Patent Description:
The present disclosure relates to a battery pack including a cell assembly unit.

As technology development and demand for mobile devices and electric vehicles increase, a demand for battery cells (secondary battery cells) as an energy source is rapidly increasing. A battery cell is a battery capable of repeating charging and discharging because an interconversion between chemical energy and electrical energy is reversible.

A plurality of battery modules, each of which is mounted with a plurality of battery cells, may be mounted on an electric vehicle to implement a battery pack.

Recently, when battery cells are installed in the electric vehicle, a technology (called Cell-to-Pack (CTP) technology) has been presented to omit a process of manufacturing and installing battery modules mounted with the battery cells and form a battery pack by directly installing the battery cells in the electric vehicle.

However, the battery cells generate heat while going through charging and discharging. Hence, there is a problem in that any one of the battery cells explodes due to an increase in a temperature of the battery cell or any one of the battery cells explodes due to an external shock.

Flames, gases, etc. caused by such an explosion propagate heat to other battery cells or other battery packs through the flow, and eventually all the battery cells in the electric vehicle explode, causing damage to users and surroundings.

An object of the present disclosure is to address the above-described and other problems.

Another object of the present disclosure is to provide a cell assembly unit and a battery pack including the same capable of smoothly discharging a flame or gas caused by an explosion of a battery cell and capable of preventing heat propagation by heat conduction.

In order to achieve the above-described and other objects and needs, in one aspect of the present disclosure, there is provided a battery pack comprising a cell assembly unit including a plurality of battery cells and a bus bar configured to electrically connect the plurality of battery cells; a frame unit accommodating the cell assembly unit; a bracket unit fixing the cell assembly unit to the frame unit, wherein the bracket unit and the frame unit form a flow path through which a gas is discharged; and a reverse flow prevention member disposed between the bus bar and the bracket unit, the reverse flow prevention member including a plurality of gas permeation holes, each of which extends from one end facing the bus bar and leads to another end facing the flow path wherein the bus bar contacts the reverse flow prevention member and wherein the reverse flow prevention member contacts the bracket unit.

In another aspect of the present disclosure, there is provided a battery pack further comprising an insulating cover disposed at one side of the bus bar and configured to insulate the bus bar; and the reverse flow prevention member is coupled to one of the bus bar and the insulating cover, wherein the reverse flow prevention member allows a gas generated in at least one of the plurality of battery cells to be discharged to an outside of the insulating cover and blocks the gas from being introduced from the outside of the insulating cover to the plurality of battery cells.

According to an aspect of the present disclosure, the present disclosure can provide a cell assembly unit and a battery pack including the same capable of securing a safety against the risk of explosion by preventing heat propagation by heat conduction when thermal runaway occurs.

Additional scope of applicability of the present disclosure will become apparent from the detailed description given blow. However, it should be understood that the detailed description and specific examples such as embodiments of the present disclosure are given merely by way of example.

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure.

Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. In general, a suffix such as "module" and "unit" may be used to refer to elements or components. Use of such a suffix herein is merely intended to facilitate description of the present disclosure, and the suffix itself is not intended to give any special meaning or function. It will be noted that a detailed description of known arts will be omitted if it is determined that the detailed description of the known arts can obscure the embodiments of the disclosure. The accompanying drawings are used to help easily understand various technical features and it should be understood that embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings.

The terms including an ordinal number such as first, second, etc. may be used to describe various components, but the components are not limited by such terms. The terms are used only for the purpose of distinguishing one component from other components.

When any component is described as "being connected" or "being coupled" to other component, this should be understood to mean that another component may exist between them, although any component may be directly connected or coupled to the other component. In contrast, when any component is described as "being directly connected" or "being directly coupled" to other component, this should be understood to mean that no component exists between them.

A singular expression can include a plural expression as long as it does not have an apparently different meaning in context.

In the present disclosure, terms "include" and "have" should be understood to be intended to designate that illustrated features, numbers, steps, operations, components, parts or combinations thereof are present and not to preclude the existence of one or more different features, numbers, steps, operations, components, parts or combinations thereof, or the possibility of the addition thereof.

In the drawings, sizes of the components may be exaggerated or reduced for convenience of explanation. For example, the size and the thickness of each component illustrated in the drawings are arbitrarily illustrated for convenience of explanation, and thus the present disclosure is not limited thereto unless specified as such.

If any embodiment is implementable differently, a specific order of processes may be performed differently from the order described. For example, two consecutively described processes may be performed substantially at the same time, or performed in the order opposite to the described order.

In the following embodiments, when layers, areas, components, etc. are connected, the following embodiments include both the case where layers, areas, and components are directly connected, and the case where layers, areas, and components are indirectly connected to other layers, areas, and components intervening between them. For example, when layers, areas, components, etc. are electrically connected, the present disclosure includes both the case where layers, areas, and components are directly electrically connected, and the case where layers, areas, and components are indirectly electrically connected to other layers, areas, and components intervening between them.

The present disclosure relates to a battery pack and can secure a flow path capable of smoothly discharging a flame or a high-temperature gas generated by an explosion of a battery cell, in a battery pack, in which battery cells are directly installed, in a vehicle or the like.

In another aspect, a battery pack according to the present disclosure can present configuration capable of preventing heat propagation by preventing a gas discharged in any one battery cell from being introduced into another battery cell in a thermal runaway situation.

Referring to <FIG>, a battery pack <NUM> according to an embodiment of the present disclosure may include a cell assembly unit <NUM>, a frame unit <NUM>, and a bracket unit <NUM>.

The cell assembly unit <NUM> may include a plurality of battery cells <NUM> that are arranged to be stacked in one direction. The frame unit <NUM> may accommodate the cell assembly unit <NUM>.

The bracket unit <NUM> may be coupled to the frame unit <NUM>. The bracket unit <NUM> may fix the cell assembly unit <NUM> to the frame unit <NUM>. The bracket unit <NUM> may form a flow path B together with the frame unit <NUM>.

When a flame or a gas is generated in any one of the plurality of battery cells <NUM>, the flow path B may be a path for discharging the flame or the gas. For example, the flow path B may be a passage or a path through which gas flows.

The battery pack <NUM> according to an embodiment of the present disclosure may include a reverse flow prevention member <NUM>. The reverse flow prevention member <NUM> may selectively discharge the flame or the gas to the flow path B.

For example, the bracket unit <NUM> may be coupled to the cell assembly unit <NUM> and may couple the cell assembly unit <NUM> to the frame unit <NUM>. The bracket unit <NUM> may prevent the cell assembly unit <NUM> from being detached. For example, the cell assembly unit <NUM> may not be detached from the frame unit <NUM> by catching on the bracket unit <NUM>.

That is, the bracket unit <NUM> can simultaneously perform a function of forming the flow path B and a function of fixing the cell assembly unit <NUM>. Therefore, an existing problem of a reduction in an energy density caused by separately providing the configuration for forming the flow path B and the configuration for fixing the battery cells <NUM> can be solved through the bracket unit <NUM> according to an embodiment of the present disclosure. Hence, the present disclosure has an advantage in that the energy density can be increased by installing a relatively large number of battery cells <NUM>.

The cell assembly unit <NUM> may include the plurality of battery cells <NUM>. The cell assembly unit <NUM> may include a bus bar <NUM> and a side cover <NUM> that electrically connect the plurality of battery cells <NUM> to each other.

The battery cell <NUM> may include an electrode assembly and an exterior material surrounding the electrode assembly.

The electrode assembly may substantially contain an electrolyte and may be accommodated in the exterior material together with the electrolyte. The electrolyte may include an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC), and a lithium salt such as LiPF<NUM> and LiBF<NUM>. The electrolyte may be a liquid, solid or gel phase.

The exterior material may protect the electrode assembly and accommodate the electrolyte. For example, the exterior material may be a pouch-shaped member or a can-shaped member. A pouch-shaped battery cell, a can-shaped battery cell, etc. are merely an example of the battery cell <NUM> accommodated in the battery pack <NUM> according to the present disclosure. The battery cell <NUM> accommodated in the battery pack <NUM> according to the present disclosure is not limited to the battery cells described above.

The frame unit <NUM> may accommodate the cell assembly unit <NUM>. The frame unit <NUM> airtightly accommodates the periphery of the cell assembly unit <NUM>, and thus can prevent a flame or gas generated by the explosion of any one of the battery cells <NUM> included in the cell assembly unit <NUM> from being discharged to the outside. In this case, the flame or the gas may be guided to the flow path B formed by the frame unit <NUM> and the bracket unit <NUM> and may be discharged to the outside.

For example, the frame unit <NUM> may accommodate a plurality of cell assembly units <NUM>, and may provide a plurality of compartments in which the respective cell assembly units <NUM> are sealed. To this end, the frame unit <NUM> according to an embodiment of the present invention may include a lower frame <NUM>, a side frame <NUM>, and an upper frame <NUM>.

The cell assembly unit <NUM> may be placed on the lower frame <NUM>. The lower frame <NUM> may face a lower part of the cell assembly unit <NUM>. A lower end of the side frame <NUM> may be coupled to the lower frame <NUM>. The side frame <NUM> may surround the side of the cell assembly unit <NUM> in a perimeter direction. The side frame <NUM> and the bracket unit <NUM> may form the flow path B. The side frame <NUM> may correspond to a side surface of the cell assembly unit <NUM>. The upper frame <NUM> may be coupled to an upper end of the side frame <NUM>. The upper frame <NUM> may cover the cell assembly unit <NUM>. The upper frame <NUM> may face an upper part of the cell assembly unit <NUM>.

The cell assembly unit <NUM> may be placed on the lower frame <NUM>. An area of the lower frame <NUM> may be divided by the side frame <NUM> so that the plurality of cell assembly units <NUM> can be isolated from each other. The lower frame <NUM> is one frame on which all the plurality of cell assembly units <NUM> are placed. The side frame <NUM> may divide the lower frame <NUM> into a plurality of areas (compartments), each of which accommodates each cell assembly unit <NUM>.

For example, the lower frame <NUM> may be a frame included in a floor portion below a boarding area of a vehicle frame. In order to improve a heat dissipation performance, a heat conducting member may be interposed between the cell assembly unit <NUM> and the lower frame <NUM>. For example, the heat conducting member may be applied between the cell assembly unit <NUM> and the lower frame <NUM>.

The side frame <NUM> may surround the periphery of the cell assembly unit <NUM>. To this end, the lower end of the side frame <NUM> may be coupled to an upper surface of the lower frame <NUM>. The side frame <NUM> may divide the lower frame <NUM> into a plurality of areas. For example, the side frame <NUM> may be disposed to form compartments corresponding to a plurality of rectangular areas on the upper surface of the lower frame <NUM>.

The side frame <NUM> according to an embodiment of the present disclosure may include a first side frame 22a and a second side frame 22b.

The first side frame 22a may be disposed on one side of the cell assembly unit <NUM>. The second side frame 22b may be disposed on another side of the cell assembly unit <NUM>.

The bracket unit <NUM> may be disposed between the second side frame 22b and the cell assembly unit <NUM>. The bracket unit <NUM> and the second side frame 22b may form the flow path B. That is, the second side frame 22b may form a part of the flow path B, and the bracket unit <NUM> may form a remaining part of the flow path B.

The upper frame <NUM> may cover upper parts of a predetermined number of battery cells <NUM> on a per number basis. Thus, a space inside the compartment formed by the frame unit <NUM> can be sealed. To this end, the upper frame <NUM> may be coupled to the upper end of the side frame <NUM> and an upper end of the bracket unit <NUM>.

At least one thermal diffusion prevention member <NUM> may be disposed between the plurality of battery cells <NUM>. The thermal diffusion prevention member <NUM> is disposed between the battery cells <NUM> that are adjacent to each other, and thus can block heat from being diffused between the battery cells <NUM> that are adjacent to each other.

The bracket unit <NUM> according to an embodiment of the present disclosure may include a support plate portion <NUM> that faces the side of the cell assembly unit <NUM> and is disposed in parallel to the bus bar <NUM>, an upper flange portion <NUM> positioned at an upper end of the support plate portion <NUM>, and a lower flange portion <NUM> positioned at a lower end of the support plate portion <NUM>.

For example, the upper flange portion <NUM> may extend from an upper end of the support plate portion <NUM> toward the second side frame 22b, or may extend toward the second side frame 22b and the cell assembly unit <NUM> in both directions. The upper flange portion <NUM> may be fastened to the second side frame 22b. Hence, the cell assembly unit <NUM> may be fixed to the frame unit <NUM>.

The upper flange portion <NUM> may be coupled to the upper frame <NUM>. For example, the upper flange portion <NUM>, the second side frame 22b, and the upper frame <NUM> may be coupled through one bolt. Hence, the present disclosure can reduce the coupling process time by reducing the number of bolt coupling operations.

The lower flange portion <NUM> may extend from the lower end of the support plate portion <NUM> toward the second side frame 22b. The lower flange portion <NUM> may allow the support plate portion <NUM> to be placed and supported on the lower frame <NUM>.

The support plate portion <NUM> may have a through hole 31a that communicates between a space, in which the cell assembly unit <NUM> is disposed, and the flow path B. A plurality of through holes 31a may be provided. The plurality of through holes 31a may be arranged along a longitudinal direction of the support plate portion <NUM>. A shape of the through hole 31a may include a quadrangle, a circle, or other polygonal shapes. The through hole 31a may be positioned or formed between the reverse flow prevention member <NUM> and the flow path B.

The through hole 31a is formed in the support plate portion <NUM>, and thus the flame or gas generated in any one battery cell <NUM> may be discharged to the flow path B. That is, the flame or the gas may pass through the through hole 31a and may be introduced into the flow path B.

For example, the bracket unit <NUM> may have heat resistance and/or fire resistance characteristics. For example, the bracket unit <NUM> may be formed of a material, such as a metal, a resin, a composite material, and a fiber-reinforced composite material, having rigidity of about <NUM> GPa or more. Accordingly, the bracket unit <NUM> can secure rigidity for fixing the cell assembly unit <NUM> to the frame unit <NUM> while forming the flow path B. In addition, the bracket unit <NUM> may be manufactured by going through post-processing such as coating and/or heat treatment in order to reinforce heat resistance and/or fire resistance and/or rigidity.

A shape of the reverse flow prevention member <NUM> according to an embodiment of the present disclosure may have a pad shape. The reverse flow prevention member <NUM> may be made of a heat resistant material with air permeability. The reverse flow prevention member <NUM> may extend in parallel to the support plate portion <NUM> of the bracket unit <NUM> along the bus bar <NUM> of the cell assembly unit <NUM>. For example, the reverse flow prevention member <NUM> may be disposed between the bus bar <NUM> and the bracket unit <NUM>. Accordingly, the reverse flow prevention member <NUM> may selectively pass through the flame or the gas so that the flame or the gas flows in one direction.

For example, since a plurality of "gas permeation holes" are formed in the reverse flow prevention member <NUM>, the reverse flow prevention member <NUM> may have air permeability (or gas permeability). The gas permeation hole of the reverse flow prevention member <NUM> may extend from one end and lead to the other end. For example, one end of the gas permeation hole may be opened facing the bus bar <NUM>. For example, the other end of the gas permeation hole may be opened toward the flow path B. For example, the other end of the gas transmission hole may face the through hole 31a and communicate with the through hole 31a.

A cross-sectional size of each of the plurality of gas permeation holes (not shown) of the reverse flow prevention member <NUM> may be smaller than the size of the flow path B. Here, a cross section of each of the plurality of gas permeation holes (not shown) may mean a cross section obtained by cutting the gas permeation hole (not shown) perpendicular to a longitudinal direction of the gas permeation hole (not shown). The longitudinal direction of the gas permeation hole (not shown) may be a direction from one end of the gas permeation hole (not shown) toward the other end.

That is, when thermal runaway due to explosion occurs in any one of the plurality of battery cells <NUM>, a gas generated inside the battery cells <NUM> may pass through a small space between the bus bars <NUM> and may be rapidly discharged. Therefore, a flow rate of the gas can increase, and thus the gas can pass through the reverse flow prevention member <NUM> with a strong pressure.

The gas that has passed through the reverse flow prevention member <NUM> may pass through the through hole 31a of the bracket unit <NUM> and may be introduced into the flow path B, which is a wide space. A density and a velocity of the gas in the flow path B may be less than a density and a velocity of the gas in the reverse flow prevention member <NUM>, respectively. That is, a pressure (atmospheric pressure) in the flow path B may be less than a pressure (higher than atmospheric pressure) in the reverse flow prevention member <NUM>.

Accordingly, it may be difficult for the gas positioned in the flow path B to pass through the reverse flow prevention member <NUM> and enter the battery cell <NUM>. That is, the gas in the flow path B does not pass through the reverse flow prevention member <NUM> and enter the battery cell <NUM>, and can be discharged to the outside along the flow path B.

In other words, the reverse flow prevention member <NUM> can allow the gas to be introduced from the cell assembly unit <NUM> to the flow path B and can block the gas from reversely flowing from the flow path B into the cell assembly unit <NUM>.

As described above, the battery pack <NUM> according to the present disclosure includes the reverse flow prevention member <NUM>, and thus can selectively pass through the gas so that the gas flows in only one direction. Hence, when thermal runaway occurs in any one compartment, the battery pack <NUM> according to the present disclosure can prevent heat from being propagated to other compartments after only the battery cells <NUM> in the corresponding compartment are burned out.

The cell assembly unit <NUM> may include the bus bar <NUM> to which electrode leads 11a of the plurality of battery cells <NUM> are coupled, an insulating cover <NUM> covering the bus bar <NUM>, the side cover <NUM> covering outermost side portions of the plurality of battery cells <NUM>, and the reverse flow prevention member <NUM> coupled to the bus bar <NUM> or the insulating cover <NUM>.

The bus bar <NUM> may be coupled to the plurality of battery cells <NUM>. The bus bar <NUM> may support all the plurality of battery cells <NUM>. To this end, the bus bar <NUM> may include a plurality of coupling holes (not shown) coupled to the electrode leads 11a of the battery cells <NUM>.

The bus bar <NUM> may be connected to an electrode strip (not shown). The bus bar <NUM> may transfer electrical energy generated in the plurality of battery cells <NUM> to the electrode strip (not shown), and the electrode strip may supply the electrical energy to an external device (not shown) such as an electric vehicle. For example, the external device is not limited to the electric vehicle and may include a power tool, an electric bicycle, urban air mobility (UAM), an energy storage system (ESS), and the like.

The insulating cover <NUM> may cover and protect the bus bar <NUM>. For example, the insulating cover <NUM> may insulate between the bus bar <NUM> and an external metal structure. The insulating cover <NUM> may be disposed between the reverse flow prevention member <NUM> and the support plate portion <NUM>.

The reverse flow prevention member <NUM> may be disposed between the bus bar <NUM> and the insulating cover <NUM>. The reverse flow prevention member <NUM> may extend along the bus bar <NUM> or the insulating cover <NUM>. The reverse flow prevention member <NUM> may be formed to discharge the flame or gas generated in the battery cell <NUM> to the flow path B. To this end, the reverse flow prevention member <NUM> may be made of a flame retardant material.

The reverse flow prevention member <NUM> may allow the gas generated in one of the plurality of battery cells <NUM> to be discharged to the outside of the insulating cover <NUM> and may block the gas positioned outside the insulating cover <NUM> from being introduced into the plurality of battery cells <NUM>.

In order to discharge the gas generated in the battery cell <NUM> to the flow path B, the insulating cover <NUM> may have an open hole 14a corresponding to the through hole 31a. A position on the open hole 14a may correspond to a position where the through hole 31a is formed.

A plurality of opening holes 14a may be provided. The plurality of open holes 14a may be arranged along a longitudinal direction of the insulating cover <NUM>. The number of open holes 14a may correspond to the number of through holes 31a.

The side cover <NUM> may be provided to pack the plurality of battery cells <NUM> in association with the insulating cover <NUM> and the bracket unit <NUM>. For example, the side cover <NUM> may cover the outermost side portions of the stacked plurality of battery cells <NUM> to protect the battery cells <NUM>.

Claim 1:
A battery pack (<NUM>) comprising:
a cell assembly unit (<NUM>) including a plurality of battery cells (<NUM>) and a bus bar (<NUM>) configured to electrically connect the plurality of battery cells (<NUM>);
a frame unit (<NUM>) accommodating the cell assembly unit (<NUM>);
a bracket unit (<NUM>) fixing the cell assembly unit (<NUM>) to the frame unit (<NUM>), wherein the bracket unit (<NUM>) and the frame unit (<NUM>) form a flow path (B) through which a gas is discharged; and
a reverse flow prevention member (<NUM>) disposed between the bus bar (<NUM>) and the bracket unit (<NUM>), the reverse flow prevention member (<NUM>) including a plurality of gas permeation holes, each of which extends from one end facing the bus bar (<NUM>) and leads to another end facing the flow path (B),
wherein the bus bar (<NUM>) contacts the reverse flow prevention member (<NUM>), and
wherein the reverse flow prevention member (<NUM>) contacts the bracket unit (<NUM>).