Patent Description:
A battery pack applied to an energy storage system (ESS) and/or an electric vehicle may be manufactured to include a plurality of battery modules to which high-power and high-capacity lithium secondary batteries are applied. In order to satisfy the output power characteristics of a battery pack required by an ESS and/or an electric vehicle and realize high capacity, the number of lithium secondary batteries included in one battery module may be increased, and the number of battery modules included in one battery pack may be increased.

However, when a fire or explosion occurs in a battery pack including such a large number of lithium secondary batteries, damage is inevitably increased.

A fire occurring in a battery pack starts from an abnormal temperature rise and internal gas generation of a lithium secondary battery in a battery module. When a temperature of a lithium secondary battery abnormally rises and internal gas is generated, and thus internal pressure of the lithium secondary battery increases to a certain level or higher, venting of the lithium secondary battery occurs, and thus, high-temperature gas is ejected to the outside of the lithium secondary battery, and a high-temperature spark containing electrode active material and aluminum particles is ejected.

In order to ensure the safety in use of a battery module and/or a battery pack, venting gas should be able to be rapidly discharged to the outside of the battery module so that internal pressure of the battery module is no longer increased when an event occurs. However, when a high-temperature spark is discharged along with the venting gas to the outside of the battery module, the venting gas, the high-temperature spark, and oxygen may meet to cause a fire.

Accordingly, there is a demand to develop a battery module having a structure capable of, even when thermal runaway occurs due to abnormality such as a short circuit in a battery cell, rapidly discharging venting gas to the outside of the battery module and effectively preventing a high-temperature spark containing electrode active material and aluminum particles from leaking to the outside.

Also, when a structure such as a bus bar frame applied to prevent a short circuit between a plurality of lithium secondary batteries is damaged due to continuous contact with a spark and high-temperature gas, oxygen may be easily introduced from the outside of the battery module into the battery module, and a fire may even spread into the battery module. Also, when the bus bar frame is damaged, electrode leads of adjacent lithium secondary batteries which are kept apart from each other due to the bus bar frame may contact each other, and an event may spread.

Accordingly, there is a demand to develop a battery module having a structure capable of, even when some structures are damaged due to a spark and high-temperature gas, preventing a free inflow of external oxygen and preventing an event from spreading due to a short circuit between adjacent lithium secondary batteries.

<CIT> relates to a spacer and battery pack. The battery pack includes a stacked body obtained by stacking a plurality of unit cells. A pressurizing unit includes an upper plate, a lower plate, and left and right side plates <NUM>. A bus bar unit includes a bus bar holder that integrally holds a plurality of bus bars, wherein the bus bars electrically interconnect vertically adjacent electrode tabs of the unit cells.

<CIT> concerns a battery module, a battery pack including such a battery module, and an automobile including such a battery pack. The battery module includes a battery cell assembly including battery cells, an end plate and side plates. A lead cover includes a bus bar electrically connecting a plurality of electrode leads.

<CIT> concerns a shield, battery unit assembly, battery module and vehicle. A protective plate including a plurality of guide grooves is fixed to the battery module. The guide groove is used to guide the flow direction of the flame ejected from the battery cell.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing a battery module having a structure capable of, when an internal event occurs, rapidly discharging venting gas, effectively preventing a high-temperature spark from leaking to the outside, and after the venting gas is discharged, preventing external air from being introduced into the battery module.

The present disclosure is also directed to providing a battery module having a structure capable of, even when some structures are damaged due to high-temperature gas and sparks, preventing external oxygen from being easily introduced into the battery module and preventing a short circuit between adjacent lithium secondary batteries.

However, the technical purpose to be solved by the present disclosure is not limited to the above, and other objects not mentioned herein will be clearly understood by one of ordinary skill in the art from the following disclosure.

A battery module according to the present invention is defined in claim <NUM> and includes: a cell stack in which a plurality of battery cells are vertically stacked; a module housing including a base plate supporting the cell stack and a pair of side plates covering both side portions of the cell stack; and a bus bar frame assembly covering an opening portion formed on a side of the module housing in a longitudinal direction of the module housing, wherein each of the pair of side plates includes: a plurality of spark delay protrusions protruding from an inner surface of the side plate; and a plurality of spark delay concave portions recessed from the inner surface of the side plate.

Each of the pair of side plates includes a spark direction changing portion formed by bending an end portion of the side plate in a longitudinal direction toward the cell stack.

The opening portion may be formed between a pair of spark direction changing portions respectively provided on the pair of side plates, wherein an electrode lead of the battery cell is exposed to outside of the module housing through the opening portion.

The bus bar frame assembly may include: a bus bar frame covering the opening portion, and including a plurality of frame slits through which an electrode lead of the battery cell passes; and at least one bus bar located on an outer surface of the bus bar frame and coupled to the electrode lead passing through the frame slit.

The battery module may further include a fire-proof sheet assembly located between the bus bar frame assembly and the cell stack and coupled to the bus bar frame assembly.

The fire-proof sheet assembly may include a fire-proof sheet including a plurality of sheet slits through which an electrode lead of the battery cell passes.

The fire-proof sheet assembly may further include a sheet cover including a plurality of cover slits through which the electrode lead of the battery cell passes, and covering the fire-proof sheet.

The fire-proof sheet may be a mica sheet.

The sheet cover may completely cover the fire-proof sheet so that the fire-proof sheet is not exposed to external air.

Each of the plurality of cover slits may have a shape whose width decreases toward the bus bar frame assembly.

Each of the plurality of spark delay protrusions and each of the plurality of spark delay concave portions may extend in a height direction of the side plate, and extend to a length corresponding to the stacked height of the cell stack.

The plurality of spark delay protrusions and the plurality of spark delay concave portions may be alternately formed from a central portion to an end portion of the side plate in a longitudinal direction of the side plate.

A battery pack according to the present invention is defined in claim <NUM> and includes the above battery module.

An energy storage system (ESS) according to the present invention is defined in claim <NUM> and includes the above battery pack.

A vehicle according to the present invention is defined in claim <NUM> and includes the above battery pack.

According to an aspect of the present disclosure, even when some structures are damaged due to a spark and high-temperature gas caused by an event, venting gas may be rapidly discharged, a high-temperature spark may be effectively prevented from leaking to the outside, and after the venting gas is discharged, external air may be prevented from being introduced into a battery module.

According to another aspect of the present disclosure, even when some structures are damaged due to high-temperature gas and sparks, external oxygen may be prevented from being easily introduced into a battery module and a short circuit between adjacent lithium secondary batteries may be prevented.

Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the disclosure.

Referring to <FIG>, a battery module according to an embodiment of the present disclosure includes a cell stack in which a plurality of battery cells <NUM> are stacked in a vertical direction (direction parallel to a Z-axis), a module housing <NUM> in which the cell stack is accommodated, and a bus bar frame assembly <NUM> covering an opening portion formed on a side of the module housing <NUM> in a longitudinal direction (direction parallel to an X-axis) of the module housing <NUM>. The battery module may further include, in addition to the above elements, a fire-proof sheet assembly <NUM> located between the bus bar frame assembly <NUM> and the cell stack and coupled to the bus bar frame assembly <NUM>.

The battery cell <NUM> may be a pouch-type battery cell. In this case, the battery cell <NUM> includes an electrode assembly (not shown), a pouch case <NUM> in which the electrode assembly is accommodated, and a pair of electrode leads <NUM> connected to the electrode assembly and drawn out of the pouch case <NUM>. The pair of electrode leads <NUM> are drawn in opposite directions in a longitudinal direction (direction parallel to the X-axis) of the battery cell <NUM>.

The module housing <NUM> includes a base plate <NUM> supporting the cell stack and a pair of side plates <NUM> covering both side portions of the cell stack. Each of the pair of side plates <NUM> includes a spark direction changing portion 200a formed by bending an end portion of the side plate <NUM> in a longitudinal direction toward the cell stack.

The opening portion formed on a side of the module housing <NUM> in the longitudinal direction of the module housing <NUM> is formed between a pair of spark direction changing portions 200a respectively provided on the pair of side plates <NUM>. The electrode lead <NUM> of the battery cell <NUM> may be exposed to the outside of the module housing <NUM> through the opening portion formed between the pair of spark direction changing portions 200a.

Because the battery module according to an embodiment of the present disclosure includes the spark direction changing portion 200a as described above, a high-temperature spark discharged during venting of the battery cell <NUM> is prevented from being ejected to the outside of the module housing <NUM> in the longitudinal direction of the module housing <NUM>. That is, a high-temperature spark ejected through both side portions of the battery cell <NUM> in a width direction (direction parallel to a Y-axis) of the battery cell <NUM> of the cell stack during venting of the battery cell <NUM> moves toward an end portion and/or the other end portion of the battery module in a longitudinal direction (direction parallel to the X-axis) of the battery module and then switches a moving direction toward the cell stack (see an arrow direction of <FIG>). Accordingly, the spark direction changing portion 200a prevents a spark from being discharged to the outside of the battery module through opening portions on both sides of the module housing <NUM> in the longitudinal direction (direction parallel to the X direction) of the module housing <NUM>.

Referring to <FIG>, the side plate <NUM> of the module housing <NUM> includes a plurality of spark delay protrusions 220a and a plurality of spark delay concave portions 220b, in addition to the spark direction changing portion 200a described above. The spark delay protrusion 220a protrudes from an inner surface of the side plate <NUM>. The spark delay concave portion 220b is recessed from the inner surface of the side plate <NUM>.

The spark delay protrusion 220a and the spark delay concave portion 220b extend in a height direction (direction parallel to the Z-axis) of the side plate <NUM>. The spark delay protrusion 220a and the spark delay concave portion 22b extend to a length corresponding to a stacked height of the cell stack <NUM>.

The spark delay protrusion 220a and the spark delay concave portion 220b may be alternately formed from a central portion to an end portion of the side plate <NUM> in the longitudinal direction (direction parallel to the X-axis) of the side plate <NUM>. Likewise, the spark delay protrusion 220a and the spark delay concave portion 220b may alternately formed from the central portion to the other end portion of the side plate <NUM> in the longitudinal direction (direction parallel to the X-axis) of the side plate <NUM>.

When a spark containing electrode active material and aluminum particles ejected through both side portions of the battery cell <NUM> in the width direction (direction parallel to the Y-axis) of the battery cell <NUM> moves in the longitudinal direction (direction parallel to the X-axis) of the side plate <NUM>, the spark delay protrusion 220a and the spark delay concave portion 220b increase a path and obstruct the spark. Accordingly, the spark delay protrusion 220a and the spark delay concave portion 220b may prevent, along with the spark direction changing portion 200a described above, a spark from leaking to the outside of the battery module through the opening portions on both sides of the module housing <NUM> in the longitudinal direction (direction parallel to the X-axis) of the module housing <NUM>. The battery module according to an embodiment of the present disclosure may include only the spark delay protrusion 220a and the spark delay concave portion 220b, without including the spark direction changing portion 200a.

The module housing <NUM> may further include a fastening frame <NUM> connecting one pair of spark direction changing portions 200a and having an empty central portion. The fastening frame <NUM> is located between the bus bar frame assembly <NUM> and the fire-proof sheet assembly <NUM>. When the fastening frame <NUM> is provided, the bus bar frame assembly <NUM> and the fire-proof sheet assembly <NUM> may be closely attached to the fastening frame <NUM>, and may be fastened to each other through the empty central portion of the fastening frame <NUM>.

Although not shown, the opening portions of the module housing <NUM> of the present disclosure may be formed on both sides of the module housing <NUM> in the longitudinal direction of the module housing <NUM>. In this case, the pair of spark direction changing portions 200a may also be provided on a side and the other side of the module housing <NUM> in the longitudinal direction of the module housing <NUM>.

Referring to <FIG>, the bus bar frame assembly <NUM> includes a bus bar frame <NUM> and at least one bus bar <NUM>. A pair of bus bar frame assemblies <NUM> may be provided, and in this case, the pair of bus bar frame assemblies <NUM> respectively cover the opening portion formed on a side and the opening portion formed on the other side of the module housing <NUM> in the longitudinal direction (direction parallel to the X-axis) of the module housing <NUM>.

The bus bar frame <NUM> covers the opening portion of the module housing <NUM> and includes a plurality of frame slits 310b through which the electrode lead <NUM> of the battery cell <NUM> passes. The bus bar frame <NUM> may further include at least one frame protrusion 310a for coupling with the fire-proof sheet assembly <NUM>.

The bus bar frame <NUM> has a shape corresponding to an end portion and/or the other end portion of the module housing <NUM> in the longitudinal direction of the module housing <NUM> and is closely attached to the module housing <NUM>. When the module housing <NUM> includes the fastening frame <NUM> as described above, the bus bar frame <NUM> is closely attached to the spark direction changing portion 200a and the fastening frame <NUM>.

The bus bar <NUM> is located on an outer surface of the bus bar frame <NUM>, and is coupled to the electrode lead <NUM> passing through the frame slit 310b, to electrically connect the plurality of battery cells <NUM>. The bus bar <NUM> may include a bus bar slit 320b through which the electrode lead <NUM> passes. In this case, the bus bar slit 320b and the frame slit 310b may be formed at positions corresponding to each other.

Referring to <FIG>, the fire-proof sheet assembly <NUM> includes a fire-proof sheet <NUM> and a sheet cover <NUM>. The same number of fire-proof sheet assemblies <NUM> as the bus bar frame assemblies <NUM> may be provided.

The fire-proof sheet <NUM> may be a sheet formed of a mica material capable of withstanding high-temperature venting gas and sparks and even flames. The fire-proof sheet <NUM> includes a plurality of sheet slits 410b through which the electrode lead <NUM> passes.

Even when the bus bar frame <NUM> formed of a resin material is damaged due to high-temperature venting gas and sparks, the fire-proof sheet <NUM> may maintain its structure, and thus, positions of the plurality of electrode leads <NUM> respectively inserted into the plurality of sheet slits 410b may be maintained. Also, the fire-proof sheet <NUM> may allow high-temperature venting gas to be discharged to the outside through a gap between the sheet slit 410b and the electrode lead <NUM>, and may minimize outward ejection of a high-temperature spark containing active material and aluminum particles. Also, even when the bus bar frame <NUM> formed of a resin material is damaged, the fire-proof sheet <NUM> may prevent oxygen from being easily introduced from the outside into the battery module.

Accordingly, the fire-proof sheet <NUM> may minimize the risk of a fire around the bus bar frame <NUM> even when an event occurs in the battery module, and even when a fire occurs around the bus bar frame <NUM>, the fire-proof sheet <NUM> may delay the spread of the fire into the battery module. Also, the fire-proof sheet <NUM> may prevent an event from spreading due to a short circuit between the battery cells <NUM> caused by damage to the bus bar frame <NUM>.

The sheet cover <NUM> completely surrounds the fire-proof sheet <NUM> so that the fire-proof sheet <NUM> is not exposed to the outside. This is because the fire-proof sheet <NUM> formed of a mica material has hygroscopicity, and thus, when the fire-proof sheet <NUM> formed of a mica material is exposed to external air of the sheet cover <NUM>, the fire-proof sheet <NUM> may absorb moisture, thereby degrading insulation performance.

The sheet cover <NUM> may be a resin injection molding product, and in this case, the fire-proof sheet <NUM> may be located in the sheet cover <NUM> through insert injection molding. The sheet cover <NUM> includes a plurality of cover slits 420b through which the electrode lead <NUM> passes. The cover slit 420b has a shape whose width decreases toward the bus bar frame assembly <NUM>.

This is to, when the sheet cover <NUM> formed of a resin injection molding product is melted by high-temperature venting gas and sparks, the cover slit 420b is rapidly closed to block the inflow of air from the outside of the battery module. As such, when the inflow of external air is rapidly blocked, the supply of oxygen into the battery module may be blocked, and thus a fire may be prevented from spreading into the battery module.

The cover slit 420b, the sheet slit 410b, and the frame slit 310b are formed at positions corresponding to one another.

When the bus bar frame <NUM> includes the frame protrusion 310a, the fire-proof sheet <NUM> and the sheet cover <NUM> respectively include at least one sheet hole 410a and cover hole 420a formed to have positions and shapes corresponding to the frame protrusion 310a for fastening to the bus bar frame <NUM>.

Although the fire-proof sheet assembly <NUM> includes both the fire-proof sheet <NUM> and the sheet cover <NUM> surrounding the fire-proof sheet <NUM> in the drawings, the present disclosure is not limited thereto, and the fire-proof sheet assembly <NUM> may include only the fire-proof sheet <NUM> without including the sheet cover <NUM>.

A battery pack according to an embodiment of the present disclosure includes the battery module according to an embodiment of the present disclosure. The battery pack may include a plurality of battery modules. An energy storage system (ESS) according to an embodiment of the present disclosure includes the battery pack according to an embodiment of the present disclosure. A vehicle according to an embodiment of the present disclosure includes the battery pack according to an embodiment of the present disclosure. The vehicle includes an electric vehicle.

Claim 1:
A battery module comprising:
a cell stack in which a plurality of battery cells (<NUM>) are vertically stacked;
a module housing (<NUM>) comprising a base plate (<NUM>) supporting the cell stack and a pair of side plates (<NUM>) covering both side portions of the cell stack; and
a bus bar frame assembly (<NUM>) covering an opening portion formed on a side of the module housing (<NUM>) in a longitudinal direction of the module housing (<NUM>),
characterised in that each of the pair of side plates (<NUM>) comprises:
a plurality of spark delay protrusions (220a) protruding from an inner surface of the side plate (<NUM>); and
a plurality of spark delay concave portions (220b) recessed from the inner surface of the side plate (<NUM>); and
a spark direction changing portion (200a) formed by bending an end portion of the side plate (<NUM>) in a longitudinal direction toward the cell stack.