BATTERY ASSEMBLY AND METHOD OF ASSEMBLING THE SAME

Embodiment of the present disclosure relates to a battery assembly including a plurality of battery cells stacked in a preset stacking direction, an accommodation case configured to accommodate the plurality of battery cells, an insertion space formed between the plurality of battery cells and the accommodation case, and a fire-retardant assembly disposed in the insertion space, wherein the fire-retardant assembly includes a fire-retardant member including a fire-retardant material, and a pillar-shaped exterior material configured to accommodate the fire-retardant member therein and extending in a height direction of the accommodation case.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. § 119 (a) to Korean patent application number 10-2023-0071715 filed on Jun. 2, 2023 and Korean patent application number 10-2023-0154245 filed on Nov. 9, 2023 and Korean patent application number 10-2024-0050194 filed on Apr. 15, 2024, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

1. Field of the Invention

Embodiments of the present disclosure relates to generally a battery assembly and a method of assembling the same. Specifically, the embodiments of the present disclosure relates to a battery assembly with improved thermal stability and a method of assembling the same.

2. Discussion of Related Art

Due to recent fires and explosions that have occurred during the use of lithium secondary batteries, social concerns about the safety of secondary battery use are increasing. Based on such social concerns, one of the recent major development tasks for lithium secondary batteries is to eliminate unsafe conditions such as fires and explosions caused by thermal runaway of battery cells.

In particular, a typical battery module/pack may have an empty space therein in addition to the battery cells which are energy sources. When a fire occurs due to an external impact or a problem with the battery cell, the flame may spread to adjacent cells through the empty space, resulting in an increase in the damage from the fire. Since such risk of fire may be one of the biggest obstacles to an electric vehicle market, methods of reducing the spread of fire are being continuously researched.

SUMMARY OF THE INVENTION

First, one embodiment of the present disclosure is directed to preventing or mitigating hot gas generated from a battery assembly, for example, a battery cell in which thermal runaway has occurred among one or more battery cells provided inside the battery assembly, from being discharged toward a tab of the battery cell.

Second, another embodiment of the present disclosure is directed to venting hot gas generated from a battery cell in which thermal runaway has occurred along an intended path.

Third, still another embodiment of the present disclosure is directed to increasing the stability of a battery assembly by increasing heat resistance and fire resistance.

Fourth, yet another embodiment of the present disclosure is directed to a method of inserting a fire-retardant assembly (or a fire-retardant assembly material or a filler) into an empty space formed between a busbar assembly and a cell tab of a battery to the assembling process of the conventional battery assembly.

Fifth, yet another embodiment of the present disclosure is directed to providing an improved assembly method of more easily arranging a fire-retardant assembly when a battery assembly is assembled.

The battery assembly according to an embodiment of the present disclosure may be widely applied in the field of a green technology such as electric vehicles, battery charging stations, energy storage systems (ESS), photovoltaics using batteries, and wind power generation. In addition, the battery assembly according to an embodiment of the present disclosure may be used for eco-friendly mobility including electric vehicles and hybrid electric vehicles to prevent climate change by suppressing air pollution and greenhouse gas emission.

A battery assembly according to an embodiment of the present disclosure includes a plurality of battery cells stacked in a preset stacking direction, an accommodation case configured to accommodate the plurality of battery cells, an insertion space formed between the plurality of battery cells and the accommodation case, and a fire-retardant assembly disposed in the insertion space, wherein the fire-retardant assembly includes a fire-retardant member including a fire-retardant material, and an exterior material configured to accommodate the fire-retardant member therein.

The exterior material may start to melt when a preset temperature is reached.

The temperature may be lower than a melting point of the fire-retardant member.

The fire-retardant member may include silicon dioxide (SiO2).

At least one of both end portions of the exterior material may have a tapered shape.

The exterior material may include a body portion in a pipe shape extending in a height direction of the accommodation case, a first end portion coupled to an upper side of the body portion to close one end of both open ends of the body portion, and a second end portion coupled to a lower side of the body portion to close the other open end, and the first end portion may have a tapered shape in a direction away from the body portion.

The second end portion may have an end face disposed parallel to a bottom surface of the accommodation case.

The accommodation case may include an accommodation body including an open upper surface and for accommodating the plurality of battery cells through the open upper surface, and an accommodation cover coupled to the accommodation body to cover the open upper surface, and the fire-retardant assembly may be disposed so that the first end portion is disposed to face the accommodation cover.

The exterior material may include a body portion in a cylindrical shape, in which at least one end of both ends of the body portion is open, and an end portion coupled to the body portion to close at least one open end.

A length of the exterior material in the height direction of the accommodation case may be greater than a length of the exterior material in the stacking direction.

A maximum length of the fire-retardant assembly in the stacking direction may be smaller than or equal to a thickness of any one of the plurality of battery cells.

The fire-retardant member may include a plurality of fire-retardant particles.

The fire-retardant member may include a roll-shaped fire-retardant sheet.

The exterior material may have a cylindrical shape.

The exterior material may have a polyhedral shape.

The battery assembly according to an embodiment of the present disclosure may further include a busbar electrically connected to the plurality of battery cells, wherein the insertion space may be located between the busbar and the plurality of battery cells.

The plurality of battery cells may each include a main body unit for accommodating an electrode assembly, and a lead tab unit of which at least a portion is located outside the main body unit and which is electrically connected to the electrode assembly, and the busbar may be electrically connected to the lead tab unit.

The insertion space may include a first insertion space formed between the plurality of battery cells and one side surface of the accommodation case extending in the stacking direction, and a second insertion space formed between the plurality of battery cells and the other side surface of the accommodation case facing the one side surface of the accommodation case, and the fire-retardant member may be disposed in at least any one of the first insertion space and the second insertion space.

The fire-retardant member may be a solid filler.

The solid filler may be in the form of a plurality of granular materials.

The exterior material may have a pillar shape extending in a height direction of the accommodation case.

A method of assembling a battery assembly includes stacking the plurality of battery cells, coupling the plurality of stacked battery cells to an accommodation cover, inserting the fire-retardant assembly, which includes a bead-shaped fire-retardant member including a fire-retardant material, into the insertion space, and an exterior material for accommodating the fire-retardant member therein and extending in a height direction of the accommodation case, and coupling an accommodation body, which is coupled to the accommodation cover to form the accommodation case, to the accommodation cover.

The method of assembling the battery assembly according to an embodiment of the present disclosure may further include, before the inserting of the fire-retardant assembly into the insertion space and after the coupling of the plurality of stacked battery cells to the accommodation cover, a first inverting operation of inverting the plurality of stacked battery cells.

The method of assembling the battery assembly according to an embodiment of the present disclosure may further include, after the coupling of the accommodation body to the accommodation cover, a second inverting operation of inverting the accommodation case.

The coupling of the accommodation body to the accommodation cover may include forming a heat sink unit on a body bottom surface forming a bottom surface of the accommodation body.

A battery assembly according to the present disclosure comprises at least one stack of a plurality of battery cells inside a casing; a fire-retardant assembly disposed between at least two adjacent battery cells and including a fire-retardant material enclosed inside an exterior material, wherein the exterior material has a melting point lower than a melting point of the fire-retardant member.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. A configuration or control method of a device to be described below is only for describing embodiments of the present disclosure and is not intended to limit the scope of the present disclosure, and the same reference numbers used throughout the specification denote the same components.

Specific terms used in the present specification are merely for convenience of description and are not used to limit the exemplary embodiments.

For example, terms such as “same” and “is the same” not only indicate the strictly same state, but also indicate a state in which there is a difference in tolerance or the degree to which the same function can be obtained.

For example, the term such as “toward any direction,” “in any direction,” “parallel to,” “perpendicularly,” “at the center,” “concentric,” or “coaxial,” which indicates the relative or absolute arrangement, strictly indicates such arrangement, but also indicates a state of being relatively displaced with a tolerance, or an angle or distance of the degree to which the same function may be performed.

To describe the present disclosure, the following description will be made based on a spatial orthogonal coordinate system with X-, Y-, and Z-axes perpendicular to each other. Unless especially stated, a Z direction indicates a height direction, and an X-axis direction (or a first direction) indicates any one of directions perpendicular to the height direction. In addition, a Y-axis direction (or a second direction) indicates a direction perpendicular to the Z-axis direction and the X-axis direction.

However, the X-axis direction, Y-axis direction, and Z-axis direction, which will be described below, are for description for clear understanding of the present disclosure, and it goes without saying that the directions can be differently defined depending on a determined reference direction.

The use of terms such as “first,” “second,” and “third” in front of components to be described below is only to avoid confusion about the stated components, and are irrelevant to the order, importance, or master-slave relationship between the components. For example, an invention including only the second component without the first component may also be implemented.

The singular expression used herein includes the plural expression unless the context clearly dictates otherwise.

In addition, battery assemblies200and300according to an embodiment of the present disclosure are a general term for battery modules or battery packs. Therefore, the battery assemblies200and300according to an embodiment of the present disclosure may indicate both a battery module and a battery pack for accommodating battery cells without a battery assembly, such as a cell to pack (CTP).

FIG.1is a view of a battery assembly200according to an embodiment of the present disclosure.

Referring toFIG.1, the battery assembly200may include a plurality of battery cells110and an accommodation case210for accommodating the plurality of battery cells110.

Each of the plurality of battery cells110may include a main body unit115for producing or storing electrical energy, and lead tab units111and112protruding outward from the main body unit115. The main body unit115may include an electrode assembly (not shown) including a positive electrode and a negative electrode therein to produce and store electrical energy therein.

In addition, the main body unit115further includes an electrolyte (not shown) in contact with the electrode assembly. The electrolyte may be liquid or solid. In addition, when the electrolyte is liquid, the electrode assembly may further include a separator for separating the positive electrode and the negative electrode. Referring toFIG.1, the main body unit115may be in the form of a pouch sealed with a film-shaped exterior material.

AlthoughFIG.1shows a pouch-shaped battery cell110, the embodiments of the present disclosure are not limited thereto. Therefore, prismatic and cylindrical battery cells are also applicable.

Specifically, the lead tab units111and112may include the first lead tab unit111and the second lead tab unit112that protrude from both side surfaces of the main body unit115in a direction away from the main body unit115. In another embodiment the lead tab units111and112may have both tabs provided on one side surface thereof.

The accommodation case210is intended to protect the plurality of battery cells110from an external impact such as vibrations. The accommodation case210may include an accommodation body219that forms a portion of an accommodation space280for accommodating the plurality of battery cells110to be described below.

In addition, the battery assembly200may further include a busbar assembly150for electrically connecting the plurality of battery cells110to external parts. The busbar assembly150may include a busbar170(seeFIG.2) for electrically connecting the plurality of battery cells110to output a preset voltage. The form in which the busbar assembly150or the busbar170to be described below, is assembled with the plurality of battery cells110may be referred to as a cell stack100.

FIG.2is an exploded view of a battery assembly200according an embodiment of to the present disclosure.

Referring toFIG.2, the accommodation case210may include the accommodation body219forming a portion of the accommodation space280for accommodating the plurality of battery cells110, and an accommodation cover215coupled to the accommodation body219to form the accommodation space280together.

Inside the accommodation body219, the plurality of battery cells110may be located to overlap each other in a preset stacking direction (e.g., the X-axis direction).

More specifically, the accommodation case210may include an open upper surface2195and further include the accommodation body219for accommodating the plurality of battery cells110through the open upper surface2195, and the accommodation cover215coupled to the accommodation body219to close the open upper surface2195.

Therefore, the accommodation cover215may be coupled to the accommodation body219to form an upper surface of the accommodation space280or an upper surface of the accommodation case210. That is, the accommodation cover215is coupled to the accommodation body219to close the open upper surface2195and forms the accommodation space280together with the accommodation body219.

The accommodation space280may be formed inside the accommodation body219and include a space for accommodating the cell stack100. In addition, the accommodation space280may further include an insertion space288to be described below.

The accommodation body219may be provided in a channel shape or U shape with an open upper portion. Referring toFIG.2, both side surfaces2197and2198facing each other in the X-axis direction among the side surfaces of the accommodation body219may also be open.

That is, the accommodation body219may include a body bottom surface2194forming a bottom surface of the accommodation space280, and body side surfaces2191and2192extending from edges (not shown) provided parallel to each other in the stacking direction among edges of the body bottom surface2192toward the accommodation cover215. Free ends of the body side surfaces2191and2192may be bent to form flanges (not shown), which can be easily coupled with the accommodation cover215.

Referring toFIGS.1and2, a height of the accommodation body219may be smaller than heights of the plurality of battery cells110. However, in another embodiment the height of the accommodation body219may be greater than or equal to the heights of the plurality of battery cells110.

The cell stack100may further include a buffering member117or a heat blocking member119(seeFIG.3) located between the plurality of battery cells110. The buffering member117may be located between the battery cells110or located between battery groups BG1to BG5(seeFIG.12) in which the plurality of battery cells110are grouped. It is also applied to the heat blocking member119.

The heat blocking member119may serve as a thermal barrier for preventing flame or heat from spreading to adjacent battery cells110when thermal runaway occurs in any one battery cell110.

The cell stack100may include one or more buffering members117. Likewise, the cell stack100may include one or more heat blocking members119. The buffering member117and the heat blocking member119may be formed as a single member to simultaneously perform a heat blocking function and a buffering function.

To this end, the heat blocking member119may be formed in a multilayered structure in a direction in which the plurality of battery cells110are stacked. That is, one layer of the multilayered structure may be made of a flame-retardant material (or a fire-retardant material). In addition, another layer of the multilayered structure may serve to reduce a pressure applied to another battery cell110upon swelling of the battery cell110.

The plurality of battery cells110and the plurality of buffering members117may be stacked by being provided at preset locations. For example, referring toFIG.2, an example in which long edges of the plurality of battery cells110are provided parallel to the Y-axis direction. Therefore, the plurality of battery cells110and the plurality of buffering members117will be located to overlap each other in the X-axis direction. It is also applied to the heat blocking member119.

The heat blocking member119may be made of a fire-retardant (heat-resistant or flame-retardant) material. For example, the heat blocking member119may include a material such as fire-retardant polymer or mica.

Referring toFIG.2, the battery assembly200may further include end plates212and213at both ends of the cell stack100in the stacking direction. The end plates212and213may be provided at both ends of the cell stack100or formed to be connected to both side surfaces2197and2198of the accommodation body219.

The end plates212and213are used to prevent both side surfaces of the cell stack100from being exposed to the outside.

The battery assembly200may include a busbar170electrically connected to the plurality of battery cells110. In addition, the battery assembly200may further include busbar frames151,152, and155for supporting the busbar170and the plurality of battery cells110. The busbar170and the busbar frames151,152, and155may be collectively referred to as the busbar assembly150. That is, the busbar assembly150may include the busbar170electrically connected to the plurality of battery cells110.

The busbar frames151,152, and155may be electrically connected to the outside to store (or charge) electrical energy in the plurality of battery cells110or supply (or discharge) the electrical energy stored in the plurality of battery cells110to the outside.

The busbar assembly150may include the first busbar frame151and the second busbar frame152that extend in the stacking direction of the plurality of battery cells110with the plurality of battery cells110interposed therebetween.

In addition, the busbar assembly150may further include a support frame155located at one side of the busbar assembly150to connect the first busbar frame151with the second busbar frame152.

The busbar assembly150is described using a case in which the lead tab units111and112are each located in opposite directions of the main body unit115. On the other hand, when the lead tab units111and112are located at one side of the main body unit115and located in the same direction, the busbar frames151and152may be located at one side of the main body unit115, for example, above the main body unit115and electrically connected to the lead tab units111and112.

The support frame155may serve to prevent the deformation of the first busbar frame151and the second busbar frame152and support the first busbar frame151and the second busbar frame152. In addition, some of the electrical devices for sensing and controlling the plurality of battery cells110may be disposed on the support frame155.

Referring toFIG.2, the shape of the busbar assembly150may be a tunnel shape. In addition, lengths of the first busbar frame151and the second busbar frame152may be greater than a length of the support frame155in the stacking direction.

That is, the support frame155may be connected to the first busbar frame151and the second busbar frame152to cover the upper portions of the plurality of battery cells110. That is, the support frame155may cover some or all of the upper portions of the plurality of battery cells110.

Referring toFIG.2, the busbar170may include a first busbar171supported by the first busbar frame151and electrically connected to the first lead tab unit111and a second busbar172supported by the second busbar frame152and electrically connected to the second lead tab unit112.

The first busbar171and the second busbar172may be located away from the plurality of battery cells110more than the first busbar frame151and the second busbar frame152, respectively. That is, the first busbar171and the second busbar172may be located closer to the body side surfaces2191and2192than the first busbar frame151and the second busbar frame152. Therefore, the first lead tab unit111and the second lead tab unit112may be inserted into a slit hole (not shown) formed in the first busbar frame151and the second busbar frame152and electrically connected to the first busbar171and the second busbar172, respectively. However, it is only an example, and the first lead tab unit111and the second lead tab unit112may be electrically connected in a different manner from the first busbar171and the second busbar172, respectively.

The battery assembly200may further include a heat sink unit295located between the body bottom surface2194and the plurality of battery cells110to transfer heat generated from the plurality of battery cells110to the outside of the battery assembly200. The heat sink unit295may be formed of an adhesive material having thermal conductivity, such as a heat sink adhesive. Therefore, the plurality of battery cells110may be bonded to the body bottom surface2194through the heat sink unit295. To this end, the heat sink unit295may be sprayed or applied on the body bottom surface2194.

FIG.3is a top view of the battery assembly200according to an embodiment of the present disclosure.

The busbar assembly150may include the first busbar171electrically connected to the first lead tab unit111and the first busbar frame151for supporting the first busbar171. The first busbar171and the first busbar frame151may be collectively referred to as a first busbar assembly1501. That is, the first busbar assembly1501may be electrically connected to the first lead tab unit111and support the cell stack100.

The busbar assembly150may further include the second busbar172electrically connected to the second lead tab unit112and the second busbar frame152for supporting the second busbar172. The second busbar172and the second busbar frame152may be collectively referred to as a second busbar assembly1502. That is, the second busbar assembly1502may be electrically connected to the second lead tab unit112and support the cell stack100together with the first busbar assembly1501.

Referring toFIG.3, due to the electrical connection between the lead tab units111and112and the busbar assembly150, an empty space (hereinafter referred to as “insertion space288”) may be formed between the plurality of battery cells110and the busbar assembly150.

That is, a portion of the accommodation space280formed inside the accommodation case210may be a space for accommodating the plurality of battery cells110, and the remaining portion of the accommodation space280may be a space for the insertion space288.

Specifically, the insertion space288is a space formed by each main body unit115, each of the lead tab units111and112, and the busbar170. Typically, when thermal runaway occurs in any of the plurality of battery cells110and off-gas is generated, high-temperature heat may be transferred to adjacent battery cells through the insertion space288. To prevent such heat transfer, it is necessary to fill or close the insertion space288.

To this end, the battery assembly200according to an embodiment of the present disclosure may include a fire-retardant assembly270(seeFIG.5) located by being inserted into the insertion space288.

That is, the battery assembly200according to an embodiment of the present disclosure may include the plurality of battery cells110arranged by being stacked in a preset stacking direction, the accommodation case210for accommodating the plurality of battery cells110, the insertion space288formed between the plurality of battery cells110and the accommodation case210, and the fire-retardant assembly270located in the insertion space288.

Referring toFIG.3, the buffering member117may be located between the plurality of battery cells110. The buffering member117may be provided in each space between the plurality of battery cells110. Alternatively, the buffering member117may be located between the battery groups BG1to BG5(seeFIG.12) in which adjacent battery cells110are grouped into a preset number of groups.

Referring toFIG.3, although an example in which the length of the buffering member117in a direction from the first busbar frame151to the second busbar frame152is smaller than the length or less of the main body unit115(seeFIG.1) is shown, but the present disclosure is not limited thereto.

Referring toFIG.3, the heat blocking member119may be located between the plurality of battery cells110. The heat blocking member119may be provided in each space between the plurality of battery cells110. Alternatively, the heat blocking member119may be located between the battery groups BG1to BG5in which the adjacent battery cells110are grouped into the preset number of groups.

The battery groups BG1to BG5indicate a set of battery cells in which the adjacent battery cells110among the plurality of battery cells110are grouped into the preset number of groups. The plurality of battery cells110may be grouped into the number of groups for a preset target voltage or target current, and then the battery groups BG1to BG5may be grouped using the busbar170and connected in series or parallel.

Referring toFIG.3, although an example in which the length of the buffering member117in a direction from the first busbar frame151to the second busbar frame152is smaller than the length or less of the main body unit115(seeFIG.1) is shown, but the present disclosure is not limited thereto.

Referring toFIG.3, the heat blocking member119and the buffering member117are shown as separate members, but alternatively, may be formed as one member as described above. It may be referred to as a fire-retardant assembly (not shown).

That is, the fire-retardant assembly may be located between the plurality of battery cells110to block heat during thermal runaway and buffer a surface pressure of the battery cells during swelling.

A length of the heat blocking member119may be greater than a length of the main body unit115in the direction from the first busbar frame151to the second busbar frame152. More specifically, the heat blocking member119may be in contact with the first busbar assembly1501and the second busbar assembly1502. Therefore, the heat blocking member119will be able to block or delay the spread of heat or flame to another location in case of thermal runaway of any battery cell110.

FIG.4is an enlarged view of portion S1inFIG.3.

Specifically, portion S1may be a partial area of the insertion space288. The battery assembly200may further include the insertion space288formed between the cell stack100and the busbar assembly150or the plurality of battery cells110and the busbar170.

Specifically, the battery assembly200may include a first insertion space2881and a second insertion space2882(seeFIG.3) between one side surface of the main body unit115of each of the plurality of battery cells110and the first busbar171and between the other side surface of the main body unit115of each of the plurality of battery cells110and the second busbar172, respectively.

Referring toFIGS.3and4, the fire-retardant assembly270may be located in at least one of the first insertion space2881and the second insertion space2882. InFIG.4, only the corresponding location of the fire-retardant assembly270is marked to emphasize that it is located in the insertion space288, and the shape of the fire-retardant assembly270is not specifically shown.

That is, the fire-retardant assembly270may be located in at least one of the first insertion space2881and the second insertion space2882.

More specifically, portion S1inFIG.4shows a portion of the first insertion space2881. One side surface of the main body unit115may be a side surface on which the first lead tab unit111is located, and the other side surface of the main body unit115may be a side surface on which the second lead tab unit112is located.

The first insertion space2881may be divided by the first lead tab unit111. In addition, the second insertion space2882may be divided by the second lead tab unit112. However, when the cell stack100is accommodated in the accommodation body219, since lengths of the first lead tab unit111and the second lead tab unit112in a height direction of the accommodation case210or the accommodation body219are smaller than the height of the battery cell110, each of the divided first insertion spaces2991and the divided second insertion spaces2882may communicate with each other.

In addition, the first insertion space2881and the second insertion space2882may communicate with each other through a space between the plurality of battery cells110and the accommodation cover215. Therefore, the first insertion space2881and the second insertion space2882are not spaces that are isolated by being separated from each other, but may be spaces that may communicate with each other.

FIG.5is a schematic top view showing a fire-retardant assembly270accommodated in an insertion space288according to an embodiment of the present disclosure.

The battery assembly200may have the insertion space288formed between the plurality of battery cells110and the busbar assembly150(or the busbar170). The insertion space288may be formed by connecting each of the lead tab units111and112to the busbar assembly150(or the busbar170).

The insertion space288may include a plurality of separation spaces2889separated by each of the lead tab units111and112. Each of the lead tab units111and112does not separately isolate the plurality of separation spaces2889. That is, since the length of each of the lead tab units111and112in the height direction of the accommodation case210is smaller than the height of the accommodation space280, each of the lead tab units111and112separates only at least some separation spaces2889in the height of the accommodation space280.

That is, since the length of each of the lead tab units111and112in the height direction of the accommodation case210is smaller than the length of each of the main body unit115, the plurality of insertion spaces288may be separated by each of the lead tab units111and112or may communicate with each other.

More specifically, a plurality of first insertion spaces2881may be formed by the first lead tab unit111, and the plurality of first insertion spaces2881may communicate with each other. Likewise, the plurality of second insertion spaces2882may be formed by the second lead tab unit112, and the plurality of second insertion spaces2882may communicate with each other.

Therefore, as described above, the plurality of separation spaces2889may communicate with each other. In addition, a plurality of fire-retardant assemblies270may be provided and inserted one-to-one into the plurality of separation spaces2889.

Referring toFIG.5, the battery assembly200may further include the heat blocking member119located between the plurality of battery cells110. Alternatively, the battery assembly200may further include the heat blocking member119located between the battery groups BG in which the plurality of battery cells110are grouped.

Referring toFIG.5, the heat blocking member119may be provided parallel to the plurality of battery cells110and extend to the busbar assembly150. More specifically, the heat blocking member119may extend to the busbar frames151and152and may be inserted into the busbar frames151and152. In this case, the fire-retardant assembly270may not be inserted into the space in which the heat blocking member119is inserted, which is to prevent interference between the fire-retardant assembly270and the heat blocking member119.

FIG.6Ais a view of the fire-retardant assembly270accommodated in the insertion space288,FIG.6Bis a cross-sectional view of the fire-retardant assembly270shown inFIG.6A, andFIG.6Cis another example view of the fire-retardant assembly270accommodated in the insertion space288, according to embodiments of the present disclosure.

As shown inFIG.6A, the fire-retardant assembly270may have a cylindrical shape. Therefore, the fire-retardant assembly270may have the same shape as a circular shape shown above the cylindrical shape ofFIG.6A.

Referring toFIG.6A, the schematic shape of the fire-retardant assembly270may be cylindrical. In addition, a height of the cylindrical fire-retardant assembly270may be smaller than a diameter of the fire-retardant assembly.

In addition, considering the size of the insertion space288, the diameter of the fire-retardant assembly270may be smaller than or equal to a thickness of any of the plurality of battery cells, which is to allow the fire-retardant assembly270to be easily inserted into the insertion space288.

Both ends of the cylindrical fire-retardant assembly270may be provided in a tapered shape, which is to allow the fire-retardant assembly270to be easily inserted into the insertion space288. That is, when the fire-retardant assembly270is inserted into the insertion space288, areas C1and C2including both ends of the fire-retardant assembly270have a tapered shape to allow the fire-retardant assembly270to be guided into the insertion space288.

In addition, the shapes of the areas C1and C2including both ends of the fire-retardant assembly270may be symmetrical, which is to increase the convenience of assembly of the battery assembly200by inserting the fire-retardant assembly270into the insertion space288regardless of the top and bottom of the fire-retardant assembly270.

That is, the schematic shapes of the areas C1and C2including both ends of the fire-retardant assembly270may be the same.

FIG.6Ais only the schematic shape of the fire-retardant assembly270, and specifically, as shown inFIG.6B, the fire-retardant assembly270may include a fire-retardant member271containing a fire-retardant material, and an exterior material273for accommodating the fire-retardant member271therein.

That is, the exterior material273may further include a fire-retardant space274formed by the exterior material273to accommodate the fire-retardant member271.

The exterior material273may have a pillar shape extending in the height direction of the accommodation case210.

FIG.6Ais a view in which the exterior material273has the cylindrical shape, whereasFIG.6Cis another view in which the exterior material273has a polyhedral shape. For example, the exterior material273may have a rectangular parallelepiped or polyhedral shape. The shape of the exterior material273is not limited thereto and may have any shape as long as it may be inserted into the insertion space288.

InFIGS.6A to6C, although fire-retardant particles271aare spherical for illustration, the shapes of the fire-retardant particles271aare not limited to a sphere. Therefore, the fire-retardant particles271amay have an amorphous shape. In addition, the fire-retardant particles271aare not limited to any one size, but may be a shape in which various sizes of the fire-retardant particles271aare mixed.

Referring toFIG.6C, the fire-retardant assembly270may include the fire-retardant particles271aand an exterior material273for accommodating the fire-retardant member271therein and is formed into a preset three-dimensional shape.

The three-dimensional shape is a rectangular parallelepiped shape which is shown as an example, but may also be a cylindrical shape as shown inFIG.6A. The exterior material273may have any three-dimensional shape as long as it may accommodate the fire-retardant member271therein.

In addition, referring toFIG.6C, both ends T1and T2of the rectangular parallelepiped-shaped fire-retardant assembly270are shown as planar shapes, but alternatively, may be provided as curved shapes.

A maximum length of the fire-retardant assembly270in a direction parallel to the height direction of the accommodation case210may be greater than a maximum length of the fire-retardant assembly270in a direction parallel to the stacking direction. It is the same reason why the height of the cylindrical fire-retardant assembly270described inFIG.6Ais greater than the diameter of the cylindrical fire-retardant assembly270.

Likewise, considering that the fire-retardant assembly270should be inserted into the plurality of separation spaces2889(seeFIG.5), the maximum length of the fire-retardant assembly270in the stacking direction may be smaller than or equal to the thickness of any of the plurality of battery cells in the stacking direction.

The fire-retardant particles271amay be solid fillers provided in the form of solid particles, powder, granules, pellets, or beads, which is to prevent or delay flame transfer or heat transfer through the insertion space288when thermal runaway occurs in any battery cell110.

The sizes of the fire-retardant particles271amay preferably be 2 μm or more and less than or equal to the length or thickness of one battery cell110in the stacking direction.

Preferably, the fire-retardant particles271amay have a micrometer scale. The micrometer-scaled fire-retardant particles271amay be referred to as microbeads or microgranules.

In an embodiment, the sizes of the fire-retardant particles271amay be the size of the diameter of a spherical shape of which a radius is a distance from the center (or center of gravity) of the fire-retardant particle271ato the farthest outer edge. Therefore, the size of the fire-retardant particle271amay be the maximum outer diameter of the fire-retardant particle271a. Alternatively, the size of the fire-retardant particle271amay be an average value calculated after measuring the fire-retardant particles271ain several directions. It may also be applied even when the fire-retardant particles271aare in the form of particles.

The reason why the size of the fire-retardant particle271ashould be 2 μm or more is to prevent the fire-retardant particles271afrom being discharged into a space other than the insertion space288, such as a space between the accommodation case210(seeFIG.1) and the busbar assembly150(seeFIG.2).

The lead tab units111and112(seeFIG.1) may be formed to pass through the busbar170to be electrically connected to the busbar170(seeFIG.2). To this end, the busbar170may include a slit hole (not shown) formed to pass through the busbar170. The lead tab units111and112may be welded after being inserted into the slit hole. The slit hole will be closed by welding, and at this time, a welding bead (not shown) may be formed in the welding area of the slit hole due to welding. The welding bead has a unique shape that may occur during welding. The welding bead may also have microscopic air gaps, and since the size of the air gap formed in the welding bead is about 2 μm, the size or outer diameter of the fire-retardant particle271amay preferably be 2 μm or more to prevent the fire-retardant particles271afrom being discharged through the air gaps. That is, the size of the fire-retardant particle271amay be preferably greater than or equal to the size of the air gap formed in the welding bead.

In addition, the size or outer diameter of the fire-retardant particle271amay be smaller than the length or thickness of one battery cell in the stacking direction. The reason is that only when the size or diameter of the fire-retardant particle271ais smaller than the distance between one of the lead tab units111and112and the other of the lead tab units111and112adjacent to the one of the lead tab units111and112, the fire-retardant particle271amay be accommodated in the insertion space288(seeFIG.3) formed between the one of lead tab units111and112and the other of the lead tab units111and112.

For example, when the thickness of the battery cell110is 15 mm, the size or outer diameter of the fire-retardant particle271amay be 15 mm or less.

That is, the size of the fire-retardant particle271ashould be less than or equal to a distance between one of the battery cells110among the plurality of battery cells110and another adjacent to the one battery cell110in the stacking direction and may be smaller than or equal to a distance between the one and the other of the lead tab units111and112in the stacking direction.

In addition, the fire-retardant particles271aare not determined to be the same size or material, but may be a form in which various sizes or various materials of the fire-retardant particles271aare mixed.

The melting point of the fire-retardant particles271amay preferably be higher than a preset temperature (or an allowable temperature) to be described below. Preferably, the preset temperature (or the allowable temperature) may be 50° C. or higher and 300° C. or lower. The exterior material273may start to melt when the preset temperature is reached. Therefore, the melting point of the fire-retardant particles271ashould be higher than the preset temperature.

In addition, the melting point of the fire-retardant particles271amay be higher than the ignition points of the plurality of battery cells110. The ignition points of the plurality of battery cells110may be the temperature when venting occurs in the battery cell110. Alternatively, when the exterior material (or the accommodation case) of the battery cell110is torn or opened in the thermal runway situation, the ignition points of the plurality of battery cells110may be the temperature of the electrolyte accommodated inside the battery cell110, that is, inside the main body unit115.

Therefore, when thermal runaway starts to occur in any of the battery cells110, the exterior material273starts to melt, but the fire-retardant particles271acan maintain the solid form, which is to prevent the fire-retardant particles271afrom burning or melting.

For example, even when the thermal runaway occurs in the battery cell110, the fire-retardant particles271aare not burnt or melted, and the external shape of the fire-retardant particles271acan be maintained without significant change.

The fire-retardant member271or the fire-retardant particles271amay include a porous material. The porous material indicates a material including pores inside a structure. A shape of the pore may be an irregular and amorphous shape. Specifically, when the fire-retardant member271or the fire-retardant particles271ainclude silica gel in particles or powder form, the porosity of the fire-retardant particle271amay be in the range of 20% or more and 30% or less.

The fire-retardant member271or the fire-retardant particles271amay be inserted into the fire-retardant space274formed by the exterior material273and may move freely. That is, the fire-retardant member271or the fire-retardant particles271amay not be fixed or coupled to other structures or components of the battery assembly200. Simply, the fire-retardant member271or the fire-retardant particles271aare located in the fire-retardant space274and are in contact with each other without separate restraint.

That is, the fire-retardant member271or the fire-retardant particles271amay be a solid filler. The solid filler may be in the form of a plurality of granular materials.

Therefore, the fire-retardant assembly270may include a plurality of air gaps (not shown) formed between the fire-retardant members271or the fire-retardant particles271a. When the exterior material273melts and the fire-retardant member271or the fire-retardant particles271alocated in the fire-retardant space274are exposed to the accommodation space280, the plurality of air gaps may serve to delay heat transfer and disperse flame in various paths rather than a straight line.

In addition, in a high-temperature and high-humidity environment during thermal runaway, the plurality of air gaps (not shown) may serve as electrical insulating members or thermal insulating members.

In addition, the fire-retardant material may be an inorganic compound. That is, the fire-retardant particles271amay include a fire-retardant material formed of an inorganic compound. The inorganic compound may include any compound selected from the group consisting of alum (K2SO4·Al2(SO4)3·24H2O), borax (Na2B4O7·10H2O), lime water (Ca(OH)2aqueous solution), quicklime (CaO), white emulsion obtained by mixing milk of lime (Ca(OH)2) with water, slaked lime (Ca(OH)2), washing soda (Na2CO3·10H2O), apatite (Ca5(PO4)·3OH), baking powder (salt mixture of NaHCO3and tartaric acid), baking soda (NaHCO3), sodium thiosulfate pentahydrate (Na2S2O3·5H2O), silica (or silicon dioxide (SiO2)), alumina (or aluminum oxide Al2O3), calcium oxide (CaO), calcium sulfate (CaSO4), calcium chloride (CaCl2)), sodium carbonate (Na2CO3), potassium chloride (KCl), magnesium oxide (MgO), zirconium oxide (ZrO2), chromium oxide (Cr2O3), aluminum hydroxide (Al(OH)3), antimony trioxide (Sb2O3), antimony pentoxide (Sb2O5), magnesium hydroxide (Mg(OH)2), a zinc borate compound, a phosphorus compound, a nitrogen-based guanidine compound, or a molybdenum compound, or mixtures thereof.

For example, when the fire-retardant particles271aare made of silica (silicon dioxide), considering the melting point (1713° C.) of silica, the fire-retardant particles271acan minimize the transfer of heat or off-gas generated when thermal runaway occurs to another location. In addition, the fire-retardant particles271awill maintain the shape without any change in the thermal runaway situation of the battery cell.

In another example, the fire-retardant particles271amay be made of silica gel. The silica gel is a porous material in a powder form made by treating an aqueous solution of sodium silicate (Na2SiO3) with acid. Specifically, the silica gel may be obtained by mixing sodium silicate with an aqueous inorganic acid solution (e.g., sulfuric acid) to form a silica hydrosol and curing the hydrosol into a hydrogel. Considering the above-described typical method of producing the silica gel, the main component (accounting for 50% or more) of the silica gel is silicon dioxide, and as other components, may include aluminum oxide, iron (III) oxide (Fe2O3, iron (III) oxide or ferric oxide) or may further contain sodium. Therefore, the melting point of the silica gel may be about 1600° C. or higher.

Preferably, the silica gel may contain silicon dioxide at 90% or more. In addition, since the silica gel is a porous material, the porosity of the fire-retardant particle271amay be in the range of 20% or more and 30% or less.

In addition, the fire-retardant particles271amay be made of aerogel. It is because aerogel has both low thermal conductivity and the property of retaining moisture and expanding in a high-humidity environment.

Considering that the fire-retardant particles271aare made of a fire-retardant material such as silica gel, alumina gel, or aerogel, the fire-retardant particles271amay contain silicon dioxide (SiO2).

The fire-retardant particles271amay be made of other materials than silica gel as long as it has porosity and flame retardant property (heat resistance or fire resistance).

As another example, the fire-retardant particles271amay indicate a polymer material having a V-0 rating in the 94V test (vertical burning test) of Underwriter's Laboratory (UL), which is the flame-retardant standard for polymer materials.

Specifically, the fire-retardant particles271amay include a flame-retardant polymer such as, for example, phosphorus-based, halogen-based, and inorganic flame retardants, and preferably, the phosphorus-based flame-retardant material may include a phosphate compound, a phosphonate compound, a phosphinate compound, a phosphine oxide compound, and a phosphazene compound, metal salts thereof, etc. These may be used alone or in combination of two or more types.

In addition, the fire-retardant particles271amay comprise a phosphorus-based compound such as monoammonium phosphate ((NH4)H2PO4) or diammonium phosphate ((NH4)2HPO4), or a combination thereof.

FIG.7Ais still another view of the fire-retardant assembly270accommodated in the insertion space288(seeFIG.3) andFIG.7Bis a cross-sectional view of the fire-retardant assembly270shown inFIG.7A, according to embodiments of the present disclosure.

Referring toFIGS.7A and7B, the fire-retardant assembly270may include the fire-retardant member271in the form of a roll-shaped fire-retardant sheet271b, and the exterior material273for accommodating the fire-retardant member271formed as the roll-shaped fire-retardant sheet271btherein.

More specifically, the exterior material273may include the fire-retardant space274therein, and the roll-shaped fire-retardant sheet271bmay be located in the fire-retardant space274.

The exterior material273may be melted at a preset temperature (or an allowable temperature) or higher. That is, when the thermal runaway occurs in at least one of the plurality of battery cells110and the temperature increases, the temperature near the battery cell110in which thermal runaway has occurred will increase. At this time, when the temperature of the exterior material273reaches the above temperature, the exterior material273may start to melt. Considering the preset temperature when the thermal runaway occurs in the battery cell110, the temperature may preferably be in the range of 50° C. or higher and 300° C. or lower.

Unlike an example in which the fire-retardant member271is formed of the fire-retardant particles271a(seeFIG.6B), even when the exterior material273melts at the above temperature or higher, the roll-shaped fire-retardant sheet271bcan be maintained even when the size of the roll shape may be changed.

The roll-shaped fire-retardant sheet271bmay be formed by rolling a flat sheet into a roll shape. That is, when the exterior material273starts to melt, the exterior material273restraining the roll-shaped fire-retardant sheet271bis removed or disappears, and thus similar to a spiral spring, the diameter of the roll-shaped fire-retardant sheet271bmay increase. Therefore, the space of the roll-shaped fire-retardant sheet271bin the insertion space288will be greater than when restrained by the exterior material273. It will be effective in delaying or blocking heat transfer through the insertion space288.

Regardless of the case in which the fire-retardant member271is formed of the fire-retardant particles271aor the roll-shaped fire-retardant sheet271b, the movement and deformation of the fire-retardant member271are limited to only the internal space of the exterior material273.

However, when the exterior material273starts to melt at the above temperature or higher, while the fire-retardant particles271amay freely move in the insertion space288, the roll-shaped fire-retardant sheet271bcan maintain the original location in the insertion space288.

To this end, the material of the roll-shaped fire-retardant sheet271bmay include any one of the materials described for the fire-retardant particles271aor a combination thereof.

Likewise, the melting temperature of the roll-shaped fire-retardant sheet271bwill preferably be higher than the allowable temperature. The reason is that the roll-shaped fire-retardant sheet271bshould be prevented from burning or melting at the allowable temperature or higher.

The exterior material273may be made of a material that melts at the allowable temperature or higher while accommodating the fire-retardant member271. More specifically, the exterior material273may be made of a heat-resistant (fire-retardant or flame-retardant) material that does not melt up to the allowable temperature. For example, the exterior material273may be made of a polymer such as polypropylene (PP), polyethylene (PE), rubber, cellulose, or a resin. Alternatively, the exterior material273may be made of a foam-type polymer.

The exterior material273allows the fire-retardant assembly270to maintain a constant shape regardless of the shape of the fire-retardant member271. Even when the fire-retardant member271is in a liquid state, the fire-retardant assembly270can maintain a preset three-dimensional shape by the exterior material273.

In addition, by obtaining the effect of coating the outer surface of the fire-retardant assembly270with the exterior material273, it is possible to enhance the moisture resistance or moisture-proof effect of the fire-retardant assembly270.

FIG.8is a cross-sectional top view of the battery assembly200according to an embodiment the present disclosure.

Referring toFIGS.2and8,FIG.8shows a portion (specifically, an area in which the accommodation body219meets one of the end plates212and213) viewing the accommodation body219from the top after removing the accommodation cover215.

As described above, the movement of the fire-retardant particle271a(seeFIG.6B), which is an example of the fire-retardant member271, may be suppressed by the exterior material273, and at least some of the fire-retardant particles271amay be released from the restricted coupling by the exterior material273due to the melting of the exterior material. On the other hand, the roll-shaped fire-retardant sheet271bmay expand due to the melting of the exterior material273and fill the insertion space288better than when restrained by the exterior material273.

Referring toFIG.8, the insertion space288may be partitioned into the plurality of separation spaces2889(seeFIG.5), and the plurality of fire-retardant assemblies may be inserted into at least some of the plurality of separation spaces2889.

The battery assembly200may further include the heat blocking member119located between the battery cells110in the stacking direction (e.g., the X-axis direction) of the plurality of battery cells110. Since the heat blocking member119extends in a direction (e.g., the Y-axis direction) in which the lead tab units111and112protrude among directions perpendicular to the stacking direction and is connected to the busbar assembly150, the fire-retardant assembly270may not fill all the plurality of separation spaces2889.

However, when the heat blocking member119is not present, the fire-retardant assembly270may be inserted into each of the plurality of separation spaces2889.

AlthoughFIG.8shows an example in which the fire-retardant member271(seeFIG.6C) is the fire-retardant particle271a(seeFIG.6B), alternatively, the above description may also be applied to a case in which the fire-retardant member271is the roll-shaped fire-retardant sheet271b(seeFIG.7B).

FIG.9is a side view of the battery assembly200according to an embodiment of the present disclosure.

Specifically, referring toFIGS.2and9,FIG.9shows an area in contact with any one of the end plates212and213when viewing the battery assembly200after removing the body side surfaces2191and2192and the busbar assembly150.

Referring toFIG.9, the insertion space288may include the plurality of separation spaces2889, and the fire-retardant assembly270may be located in the separation spaces2889of at least some of the plurality of separation spaces2889. The fire-retardant assembly270can delay the thermal runaway of the battery cell110. The fire-retardant assembly270may not be added in each one of the plurality of separation spaces2889.

Referring toFIG.9, an example in which the fire-retardant member271is the fire-retardant particle271a(seeFIG.6B) is shown. However, as described above, the fire-retardant member271may be the roll-shaped fire-retardant sheet271b(seeFIG.7B).

FIG.10Ais another view of the fire-retardant assembly270accommodated in the insertion space288,FIG.10Bis a cross-sectional view of the fire-retardant assembly270shown inFIG.10A, andFIG.10Cis an exploded view of an exterior material273.FIG.10Dis another exploded view of an exterior material273, according to embodiments of the present disclosure.

As described above, the battery assembly200according to an embodiment of the present disclosure may include the plurality of battery cells110arranged by being stacked in the preset stacking direction, the accommodation case210for accommodating the plurality of battery cells110, the insertion space288formed between the plurality of battery cells110and the accommodation case210in the stacking direction, and the fire-retardant assembly270located in the insertion space288.

Referring toFIGS.10A and10B, the fire-retardant assembly270may include a pillar-shaped exterior material273for accommodating a bead-shaped fire-retardant member271containing the fire-retardant material and extending in the height direction of the accommodation case210. Considering the function and form of the fire-retardant member271and the exterior material273, the fire-retardant assembly270may be referred to as a fire-retardant capsule or fire-mitigation capsule, or an FR (or FM) capsule.

A ratio at which the fire-retardant member271fills the exterior material273may be changed depending on a usage environment. That is, a filling rate of the fire-retardant member271may be changed in consideration of a location at which the fire-retardant assembly270is located in the accommodation case210. The filling rate may indicate the percentage of a volume of the fire-retardant member271to an internal volume of the exterior material273.

The height of the fire-retardant assembly270in the height direction of the accommodation case210may be greater than the length (or the diameter) of the fire-retardant assembly270in the stacking direction. That is, the fire-retardant assembly270may have a cylindrical shape formed to extend in the height direction of the accommodation case210.

In addition, considering the size of the insertion space288, the length (or the diameter) of the fire-retardant assembly270in the stacking direction may be smaller than or equal to the thickness of any one of the plurality of battery cells, which is to allow the fire-retardant assembly270to be easily inserted into the insertion space288.

The fire-retardant assembly270may preferably have a cylindrical shape. Therefore, the length of the fire-retardant assembly270in the stacking direction may indicate the diameter of the fire-retardant assembly270whose end face has a circular shape.

The fire-retardant assembly270or at least one of both end portions276and277of the exterior material273may be provided in a tapered shape.

The above is to allow the fire-retardant assembly270to be easily inserted into the insertion space288. That is, when the fire-retardant assembly270is inserted into the insertion space288, at least one end portion of the fire-retardant assembly270may have a tapered shape to allow the fire-retardant assembly270to be guided into the insertion space288.

Referring toFIG.10B, the exterior material273may further include the fire-retardant space274formed by the exterior material273to accommodate the fire-retardant member271or the fire-retardant particles271a.

FIG.10Ashows an example in which the exterior material273has a cylindrical shape. However, the shape of the exterior material273is not limited thereto and may have any shape as long as it may be inserted into the insertion space288.

In the drawings of the present specification, the fire-retardant member271is spherical for convenience, and the shape of the fire-retardant member271is not limited to a sphere. Therefore, the fire-retardant member271may have an amorphous shape. In addition, the fire-retardant member271is not limited to one size, but may be a shape in which various sizes of the fire-retardant members271are mixed. In addition, the fire-retardant member271is shown exaggerated from the actual size for description.

Referring toFIG.10C, the exterior material273may include a pipe-shaped body portion275extending in the height direction of the accommodation case210, the first end portion276coupled to an upper side of the body portion275to close one end of both open ends of the body portion275, and the second end portion277coupled to a lower side of the body portion275to close the other open end.

InFIG.10C, although the first end portion276and the body portion275are shown separately, alternatively, the first end portion276and the body portion275may be molded integrally. Thereafter, the fire-retardant member271may fill the first end portion276and the body portion275, and the second end portion277may be coupled to the body portion275to close the open end of the body portion275. That is, the second end portion277may serve as a lid.

That is, the exterior material273may include the cylindrical body portion275whose at least one end of both ends is open, and the end portions276and277coupled to the body portion275to close the at least open one end.

Referring toFIGS.10A,10B, and10C, a length B of the body portion275may be greater than a length D1of the first end portion276and a length D2of the second end portion277.

In addition, the body portion275may have a cylindrical shape. The fire-retardant assembly270may further include grooves G1and G2recessed inward along a circumferential surface of the cylindrical body portion275. The grooves G1and G2may be formed between the first end portion276and the body portion275and between the second end portion277and the body portion275, which is to prevent damage to the battery cell110adjacent to the fire-retardant assembly270when the fire-retardant assembly270is inserted.

In addition, the first end portion276may have a tapered shape in a direction away from the body portion275.

That is, at least one of both end portions of the exterior material may have a tapered shape, for allowing the fire-retardant assembly270to be easily inserted into the insertion space288using the tapered end portion.

Alternatively, the second end portion277may include a flat end face. That is, the second end portion277may include an end face277a(seeFIG.11) disposed parallel to the body bottom surface2194, which is the bottom surface of the accommodation case210.

Referring toFIGS.10A and10B, the plurality of fire-retardant members271are provided, mixed, and accommodated in the exterior material273.

As described throughFIGS.6A and6B, the fire-retardant member271may be a solid filler (or the fire-retardant particles271a, seeFIG.6B) provided in the form of solid particles, powder, granules, pellets, or beads, which is to prevent or delay flame transfer or heat transfer through the insertion space288when thermal runaway occurs in any battery cell110.

Referring toFIG.10D, unlikeFIG.10C, one end of the exterior material273may have a closed shape. That is, the second end portion277may be formed integrally with the body portion275. Therefore, the first end portion276may be coupled to the body portion275to close the open end of the body portion275.

Alternatively, the first end portion276may be formed integrally with the body portion275, and the second end portion277may be coupled to the body portion275to close the other open end of the body portion275.

As a result, the exterior material273may include the cylindrical body portion275whose at least one end is open, and the end portions276and/or277coupled to the body portion to close at least one open end.

Since the size (or shape) and material of the fire-retardant member271are the same as those of the fire-retardant member271shown inFIGS.6A to6C, detailed descriptions thereof are omitted.

FIG.11is another side view of the battery assembly200according to an embodiment of the present disclosure.

Specifically, referring toFIGS.2and11,FIG.11shows an area in contact with any one of the end plates212and213when viewing the battery assembly200after removing the body side surfaces2191and2192and the busbar assembly150.

Referring toFIGS.1,2, and11, the insertion space may be partitioned into the plurality of separation spaces2889by each of the lead tab units111and112located outside the plurality of battery cells110to connect the busbar170with the plurality of battery cells110, the plurality of fire-retardant assemblies270may be provided and inserted into at least some of the plurality of separation spaces2889.

FIG.11is an exemplary view of the plurality of fire-retardant assemblies270inserted one-to-one into the plurality of separation spaces2889but disposed only in at least some of the plurality of separation spaces2889. When the fire-retardant assembly270may delay the thermal runaway of the battery cell110, the fire-retardant assembly270does not necessarily need to be located in each of the plurality of separation spaces2889.

Referring toFIG.11, the plurality of fire-retardant assemblies270may have different filling rates of the fire-retardant members271filling each exterior material273, which is to consider the location in the battery assembly200at which thermal runaway occurs frequently. That is, the filling rate of the fire-retardant member271filling any one located on a central portion of the accommodation case210among the plurality of fire-retardant assemblies270may differ from the filling rate of the fire-retardant member271filling any one fire-retardant assembly270located on the side surface portions of the accommodation case210.

Referring toFIGS.2and11, the accommodation case210may include an open upper surface2195and further include the accommodation body219for accommodating the plurality of battery cells110through the open upper surface2195, and the accommodation cover215coupled to the accommodation body219to cover the open upper surface2195.

In addition, the fire-retardant assembly270or one end portion closer to the accommodation cover215than the accommodation body219among both end portions of the exterior material273may have a tapered shape.

FIG.12is a schematic view illustrating that the exterior material273melts and the fire-retardant particles271a(seeFIG.6B), which are an example of the fire-retardant member271, are stacked granularly in the insertion space288.

Specifically,FIG.12shows an example in which the exterior material273melts at the allowable temperature or higher and the fire-retardant particles271aare separated granularly to fill the insertion space288up to a preset filling height H1in the height direction of the accommodation case210or the accommodation body219.

The insertion space288may be partitioned into the plurality of separation spaces2889, and the plurality of fire-retardant assemblies270may be inserted into at least some of the plurality of separation spaces2889. The volume of each of the insertion spaces288may be greater than the total volume of the fire-retardant assemblies270inserted into the plurality of separation spaces2889.

As a result, even when it is assumed that the exterior material273fully melts during thermal runaway of the plurality of battery cells110, the fire-retardant particles271amay not fill the insertion space288up to the uppermost end in the height direction of the battery cell110.

That is, assuming that the battery assembly200reaches the allowable temperature and the exterior material273fully melts, the fire-retardant particles271amay granularly fill the insertion space288up to the filling height H1.

Referring toFIG.12, the filling height may be a height marked by H1from the body bottom surface2194, which is the bottom surface of the accommodation body219.

For example, an example in which the filling height H1shown inFIG.12is the height corresponding to when 50% of the volume of the insertion space288is filled with the fire-retardant particles271aafter the exterior material273melts is shown.

The battery assembly200may further include the heat sink unit295between the plurality of battery cells110and the body bottom surface2194. The heat sink unit295may be made of a material that may be cured when a preset elapse time elapses after the plurality of battery cells110are accommodated after a liquid is first applied onto the body bottom surface2194before the plurality of battery cells110are accommodated.

The thickness of the heat sink unit295may be negligible compared to the height of the accommodation body219or the filling height H1.

The battery assembly200may have the end plates212and213located at both ends of the plurality of battery cells110in the stacking direction. In addition, some adjacent to each other among the plurality of battery cells110may be grouped to form the battery groups BG1to BG5. The plurality of battery cells110in one battery group may be disposed at the same polarity and connected in parallel. Therefore, each of the battery groups BG1to BG5may have a different pole arrangement from the adjacent battery groups BG1to BG5.

In addition, the battery assembly200may further include the heat blocking member119(seeFIG.3) or the buffering member117between the plurality of battery groups BG1to BG5.

Unlike that shown inFIG.12, when the fire-retardant member271is provided as the roll-shaped fire-retardant sheet271b, the roll shape of the fire-retardant sheet271bmay expand in the diameter direction when the exterior material273melts, and the appearance of the roll shape can be maintained.

FIG.13is a view of the movement of the fire-retardant particles271a(seeFIG.6B), which are an example of the fire-retardant member271(seeFIG.6B), due to flame or hot gas according to an embodiment of the present disclosure.

Referring toFIG.13, when the exterior material273restraining the fire-retardant particles starts to melt at the allowable temperature or higher, the fire-retardant particles may not maintain the appearance of the fire-retardant assembly270and may be sequentially stacked from the body bottom surface2194by gravity.

That is, since the fire-retardant particles271aare accommodated in the exterior material273, when the exterior material273is removed, the fire-retardant particles271aaccumulate in the insertion space288rather than being coupled.

FIG.13schematically shows an example in which the exterior materials273of all fire-retardant assemblies270inserted into the insertion spaces288melt. The shape of the fire-retardant particles271ais shown exaggerated in size and as being a spherical shape for description. In addition, for convenience, it is assumed that all exterior materials273are in a melted state.

Alternatively, in any one battery cell110, the exterior material273may first melt in any one insertion space288in which the corresponding battery cell110is located. Therefore, some of the plurality of fire-retardant assemblies270may melt, and others can maintain the three-dimensional shape of the fire-retardant assemblies270.

In addition, in any one fire-retardant assembly270, some regions may be melted, while other portions may still maintain the appearance of the fire-retardant assembly270.

When the temperature of the fire-retardant assembly270reaches the allowable temperature or higher, the exterior material273starts to melt, and as shown inFIGS.12and13, the fire-retardant particles, which are an example of the fire-retardant member271, may be separated granularly and stacked freely.

The plurality of fire-retardant particles may be provided.

Since the exterior material273restraining the fire-retardant particles has been removed, the fire-retardant particles, which are an example of the fire-retardant member271, may move freely. Therefore, due to the flow of flame or off-gas generated during thermal runaway, the fire-retardant particles, which are an example of the fire-retardant member271, may receive a force and move to other locations.

As described above, since the plurality of insertion spaces288communicate with each other, when flame or off-gas moves (in an arrow direction) from any one insertion space288in which the battery cell110in which thermal runaway has occurred is located toward another battery cell110, the fire-retardant particles, which are an example of the fire-retardant member271, may move from the insertion space288corresponding to the battery cell110in which thermal runaway has occurred to another insertion space288.

For example, referring toFIG.13, when thermal runaway occurs in one battery cell (e.g., any one battery cell belonging to BG3), a temperature of an area adjacent to the one battery cell will increase first. Therefore, the exterior material273of the fire-retardant assembly270adjacent to the one battery cells110in which the thermal runaway has occurred may melt. Therefore, the restrained fire-retardant particles, which are an example of the fire-retardant member271, may freely move due to the melting of the exterior material273.

Therefore, when the flame or hot gas spreads to adjacent battery groups, the fire-retardant particles, which are an example of the granular fire-retardant member271, may move to sides along the flame or hot gas.FIG.13schematically shows this for description. Therefore, since the granular fire-retardant particles move to and fill the remaining spaces in which flame or hot gas does not spread yet among the insertion spaces288, it is possible to delay the transfer of the flame or hot gas.

That is, the fire-retardant particles, which are an example of the fire-retardant member271and which have been separated granularly, and may move freely due to the melting of the exterior material273, may move to the insertion space288corresponding to the location of the battery cell110in which the thermal runaway has not occurred and which may be operated normally due to the pressure generated upon the occurrence of the thermal runaway in any one of the plurality of battery cells110.

Therefore, referring toFIG.13, the fire-retardant particles, which are an example of the fire-retardant member271, may move to other areas excluding the insertion space288corresponding to the area of the third battery group BG3. Therefore, a filling height H3of the fire-retardant particles may be greater than the filling height H1of the fire-retardant particles inFIG.12.

It is only an example, and the filling height H3of the fire-retardant particles, which are an example of the fire-retardant member271, may be changed depending on a transfer rate of the flame and a venting speed of the off-gas.

FIG.14is a flowchart of a process of manufacturing the battery assembly200according to an embodiment of the present disclosure.

Referring toFIG.14, a method of assembling the battery assembly200according to an embodiment of the present disclosure may include stacking the plurality of battery cells110in the preset stacking direction (S110), coupling the plurality of stacked battery cells110to the accommodation cover215(S200), inserting the fire-retardant assembly270including the bead-shaped fire-retardant member271including the fire-retardant material in the insertion space288and the exterior material273for accommodating the fire-retardant member271therein and extending in the height direction of the accommodation case210(S400), and coupling the accommodation body219coupled to the accommodation cover215to form the accommodation case210to the accommodation cover215(S500).

The method of assembling the battery assembly200according to an embodiment of the present disclosure may include, after the stacking of the plurality of battery cells (S110), coupling the busbar assembly150electrically connected to the plurality of battery cells110(S150).

The stacking of the plurality of battery cells110(S110) and the coupling of the busbar assembly150may be collectively referred to as assembling the cell stack100(S100).

Specifically, the assembling of the cell stack100(S100) may further include, after the stacking of the plurality of battery cells110(S110), stacking the plurality of battery cells110and the buffering member117and/or the heat blocking member119that are located between the plurality of battery cells110(not shown).

In addition, the assembling of the cell stack100(S100) may further include stacking each of the end plates212and213located at both ends of the plurality of battery cells110in the stacking direction in which the plurality of battery cells110are stacked (not shown).

The assembling of the cell stack100(S100) may further include, after the stacking (S110) is finished, connecting the busbar assembly150to the stacked battery cells110(S150). Through the connecting of the busbar assembly150(S150), the plurality of battery cells110and the busbar assembly150may be electrically connected by being welded.

Thereafter, the assembly method of the present disclosure may include coupling the accommodation cover215to the cell stack100(S200). The reason for assembling the accommodation cover215before the accommodation body219is to protect the busbar assembly150located to face the accommodation cover215during the assembly process.

Thereafter, the assembly method of the present disclosure may perform a first inverting operation (S300) of inverting the battery assembly200being assembled. That is, the assembly method of the present disclosure may further include, before the inserting of the fire-retardant assembly270into the insertion space288(S400), the first inverting operation (S300) of coupling the plurality of stacked battery cells110to the accommodation cover215and then inverting the battery assembly200. That is, through the first inverting operation (S300), the accommodation cover215is located under the plurality of battery cells110in a direction in which gravity acts.

The reason for inverting the battery assembly200being assembled is to locate the fire-retardant assembly270in the insertion space288. Since it is difficult to insert the fire-retardant assembly270from the top due to the already coupled accommodation cover215, the battery assembly200being assembled is inverted to locate the fire-retardant assembly270.

The assembly method of the present disclosure may proceed to the inserting of the fire-retardant assembly270(S400) after the first inverting operation (S300).

When the shape of the fire-retardant assembly270is as shown inFIG.10A, in the inserting of the fire-retardant assembly270(S400) of the assembly method of the present disclosure, the first end portion276may be inserted into the insertion space288to be disposed toward the accommodation cover215prior to the second end portion277.

Thereafter, the assembly method of the present disclosure may further include coupling the accommodation body219to the accommodation cover215(S500).

The coupling of the accommodation body to the accommodation cover (S500) may include, after the first inverting operation (S300), coupling the accommodation body219to the accommodation cover215and the cell stack100in the inverted state (S550).

In addition, the coupling of the accommodation body219to the accommodation cover215(S500) of the assembling method of the present disclosure may further include, before the coupling of the accommodation body219to the accommodation cover215and the cell stack100in the inverted state, forming the heat sink unit295on the body bottom surface2194forming the bottom surface of the accommodation body219(S510).

The heat sink unit295may be formed on the body bottom surface2194and may be in contact with the cell stack100when the cell stack100is coupled to the accommodation body219.

After the accommodation body219and the accommodation cover215are coupled, the assembly method of the present disclosure may include a second inverting step (S600) of re-inverting the battery assembly200so that the accommodation cover215is located at the top.

When the shape of the fire-retardant assembly270is the form shown inFIG.10A, through the second inverting operation (S600), the first end portion276may be disposed at the top and the second end portion277may be disposed at the bottom as in an example ofFIG.11.

The assembling method of the battery assembly200according to an embodiment of the present disclosure is described using an example in which the accommodation cover215is located at the top, but is not limited thereto. That is, the first inverting operation (S300) and the second inverting operation (S600) may indicate both vertical inversion and horizontal inversion. Alternatively, “inverting operation” may indicate that the accommodation cover215is located to face one direction and then face a direction opposite to the one direction by the inverting operation.

Thereafter, the assembly method of the present disclosure may perform inspecting the battery assembly200(S700).

FIG.15is another view of a battery assembly300according to an embodiment of the present disclosure.

Although the battery assembly200is described based on the battery assembly,FIG.15shows another example of the battery assembly300provided in the form of a battery pack. That is, the battery assembly200may be configured in the form of a CTP structure in which the plurality of battery cells110are accommodated in the form of a pack in a state of omitting the battery assembly.

The battery assembly300may include the plurality of battery cells110arranged by being stacked in the preset stacking direction, an accommodation case310for accommodating the plurality of battery cells, an insertion space388formed between the plurality of battery cells110and the accommodation cases in the stacking direction, and the fire-retardant assembly (not shown) located in the insertion space.

The fire-retardant assembly270(seeFIG.6A) may include the fire-retardant member271and the exterior material273(seeFIG.6A) for accommodating the fire-retardant member271therein. InFIG.13, the fire-retardant assembly270is omitted for the description of the accommodation case210.

The accommodation case310may include an accommodation body311for accommodating the plurality of battery cells110and an accommodation cover (not shown) coupled to the accommodation body311. In addition, the accommodation case310may further include a partition330for partitioning the insertion space388.

The partition330may further include a first frame333and a second frame335for partitioning the plurality of battery cells110horizontally and vertically, respectively. The first frame333and the second frame335are used to prevent the deformation of the accommodation body311and support and distinguish the plurality of battery cells110.

FIG.16Ais a view of a portion of another example of the battery assembly according to an embodiment of the present disclosure.FIG.16Bis a view of a portion of still another example of the battery assembly200according to an embodiment of the present disclosure.

Referring toFIG.16A, the shape of the battery cell included in the battery assembly200according to an embodiment of the present disclosure may be a prismatic battery cell. That is, the battery assembly200according to an embodiment of the present disclosure may include the plurality of battery cells110stacked in the preset direction, and the fire-retardant assembly270disposed with the plurality of battery cells110interposed therebetween. For convenience, the accommodation case for accommodating the plurality of battery cells110and the fire-retardant assembly270is omitted.

A terminal of the prismatic battery cell110may be located on an upper portion of the prismatic battery cell110in the height direction of the accommodation case. Therefore, the busbar for electrically connecting the plurality of battery cells110may be located on the upper portions of the plurality of battery cells110.

The battery assembly200may include the fire-retardant assembly270disposed with the plurality of battery cells interposed therebetween. For convenience, the accommodation case for accommodating the plurality of battery cells110and the fire-retardant assembly270is omitted.

Referring toFIG.16B, the shape of the battery cell included in the battery assembly200according to an embodiment of the present disclosure may be a cylindrical battery cell. That is, the battery assembly200according to an embodiment of the present disclosure may include the plurality of battery cells110, the accommodation case (not shown) for accommodating the plurality of battery cells110, and the fire-retardant assembly270disposed between the plurality of battery cells110or between the plurality of battery cells110and the accommodation case210.

In the cylindrical battery cell110, unlike the prismatic or pouch-shaped battery cell110, an empty space into which the fire-retardant assembly270may be inserted may also be formed between the cylindrical battery cells110. Therefore, the fire-retardant assembly270may also be inserted into the empty space.

First, according to one aspect of the present disclosure, it is possible to prevent or mitigate hot gas generated from a battery cell in which thermal runaway has occurred among one or more battery cells provided inside a battery assembly from being discharged toward a tab of the battery cell.

Second, according to another aspect of the present disclosure, it is possible to vent hot gas generated from the battery cell in which thermal runaway has occurred along an intended path.

Third, according to still another aspect of the present disclosure, it is possible to add a process of inserting a fire-retardant assembly (or a fire-retardant assembly material or a filler) into an empty space formed between a busbar assembly and a cell tab of a battery to the assembling process of the conventional battery assembly.

Fourth, according to yet another aspect of the present disclosure, it is possible to easily arrange a fire-retardant assembly when the battery assembly is assembled.

Fifth, according to yet another aspect of the present disclosure, it is possible to increase the stability of the battery assembly by increasing the heat resistance or fire resistance of the battery assembly.

Since the present disclosure may be carried out by being modified in any of various forms, the scope of the present disclosure is not limited to the above-described embodiments. Therefore, when the modified embodiments include the components of the claims of the present disclosure, the modified embodiments belong to the scope of the present disclosure.