Battery module having improved cooling structure

A battery module includes a module housing having a lower housing, a pair of side housings, front and rear housings, and an upper housing, for respectively covering a lower portion, both side portions, front and rear portions, and an upper portion of a cell stack. The lower housing includes a base plate configured to cover an entire lower surface of the cell stack and having a hole region forming a channel in at least one side of the base plate along a longitudinal direction; and a plurality of spacers disposed at predetermined intervals along the base plate and configured to support the cell stack apart from a surface of the base plate to form an empty space between the cell stack and the base plate. The hole region communicates with the empty space so that a cooling medium can be supplied to the empty space.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2019/002747 filed Mar. 8, 2019, which claims priority to Korean Patent Application No. 10-2018-0066302 filed on Jun. 8, 2018, the disclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a battery module with an improved cooling structure, and more particularly, to a battery module with an improved cooling efficiency, which uses an insulating oil for cooling and has a cooling structure for allowing the insulating oil to directly contact battery cells.

BACKGROUND ART

Secondary batteries commercially used at present include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, the lithium secondary batteries are highly notable due to substantially no memory effect to ensure free charging and discharging, very low self-discharge rate and high energy density, compared to nickel-based secondary batteries.

The lithium secondary battery mainly uses a lithium-based oxide and a carbonaceous material as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate coated with a positive electrode active material and a negative electrode active material are disposed with a separator being interposed therebetween, and an exterior, namely a battery case, for hermetically accommodating the electrode assembly along with an electrolyte.

Generally, the lithium secondary battery may be classified into a can-type secondary battery in which the electrode assembly is included in a metal can and a pouch-type secondary battery in which the electrode assembly is included in a pouch made of aluminum laminate sheets, depending on the shape of the exterior.

Recently, secondary batteries have been widely used not only in small-sized devices such as portable electronic devices but also in medium-sized or large-sized devices such as vehicles and power storage systems. When used in the medium-sized or large-sized devices, a large number of secondary batteries are electrically connected to increase capacity and power. In particular, pouch-type cells are widely used for the medium-sized or large-sized devices because of they may be easily stacked.

However, the pouch-type cell is generally packaged in the battery case made of a laminate sheet of aluminum and polymer resin, and thus its mechanical stiffness is not large. Thus, when the battery module including a plurality of pouch-type cells is configured, a frame is often used to protect the secondary batteries from external impact, prevent shaking thereof, and facilitate stacking thereof.

The frame may be called by different names, such as a cartridge. In many cases, the frame has a rectangular shape having an empty center portion, and at this time, four sides of the frame surround the outer circumference of the pouch-type cell. In addition, a plurality of frames are stacked to configure the battery module, and the pouch-type cells may be placed in the empty space inside the frame when the frames are stacked.

Meanwhile, referring toFIG.1, a conventional battery module structure is shown. If a plurality of pouch-type cells1are stacked by using a plurality of frames2, in the conventional battery module structure, plate-shaped cooling fins3are applied on the outer surfaces of each of the pair of pouch-type cells1, thereby increasing the cooling efficiency.

The secondary battery may be used in high temperature environments such as summer, and the secondary battery may also generate heat from itself. At such time, if a plurality of secondary batteries are stacked on each other, the temperature of the secondary batteries may become higher. If the temperature is higher than a proper temperature, the performance of the secondary batteries may deteriorate, and in severe cases, explosion or ignition may occur. Thus, when the battery module is configured, the cooling fins3are applied to contact the surface of the pouch-type cell1, and the cooling fins3are brought into contact with a cooling plate4located therebelow to prevent the overall temperature of the battery module from rising. This configuration is used frequently.

However, if the cooling fin3usually made of a metal material is interposed between the pouch-type cells1facing each other to configure the battery module, the contact heat resistance is inevitably very large due to the difference in material between the cooling fin3and the surface of the pouch-type cell1. Also, only with the cooling method that depends on the conductivity of the metal, sufficient cooling is achieved in a situation where a large amount of heat is generated.

Thus, there is an urgent need to develop a battery module structure using a cooling method capable of reducing contact thermal resistance and allowing heat to be emitted more efficiently, compared to a simple thermal conduction method.

DISCLOSURE

Technical Problem

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, which adopts a cooling structure capable of allowing direct contact between a cooling medium and battery cells so that the battery module may be efficiently cooled even when the amount of heat increases by applying a battery module with a high capacity and/or a high output.

However, the technical problem to be solved by the present disclosure is not limited to the above, and other objects not mentioned herein will be understood from the following description by those skilled in the art.

Technical Solution

In one aspect of the present disclosure, there is provided a battery module, comprising: a cell stack formed by stacking a plurality of battery cells; and a module housing configured to accommodate the cell stack and having a lower housing, a pair of side housings, a pair of front and rear housings and an upper housing for respectively covering a lower portion, both side portions, front and rear portions and an upper portion of the cell stack, wherein the lower housing includes: a base plate having a hole region forming a channel in at least one side thereof along a longitudinal direction and configured to cover an entire lower surface of the cell stack; and a plurality of spacers disposed in the base plate at predetermined intervals and configured to support the cell stack to be spaced apart from a surface of the base plate so that an empty space is formed between the cell stack and the base plate, wherein the hole region communicates with the empty space so that a cooling medium is supplied to the empty space.

The plurality of spacers may include a first spacer and a second spacer respectively provided at one side and the other side of the base plate in the longitudinal direction, and the first spacer and the second spacer may be formed to extend along a width direction of the base plate so that both ends thereof are in contact with both sides of the base plate.

The plurality of spacers may further include at least one third spacer spaced apart from the first spacer and the second spacer and provided between the first spacer and the second spacer.

The at least one side of the base plate may be defined as a first side and a second side, which correspond to both sides of the base plate opposite to each other, and the hole region may include a first region formed in the first side to communicate from an outside of the base plate to a first empty space positioned between the first spacer and the third spacer; a second region formed in the second side to communicate from the first empty space to a second empty space positioned between the third spacer and the second spacer; and a third region formed in the first side to communicate from the second empty space to the outside of the base plate.

The third spacer may have a third spacer channel formed therethrough so that the cooling medium passes through the third spacer.

The first spacer and the second spacer may respectively have a first spacer channel and a second spacer channel formed therethrough, and the battery module may further comprise a first cooling pipe configured to connect the hole region and the first spacer channel; and a second cooling pipe configured to connect the hole region and the second spacer channel.

The at least one side of the base plate may be defined as a first side and a second side, which correspond to both sides of the base plate opposite to each other, and the first and second sides may be formed higher than other portions of the base plate and further have a coupling groove provided to engage with a coupling protrusion formed at a lower end of the side housing to protrude downward.

The first and second sides may further have a leakage prevention protrusion protruding to extend toward the cell stack and come into contact with an outermost cell of the cell stack.

An adhesive may be interposed between the cell stack and the spacer so that the cooling medium is not leaked between the cell stack and the spacer.

The battery module may further comprise a supply tube and a discharge tube respectively connected to one side and the other side of the hole region of the base plate so that the cooling medium flows into or out of the empty space.

In another aspect of the present disclosure, there is also provided a battery pack, which is implemented by connecting a plurality of battery modules described above.

In another aspect of the present disclosure, there is also provided a vehicle, comprising the battery pack.

Advantageous Effects

According to an embodiment of the present disclosure, since a battery module with a cooling structure capable of direct contact between a cooling medium and battery cells is provided, the battery module may be efficiently cooled even when the amount of heat increases by applying a battery module with a high capacity and/or a high output, thereby improving the performance of the battery module. Moreover, it is possible to prevent safety accidents such as ignition and explosion of the battery cells due to the temperature rise.

BEST MODE

First, components of a battery module according to an embodiment of the present disclosure will be described briefly with reference toFIGS.2and3.

FIG.2is a perspective view showing an appearance of a battery module according to an embodiment of the present disclosure, andFIG.3is an exploded perspective view showing the battery module according to an embodiment of the present disclosure.

Referring toFIGS.2and3, a battery module10according to an embodiment of the present disclosure includes a cell stack100and a module housing20for accommodating the cell stack100. Also, the module housing20includes a lower housing200, a pair of side housings300, a pair of front and rear housings400, and an upper housing500.

The cell stack100is prepared by stacking a plurality of battery cells110. The battery cell110used herein is not particularly limited as long as it is a secondary battery capable of charging and discharging. For example, the battery cell110may be a pouch-type battery cell110.

Each of the battery cells110may have a pair of electrode leads111extending to one side and the other side. The electrode leads111include a positive electrode lead and a negative electrode lead. As explained later, the stacked battery cells110may be firmly fixed and sealed by an adhesive or the like so that a cooling medium such as an insulating oil, which is in contact with a lower portion of the cell stack100, is not able to penetrate through the space between the battery cells110of the cell stack100.

In addition, the electrode leads111may be arranged or connected such that the battery cells110of the cell stack100are connected in series, in parallel, or both in series and in parallel.

The lower housing200includes a base plate210configured to cover an entire lower surface of the cell stack100and has a hole region213that forms a channel as a hollow structure in at least one side along the longitudinal direction, and a plurality of spacers220for forming an empty space S1, S2between the cell stack100and the base plate210by supporting the cell stack100to be spaced apart from the surface of the base plate210.

Here, the empty space S1, S2means a sealed space surrounded by the cell stack100, the spacer220and the base plate210. The empty space S1, S2communicates with the hole region213so that a cooling medium is supplied into the empty space.

The cooling medium may be supplied into and out of the battery module10by connecting a supply tube230and a discharge tube240to an inlet and an outlet of the hole region213, respectively. For example, as shown inFIG.4, the supply tube230may be connected to the inlet of the hole region213of the base plate210from the front of the battery module10, and the discharge tube240may be connected to the outlet of the hole region213from the rear of the battery module10. The flow of the cooling medium inside the battery module10will be explained later in detail.

The pair of side housings300respectively cover both sides of the cell stack100and face wide surfaces of the battery cells110disposed on outermost sides among the battery cells110of the cell stack100. The pair of side housings300may press the cell stack100at both sides thereof to prevent a gap from being created between the battery cells110of the cell stack100.

The pair of front and rear housings400may include a bus bar frame410, an insulation cover420, and front and rear covers430, respectively.

The bus bar frame410is coupled to the cell stack100from the front or rear portion of the cell stack100. The electrode leads111are inserted into the bus bar frame410to facilitate the work of bending the electrode lead111for electrical connection between the battery cells110. That is, the electrode leads111are inserted through insert slits formed in the bus bar frame410and then bent so that the adjacent electrode leads111are coupled to each other by welding or the like.

The insulation cover420is a component provided to prevent the electrode leads111, which are coupled to each other by being inserted into the bus bar frame410and bent but should not be in contact with each other, from contacting each other. The insulation cover420is coupled onto the bus bar frame410to prevent a short caused by an external factor.

The front and rear covers430are components coupled onto the insulation cover420and serve to protect internal components such as the cell stack100, the bus bar frame410, and the insulation cover420.

The upper housing500may include a sensor assembly510disposed at an upper portion of the cell stack100and electrically connected to the electrode leads111inserted and bent through the bus bar frame410, and a top plate520coupled to an upper portion of the sensor assembly510to form an outermost layer of the upper housing500.

Subsequently, referring toFIGS.4to11along withFIGS.2and3, the cooling structure of the battery module10according to an embodiment of the present disclosure will be described in more detail.

Hereinafter, portions of the base plate210corresponding to both sides opposite to each other along the longitudinal direction as shown inFIGS.4and5will be defined as a first side211and a second side212.

The first side211and the second side212may be formed higher than other portions (plate surfaces) of the base plate210. The lower surface of the cell stack100is supported by the spacers220between the first side211and the second side212so as to be spaced apart from the surface of the base plate210, and both sides of the cell stack100are supported by the side housings300.

Referring toFIGS.6and7, the side housing300according to this embodiment has a coupling protrusion310formed at a lower end thereof to protrude downward. In addition, the first side211and the second side212of the base plate210respectively have a coupling groove G provided to engage with the coupling protrusion310. The coupling protrusion310is inserted and fixed in the coupling groove G so that the side housing300may be fixed to the first side211and the second side212of the base plate210. Here, unlike this embodiment, the coupling protrusion310may be provided to the first and second sides212, and the coupling groove G may be provided to the side housing300, so that the coupling protrusion310and the coupling groove G are fixed.

The first and second sides211,212, for example, may serve as fences for holding the cooling medium in the empty space S1, S2, and may further include a leakage prevention protrusion P at a place in contact with the cell stack100. As shown inFIG.7, the leakage prevention protrusion P may be provided to extend horizontally toward the cell stack100so as to come into contact with an outermost cell of the cell stack100. The leakage prevention protrusion P may prevent a gap from being formed between the base plate210and the cell stack100, and thus resulting in the leakage of the cooling medium. Preferably, an adhesive may be further interposed along the leakage prevention protrusion P.

Also, the spacers220may be fabricated to correspond to the shape of the lower surface of the cell stack100. Considering that the lower surface of the cell stack100including the pouch-type battery cells110does not have a flat lower surface due to the nature of the pouch-type battery cells110, the upper surface of the unit spacers220may be formed to conform to the shape of the lower surface of the cell stack100to eliminate the gap between the unit spacers220and the lower surface of the cell stack100.

In addition, an adhesive is interposed between the cell stack100and the spacer220so that the cooling medium such as an insulating oil is not leaked between the cell stack100and the spacer220. The adhesive not only couples and fixes the cell stack100and the spacer220to each other but also functions as a gasket.

Meanwhile, the spacer220may be formed with a plurality of unit spacers220spaced apart from each other. For example, as shown inFIG.5, the spacer220may include a first spacer221provided at one end of the base plate210in a longitudinal direction, a second spacer222provided at the other end of the base plate210in the longitudinal direction, and a third spacer223spaced apart from the first spacer221and the second spacer222and provided between the first spacer221and the second spacer222.

However, even though three unit spacers220are depicted in the figures, the number of unit spacers is not limited thereto, and two or more units may be provided. That is, the third spacer223may be omitted, and one or more unit spacers220such as the third spacer223spaced apart from each other may be provided between the first spacer221and the second spacer222. However, hereinafter, for convenience of explanation, it will be described that three unit spacers220are provided.

The unit spacers220extend along the width direction of the base plate210, and both ends of the unit spacers220are disposed in contact with both sides of the base plate210, namely in contact with the first side211and the second side212. The cell stack100is placed on the unit spacers220so that its lower surface is not in contact with the surface of the base plate210. Accordingly, a predetermined empty space S1, S2is formed between the cell stack100and the base plate210.

Referring toFIGS.4to11, it may be found that the upper and lower sides of the empty space S1, S2are blocked by the cell stack100and the base plate210, the front and rear sides of the empty space S1, S2are blocked by the first spacer221and the second spacer222, and the left and right sides of the empty space S1, S2are blocked by the first side211and the second side212, respectively. In addition, the empty space S1, S2may be partitioned by the third spacer223into a first empty space S1and a second empty space S2. The third spacer223is a component for providing a stable supporting force to the cell stack100and may be added or omitted according to the size of the battery cell110.

The first side211and/or the second side212of the base plate210are utilized as a cooling medium moving path for supplying the cooling medium to the empty space S1, S2. As described above, the first side211and the second side212respectively have a channel formed therein along the longitudinal direction of the base plate210and have the hole regions213communicating with the empty space S1, S2. In addition, the hole region213has an opening O at every predefined location that communicates with the empty space S1, S2so that the cooling medium may penetrate into the empty space S1, S2through the opening O.

As shown inFIG.5, the hole region213according to this embodiment includes a first region213aand a third region213cformed in the first side211and a second region213bformed in the second side212.

The first region213ais a channel region extending from the inlet of the hole region213to the first empty space S1positioned between the first spacer221and the third spacer223. The cooling medium flowing from the outside through the supply tube230moves along the first region213aand permeates into the first empty space S1through the opening of the first region213a.

The second region213bis a channel region extending from the first empty space S1to the second empty space S2positioned between the third spacer223and the second spacer222. Two openings O are formed in the second region to face the first empty space S1and the second empty space S2, respectively. The second region213bmay be a channel region for moving the cooling medium of the first empty space S1to the second empty space S2by bypassing the third spacer223.

The third region213cis a channel region extending from the second empty space S2to the outlet of the hole region213. The cooling medium of the second empty space S2moves along the third region213cand is discharged to the outside through the discharge tube240.

That is, if the flow of the cooling medium is summarized, the cooling medium moves in the order of the supply tube230, the first region213a, the first empty space S1, the second region213b, the second empty space S2, the third region213c, and the discharge tube240. The battery module10according to an embodiment of the present disclosure having the cooling medium flow described above may have higher cooling performance compared to existing techniques since the cooling medium directly contacts the battery cells110.

Meanwhile, in this embodiment, three hole regions213are provided, depending on the number of the unit spacers220and the empty spaces S1, S2. However, the number of hole regions213may be changed as desired depending on the number of unit spacers220and empty spaces S1, S2. In addition, the inlet or the outlet of the hole region213may be connected to a connection tube (not shown) for connecting two battery modules10instead of the supply tube230or the discharge tube240. For example, if a plurality of battery modules10are connected to form a battery pack (not shown), the outlet of the hole region213of any one battery module10may be connected to the inlet of the hole region213of another battery module10by means of the connection tube.

Subsequently, referring toFIGS.12to14, the cooling channel of the battery module10according to another embodiment of the present disclosure will be described.

The battery module10according to another embodiment of the present disclosure will be described mainly based on features different from the former embodiment, and features similar or identical to the former embodiment will not be described in detail again.

The first spacer221, the second spacer222and the third spacer223according to another embodiment of the present disclosure respectively have channels formed therethrough so that the cooling medium passes through the channels. The channels corresponding to the first to third spacers221to222will be called a first spacer channel221a, a second spacer channel222aand a third spacer channel223a, respectively. A plurality of the first spacer channels221a, the second spacer channels222aand the third spacer channels223amay be provided.

In addition, the battery module10according to another embodiment of the present disclosure may further include a first cooling pipe250installed at the front of the first spacer221and a second cooling pipe260installed at the rear of the second spacer222.

The first cooling pipe250is provided to individually connect the hole region213formed at one end of the first side211to the plurality of first spacer channels221aexposed at the front side of the first spacer221. In this case, the cooling medium may flow into the first empty space S1through the first spacer channels221avia the supply tube230, the hole region213and the first cooling pipe250.

The second cooling pipe260is provided to individually connect the hole region213formed at the other end of the first side211to the plurality of second spacer channels222aexposed at the rear of the second spacer222. In this case, the cooling medium may pass through the second spacer channel222ain the second empty space S2and be discharged to the outside through the discharge tube240via the second cooling pipe260and the hole region213.

The third spacer223may be provided to have third spacer channels223aformed through the inside of the third spacer223so that the cooling medium flowing into the first empty space S1through the first spacer channel221ais sent toward the second spacer222.

Thus, if the flow of the cooling medium of the battery module10according to this embodiment is summarized, the cooling medium may be discharged out of the battery module10by moving in the order of the supply tube230, the front side of the hole region213, the first cooling pipe250, the first spacer channels221a, the first empty space S1, the third spacer channels223a, the second empty space S2, the second spacer channels222a, the second cooling pipe260, the rear side of the rear hole region213, and the discharge tube240.

In this embodiment, since the cooling medium may pass without bypassing the third spacer223, the hole region213may not be provided in the second side212of the base plate210, unlike the former embodiment. Also, the hole region213may be formed relatively short as a connection path of the supply tube230and the first cooling pipe250or of the second cooling pipe260and the discharge tube240.

As described above, in the battery module10according to the present disclosure, the spacer220is partially applied between the cell stack100and the base plate210, and the cooling medium is supplied into the empty spaces S1, S2formed between the cell stack100and the base plate210so that the cell stack100may be brought into direct contact with the cooling medium, thereby maximizing the cooling efficiency.

Also, the battery module10according to the present disclosure has a function with an improved sealing property to solve the leakage of the cooling medium, which may occur when a liquid cooling medium such as a cooling water and an insulating oil is in direct contact with the battery cell110, thereby enhancing the reliability of the product.

In addition, a battery pack according to an embodiment of the present disclosure, which is implemented by electrically connecting plurality of the battery modules10described above, and a vehicle having the battery pack may also exhibit excellent performance since they have the above advantages of the battery module10.

Meanwhile, when the terms indicating up, down, left and right directions are used in the specification, it is obvious to those skilled in the art that these merely represent relative locations for convenience in explanation and may vary based on a location of an observer or an object to be observed.