) has two connection electrodes (12), arranged correspondingly on opposite narrow sides of the pouch cell (10), and the battery module (1) has two connection elements (40), arranged on opposite end sides of the housing (20), for contacting the corresponding connection electrodes (12). [8] Battery module (1) according to one of the preceding claims, characterized by that heat shields (30) are installed between the pouch cells (10). [9] Battery module (1) according to one of the preceding claims, characterized bythat the housing (20) is partially or completely coated or connected on the inside with an insulating material (25). [10] Battery module (1) according to claim 2 and 9, characterized by that the insulating material (25) has no degassing openings in the region of the cover plate (24), so that the insulating material (25) spans the degassing openings (24a) of the cover plate (24). [11] Battery module (1) according to one of the preceding claims, characterized by that the housing (20) is made of aluminum.

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