Battery module, battery pack including same, and method for manufacturing battery module

Abstract

The present invention includes a battery module and a battery pack including the same. A battery module according to one embodiment of the present invention includes a battery cell stack in which a plurality of battery cells are stacked, a module frame that houses the battery cell stack, and a thermally conductive resin layer located between a lower surface of the module frame and a first end of the battery cell stack, and the first end of the battery cell stack has a double-fold sealing portion.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0007655 dated January 19, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a battery module, a battery pack including the same, and a method for manufacturing the battery module, and more particularly to a battery module with improved safety, and a battery pack including the same, and a method for manufacturing the battery module. [Background technology]

[0003] With technological development and increasing demand for mobile devices, the demand for secondary batteries as an energy source is growing rapidly. As a result, much research is being conducted on secondary batteries that can meet various demands.

[0004] Secondary batteries have attracted much attention not only for use in mobile devices such as mobile phones, digital cameras, and notebook computers, but also as energy sources for power plants such as electric bicycles, electric cars, and hybrid electric cars.

[0005] Recently, as the need for large-capacity secondary battery structures has increased, including the use of secondary batteries as energy storage sources, the demand for medium- to large-sized modular battery packs that assemble battery modules in which a number of secondary batteries are connected in series / parallel has been increasing.

[0006] Meanwhile, when a battery pack is constructed by connecting a plurality of battery cells in series / parallel, a battery module consisting of at least one battery cell is generally constructed, and other components are added to the at least one battery module to construct a battery pack. The battery cells constituting such a medium- to large-sized battery module are composed of rechargeable secondary batteries, and such high-output, large-capacity secondary batteries generate a large amount of heat during the charging and discharging process.

[0007] The battery module includes a battery cell stack in which a plurality of battery cells are stacked, a frame that houses the battery cell stack, and end plates that cover the front and rear surfaces of the battery cell stack.

[0008] Fig. 1 is a diagram showing a state where a battery module installed in a conventional battery pack ignites. Fig. 2 is a diagram showing a portion AA in Fig. 1, showing a state of flames affecting adjacent battery modules when a battery module installed in a conventional battery pack ignites.

[0009] 1 and 2, a conventional battery module includes a battery cell stack in which a number of battery cells 10 are stacked, a frame 20 that houses the battery cell stack, end plates 30 formed on front and rear surfaces of the battery cell stack, and terminal bus bars 40 formed to protrude from the end plates.

[0010] The frame 20 and the end plates 30 may be joined to be hermetically sealed by welding. When the frame 20 housing the battery cell stack and the end plates 30 are joined in this manner, if the internal pressure of the battery cells 10 increases during overcharging of the battery module and exceeds the limit of the fusion strength of the battery cells 10, high temperature heat, gas, and flames generated in the battery cells 10 are discharged to the outside of the battery cells 10.

[0011] At this time, the high temperature heat, gas and flames are exhausted through the openings formed in the end plates 30, but in a battery pack structure in which a plurality of battery modules are arranged so that the end plates 30 face each other, the battery module emitting the high temperature heat, gas and flames may affect the adjacent battery modules. This may damage the terminal bus bars 40 formed on the end plates 30 of the adjacent battery modules, and the high temperature heat, gas and flames may enter the interior of the battery modules through the openings formed in the end plates 30 of the adjacent battery modules, causing damage to the multiple battery cells 10.

[0012] In order to reduce the occurrence of the above problems, there have been attempts to form separate holes through which flames can escape. However, in order to increase the safety of the battery module by forming such vent holes, it is necessary to adjust the intensity of the flame escape. Summary of the Invention [Problem to be solved by the invention]

[0013] An object of the present invention is to provide a battery module with improved safety, a battery pack including the same, and a method for manufacturing the battery module.

[0014] However, the problems to be solved by the embodiments of the present invention are not limited to the above problems, and can be variously expanded within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0015] A battery module according to one embodiment of the present invention includes a battery cell stack in which a plurality of battery cells are stacked, a module frame that houses the battery cell stack, and a thermally conductive resin layer located between a lower surface of the module frame and a first end of the battery cell stack, and the first end of the battery cell stack has a double fold sealing portion.

[0016] An injection hole for injecting a thermally conductive resin is formed in the lower surface of the module frame.

[0017] The liquid injection holes are formed in a plurality of holes at a central portion of a lower surface of the module frame and at both ends along a longitudinal direction.

[0018] The battery module may further include a vent hole formed in an upper surface of the module frame adjacent to a second end located opposite to the first end of the battery cell stack.

[0019] The battery module may further include a flame retardant mesh covering the vent hole.

[0020] A method for manufacturing a battery module according to another embodiment of the present invention includes stacking a plurality of battery cells to form a battery cell stack, accommodating the battery cell stack in a module frame, inverting the module frame upside down so that a lower surface of the module frame faces upward, and injecting a thermally conductive resin through an injection hole formed in the lower surface of the module frame, wherein the thermally conductive resin covers a first end of the battery cell stack having a double folded sealing portion.

[0021] The method for manufacturing the battery module may further include, after the step of injecting the thermally conductive resin, turning the module frame upside down so that a lower surface of the module frame faces downward.

[0022] The method for manufacturing a battery module may further include, before the step of accommodating the battery cell stack in a module frame, turning the battery cell stack upside down so that a first end of the battery cell stack is disposed on a lower surface of the module frame.

[0023] The method of manufacturing the battery module may further include forming a vent hole on an upper surface of the module frame, and forming a flame retardant mesh covering the vent hole.

[0024] A battery pack according to yet another embodiment of the present invention includes the battery module described above and a cooling plate located under a lower surface of the module frame. Effect of the Invention

[0025] According to the embodiment, by applying a thermally conductive resin to the joints of the battery cells, the strength of the battery module can be improved.

[0026] Furthermore, by providing a fire-retardant net at the upper end of the module frame located on the opposite side to the joints of the battery cells, the fire-retardant net can reduce the intensity of flame emission, improving safety.

[0027] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. [Brief description of the drawings]

[0028] [Figure 1] FIG. 13 is a diagram showing a state in which a battery module mounted in a conventional battery pack ignites. [Diagram 2] 2 is a cross-sectional view taken along the line AA in FIG. 1, showing a state of flames affecting adjacent battery modules when a battery module mounted in a conventional battery pack catches fire. [Diagram 3] 1 is an exploded perspective view showing a battery module according to an embodiment of the present invention; [Figure 4] FIG. 4 is a diagram showing a state in which the battery module components of FIG. 3 are combined. [Diagram 5] 4 is a perspective view showing one battery cell included in the battery cell stack of FIG. 3. FIG. [Figure 6] 5 is a perspective view showing the battery module of FIG. 4 turned upside down. FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line BB in FIG. 6. [Figure 8] FIG. 8 is an enlarged perspective view of part A in FIG. 7. [Figure 9] FIG. 2 is a diagram showing a thermally conductive resin layer structure according to the present embodiment. [Figure 10] 10 is a diagram showing a battery module on which the thermally conductive resin layer of FIG. 9 is formed. FIG. [Figure 11] 5A to 5C are diagrams illustrating a method for manufacturing a battery module according to another embodiment of the present invention. [Figure 12] 11A and 11B are diagrams showing how gas and flames are ejected when a flame occurs in a battery module according to a comparative example. [Figure 13]13 is a cross-sectional view taken along a cutting plane CC in the yz plane of FIG. 12. [Figure 14] 1 is a diagram showing how gas and flames are ejected when a flame occurs in a battery module according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: FIG. 1 is a block diagram of a semiconductor device according to an embodiment of the present invention;

[0030] In order to clearly explain the present invention, parts that are not necessary for the explanation will be omitted, and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0031] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings. In the drawings, thicknesses are enlarged to clearly express various layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0032] In addition, when a part such as a layer, film, region, or plate is said to be "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part in between. Conversely, when a part is said to be "directly on" another part, it means that there is no other part in between. Furthermore, being "on" a reference part means being located above or below the reference part, and does not necessarily mean being located "on" in the opposite direction of gravity.

[0033] In addition, throughout the specification, when a part "comprises" a certain element, this means that it can further include other elements, not excluding other elements, unless specifically stated to the contrary.

[0034] In addition, throughout the specification, when we refer to "on a plane," this means when the subject part is viewed from above, and when we refer to "on a cross section," this means when the subject part is cut vertically and viewed from the side.

[0035] Fig. 3 is an exploded perspective view of a battery module according to an embodiment of the present invention. Fig. 4 is a view showing a state where components of the battery module of Fig. 3 are combined. Fig. 5 is a perspective view showing one battery cell included in the battery cell stack of Fig. 3. Fig. 6 is a perspective view showing the battery module of Fig. 4 turned upside down. Fig. 7 is a cross-sectional view taken along the line BB of Fig. 6. Fig. 8 is an enlarged perspective view of part A of Fig. 7.

[0036] 3 and 4, the battery module according to this embodiment includes a battery cell stack 120 in which a plurality of battery cells 110 are stacked, and a module frame 100 that houses the battery cell stack 120 and has a lower surface 101 and an upper surface 102 that correspond to each other, and the lower surface 101 of the module frame 100 is formed with an injection hole 135 and / or a check hole 130 for injecting a thermally conductive resin. A plurality of injection holes 135 are formed in the middle portion of the lower surface 101 of the module frame 100 and at both ends along the longitudinal direction. Here, the longitudinal direction may be the same direction as the direction in which the battery cell stack 120 is inserted into the module frame 100.

[0037] The module frame 100 according to this embodiment surrounds the remaining outer surfaces of the battery cell stack 120 except for the front and rear surfaces, and end plates 150 are located on the front and rear surfaces of the battery cell stack 120, respectively, and a bus bar frame 145 is located between the battery cell stack 120 and the end plates 150. The remaining outer surfaces of the battery cell stack 120 except for the front and rear surfaces may be the top, bottom, left and right surfaces of the battery cell stack. The upper surface 102 and the lower surface 101 of the module frame 100 may face each other along a direction perpendicular to the stacking direction of the battery cell stack 120. The stacking direction of the battery cell stack 120 is the y-axis direction in FIG. 3, and the direction perpendicular thereto may be the z-axis direction.

[0038] 3 and 6, according to this embodiment, a thermally conductive resin layer 400 is positioned between a lower surface 101 of a module frame 100 and a battery cell stack 120. The thermally conductive resin layer 400 is formed by curing a thermally conductive resin injected through an injection hole 135, and serves to transfer heat generated in the battery cell stack 120 to the outside of the battery module and to fix the battery cell stack 120 within the battery module.

[0039] 7, the battery module according to this embodiment may further include a compression pad 116 located between the battery cell 110 located at the outermost corner and a side portion of the module frame 100. The compression pad 116 may be formed using a polyurethane-based material. The compression pad 116 may absorb thickness deformation due to swelling of the battery cell 110 and changes in the battery cell 110 due to external impact. At least one compression pad 116 is formed not only between the outermost battery cell 110 and the side portion of the module frame 100, but also between adjacent battery cells 110.

[0040] The battery cell stack 120 includes a plurality of battery cells 110 stacked in one direction, and the plurality of battery cells 110 are stacked in the y-axis direction as shown in FIG. 3. The battery cells 110 are preferably pouch-type battery cells. For example, referring to FIG. 5, the battery cell 110 according to this embodiment may have a structure in which two electrode leads 111 and 112 protrude from one end 114a and the other end 114b of a battery body 113 in opposite directions. The battery cell 110 is manufactured by bonding both ends 114a and 114b of the cell case 114 to both side surfaces 114c connecting them with each other in a state in which an electrode assembly (not shown) is housed in the cell case 114. In other words, the battery cell 110 according to this embodiment has a total of three sealing portions 114sa, 114sb, and 114sc, and the sealing portions 114sa, 114sb, and 114sc are structured to be sealed by a method such as heat fusion, and the remaining other side portion comprises the connecting portion 115. The distance between both ends 114a, 114b of the cell case 114 can be defined as the longitudinal direction of the battery cell 110, and the distance between one side 114c connecting both ends 114a, 114b of the cell case 114 and the connecting portion 115 can be defined as the width direction of the battery cell 110.

[0041] The connecting portion 115 is a region extending long along one edge of the battery cell 110, and a protrusion 110p of the battery cell 110 is formed at an end of the connecting portion 115. The protrusion 110p may be formed on at least one of both ends of the connecting portion 115 and protrude in a direction perpendicular to the extension direction of the connecting portion 115. The protrusion 110p may be located between the connecting portion 115 and one of the sealing portions 114sa, 114sb of both ends 114a, 114b of the cell casing 114.

[0042] The cell case 114 generally has a laminate structure of a resin layer / metal thin film layer / resin layer. For example, when the surface of the cell case is made of an O(oriented)-nylon layer, it tends to slip due to external impact when a number of battery cells are stacked to form a medium- to large-sized battery module. Therefore, in order to prevent this and maintain a stable stacked structure of the battery cells, the battery cell stack 120 can be formed by attaching an adhesive such as a double-sided tape or a chemical adhesive that bonds by a chemical reaction when bonding to the surface of the cell case. In this embodiment, the battery cell stack 120 is stacked in the y-axis direction and housed inside the module frame 100 in the z-axis direction, and is cooled by a thermally conductive resin layer to be described later. As a comparative example, the battery cells may be formed of cartridge-shaped parts, and the battery cells may be fixed to each other by assembly using a battery module frame. In such a comparative example, the cooling effect is almost nonexistent or occurs in the surface direction of the battery cells due to the presence of the cartridge-shaped parts, and cooling is not performed well in the height direction of the battery module.

[0043] 3, the battery module according to this embodiment may further include a vent hole 105 formed in an upper surface 102 of the module frame adjacent to a second end located opposite to the first end of the battery cell stack 120. A fire-extinguishing mesh 107 is formed to cover the vent hole 105, thereby reducing the intensity of a flame generated inside the battery module being discharged to the outside.

[0044] 8, an air gap may exist between the lower surface 101 of the module frame and the battery cell stack 120. The air gap may reduce thermal conductivity, and the cooling efficiency may decrease due to heat at the upper end of the battery cell 110, particularly the portion of the battery cell 110 adjacent to the double folded sealing part DSF. According to this embodiment, a thermally conductive resin layer 400 formed by injecting a thermally conductive resin through the injection hole 135 of FIG. 7 may cover a first end of the battery cell stack 120 having the double folded sealing part DSF.

[0045] Fig. 9 is a diagram showing a thermally conductive resin layer structure according to this embodiment, and Fig. 10 is a diagram showing a battery module in which the thermally conductive resin layer of Fig. 9 is formed.

[0046] 9 and 10, the thermally conductive resin layer 400 according to the present embodiment is located between the lower surface 101 of the module frame and the battery cell stack 120. The thermally conductive resin layer 400 has a recessed pattern 400DP formed on a surface facing the battery cell stack 120. The recessed pattern 400DP may have a sawtooth shape. The recessed pattern 400DP is a structure corresponding to a first end of the battery cell 110, and the first end of the battery cell 110 may have a double side folded shape. Such a double side folded shape is a shape of a double folded sealing part DSF formed by folding the sealing part of the cell case at least twice. Specifically, the first end of the battery cell 110 may be a part 114sc where both side surfaces 114c of the cell case 114 that connect both ends 114a and 114b of the cell case 114 are bonded, as described in FIG. 5. In FIG. 5, the electrode leads 111, 112 may be located at both ends of the battery cell 110 located along a direction perpendicular to the first end of the battery cell 110, and the battery cell 110 may have a rectangular structure formed long in the direction in which the electrode leads 111, 112 protrude.

[0047] 9 and 10, the recessed pattern 400DP of the thermally conductive resin layer 400 according to this embodiment includes a plurality of recesses 401DP corresponding to the double-folded sealing portions DSF of each of the plurality of battery cells 110. As shown in FIG.

[0048] The first end of the battery cell 110 has two different inclined surfaces, and the thermally conductive resin layer 400 also has a first inclined surface SP1 and a second inclined surface SP2 corresponding to the first end of the battery cell 110. The first inclined surface SP1 of the thermally conductive resin layer 400 may abut against the first end of the battery cell 110, and the second inclined surface SP2 of the thermally conductive resin layer 400 may abut against the inclined surface of the double folded sealing part DSF. To form such a structure, the double folded sealing part DSF may be in close contact with the recessed part 401DP of the thermally conductive resin layer 400. By realizing such a structure, the contact area between the battery cell stack 120 and the thermally conductive resin layer 400 may be maximized, thereby improving the cooling performance.

[0049] Due to the double folded sealing part DSF structure, an air gap may be formed between the battery cell 110 and the double folded sealing part DSF. As a result, the adhesive strength is weaker at a portion where the second inclined surface SP2 of the thermally conductive resin layer 400 and the inclined surface of the double folded sealing part DSF contact each other than a portion where the first inclined surface SP1 of the thermally conductive resin layer 400 contacts the first end of the battery cell 110. Therefore, as shown in FIG. 9, the amount of heat moving in the direction of the arrow passing through the second inclined surface SP2 is relatively small compared to the amount of heat moving in the direction of the arrow passing through the first inclined surface SP1. Specifically, since the double folded sealing part DSF is folded twice to complete the sealing part, the thermal efficiency of the die sealing gap existing therebetween can be supplemented through the thermally conductive resin layer 400.

[0050] Hereinafter, with reference to FIG. 11, a method for manufacturing a battery module according to another embodiment of the present invention will be described.

[0051] Referring to FIG. 11, a method for manufacturing a battery module according to this embodiment may include the steps of: (a) stacking a plurality of battery cells to form a battery cell stack; (b) inverting the battery cell stack upside down so that a first end of the battery cell stack is disposed on a lower surface of a module frame; (c) coupling bus bar frames to front and rear surfaces of the battery cell stack; (d) accommodating the battery cell stack within a module frame and coupling end plates to the open front and rear ends of the module frame; (e) inverting the module frame upside down so that the lower surface of the module frame faces upward; and (e) injecting thermally conductive resin through an injection hole formed on the lower surface of the module frame.

[0052] In the step (a) of stacking the plurality of battery cells to form a battery cell stack, the battery cells 110 may be stacked in sequence along the y-axis direction as shown in FIG.

[0053] Step (b) of inverting the battery cell stack upside down so that a first end of the battery cell stack is disposed on a lower surface of the module frame may be such that the first end having a double-folded sealing portion faces downward.

[0054] Step (e) of inverting the module frame upside down so that the lower surface of the module frame faces upward can be performed so that the lower surface 101 of the module frame, in which the injection hole 135 is formed, faces upward to inject the thermally conductive resin, as shown in FIG.

[0055] Step (e) of injecting the thermally conductive resin through the injection hole formed on the lower surface of the module frame allows the thermally conductive resin to cover the first end of the battery cell stack having the double folded sealing portion DSF, as shown in FIG. 10.

[0056] The method for manufacturing a battery module according to this embodiment may further include forming a vent hole 105 on an upper surface 102 of the module frame 100 and forming a flame retardant mesh 107 to cover the vent hole 105, as shown in FIG.

[0057] Fig. 12 is a diagram showing how gas and flames are ejected when a flame occurs in a battery module according to a comparative example, and Fig. 13 is a cross-sectional view taken along a cutting plane CC in the yz plane of Fig. 12 .

[0058] 12 and 13, unlike the battery module according to this embodiment, the end of the battery cell stack having the double folded sealing part is disposed on the opposite side to the lower surface of the module frame on which the thermally conductive resin layer is formed. With this structure, when a fire occurs in the battery module, gas and flame can escape through the three joints corresponding to the weak parts of the battery cells, but the flame can escape very strongly through the vent hole and flame-extinguishing net formed at the upper end of the battery module, making it difficult for the flame-extinguishing net to perform its intended function.

[0059] FIG. 14 is a diagram showing how gas and flames are ejected when a flame occurs in a battery module according to one embodiment of the present invention.

[0060] 14, in the battery module according to this embodiment, the first end of the battery cell stack having a double folded sealing part is covered with a thermally conductive resin layer, thereby strengthening the cell stack and blocking the flame through the first end of the battery cell stack, thereby minimizing the flame eruption at the upper end of the battery module located opposite to the first end of the battery cell stack. Therefore, since the flame mainly erupts only from the lead end of the battery module through the flame-extinguishing net formed at the upper end of the battery module, the flame intensity discharged through the flame-extinguishing net is weakened, and the function of the flame-extinguishing net is maximized.

[0061] Meanwhile, one or more battery modules according to the embodiment of the present invention may be packaged in a pack case to form a battery pack. Although not shown, a cooling plate may be positioned under a lower surface of the module frame, and the battery cell stack is received in the module frame such that a double-folded sealing part is disposed on the lower surface of the module frame adjacent to the cooling plate.

[0062] The above-mentioned battery module and the battery pack including the same can be applied to various devices. Such devices can be applied to transportation means such as electric bicycles, electric cars, and hybrid cars, but the present invention is not limited thereto, and the battery module and the battery pack including the same can be applied to various devices that can use the battery module, and these also fall within the scope of the present invention.

[0063] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention. [Explanation of symbols]

[0064] 100:Module frame 105: Vent Hole 107: Anti-inflammatory net 135: Injection hole 140: Thermally conductive resin layer DSF: Double-fold sealing section

Claims

1. a battery cell stack in which a plurality of battery cells are stacked; a module frame that houses the battery cell stack; a thermally conductive resin layer located between a lower surface of the module frame and a first end of the battery cell stack; Including, the first end of the battery cell stack has a double fold sealing portion; The lower surface of the module frame is formed with an injection hole for injecting a thermally conductive resin, There is no thermally conductive resin between each of the plurality of battery cells. Battery module.

2. The liquid injection holes are formed in a plurality of holes, and the plurality of liquid injection holes are formed in a middle portion of the lower surface of the module frame and at both ends along a longitudinal direction. The battery module according to claim 1 .

3. A battery cell stack in which a plurality of battery cells are stacked; a module frame that houses the battery cell stack; a thermally conductive resin layer located between a lower surface of the module frame and a first end of the battery cell stack; Including, the first end of the battery cell stack has a double fold sealing portion; a second end portion opposite the first end portion includes a connecting portion having no double fold sealing portion; a vent hole formed in an upper surface of the module frame adjacent to the second end, Battery module.

4. Further comprising a flame retardant mesh covering the vent hole; The battery module according to claim 3 .

5. stacking a plurality of battery cells to form a battery cell stack having a first end portion having a double fold sealing portion and a second end portion opposite the first end portion having a connecting portion without the double fold sealing portion; housing the battery cell stack within a module frame; inverting the module frame upside down so that a lower surface of the module frame faces upward; injecting a thermally conductive resin through an injection hole formed on the lower surface of the module frame; Including, The thermally conductive resin covers the first end of the battery cell stack. A method for manufacturing a battery module.

6. and after the step of injecting the thermally conductive resin, the step of inverting the module frame upside down so that the lower surface of the module frame faces downward. The method for manufacturing the battery module according to claim 5 .

7. and, before the step of placing the battery cell stack in a module frame, further including the step of inverting the battery cell stack upside down so that the first end of the battery cell stack is disposed on the lower surface of the module frame. The method for manufacturing the battery module according to claim 5 .

8. forming a vent hole on an upper surface of the module frame; forming a flame retardant net covering the vent hole; Further comprising: The method for manufacturing the battery module according to any one of claims 5 to 7.

9. The battery module according to any one of claims 1 to 4, a cooling plate located below the lower surface of the module frame; Includes Battery pack.

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