SE2251433A1

SE2251433A1 - A battery assembly

Info

Publication number: SE2251433A1
Application number: SE2251433A
Authority: SE
Inventors: Csaba Dobi; Rodyn Gilharry
Original assignee: Northvolt Ab
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2024-06-08
Also published as: WO2024120869A1

Abstract

A battery assembly configured to receive a plurality of battery cells at respective predetermined locations, wherein the battery assembly comprises a plurality of vent apertures located at said predetermined locations and at least one venting channel extending adjacent to at least a first subset of said predetermined locations and wherein the vent apertures located at the first subset of said predetermined locations are configured to allow material ejected from a battery cell located at a respective one of the predetermined locations to exit therethrough and into the at least one venting channel, wherein the at least one venting channel includes an open cell foam at least adjacent the vent apertures to receive said material that exits through said vent apertures.

Description

The present disclosure relates to a battery assembly and, in particular, to a battery assembly comprising a vent channel for receiving material ejected from battery cells. The disclosure also relates to a battery module.

Background The safety of electrochemical battery cells is important. It is known for battery cells to experience thermal runaway, in which there is uncontrolled self- heating. Thermal runaway may be caused by damage to the battery cell or a defect. Pressure may build within a casing of the battery cell during such a thermal runaway event, which may lead to rupture and the violent ejection of material. A plurality of battery cells may be mounted together and thus the ejection of material from one of the battery cells presents a hazard to the other battery cells.

Summary According to a first aspect of the present disclosure there is provided a battery assembly configured to receive a plurality of battery cells at respective predetermined locations, wherein the battery assembly comprises a plurality of vent apertures located at said predetermined locations and at least one venting channel extending adjacent to at least a first subset of said predetermined locations and wherein the vent apertures located at the first subset of said predetermined locations are configured to allow material ejected from a battery cell located at a respective one of the predetermined locations to exit therethrough and into the at least one venting channel, wherein the at least one venting channel includes an open cell foam at least adjacent the vent apertures to receive said material that exits through said vent apertures.

In one or more embodiments, the battery assembly comprises a plate having a first surface and a second surface opposed the first surface, wherein the predetermined locations are located over the first surface of the plate and the plurality of vent apertures extend through said plate from the first surface to the second surface and wherein the at least one venting channel extends along the second surface of the plate.

In one or more embodiments, the venting channel is only partly filled with said foam. In one or more embodiments, the venting channel is completely filled with said foam.

In one or more embodiments, the foam is arranged in the venting channel to provide a continuous path through the venting channel that is absent of said foam.

In one or more embodiments, the foam comprises Aluminium metal foam.

In one or more embodiments, the foam comprises one of: metal based foam, a polymer based foam, a composite based foam, a polyurethane based foam, a silicone based foam or an epoxy based foam.

In one or more embodiments, the at least one venting channel comprises a first wall arranged opposite the plate and two side walls extending from the first wall and arranged to abut and support the plate, wherein the foam extends between the first wall and the second side of the plate to provide structural support to the plate.

In one or more embodiments, the foam is bonded to the second surface of the plate.

In one or more embodiments, the plate is of mica.

In one or more embodiments, the battery assembly comprises one or more separator walls configured to separate the plurality of cells from one another when received by the battery assembly and wherein each predetermined location is associated with at least one vent aperture. In one or more examples, the separator walls may comprise thermal barriers and/or cooling elements, such as cooling snakes.

In one or more embodiments, the battery assembly comprises an extruded section that defines a plurality of venting channels comprising at least a first venting channel and a second venting channel, wherein the first venting channel extends adjacent to the first subset of predetermined locations at the second surface of the plate and wherein the vent apertures located at the first subset of said predetermined locations are configured to allow the material ejected from the battery cells exit therethrough and into the first venting channel; and wherein the second venting channel extends adjacent to a second subset, different to the first subset, of said predetermined locations at the second surface of the plate and wherein the vent apertures located at the second subset of said predetermined locations are configured to allow the material ejected from the battery cells at those second subset of said predetermined locations to exit therethrough and into the second venting channeh and wherein the extruded section and the plate are provided with cooperating features to couple them together.

In one or more embodiments, the battery assembly comprises a plurality of side walls configured to couple to the extruded section and engage with the plurality of battery cells received at the first surface.

According to a second aspect of the disclosure we provide a battery module or battery pack comprising: the battery assembly of the first aspect; a plurality of cylindrical battery cells mounted in the predetermined locations; and an enclosure of one or more parts to enclose said plurality of cylindrical battery cells.

While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail.

The figures and Detailed Description that follow also exemplify various example embodiments. Various example embodiments may be more completely understood in consideration of the following Detailed Description in connection with the accompanying Drawings.

Brief Description of the Drawings One or more embodiments will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 shows a first view of an example battery assembly; and Figure 2 shows a second view of the example battery assembly of Figure 1 with several walls removed to show the plate, vent apertures and venting channel.

Detailed Description Example figure 1 shows a battery assembly 100. The battery assembly comprises a plurality of component parts configured to connect together. The battery assembly 100, once assembled and loaded with battery cells 101 comprises a battery module or battery pack.

The battery cells 101 in the present examples comprise cylindrical cells. However, the disclosure is not limited to an implementation in which the battery assembly 100 is configured to receive cylindrical cells. Thus, in other embodiments, the battery cells 101 may be pouch cells or prismatic cells.

It will be appreciated that defects in battery cells, such as caused by damage or by other reasons, may lead to an increase in heat and pressure within the battery cell. As will be known in the art, the battery cells 101 may experience "thermal runaway" in which chemical reactions within the battery cell create temperatures and pressures beyond their design limits which can lead to ejection of material including gases and/or particulate matter.

When a plurality of battery cells 101 are arranged together, such as in the battery module, it is important, in one or more embodiments, that the ejection of material from one battery cell does not cause damage to a different battery cell in the battery module. The ejected material may affect a nearby cell for one or more reasons such as by virtue of it being conductive, its temperature, the speed of ejection or the direction of ejection. Thus, it may be important to make provision so that a battery cell that ejects material and/or experiences thermal runaway will not cause further damage that may cause further battery cells to experience thermal runaway.

With reference to Figures 1 and 2, the battery assembly 100 is configured to receive the plurality of battery cells 101 at respective predetermined locations 102. In this example, the predetermined locations are positions in the battery assembly 100, such as on a base plate, at which a battery cell will be located when stacked together with the other battery cells and any "separator walls" that may comprise thermal barriers or cooling elements that may also be part of the battery assembly 100.

The battery assembly 100 comprises a plurality of vent apertures 103 located at said predetermined locations.

In the present example, the battery assembly 100 may be configured to be compartmentalised by the one or more walls (e.g. formed of said thermal barriers or cooling elements) such that the battery cells 101 are contained by those one or more walls and the vent apertures 103 provide an exit for ejected material. As will be appreciated, the battery cells 101 typically have a vent formed in their respective cell casings or outer structure and thus the battery assembly 100 and battery cells 101 may be arranged together such that the vents in the cell casings or outer structure are substantially aligned with the vent apertures 103. In the present example, each predetermined location 102 is configured to receive one battery cell 101, although in other examples this may be different. Further, in the present example, each predetermined location is associated with one vent aperture 102. However, in other examples, each predetermined location may be associated with more than one vent aperture. Further, in other examples, some of the battery cells may not be located in a location that has a vent aperture. In one or more examples, the vent apertures 103 are provided in a base plate 104 upon which the battery cells 101 are stacked side by side along with said one or more walls (if provided).

The battery assembly 100 further comprises at least one venting channel extending adjacent to at least a first subset of said predetermined locations. In the present example, three venting channels 105, 106, 107 are shown. With reference to Figure 2, the first subset of predetermined locations 102 comprise those in the row 207 and, as such, the vent apertures 103 located at each of the first subset of said predetermined locations are configured to allow material ejected from a battery cell 101 located at a respective one of the predetermined locations to exit therethrough and into the venting channel 105, namely the first venting channel. Likewise the battery cells that are to be located at the predetermined locations in rows 208 (i.e. a second subset of predetermined locations) have vent apertures 103 configured to allow ejected material to exit into a second venting channel 106. Further, the battery cells that are to be located at the predetermined locations in row 209 (i.e. a third subset of predetermined locations) have vent apertures 103 configured to allow ejected material to exit into a third venting channel 107.

The at least one venting channel, or, in this example, three venting channels 105, 106, 107, include an open cell foam 110, 111, 112 at least adjacent the vent apertures 103 to receive the material that exits through the vent apertures 103. The foam is non-combustible and may be of metal. Thus, the foam is non-combustible to a degree such that on receipt of material ejected from a battery cell experiencing thermal runaway it does not combust.

By including foam adjacent the vent apertures 103 and opposite the vent apertures, particulate ejecta may be caught whilst allowing gaseous ejecta and heat to diffuse through the venting channel. Further, the foam may also suppress any flames associated with the ejection of material. In addition, the open cell foam may be advantageous in that flame and/or ejecta will be received into its open cell structure rather than being deflected back towards the venting battery cell.

In one or more examples, the foam may be configured to partially melt during venting from a battery cell 101 through the respective vent aperture 103, but this melt has been found to be localised and the foam may assist in energy absorption due to the change in phase and thereby reduce the potential impact on other battery cells 101.

In one or more examples, the foam comprises an Aluminium metal foam. In other examples, the foam comprises one of: metal based foam, a polymer based foam, a composite based foam, a polyurethane based foam, a silicone based foam or an epoxy based foam.

The base plate 104 has a first surface 113 and a second surface 114 opposed the first surface. The predetermined locations are located over the first surface 113 of the plate 104 and the plurality of vent apertures extend through the plate from the first surface 113 to the second surface 114. In one or more examples, the or each of the venting channels 105, 106, 107 extend along the second surface 114 of the plate, parallel to the plate 104 at least partly (or wholly) over their length. The venting channels 105, 106, 107 are open at at least one end or at both ends. In the present example, the venting channels 105, 106 ,107 have an open end adjacent an edge of the base 104. The battery assembly 104 may include further structures to route gases from the venting channels to other positions of the battery assembly 100.

In one or more examples, the one or more of the venting channels 105, 106 107 are completely filled with said open cell metal foam. However, in the present example, the venting channels 105, 106, 107 are only partly filled with the open cell metal foam 110, 111, 112. If there are a plurality of venting channels provided, some of the venting channels may be filled and others partially filled.

In one or more examples, the open cell metal foam 110, 111, 112 takes the form of a block arranged in the respective venting channels 105, 106, 107 such that it is aligned to extend at least over the second surface 114 at the vent apertures 103 such that any material ejected therethrough is received directly into the foam.

In the present example, the foam 110, 110, 112 comprises a continuous block that partially fills the venting channels 105, 106 107 leaving an air gap 115, 116 at at least one side of the block to provide a continuous path through the venting channels 105, 106, 107 that is absent of said metal foam. Thus, gases received into the foam 110, 111, 112 from the vent apertures 103 may diffuse therethrough and its energy may be transferred to the foam, wherein the continuous air gap allows free flow of the gases through the venting channel 105, 106, 107.

It will be appreciated however that the arrangement of the foam in the venting channels 105, 106, 107 could take other forms. For example, there may be provided a discrete block of foam adjacent each vent aperture 103 or that covers groups of apertures. In other examples, the foam may be arranged opposite the vent apertures but spaced from the second surface 114.

Generally, in one or more examples, the venting channels 105, 106, 107 comprise a first wall 117 arranged opposite the plate 104 and two side walls 118, 119 extending from the first wall 117 that define a space in which the foam is located between the first wall 117 and the plate 104. The side walls 118, 119, in one or more examples, are arranged to abut and support the plate 104. In the present example the side walls may include a foot 120 at a distal end of the walls, 117, 118 opposed the first wall 117. The foot 120 comprises a planar surface arranged parallel to the plate 104 and perpendicular to the side walls 118, 119 that is configured to support the plate 120.

In the present example, the side walls 118, 119 also take a further example form. The side walls 121A, 121B are configured to engage with an edge of the plate 104 rather than solely the second side 114 inward of the edges. The side The slot 122 comprises an upper part to engage the first side 113 of the plate 104 and a walls 121A,B include a slot 122 to receive the plate 104. lower part to engage the second side 114 of the plate 104. In the present example, during assembly of the battery assembly 100, that plate may be slid into the slot 122. Thus, the first venting channel 105 is defined by the first wall 117, the side wall 121A and the side wall 115. The second venting channel 106 is defined by the first wall 117, the side wall 115 and the side wall 116. The third venting channel 107 is defined by the first wall 117, the side wall 116 and the side wall 121B. include a further wall (not shown) that is located where the plate 104 is shown In other examples, the channels 105, 106 and 107 in the example figures. In such an example, the slots 122 may or may not be provided to receive the plate 104. The further wall may include the vent apertures 103 or other openings. In such an example, the plate 104 may sit face to face with, i.e. on top of, the further wall. In such an example, the channels 105, 106 and 107 may be filled or partially filled with the foam (which could be expandable foam) prior to the plate 104 being positioned.

In one or more examples, the metal foam extends between the first wall 117 and the second side 114 of the plate 104 to provide structural support to the plate. This may be advantageous because the plate 104 will be well supported by the side walls 118, 119, 121A, 121B and the foam. This may allow for an advantageous construction of the plate 104. Thus, one of the functions of the foam may be to add structural rigidity to the base plate 104 and thus the base plate 104 may be part of a sandwich structure in which the foam is the middle layer between the first wall 117 and the base plate 104. Whether the channels 105, 106, 107 are partially or fully filled with the foam may depend on the mechanical requirements of the base plate 104. Also, the foam material selection may also be, at least in part, driven by how structural the foam needs to be and how much it is expected to contribute to the mechanical performance of the base plate 104. The foam may also be configured to be highly energy absorbent and may therefore perform well in crush load cases.

The plate 104 may be configured to provide a structure on which to arrange the battery cells and act as a thermal barrier. Typically, the plates of battery assemblies are required to be structural components that can support the battery cells. Thus, they typically include a layer of metal for strength and a layer of thermally insulating material to provide a thermal barrier. However, in the present example, with the provision of the foam 110, 111, 112 that extends over the second side 114 and supports the plate 104, the plate may be only of a thermally insulating material, such as mica. Thus, a metal layer, that may have previously been required for structural support in combination with the more brittle mica may not be required. In one or more examples, the foam and, in particular, metal foam, may be bonded to the second surface 114 of the plate 104.

In the present example, the venting channels 105, 106 and 107, defined by the first wall 117 and side walls 118, 119, 121A,B, are formed of an extruded section. The side walls 121 which comprise a slot 122 are arranged on opposed sides of the extruded section and receive the plate 104. Thus, the slots 122 defined by the upper and lower parts and the edges of the plate 104 comprise cooperating features to couple them together. Further, the extruded section includes brackets 123 and 124 extending from the first wall 117 and around the edges of the plate 104. The battery assembly may first comprise battery module side walls 125, 126 (shown only in Figure 1) that are configured to couple to the brackets 123, 124. The battery assembly 100 may further comprise a cover plate 127 that couples to at least the battery module side walls 125, 126. The cover plate 127, the battery module side walls 125, 126 and the extruded section principally comprising first wall 117 thereby form an enclosure to enclose the battery cells 101. It will be appreciated that the parts that enclose the cells may take a variety of other forms depending on the intended shape or form of the battery module. The present disclosure relates to the provision of the foam 110, 111, 112 in the one or more venting channels 105, 106, 107 and therefore the shape and structure of the plate 104, the extruded section and the numerous walls may take different forms in other example embodiments.

Claims

1. A battery assembly configured to receive a plurality of battery cells at respective predetermined locations, wherein the battery assembly comprises a plurality of vent apertures located at said predetermined locations and at least one venting channel extending adjacent to at least a first subset of said predetermined locations and wherein the vent apertures located at the first subset of said predetermined locations are configured to allow material ejected from a battery cell located at a respective one of the predetermined locations to exit therethrough and into the at least one venting channel, wherein the at least one venting channel includes an open cell foam at least adjacent the vent apertures to receive said material that exits through said vent apertures.

2. The battery assembly of claim 1, comprising a plate having a first surface and a second surface opposed the first surface, wherein the predetermined locations are located over the first surface of the plate and the plurality of vent apertures extend through said plate from the first surface to the second surface and wherein the at least one venting channel extends along the second surface of the plate.

3. The battery assembly of claim 1 or claim 2, wherein the venting channel is only partly filled with said foam.

4. The battery assembly of claim 3, wherein the open cell metal foam is arranged in the venting channel to provide a continuous path through the venting channel that is absent of said foam.

5. The battery assembly of claim 1 or claim 2, wherein the venting channel is completely filled with said foam.

6. The battery assembly of any preceding claim, wherein said foam comprises Aluminium metal foam.

7. The battery assembly of any one of claims 1 to 5, wherein the foam comprises one of: a metal based foam, a polymer based foam, a composite based foam, a polyurethane based foam, a silicone based foam or an epoxy based foam.

8. The battery assembly of claim 2, wherein the at least one venting channel comprises a first wall arranged opposite the plate and two side walls extending from the first wall and arranged to abut and support the plate, wherein the foam extends between the first wall and the second side of the plate to provide structural support to the plate.

9. The battery assembly of claim 8, wherein the foam is bonded to the second surface of the plate.

10. The battery assembly of claim 8 or claim 9, wherein the plate is of mica.

11. The battery assembly of any preceding claim, comprising one or more separator walls configured to separate the plurality of cells from one another when received by the battery assembly and wherein each predetermined location is associated with at least one vent aperture.

12. The battery assembly of claim 2, wherein the battery assembly comprises an extruded section that defines a plurality of venting channels comprising at least a first venting channel and a second venting channel, wherein the first venting channel extends adjacent to the first subset of predetermined locations at the second surface of the plate and wherein the vent apertures located at the first subset of said predetermined locations are configured to allow the material ejected from the battery cells exit therethrough and into the first venting channel; and wherein the second venting channel extends adjacent to a second subset, different to the first subset, of said predetermined locations at the second surface of the plate and wherein the vent apertures located at the second subset of said predetermined locations are configured to allow the material ejected from the battery cells at those second subset of saidpredetermined locations to exit therethrough and into the second venting channeh and wherein the extruded section and the plate are provided with cooperating features to couple them together.

13. The battery assembly of claim 12, comprising a plurality of side walls configured to couple to the extruded section and engage with the plurality of battery cells received at the first surface.

14. A battery module or battery pack comprising: the battery assembly of any preceding claim; a plurality of cylindrical battery cells mounted in the predetermined locations; an enclosure of one or more parts to enclose said plurality of cylindrical battery cells.