Battery pack with improved safety

Abstract

A battery pack according to one embodiment of the present invention includes a cell module assembly including a battery cell stack in which a plurality of battery cells are stacked; a pack case that houses the cell module assembly and has a vent port on at least one surface; and an external cover that covers at least one surface of the pack case and is disposed a predetermined distance away from an outer surface of the pack case. The space between the pack case and the external cover forms a venting flow path through which venting gas generated during a thermal event of the battery cells moves, and the venting gas is discharged to the outside through an open space between the pack case and the external cover formed at at least one end of the external cover.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0179751 dated December 20, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] (Technical field) The present invention relates to a battery pack, and more particularly to a battery pack configured to ensure safety even when a thermal event occurs. [Background technology]

[0003] Currently commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Of these, lithium secondary batteries are attracting attention due to their advantages of almost no memory effect compared to nickel-based secondary batteries, free charging and discharging, very low self-discharge rate, and high energy density.

[0004] Such lithium secondary batteries mainly use lithium-based oxides and carbon materials as positive and negative electrode active materials, respectively, and include an electrode assembly in which positive and negative electrode plates coated with the positive and negative electrode active materials are disposed with a separator between them, and an exterior material, i.e., a battery case, that hermetically houses the electrode assembly together with an electrolyte.

[0005] Generally, lithium secondary batteries can be classified into can-type secondary batteries, in which an electrode assembly is housed in a metal can, and pouch-type secondary batteries, in which an electrode assembly is housed in a pouch made of an aluminum laminate sheet, depending on the shape of the exterior material.

[0006] These secondary batteries are widely used not only in small devices such as portable electronic devices but also in medium- to large-sized devices such as electric vehicles and energy storage systems (ESS), and their usage is rapidly increasing. In addition, there has been a recent trend toward using residential battery packs for storing power.

[0007] Various battery packs, including these household battery packs, include multiple battery cells (secondary batteries) to increase capacity and / or output. In particular, to increase the energy density of the battery pack, the multiple battery cells are often arranged densely in a very small space.

[0008] One of the most important issues in such battery pack configurations is safety. In particular, if a thermal event occurs in one of the multiple battery cells included in the battery pack, propagation of such an event to other battery cells must be suppressed. If thermal waves between battery cells are not properly suppressed, this can cause a thermal event in many battery cells included in the battery pack, leading to larger problems such as fire or explosion of the battery pack. Furthermore, fire or explosion in a battery pack can cause significant damage to the lives and property of surrounding people. In particular, in the case of a battery pack for residential use, fire or explosion can endanger the safety of the residents in the home and can spread to a fire in the home, causing greater damage. Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, the present invention has been devised to solve the above problems, and an object of the present invention is to provide a battery pack having an improved structure that can appropriately control thermal events that occur inside the battery pack.

[0010] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0011] A battery pack according to one embodiment of the present invention includes: a cell module assembly including a battery cell stack in which a plurality of battery cells are stacked; a pack case that houses the cell module assembly and has a vent port on at least one surface; and an external cover that covers at least one surface of the pack case and is disposed a predetermined distance away from the outer surface of the pack case. The space between the pack case and the external cover forms a venting flow path through which venting gas generated during a thermal event in the battery cells moves, and the venting gas can be discharged to the outside through an open space formed between the pack case and the external cover at at least one end of the external cover.

[0012] The pack case may include at least one partition wall that protrudes from the outer surface of the pack case toward the outer cover so as to increase the path through which the venting gas travels.

[0013] The partition wall may include a first partition wall having a shape extending along the length or width direction of the pack case.

[0014] The partition wall includes a second partition wall having a shape extending along the height direction of the pack case, and the first partition wall and the second partition wall can intersect with each other.

[0015] The outer cover may include at least one partition wall that protrudes from the inner surface of the outer cover toward the pack case so as to increase the path through which the venting gas travels.

[0016] The partition may include a first partition having a shape extending along the length or width direction of the outer cover.

[0017] The partition wall may include a second partition wall having a shape extending along the height direction of the outer cover, and the first partition wall and the second partition wall may intersect with each other.

[0018] The pack case may further include a spacer that protrudes from the outer surface of the pack case and contacts the outer cover, and the distance that the spacer protrudes may be greater than the distance that the partition wall protrudes.

[0019] The pack case includes at least one vent hole on each of the front and both side surfaces, and the outer cover can cover the front and both side surfaces of the pack case.

[0020] The outer cover includes a flange that covers the open space between the pack case and the outer cover, and the flange may include a plurality of vent holes arranged along the flange.

[0021] The pack case may further include fastening members that connect the pack case and the outer cover to each other, and the fastening members may include female fastening members and male fastening members.

[0022] A plurality of battery packs may be provided, and the battery packs may be connected to one another by mechanical and / or electrical connections.

[0023] A plurality of battery packs may be stacked vertically.

[0024] The height of the external cover may be smaller than the height of the pack case so that an open space is secured between the pack case and the external cover for each of the plurality of battery packs.

[0025] To achieve the above object, an energy storage device according to another aspect of the present invention includes one or more of the above-described battery packs according to the present invention. [Effects of the Invention]

[0026] According to one aspect of the present invention, a battery pack with improved safety can be provided.

[0027] In particular, according to one embodiment of the present invention, even if a thermal event occurs inside the battery pack, such a thermal event can be quickly controlled.

[0028] In particular, according to one embodiment of the present invention, even if a thermal event occurs inside the battery pack, the flame generated in the battery pack is not discharged to the outside of the battery pack, and can be naturally extinguished inside the battery pack.

[0029] Furthermore, if an issue such as thermal runaway or fire occurs in some of the battery cells included in the battery pack, it is possible to effectively prevent such an issue from spreading to other modules.

[0030] Furthermore, according to one aspect of the present invention, it is possible to provide a battery pack that has a simple structure but has enhanced thermal safety.

[0031] In particular, according to one embodiment of the present invention, since it is not necessary to add a new part for adding a fire extinguishing agent, it is possible to provide a battery pack that is easy to manufacture and economical.

[0032] According to one aspect of the present invention, by stacking a plurality of battery packs of the same type, it is possible to provide products with a variety of voltages and / or storage capacities.

[0033] In addition, various other additional effects may be achieved by various embodiments of the present invention. Such various effects of the present invention will be described in detail in each embodiment, or a description of effects that can be easily understood by a person skilled in the art will be omitted. [Brief explanation of the drawings]

[0034] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention, and therefore the present invention should not be interpreted as being limited solely to the matters depicted in the drawings.

[0035] [Figure 1] 1 is an exploded perspective view showing a schematic configuration of a battery pack according to an embodiment of the present invention; [Figure 2] 2 is a diagram illustrating a configuration for discharging a fire extinguishing agent in the battery pack of FIG. 1. [Figure 3] FIG. 10 is a perspective view schematically illustrating the configuration of a battery pack according to another embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view taken along line A4-A4′ in FIG. 3. [Figure 5] FIG. 10 is an exploded perspective view schematically illustrating the configuration of a battery pack according to yet another embodiment of the present invention. [Figure 6] FIG. 6 is a perspective view of a cell module assembly included in the battery pack of FIG. 5. [Figure 7] 6 is a perspective view of a blocking member included in the battery pack of FIG. 5. FIG. [Figure 8] FIG. 6 is a perspective view of a pack case included in the battery pack of FIG. 5. [Figure 9] FIG. 6 is a perspective view of an outer cover included in the battery pack of FIG. 5. [Figure 10] FIG. 10 is a perspective view of the pack case to which the outer cover is coupled. [Figure 11] This shows a cross section taken along line A6-A6' in FIG. [Figure 12] The venting gas flow is shown in detail in FIG. [Figure 13] The venting gas flow is shown in detail in FIG. [Figure 14] 9 is a diagram illustrating a case in which the cell module assembly of FIG. 8 is housed in a pack case. [Figure 15] FIG. 6 is a perspective view of a fire extinguishing tank included in the battery pack of FIG. 5. [Figure 16]FIG. 16 is a perspective cross-sectional view of the fire tank of FIG. 15. [Figure 17] 17 is a perspective view of a battery pack in which all of the components of the battery packs described above with reference to FIGS. 5 to 16 are combined. FIG. [Figure 18] FIG. 18 is a perspective view schematically showing the battery pack of FIGS. 1 to 17. [Figure 19] 19 is a view showing an embodiment in which the pack cases shown in FIG. 18 are stacked in different numbers. [Figure 20] 19 is a view showing an embodiment in which the pack cases shown in FIG. 18 are stacked in different numbers. DETAILED DESCRIPTION OF THE INVENTION

[0036] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in the specification and claims should not be interpreted in a limited manner based on their ordinary or dictionary meanings, but should be interpreted in a manner that is consistent with the technical concept of the present invention, based on the principle that an inventor can appropriately define the concept of a term in order to best describe his or her invention.

[0037] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can replace them at the time of this application.

[0038] In order to clearly explain the present invention, parts unnecessary for the explanation have been omitted and the same reference numerals have been used throughout the specification to refer to the same or similar components.

[0039] Furthermore, the size and thickness of each component shown in the drawings are merely shown arbitrarily for the convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings. In the drawings, thicknesses are exaggerated to clearly show multiple layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0040] Furthermore, when a layer, film, region, plate, or other part is said to be "above" another part, this includes not only the case where it is "directly above" that part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between. Furthermore, being "above" a reference part means being located above or below the reference part, and does not necessarily mean being "above" in the direction opposite to gravity.

[0041] Furthermore, throughout the specification, when a part is said to "comprise" a certain element, this does not mean that other elements are excluded and that other elements may also be included, unless specifically stated to the contrary.

[0042] Also, throughout the specification, "on a plane" means when the subject part is viewed from above, and "on a cross section" means when the subject part is cut vertically and viewed from the side.

[0043] FIG. 1 is an exploded perspective view schematically showing the configuration of a battery pack according to one embodiment of the present invention.

[0044] Referring to FIG. 1, a battery pack according to the present invention includes a cell module assembly 100, a pack case 300, and a fire tank 400.

[0045] The cell module assembly 100 may include one or more battery cells 110. Here, each battery cell 110 may represent a secondary battery. A secondary battery may include an electrode assembly, an electrolyte, and a battery case. In particular, the battery cells 110 included in the cell module assembly 100 may be pouch-type secondary batteries. However, other types of secondary batteries, such as cylindrical batteries and prismatic batteries, may also be used in the cell module assembly 100 of the present invention.

[0046] A plurality of secondary batteries may be stacked on one another to form a cell module assembly 100. That is, a battery cell stack may form the cell module assembly 100. For example, a plurality of battery cells 110 may be stacked in a horizontal arrangement (X-axis direction) with each battery cell 110 standing vertically (Z-axis direction in the drawing). Each battery cell 110 may have an electrode lead, which may be located at both ends or one end of each battery cell 110. A secondary battery with electrode leads protruding in both directions is called a bidirectional cell, and a secondary battery with electrode leads protruding in one direction is called a unidirectional cell. FIG. 1 illustrates a bidirectional cell. However, the present invention is not limited to the specific type or shape of such a secondary battery, and various types of secondary batteries known at the time of filing of the present invention may be used in the cell module assembly 100 of the present invention.

[0047] The pack case 300 may be configured to have an empty space formed therein to accommodate the cell module assemblies 100. For example, the pack case 300 may be configured in a box shape as shown in Fig. 1. The box-shaped pack case 300 may be integrally molded or may be manufactured by connecting at least one surface to an adjacent surface.

[0048] The fire tank 400 may contain a fire extinguishing agent. In particular, the fire tank 400 may have an internal space and may contain the fire extinguishing agent in the internal space. For example, as shown in FIG. 1, the fire tank 400 may include a lower tank 410 and an upper cover 420. Here, the lower tank 410 may be configured in the form of a box with an open top, and may provide a space in which the fire extinguishing agent can be contained. The upper cover 420 may be configured to cover the open top of the lower tank 410 and seal the fire extinguishing agent-containing space of the lower tank 410.

[0049] The fire tank 400 may be housed inside the pack case 300. In particular, the fire tank 400 may be disposed above the cell module assembly 100 in the internal space of the pack case 300.

[0050] According to this embodiment of the present invention, a thermal event in the cell module assembly 100 can be more easily controlled by discharging the extinguishing agent from the fire tank 400 located on the upper side of the cell module assembly 100. In particular, the extinguishing agent discharged from the fire tank 400 can easily move downward by gravity. Therefore, the heat and fire in the cell module assembly 100 can be more easily extinguished by the extinguishing agent.

[0051] In particular, when the cell module assembly 100 includes a plurality of battery cells 110 arranged horizontally, i.e., in the left-right direction (X-axis direction), as shown in Fig. 1, when fire extinguishing agent is discharged from the fire tank 400 located above, the fire extinguishing agent can be easily supplied to all of the battery cells 110. Therefore, according to this embodiment, a thermal event can be more effectively suppressed for the entire cell module assembly 100.

[0052] The fire extinguishing tank 400 may be configured to discharge a fire extinguishing agent toward the cell module assembly 100 when heat is applied from the cell module assembly 100. This will be described in more detail with reference to FIG.

[0053] FIG. 2 is a diagram schematically illustrating a configuration for discharging a fire extinguishing agent in the battery pack of FIG.

[0054] 2, a fire tank 400 is located above the cell module assembly 100. Among the multiple battery modules stacked in the left-right direction (e.g., the X-axis direction in the drawing), a thermal event such as overheating, fire, or thermal runaway may occur in a specific battery cell 110, as indicated by A1. In this case, heat generated in the battery cell 110 may be applied to the fire tank 400, for example, the portion indicated by A2 in FIG. 2. Then, a fire extinguishing agent may be discharged from the fire tank 400, as indicated by arrow A3.

[0055] In particular, the fire tank 400 may be configured so that at least a portion thereof melts due to heat applied from the cell module assembly 100. For example, in the configuration of Fig. 2, the portion of the fire tank 400 indicated by A2 may melt due to heat. Then, the extinguishing agent may be discharged through the melted portion as indicated by arrow A3.

[0056] For this purpose, at least a portion of the fire tank 400 may be made of a material that can melt due to heat applied from the cell module assembly 100. For example, the fire tank 400 may be entirely made of a plastic material. In particular, the fire tank 400 may be made in the form of a plastic injection molding.

[0057] The fire tank 400 may be configured to melt due to heat or venting gas emitted from the battery cell 110. For example, if thermal runaway occurs in the battery cell 110 and venting gas is emitted, the venting gas may be at a high temperature above a certain temperature. The fire tank 400 may be configured with a material and / or shape that can be melted by such high-temperature venting gas. Alternatively, if thermal runaway occurs in the battery cell 110, the battery cell 110 may be at a higher temperature than normal even if no venting gas is emitted. The fire tank 400 may be configured with a material and / or shape that can be melted by heat applied from the battery cell 110 in such an abnormally high temperature state.

[0058] In particular, the fire tank 400 may be configured so that the base plate 411 melts due to the high temperature of heat and / or gas generated during an event in the battery cell 110. In this case, the fire extinguishing agent may flow into the melted portion at the bottom of the fire extinguishing tank 400 and be discharged downward. Therefore, the fire extinguishing agent may be quickly injected toward the cell module assembly 100.

[0059] According to this embodiment of the present invention, the extinguishing agent is injected in a manner that melts the projectile, effectively suppressing the thermal event inside the battery pack while minimizing the thermal event propagation between the battery cells 110.

[0060] The fire tank 400 may contain a liquid fire extinguishing agent. In this case, the fire extinguishing agent may be referred to as a fire extinguishing liquid. For example, the fire tank 400 may contain water or other coolants as a fire extinguishing agent. The fire tank 400 may also contain antifreeze as a fire extinguishing agent. In particular, when a battery pack is used in cold seasons such as winter or in cold regions such as polar regions, the fire tank 400 may contain antifreeze as a fire extinguishing agent, which does not easily freeze even at low temperatures. Furthermore, in the case of a residential battery pack, which may be located outdoors, antifreeze may be provided as a fire extinguishing agent.

[0061] The fire tank 400 may be configured such that the thickness of the base plate 411 varies depending on the position, which will be described in more detail with reference to FIGS.

[0062] Figure 3 is a perspective view schematically illustrating the configuration of a battery pack according to another embodiment of the present invention. For ease of explanation, some components are shown transparently in Figure 3. Also, Figure 4 is a cross-sectional view taken along line A4-A4' in Figure 3. Regarding various embodiments included in this specification, including this embodiment, detailed descriptions of parts that are the same or similar to those described in other embodiments will be omitted, and differences will be mainly described.

[0063] 3 and 4, the fire extinguishing tank 400 may include a base plate 411 and a side wall 412. Here, the side wall 412 may be configured to protrude upward from the edge of the base plate 411. The bottom and sides of the fire extinguishing tank 400 are defined by the base plate 411 and the side wall 412, forming a space capable of holding an extinguishing agent. At this time, the top of the fire extinguishing tank 400 may be sealed by the pack case 300. That is, as shown in FIG. 4, the pack case 300 includes a lower case 300a and an upper case 300b, and the top of the fire extinguishing tank 400 is covered by the upper case 300b, thereby allowing the extinguishing agent to be held inside the fire extinguishing tank 400. Alternatively, the fire extinguishing tank 400 may be configured to include an upper cover 420, as shown in FIG. 1, to seal the top of the extinguishing agent holding space.

[0064] In the fire tank 400 having the base plate 411, the base plate 411 may be formed to have different thicknesses in different parts. In particular, the fire tank 400 may be configured to have a thinner thickness in a specific part, such as the part (weak part) indicated by reference numeral 411a in Figures 3 and 4. For example, the base plate 411 of the fire tank 400 may be formed in the form of a plastic injection molding having an overall thickness of 1 mm, but the part indicated by 411a may be configured to have a thickness of 0.5 mm.

[0065] In particular, the thinned portion of the base plate 411 of the fire tank 400 can function as the weak portion 411a. That is, when the temperature rises in the cell module assembly 100, the weak portion 411a can be damaged first. When the weak portion 411a is damaged, the extinguishing agent stored inside the fire tank 400 can be discharged to the cell module assembly 100 side through the weak portion 411a.

[0066] A plurality of fragile portions 411a may be provided. The fragile portions 411a may have, for example, a narrow width and a long length. That is, they may have a linear shape and be arranged parallel to one edge of the fire extinguisher tank 400, and the fragile portions 411a may be arranged parallel to each other.

[0067] According to this embodiment, when venting gas or a fire occurs due to thermal runaway in the cell module assembly 100, there is no need to provide a separate structure for injecting a fire extinguisher such as coolant. Therefore, a structure for injecting a fire extinguisher into the battery pack can be realized with a simple structure. Furthermore, in this structure, when an event occurs, the fire extinguisher can be discharged through the thin, weakened portion 411a, so the portion from which the fire extinguisher is discharged can be specified in advance.

[0068] 4, a plurality of fragile portions 411a may be provided in one fire tank 400. Furthermore, the plurality of fragile portions 411a may be arranged on the base plate 411 of the fire tank 400 at predetermined intervals along the stacking direction of the cell module assemblies 100. For example, a plurality of battery cells 110 may be stacked in the left-right direction (X-axis direction) in the cell module assembly 100, and a plurality of fragile portions may also be arranged in the left-right direction at intervals on the base plate 411 of the fire tank 400 located on top of the cell module assembly 100.

[0069] In particular, the fire extinguishing tank 400 may be configured such that a weakened portion 411a having a relatively small thickness is located in the center portion between horizontally stacked cells.

[0070] For example, in the configuration of FIG. 4, two battery cells 110, B1 and B2, are arranged adjacent to each other in the left-right direction on the left side of the cell module assembly 100. In this case, the leftmost weak portion 411a among the multiple weak portions 411a may be arranged between B1 and B2 in the left-right direction. In other words, the weak portion 411a is located above B1 and B2 in the vertical direction (Z-axis direction), but is located between B1 and B2 in the horizontal direction (X-axis direction). Furthermore, for battery cells 110 other than B1 and B2, one weak portion 411a may be configured to be located in the space between every two adjacent battery cells 110 in the horizontal direction.

[0071] According to this embodiment of the present invention, when a thermal event occurs in a specific battery cell 110 and heat is applied to the upper vulnerable portion 411a, the vulnerable portion 411a may be damaged. Then, the extinguishing agent may be discharged through the damaged vulnerable portion 411a and flow into the space between adjacent battery cells 110 as indicated by the arrows in FIG. 4 .

[0072] Therefore, this embodiment can more effectively prevent the transmission of a thermal event between battery cells 110. Furthermore, this embodiment of the present invention can inject a fire extinguishing agent intensively around a battery cell 110 where a thermal event such as overheating or ignition has occurred, thereby enabling more effective cooling and fire extinguishing operations. Therefore, this embodiment can inject a fire extinguishing agent at the right time and place when a fire or other event occurs inside the battery without the need for any other components other than the fire tank 400.

[0073] FIG. 5 is an exploded perspective view schematically showing the configuration of a battery pack according to another embodiment of the present invention.

[0074] Referring to FIG. 5, the battery pack includes a cell module assembly 100, a blocking member 200, a pack case 300, a fire tank 400, an outer cover 500, and an electrical connection unit 600.

[0075] In FIG. 5, the cell module assembly 100 may also include a plurality of battery cells 110 (see FIG. 1) stacked in a manner that they are arranged horizontally (e.g., along the X-axis direction in the drawing) with each battery cell 110 standing vertically (e.g., along the Z-axis direction in the drawing). In this case, the length direction of the battery cells 110 is, for example, along the Y-axis direction in the drawing. For ease of understanding, the illustration of the battery cells 110 is omitted in FIG. 5. If the battery cells 110 are, for example, pouch-type or prismatic battery cells, the battery cells 110 are arranged alongside (parallel to) the blocking member 200.

[0076] FIG. 6 is a perspective view of a cell module assembly 100 included in the battery pack of FIG.

[0077] For reference, in order to more clearly show the components included in the cell module assembly 100, Fig. 6 shows the remaining components excluding the plurality of battery cells 110. The plurality of battery cells 110 may be conventional pouch-type battery cells or prismatic battery cells.

[0078] 6, a pair of bus bar housings 130 are disposed on the front and rear surfaces of a stack of multiple battery cells 110. Each of the bus bar housings 130 is disposed in a direction perpendicular to the length direction of the battery cells 110 (for example, in the X-axis direction in the drawing).

[0079] A pair of end plates 120 are provided on both ends of the outermost portion of the stack of the plurality of battery cells 110. The end plates 120 are arranged parallel to the battery cells 110. The pair of end plates 120 connects the pair of bus bar housings 130, respectively.

[0080] At least one strap 140 may be included on each of the upper and lower sides between the pair of end plates 120, connecting the pair of end plates 120. The strap 140 strengthens the binding of the cell module assembly 100. More specifically, it strengthens the binding of the pair of end plates 120 and the stack of multiple battery cells 110 disposed therebetween. This makes it possible to prevent the stack of multiple battery cells 110 from becoming misaligned.

[0081] Other details regarding the cell module assembly 100 overlap with those described with reference to FIG. 1, so please refer to what was described above in connection with FIG.

[0082] Meanwhile, as shown in Fig. 5, a predetermined number of battery cells 110 may be grouped and stored. Also, as shown in Figs. 5 to 7, a blocking member 200 is provided between a group of a predetermined number of battery cells 110 and an adjacent group of a predetermined number of battery cells 110.

[0083] 7 is a perspective view of the blocking member 200 included in the battery pack of FIG. 5. The blocking member 200 may be configured to be interposed between adjacent battery cells 110 to block heat. For example, if a thermal event occurs in some battery cells 110 and heat or high-temperature venting gas is generated, the blocking member 200 can suppress or block the generated heat or gas from being transferred to adjacent battery cells 110. In addition, the blocking member 200 can play a role in blocking flames, sparks, etc. that are emitted from a specific battery cell 110.

[0084] The blocking member 200 has a generally plate-like shape. The blocking member 200 may be configured in the form of a plate that stands vertically. Furthermore, the blocking member 200 may have a height that is the same as or similar to the height of the battery cells 110 that also stand vertically. The height of the blocking member 200 may be smaller or larger than the height of the battery cells 110.

[0085] The number of blocking members 200 may correspond to the number of battery cells. As described above, the blocking members 200 may be stacked together with the battery cells 110 to form the cell module assembly 100.

[0086] According to this embodiment of the present invention, in a battery pack including a plurality of battery cells 110, the blocking member 200 can effectively prevent thermal runaway electromagnetic waves between the cells.

[0087] The blocking member 200 may also have a large triple-layer structure. For example, a pair of swelling pads 220 is provided on each side of a support plate 210. The support plate 210 maintains the shape and rigidity of the blocking member 200 and blocks flames or sparks erupting from the battery cells 110 between the battery cells 110. The support plate 210 may be made of, for example, a metal material. The swelling pads 220 reduce the pressure applied to the battery cells 110 by the support plate 210 when the battery cells 110 expand. The swelling pads 220 may be made of, for example, a silicone material or a soft plastic material.

[0088] Meanwhile, the support plate 210 includes a plurality of through holes 230 formed to penetrate the support plate 210 in the vertical direction, and the plurality of through holes 230 are arranged along the length direction of the support plate 210 .

[0089] When a fire extinguishing agent (fire extinguishing liquid) is poured into the cell module assembly 100 from the fire tank 400 located above the cell module assembly 100, the fire extinguishing agent (fire extinguishing liquid) also enters the plurality of through-holes 230. In other words, the fire extinguishing agent (fire extinguishing liquid) remains in the plurality of through-holes 230, thereby more effectively cooling and extinguishing the battery cell 110 in which a thermal event has occurred.

[0090] The plurality of through holes 230 may be open on both the upper and lower surfaces of the support plate 210. Alternatively, the plurality of through holes 230 may be open only on the upper surface and closed on the lower surface so that the extinguishing agent (extinguishing liquid) can remain for a longer period of time within the through holes 230. In the former case, if the support plate 210 of the blocking member 200 is disposed so as to be in close contact with the lower inner surface of the pack case 300, the extinguishing agent (extinguishing liquid) can remain for a longer period of time within the through holes 230, as in the latter case.

[0091] Figure 8 is a perspective view of the pack case 300 included in the battery pack of Figure 5. Referring to Figure 8, the pack case 300 may be configured in a box shape. The box-shaped pack case 300 may be integrally molded or may be manufactured in a manner in which at least one surface is coupled to an adjacent surface.

[0092] The pack case 300 includes at least one vent hole 320. A flange may be further provided on the upper surface of the vent hole 320 to prevent rain or snow from entering the pack case 300 through the vent hole 320. A filter is attached to the vent hole 320.

[0093] The pack case 300 has a partition 330 on its outer surface that protrudes outward from the outer surface. The pack case 300 also includes a fastening member 340 to which the outer cover 500 can be connected, and a spacer 350 protruding from the outer surface. The partition 330, the fastening member 340, and the spacer 350 will be described in detail below, as will the outer cover 500.

[0094] FIG. 9 is a perspective view of the outer cover 500 included in the battery pack of FIG.

[0095] The external cover 500 is coupled to the pack case 300 and covers at least one side of the pack case 300. Fig. 9 shows a case in which the external cover 500 covers the front and both side surfaces of the pack case 300. A front cover 500a of the external cover 500 covers the front surface of the pack case 300, and a pair of side covers 500b of the external cover 500 cover both side surfaces of the pack case 300.

[0096] In addition, the outer cover 500 covers the vent opening 320 of the pack case 300 at a position spaced a predetermined distance from the vent opening 320. This prevents the battery cells 110 inside the pack case 300 from being directly exposed to the outside through the vent opening 320.

[0097] 8, for example, venting ports 320 are provided on the front and both side surfaces of the pack case 300. Accordingly, an external cover 500 is also provided to cover the front and both side surfaces of the pack case 300.

[0098] Meanwhile, the present invention is not limited to the above, and it is sufficient that the outer cover 500 can cover the vent hole 320. For example, it is possible to cover all four sides of the pack case 300, i.e., the front, rear, and both side faces, or to cover only some of the four sides excluding the top and bottom faces of the pack case 300. Various modifications and variations are possible.

[0099] FIG. 10 is a perspective view of the pack case 300 coupled to the outer cover 500. FIG. 11 shows a cross section taken along line A6-A6' in FIG. 10. FIGS. 12 and 13 each show the flow of vent gas in FIG. 10 in detail. When a thermal event occurs in a battery cell 110 housed inside the pack case 300, vent gas generated in the battery cell 110 can be discharged through the vent port 320. The vent gas discharged from the vent port 320 travels through a venting passage formed in the space between the pack case 300 and the outer cover 500 and is then discharged to the outside of the outer cover 500. At this time, the venting gas traveling through the venting passage is discharged to the outside through an open space formed between the pack case 300 and the outer cover 500 at the end of the outer cover 500 (the upper and lower portions of the outer cover 500 in the case of FIG. 10).

[0100] 19 and 20, when a plurality of battery packs are stacked, if the height of the outer cover 500 is slightly smaller than the height of the pack case 300, an open space can be secured between the pack case 300 and the outer cover 500 at the upper and lower portions of each battery pack. In other words, even when a plurality of battery packs are stacked vertically, an open space can be secured between the pack case 300 and the outer cover 500 for each battery pack, allowing venting gas to be smoothly discharged to the outside.

[0101] Referring again to FIG. 8, the pack case 300 has a partition wall 330 on its outer surface that protrudes outward from the outer surface.

[0102] 12 and 13, the partition wall 330 increases the distance that the venting gas travels in the venting flow path, and the flame contained in the venting gas collides with the partition wall 330 and naturally extinguishes (spontaneous extinguishing). As a result, the flame contained in the venting gas is not discharged outside the outer cover 500.

[0103] The partition walls 330 are formed in at least one direction on the outer surface of the pack case 300. In the embodiment of Fig. 8, the partition walls 330 are formed along the horizontal direction (the length and / or width direction of the pack case 300) and the vertical direction (the height direction of the pack case 300), and the horizontal partition walls 330 intersect with the vertical partition walls 330. However, the present invention is not limited to the illustrated example, and it is sufficient if the partition walls 330 are formed to intersect with the movement path of the venting gas.

[0104] On the other hand, the partition wall 330 can also reinforce the rigidity of the pack case 300.

[0105] Referring again to FIG. 9, the front cover 500a and the pair of side covers 500b of the outer cover 500 may be integrally formed, or may be manufactured separately and then coupled to each other.

[0106] In addition, flanges 520 are provided in the open spaces between the pack case 300 and the outer cover 500 (on the upper and lower sides of the outer cover 500 in the example of FIG. 10), each of which protrudes from the body of the outer cover 500 toward the pack case 300. The inclusion of flanges 520 further enhances the function of covering the vent hole 320. The flanges 520 may have a width equal to the separation space between the outer cover 500 and the pack case 300, or may have a width smaller than that.

[0107] In addition, since the outer cover 500 is coupled to the outer surface of the pack case 300 at a predetermined distance, the venting gas discharged from the vent port 320 of the pack case 300 can travel through the venting passage formed in the space between the pack case 300 and the outer cover 500 and then be discharged to the outside of the outer cover 500, as described above.

[0108] The flange 520 has a plurality of venting holes 521 arranged in a row along the flange 520. The venting gas that moves through the venting passage formed in the space between the pack case 300 and the outer cover 500 can be discharged through the venting holes 521 of the outer cover 500.

[0109] Meanwhile, a partition wall 510 formed in at least one direction may also be provided on the surface of the main body of the outer cover 500 facing the pack case 300. The partition wall 510 increases the travel distance of the venting gas in the venting passage, and flames contained in the venting gas collide with the partition wall 510 and are naturally extinguished. As a result, the flames contained in the venting gas are not discharged to the outside of the outer cover 500.

[0110] The partition walls 510 are formed in at least one direction on the outer surface of the outer cover 500. In the embodiment of Fig. 11, the partition walls 510 are formed along the horizontal direction (the length direction and / or width direction of the outer cover 500) and the vertical direction (the height direction of the outer cover 500), respectively, and the partition walls 510 in the horizontal direction and the partition walls 510 in the vertical direction intersect. However, the present invention is not limited to this, and it is sufficient that the partition walls 510 are formed so as to intersect with the movement path of the venting gas.

[0111] On the other hand, the partition wall 510 can also reinforce the rigidity of the outer cover 500 .

[0112] The outer cover 500 further includes fastening members 530, which can be coupled to the fastening members 340 of the pack case 300. In the embodiment of Fig. 10, the fastening members 530 of the outer cover 500, which have a protruding hook shape, are coupled to the fastening members 340 of the pack case 300, which have an insertion groove shape. However, the present invention is not limited to the illustrated example with respect to the method of coupling the outer cover 500 and the pack case 300, and various modifications and variations can be implemented.

[0113] 8, the pack case 300 may include a spacer 350 protruding from the outer surface. The spacer 350 protrudes by the distance between the pack case 300 and the outer cover 500. That is, the spacer 350 can come into contact with the inner surface of the outer cover 500. As a result, the spacer 350 can maintain a predetermined distance between the pack case 300 and the outer cover 500. In particular, even if the outer cover 500 receives an external impact, the spacer 350 prevents the outer cover 500 from bending toward the pack case 300, thereby preventing the venting passage between the pack case 300 and the outer cover 500 from narrowing.

[0114] In addition, the protruding distance of the spacer 350 is greater than the protruding distance of the partition wall 330 of the pack case 300. Similarly, the protruding distance of the spacer 350 is greater than the protruding distance of the partition wall 510 of the outer cover 500. This prevents the venting gas from being blocked by the partition wall 330 of the pack case 300 and the partition wall 510 of the outer cover 500 when it moves through the space between the pack case 300 and the outer cover 500. When multiple spacers 350 are provided, the spacers 350 are spaced apart from each other so as not to block the venting flow path.

[0115] The spacer 350 may have a cross shape, for example, as shown in FIG. 8, but the present invention is not limited to this, and any shape that maintains a separation space between the pack case 300 and the outer cover 500 and enables the outer cover 500 to maintain its rigidity will suffice.

[0116] Furthermore, by covering the outer surface of the pack case 300 with the outer cover 500, it is possible to impart aesthetic functionality to the external shape of the battery pack.

[0117] Meanwhile, as shown in Fig. 14, the cell module assembly 100 shown in Fig. 6 can be housed in the internal space of an auxiliary case 310 and then attached to a pack case 300. By temporarily housing the cell module assembly 100 in the internal space of the auxiliary case 310 and then finally housing it in the pack case 300, the rigidity of the cell module assembly 100 can be enhanced and misalignment of the stack of multiple battery cells 110 in the cell module assembly 100 can be prevented. The auxiliary case 310 can be made of, for example, metal or stainless steel.

[0118] FIG. 15 is a perspective view of the fire tank 400 included in the battery pack of FIG. 5. FIG. 16 is a perspective cross-sectional view of the fire tank 400 of FIG. 15, taken along line A5-A5' in FIG. 5. As described above with reference to FIG. 1, the fire tank 400 includes a lower tank 410 and an upper cover 420. The lower tank 410 and the upper cover 420 may be manufactured separately and then hermetically coupled, or may be manufactured as a single unit. The upper cover 420 may further include an inlet 430 through which a fire extinguishing agent can be injected. The inlet 430 may be closed with a cap to seal the fire tank 400.

[0119] The thinner portion of the base plate 411 of the lower tank 410 may function as the weak portion 411a. In other words, if a thermal event occurs in the battery cell 110 of the cell module assembly 100, the weak portion 411a, which is relatively thinner, may be damaged first. If the weak portion 411a is damaged and an opening is formed in the base plate 411, the extinguishing agent held inside the fire tank 400 may be discharged to the cell module assembly 100 side through the weak portion 411a.

[0120] A plurality of fragile portions 411a may be provided. The fragile portions 411a may have, for example, a narrow width and a long length. That is, they may have a linear shape and be arranged parallel to one edge of the fire extinguisher tank 400, and the fragile portions 411a may be arranged parallel to each other.

[0121] 15, the length direction of the battery cell 110 (e.g., the X-axis direction in the drawing) and the length direction of the weak parts 411a (e.g., the X-axis direction in the drawing) can be perpendicular to each other. In other words, a plurality of weak parts 411a are arranged intersecting the length direction of the battery cell 110. This allows the extinguishing agent to be supplied simultaneously through the plurality of open weak parts 411a throughout the entire battery cell 110 along the length direction of the battery cell 110 in which a thermal event has occurred, thereby more efficiently and quickly extinguishing the fire in the battery cell 110 in which a thermal event has occurred.

[0122] 16, the base plate 411 of the lower tank 410 has a step. More specifically, the base plate 411 is roughly divided into a portion A7 where the fragile portion 411a is located, a portion A8 that abuts against the strap 140 of the pack case 300, and a portion A9 that is located on the side of the electrical connection unit 600. Of these, the height of the base plate 411 at portion A7 where the fragile portion 411a is located is the lowest.

[0123] By arranging the weak part 411a of the lower tank 410 as close as possible to the battery cells 110, when some battery cells 110 overheat or catch fire, it is possible to more effectively prevent dangerous situations such as secondary explosions caused by heat or flames being transferred to adjacent battery cells 110 through rapid initial suppression.

[0124] 6 of the cell module assembly 100, the height of the cell module assembly 100 is not uniform due to the location of the strap 140 and the location of the bus bar housing 130 (the connector 610, fuse, etc. are located outside the bus bar housing 130). Regardless of this, if the height of the base plate 411 of the lower tank 410 of the fire tank 400 were uniform overall, a space would be created between the base plate 411 of the fire tank 400 and the upper surface of the cell module assembly 100. In such a case, the space would hinder the transfer of heat from the heated battery cells 110 to the weak parts 411a, delaying fire extinguishing accordingly.

[0125] When the battery cell 110 overheats, the weak part 411a is arranged immediately adjacent to the battery cell 110 whose temperature has risen, so that the weak part 411a is immediately broken, allowing the battery cell 110 to be quickly cooled and the fire to be extinguished.

[0126] In summary, the lower surface of the base plate 411 of the fire tank 400 and the upper surface of the cell module assembly 100 have shapes that are approximately the same. As a result, the fire tank 400 is disposed in closer contact with the cell module assembly 100, which allows the battery cells 110 that have experienced temperature increases to be cooled more effectively and allows fire extinguishing agent to be injected more quickly into the battery cells 110 that have experienced overheating or ignition. In addition, more fire extinguishing agent can be efficiently stored in the fire tank 400. In other words, if the height of the base plate 411 of the lower tank 410 of the fire tank 400 is uniform overall, the fire tank 400 will store less fire extinguishing agent due to the empty space.

[0127] The extinguishing agent provided in the fire extinguishing tank 400 may be in the form of, for example, a fire extinguishing liquid, and a duplicated description will be omitted and reference will be made to the above.

[0128] FIG. 17 is a perspective view of a battery pack in which all of the components of the battery packs described above with reference to FIGS. 5 to 16 are combined.

[0129] In addition, where the description of the battery packs of FIGS. 5 to 17 overlaps with the description of the battery packs of FIGS. 1 to 4, reference should be made to what has been described above with reference to FIGS.

[0130] Meanwhile, a plurality of pack cases 300 may be provided and configured to be stackable in the vertical direction, which will be described in more detail with reference to Figures 18 to 20.

[0131] Figure 18 is a perspective view schematically illustrating the configuration of at least a portion of the battery pack of Figures 1 to 17 of the present invention. Figures 19 and 20 are drawings showing an embodiment in which a plurality of pack cases 300 shown in Figure 18 are stacked. For ease of understanding, Figures 18 to 20 illustrate the battery packs schematically, and the detailed configuration of the battery packs is described above with reference to Figures 1 to 17.

[0132] Referring to FIG. 18 , the pack case 300 may have a bottom and sidewalls. The cell module assemblies 100 may be housed in the internal space of the pack case 300, and a battery pack is constructed by covering the top of the cell module assemblies 100 with a fire tank 400. For reference, in FIG. 18 , the height of the upper side of the pack case 300 is shown to be higher than the height of the upper surface of the fire tank 400. However, FIG. 18 is a schematic view and merely an embodiment, and the present invention is not limited to what is shown in FIG. 18 . In other words, various modifications are possible, such as the opposite, the height of the upper surface of the fire tank 400 may be higher than the height of the upper side of the pack case 300, or the height of the upper surface of the fire tank 400 may be the same as the height of the upper side of the pack case 300.

[0133] A plurality of pack cases 300 shown in Fig. 18 may be provided to form a stacked battery pack structure as shown in Fig. 19 or 20. In this case, the battery pack of Fig. 18 may be one unit pack. A plurality of such unit packs may be provided to form a modular stacked overall battery pack as shown in Fig. 19 or 20.

[0134] More specifically, for example, the configuration of Fig. 19 shows a configuration in which three unit packs D are stacked vertically, and the configuration of Fig. 20 shows a configuration in which five unit packs D are stacked vertically. The present invention is not limited to the illustrated configuration, and the number of unit packs D can be changed in various ways to suit the environment in which the present invention is embodied.

[0135] For example, when the present invention is embodied as a battery pack as an energy storage system (ESS), the voltage and / or storage capacity of the energy storage system can be tailored to the environment by adjusting the number of unit battery packs. According to this embodiment of the present invention, a single unit pack having a common structure can be stacked in various ways, enabling products with various voltages to be manufactured depending on the number of stacks. For example, by adjusting the number of stacks of the same unit pack, it is possible to realize a low-voltage product as shown in FIG. 19 and a high-voltage product as shown in FIG. 20. This improves economy and compatibility compared to products limited to a specific voltage standard. Furthermore, this embodiment also enables products with various storage capacities to be manufactured depending on the number of stacks.

[0136] In other words, when stacked unit packs are connected in series, products with various voltages can be realized depending on the number of stacked packs. Also, when stacked unit packs are connected in parallel, products with various capacities (storage capacities) can be realized depending on the number of stacked packs.

[0137] In particular, each unit pack D may include a cell module assembly 100 therein. Also, as described above, each unit pack D includes a connector 610 so that the cell module assemblies 100 can be electrically connected to each other when stacked. In particular, such connector 610 may be configured to couple the unit packs D to each other by stacking them one above the other.

[0138] In addition, in the above embodiment, each unit pack D may house a fire tank 400 together with the cell module assembly 100. That is, each unit pack D includes the fire tank 400 on top of the cell module assembly 100, as described above. A battery pack formed by stacking multiple battery packs has a stacked structure of fire tank 400-cell module assembly 100-fire tank 400-cell module assembly 100 from top to bottom. The stacked battery pack of the present invention having this structure can be configured by increasing (expanding) the number of cell module assemblies 100 to increase the power storage capacity, while also safely preparing for thermal events such as a fire in the cell module assembly 100. Therefore, this embodiment of the present invention can further improve the safety of the battery pack.

[0139] Referring again to FIG. 18, another example of a coupling method between vertically stacked battery packs (pack cases) 300 is as follows. The upper end of the side wall of the pack case 300 may have a step, such as a coupling step C1, that is recessed inward. For example, this step may be a portion where the thickness of the side wall of the pack case 300 is thin. Also, although not shown in FIG. 18, the bottom of the pack case 300 may have a coupling recess into which the coupling step C1 of the side wall is inserted. That is, when different pack cases 300 are stacked vertically, the coupling step C1 formed on the upper end of the side wall of the lower pack case 300 may be inserted into the coupling recess formed on the bottom of the upper pack case 300. As a result, when multiple pack cases 300 are stacked vertically and coupled, the outer surfaces of the pack cases 300 may have an overall flat shape.

[0140] Meanwhile, the coupling method for the fastening structure between vertically stacked battery packs is not limited to that shown in FIG. 18 and / or FIG. 8, and various other coupling methods can be modified or changed and applied to the present invention.

[0141] The battery pack of the present invention may also be connected to a battery management system (BMS, not shown). The battery management system monitors and manages the battery pack(s). The battery management system may be located on the top layer of a stack of battery packs. However, the location of the battery management system is not limited to the above and may be variously modified or changed to suit the manner or environment in which the present invention is embodied.

[0142] In addition to the above-described components, the battery pack according to the present invention may further include various other components included in the battery pack. For example, the battery pack according to the present invention may include many electrical components for controlling or managing the charging and discharging of the battery pack, such as a battery management system (BMS), relays, fuses, and current sensors.

[0143] Furthermore, the present invention is not limited to the above-described embodiments, and may be embodied by partially modifying the above-described embodiments or by combining the above-described embodiments, etc., to suit various environments in which the present invention is embodied.

[0144] An energy storage system (ESS) according to the present invention includes one or more battery packs according to the present invention. In addition to the battery pack, the energy storage system according to the present invention may further include other general components included in an energy storage system.

[0145] Meanwhile, although terms indicating directions such as up, down, left, and right may be used in this specification, it will be obvious to those skilled in the art that such terms are used merely for convenience of explanation and may vary depending on the position of the object of interest, the position of the observer, etc.

[0146] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims set forth below. [Explanation of symbols]

[0147] 100: Cell module assembly 110: Battery cell 120: End plate 130: Busbar housing 140: Strap 200: Blocking member 210: Support plate 220:Swelling pad 230:Through hole 300: Pack case 300a: Lower case 300b: Upper case 310: Auxiliary case 320: Venting port 330: Bulkhead 340: Fastening member 350: Spacer 400: Fire tank 410: Lower tank 411: Base plate 411a: Weak area 412: Side wall 420: Upper cover 430: Inlet 500:External cover 500a: Front cover 500b: Side cover 510: Bulkhead 520: Tsuba 521: Venting Hall 530: Fastening member 600: Electrical connection unit 610: Connector

Claims

1. a cell module assembly including a battery cell stack in which a plurality of battery cells are stacked; a pack case that houses the cell module assembly and includes a vent on at least one surface; an outer cover that covers the at least one surface of the pack case and is disposed at a predetermined distance from an outer surface of the pack case, a space between the pack case and the outer cover forms a venting passage through which venting gas generated during a thermal event of the battery cell moves; The venting gas is discharged to the outside through an open space formed between the pack case and the outer cover at at least one end of the outer cover. Battery pack.

2. The battery pack according to claim 1 , wherein the pack case includes at least one partition protruding from an outer surface of the pack case toward the outer cover so as to increase a path through which the venting gas moves.

3. The battery pack according to claim 2 , wherein the partition wall includes a first partition wall having a shape extending along a length or width direction of the pack case.

4. the partition wall includes a second partition wall having a shape extending along a height direction of the pack case, The first partition wall and the second partition wall intersect with each other. The battery pack according to claim 3 .

5. The battery pack according to claim 1 , wherein the outer cover includes at least one partition protruding from an inner surface of the outer cover toward the pack case so as to increase a path through which the venting gas moves.

6. The battery pack according to claim 5 , wherein the partition wall includes a first partition wall having a shape extending along a length or width direction of the outer cover.

7. The partition wall includes a second partition wall having a shape extending along a height direction of the outer cover, The first partition wall and the second partition wall intersect with each other. The battery pack according to claim 6.

8. the pack case further includes a spacer that protrudes from an outer surface of the pack case and contacts the outer cover, The distance by which the spacer protrudes is greater than the distance by which the partition wall protrudes. The battery pack according to claim 2 .

9. The pack case includes at least one vent hole on each of the front and both side surfaces, The outer cover covers the front surface and both side surfaces of the pack case. The battery pack according to claim 1 .

10. the outer cover includes a flange that covers an open space between the pack case and the outer cover, The flange includes a plurality of venting holes arranged along the flange. The battery pack according to claim 1 .

11. a fastening member that connects the pack case and the outer cover to each other, The fastening member comprises a female fastening member and a male fastening member. The battery pack according to claim 1 .

12. The battery pack is provided in a plurality of pieces, The plurality of battery packs are connected to each other by mechanical or electrical connections. The battery pack according to claim 1 .

13. The battery pack according to claim 12 , wherein the plurality of battery packs can be stacked vertically.

14. 13. The battery pack according to claim 12, wherein a height of the outer cover is smaller than a height of the pack case so that an open space is secured between the pack case and the outer cover for each of the plurality of battery packs.

15. An energy storage device comprising the battery pack of any one of claims 1 to 14.

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