Battery pack

Abstract

The present invention relates to a battery pack including a pack case that houses a cell stack assembly including a plurality of cells, the pack case including a base plate that supports a lower portion of the cell stack assembly, side walls that are coupled to edges of the base plate to support sides of the cell stack assembly, and a partition wall that is interposed between any pair of adjacently arranged cell stack assemblies and is coupled to the base plate, the partition wall including a hollow portion therein and a truss beam that is inserted to define the hollow portion.

Description

[Technical Field]

[0001] The present invention relates to a battery pack. The battery pack of the present invention is characterized by having a structure that includes a hollow portion therein and uses a partition wall including a truss beam inserted to partition the hollow portion, thereby minimizing heat transfer by conduction, convection, and radiation due to thermal runaway of cells housed therein.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0015814, filed February 6, 2023, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0003] Currently widely used types of secondary batteries include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries. The operating voltage of such a unit secondary battery cell, i.e., a unit battery cell, is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, a battery pack may be configured by connecting a plurality of battery cells in series. Alternatively, a battery pack may be configured by connecting a number of battery cells in parallel depending on the required charge / discharge capacity of the battery pack. Therefore, the number of battery cells included in the battery pack may be variously set depending on the required output voltage or charge / discharge capacity.

[0004] When constructing a battery pack by connecting a plurality of battery cells in series / parallel, a common method is to first construct a battery module including at least one battery cell, and then use this at least one battery module to add other components to construct the battery pack.

[0005] A conventional battery module generally includes at least one cell stack containing battery cells, and a box-shaped metal housing structure, i.e., a module frame, that houses the at least one cell stack.

[0006] In addition, to solve the problems of a decrease in the energy density of the entire battery pack and an increase in the weight of the entire battery pack due to the weight and volume of the module frame itself, a cell stack assembly that does not have a module frame configuration that surrounds and protects the cell stack may be used instead of a conventional battery module.

[0007] FIG. 1 shows a pack case included in a conventional battery pack, and FIG. 2 is a cross-sectional perspective view of one of the partition walls included in the pack case of FIG.

[0008] A conventional battery pack in which a battery module or a cell stack assembly is housed has a configuration as shown in Fig. 1. That is, the conventional battery pack includes a pack case 10 including a base plate 20 corresponding to the bottom and side walls 30 coupled to the edges of the base plate 20, and a plurality of partition walls 40 coupled to the base plate 20 to partition the interior of the pack case 10.

[0009] In the past, a hollow partition wall 40 with a hollow center has been used to reduce the weight of the partition wall 40 and to prevent heat from being conducted to the opposite side through the partition wall 40. However, the hollow partition wall 40 has low mechanical strength, making it difficult to protect a normal cell stack assembly from high explosive pressure when thermal runaway occurs in the cell stack assembly.

[0010] Therefore, in order to solve the above-mentioned mechanical strength problem, a partition wall 40 having a reinforcing rib 50 as shown in FIG. 2 was developed. However, when the thickness of the reinforcing rib 50 is increased to improve the mechanical strength, it is difficult to reduce the weight of the partition wall 40. Furthermore, a new problem has arisen in that it is not possible to prevent large amounts of heat from being conducted through the reinforcing rib 50.

[0011] Conversely, when the thickness of the reinforcing rib 50 is reduced, there is a problem in that it is difficult to achieve the original purpose of achieving the desired mechanical strength.

[0012] Generally, heat is transferred in the form of radiation, convection, conduction, etc., and there is a need to develop a battery pack including a partition 40 that has excellent mechanical strength while effectively preventing the transfer of heat that occurs within the battery pack in the various forms described above. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Korean Patent Publication No. 10-2022-0014027 Summary of the Invention [Problem to be solved by the invention]

[0014] Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a battery pack having a structure that can prevent thermal runaway from occurring in a chain reaction due to heat being transferred to other cells when one cell experiences thermal runaway.

[0015] Another object of the present invention is to provide a battery pack using a partition wall that can withstand explosion pressure caused by thermal runaway in the event of thermal runaway of a cell.

[0016] Another object of the present invention is to provide a lightweight battery pack.

[0017] Other objects and advantages of the present invention will become apparent from the following description and become more clearly apparent from the embodiments of the present invention. Also, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0018] According to the present invention, there is provided a battery pack including a pack case that houses a cell stack assembly including a plurality of cells, the pack case including a base plate that supports a lower portion of the cell stack assembly, side walls that are coupled to edges of the base plate to support sides of the cell stack assembly, and a partition wall that is interposed between any pair of adjacently arranged cell stack assemblies and is coupled to the base plate, the pack case including a hollow portion inside the partition wall and further including a truss beam that is inserted to define the hollow portion.

[0019] The inner surface of the partition wall may be coated with a metal thin film.

[0020] The truss beam may include a plurality of bent portions and may support the bulkhead at the bent portions.

[0021] The truss beam may be bent along the longitudinal direction of the partition wall.

[0022] The truss beam may be formed to extend along the height direction of the partition wall.

[0023] The surface of the truss beam may be coated with a thin metal film.

[0024] The truss beam may include any one of the following materials: plastic, aluminum, and steel.

[0025] The pack case may include a hollow portion inside the base plate, and may further include a lower truss beam inserted to define the hollow portion.

[0026] The lower truss beam may include a plurality of bent portions and may support a base plate at the bent portions.

[0027] The lower truss beam can be bent along the horizontal direction.

[0028] The surface of the lower truss beam may be coated with a thin metal film having high reflectivity.

[0029] The lower truss beam may include any one of the following materials: plastic and steel. [Effects of the Invention]

[0030] The battery pack of the present invention can minimize internal heat transfer and reduce the risk of explosion.

[0031] Furthermore, the battery pack of the present invention can improve energy density by reducing weight.

[0032] Furthermore, the battery pack of the present invention can improve the mechanical strength of the internal skeleton and improve stability. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a perspective view of a pack case included in a conventional battery pack. [Figure 2] 2 is a cross-sectional perspective view of one of the partition walls included in the pack case of FIG. 1. FIG. [Figure 3] 1 is a perspective view of a pack case included in a battery pack according to a first embodiment of the present invention; [Figure 4] 4 is a perspective view of one of the partition walls included in the pack case of FIG. 3. [Figure 5]This shows the partition wall of FIG. 4 cut horizontally. [Figure 6] FIG. 6 is a plan view of the partition wall of FIG. 5. [Figure 7] This shows a bulkhead without truss beams. [Figure 8] This shows the process of inserting the truss beam into the bulkhead. [Figure 9] This shows the direction of force distribution in a truss beam. [Figure 10] This shows an enlarged portion of a truss beam. [Figure 11] 1 shows a pair of cell stack assemblies and a partition wall arranged adjacent to each other in a pack case. [Figure 12] 10 is a plan view of a partition wall and a cut-away plan view of the partition wall of a battery pack according to a second embodiment of the present invention. [Figure 13] 10 is a plan view of a partition wall and a cut-away plan view of the partition wall of a battery pack according to a third embodiment of the present invention. [Figure 14] 10 is a plan view of a partition wall of a battery pack according to a fourth embodiment of the present invention and a cut-away view of the partition wall. [Figure 15] 10 is a partial cross-sectional view of a pack case included in a battery pack according to a fifth embodiment of the present invention and a base plate included in the pack case. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Before that, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concepts of the terms to best describe his own invention.

[0035] Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and there may be various equivalents and modifications that can replace them at the time of this application.

[0036] Furthermore, in the description of the present invention, if it is determined that a detailed description of related publicly known structures or functions may obscure the gist of the present invention, the detailed description will be omitted.

[0037] The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and therefore the shapes and sizes of components in the drawings may be exaggerated, omitted, or shown in a schematic manner for clearer explanation. Therefore, the sizes and proportions of each component do not completely reflect the actual sizes and proportions.

[0038] The present invention relates to a battery pack. The battery pack of the present invention is characterized by having a structure that includes a hollow portion therein and uses a partition wall including a truss beam inserted to partition the hollow portion, thereby minimizing heat transfer by conduction, convection, and radiation due to thermal runaway of cells housed therein.

[0039] 3 to 11 relate to a battery pack according to a first embodiment of the present invention, and FIGS. 12 to 15 relate to battery packs according to second to fifth embodiments of the present invention, respectively.

[0040] Hereinafter, a battery pack of the present invention will be described with reference to the drawings.

[0041] (First embodiment) FIG. 3 is a perspective view of a pack case 100 included in the battery pack according to the first embodiment of the present invention.

[0042] The battery pack of the present invention includes a pack case 100 that houses a cell stack assembly A that includes a plurality of cells.

[0043] The cell stack assembly A contained in the battery pack of the present invention includes a plurality of cells stacked in one direction, is electrically connected to each of the cell stack assemblies A, and transmits the electrical energy of each cell stack assembly A to the outside.

[0044] Each cell has a pair of electrode leads having different polarities extending from one or both sides.

[0045] The cell stack assembly A includes a bus bar frame having bus bars electrically connected to each electrode lead of the stacked cells, and an end plate coupled to cover the bus bar frame.

[0046] Furthermore, if necessary, the module may further include a module frame that surrounds and covers the cell stack to protect the multiple cells.

[0047] As shown in FIG. 3, the pack case 100 includes a base plate 110, a side wall 120, and a partition wall 130.

[0048] The base plate 110 serves to support the lower part of the cell stack assembly A.

[0049] The side walls 120 are coupled to the edges of the base plate 110 to support the sides of each cell stack assembly A mounted on the base plate 110 .

[0050] The partition wall 130 is interposed between any pair of adjacent cell stack assemblies A and is coupled to the base plate 110. Therefore, the partition wall 130 serves to separate the cell stack assemblies A and also serves to protect the cell stack assemblies A from explosive pressure caused by thermal runaway if any one of the cell stack assemblies A expands due to thermal runaway.

[0051] The partition wall 130 of the present invention includes a hollow portion 131 therein, thereby ensuring light weight, and is characterized in that the mechanical strength that may be weakened by the hollow portion 131 is reinforced by a truss beam 140 inserted therein.

[0052] Figure 4 shows an oblique view of one of the partitions 130 included in the pack case 100 of Figure 3, Figure 5 shows the partition 130 of Figure 4 cut horizontally, Figure 6 is a plan view of the partition 130 of Figure 5, and Figure 7 shows the partition 130 without the truss beam 140.

[0053] The partition wall 130 has an internal space formed therein to form a hollow portion 131 as shown in FIG.

[0054] The hollow portion 131 is in a vacuum state or filled with air, and is characterized by minimizing heat transfer due to conduction and convection.

[0055] Although not shown, the partition wall 130 of the present invention is characterized in that a metal thin film structure is added to restrict the transfer of heat transmitted in a radiative manner through the hollow portion 131 .

[0056] That is, the inner surface of the partition wall 130 may be coated with a metal thin film having high reflectivity against radiant heat.

[0057] The metal thin film serves to block heat from being transferred in a radiative form through the hollow portion 131 of the partition wall 130. In this case, the metal thin film may be, for example, an aluminum foil or a silver foil.

[0058] As shown in FIGS. 5 and 6, the partition wall 130 includes a truss beam 140 inserted therein to define the hollow portion 131.

[0059] The truss beam 140 includes a plurality of bent portions 141, and the bent portions 141 serve to support the partition wall .

[0060] As shown in FIG. 6, the truss beam 140 included in the partition wall 130 of the battery pack according to the first embodiment of the present invention is extended to form an equilateral triangle or an equilateral triangle by a plurality of bent portions 141.

[0061] That is, the truss beam 140 is characterized by having a Warren truss structure. Specifically, the truss beam 140 is formed by extending a bent portion 141 and two support portions 142 extending from the bent portion 141 to opposite sides. At this time, each support portion 142 forms a diagonal line and connects one side of the partition wall 130 of the hollow portion 131 to the other side.

[0062] As shown in FIG. 6, the truss beam 140 is extended along the longitudinal direction of the partition wall 130 while forming a plurality of bent portions 141, thereby maintaining the cross-sectional shape of FIG. 6, and is extended along the height direction of the partition wall 130 as shown in FIG. 5, thereby filling all of the hollow portion 131 inside the partition wall 130.

[0063] FIG. 8 shows a process of inserting the truss beam 140 formed to extend along the length and height of the partition wall 130 into the partition wall 130.

[0064] Therefore, as shown in FIG. 8, the truss beam 140 is inserted to fill the entire hollow portion 131, and can support the partition wall 130 from the inside.

[0065] FIG. 9 shows the process by which the truss beam 140 inside the partition wall 130 disperses the force when an external force F is applied.

[0066] 9, an external force F transmitted from one side is first dispersed and transmitted to each bending portion 141 of the truss beam 140, and then the force is dispersed again in two directions from one bending portion 141 and transmitted to the opposite bending portion 141. At this time, the external force F may be momentarily dispersed and weakened as it passes through the truss beam 140 inside the partition wall 130, and as a result, only half of the force is transmitted to the opposite side of the partition wall 130.

[0067] The above-described characteristics of the truss beam 140 can also be applied to heat transfer. That is, the high-temperature heat transferred along with the external force F can be dispersed and weakened as it moves through the truss beam 140. In addition, the heat moving through the truss beam 140 can be partially cooled by the air in the hollow portion 131.

[0068] Although not shown, the surface of the truss beam 140 may be coated with a thin metal film having high reflectivity, similar to the inner surface of the partition wall 130. That is, heat radiated into the hollow portion 131 may be reflected by the surface of the truss beam 140 that defines the internal space of the hollow portion 131 and may not travel to the opposite side.

[0069] The truss beam 140 may be made of any one of reinforced plastic, aluminum, and steel. However, it is preferable that the truss beam 140 is made of the same material as the partition wall 130, which is made of metal. This is because the best method for fixing the truss beam 140 to the inside of the partition wall 130 is to join the same materials through welding. In this case, the welding is performed between the bent portion 141 of the truss beam 140 and the inner surface of the partition wall 130 that abuts the bent portion 141.

[0070] FIG. 10 shows an enlarged view of a portion of the truss beam 140.

[0071] As shown in FIG. 10, the outer end portion where the bent portion 141 is formed is flat to facilitate bonding with the inner surface of the partition wall 130 .

[0072] 11 shows a pair of cell stack assemblies A arranged adjacent to each other in a pack case 100 and a partition wall 130 interposed between them. (For ease of understanding, the upper end of the partition wall 130 is shown cut away.)

[0073] 11, the partition wall 130 supports two cell stack assemblies A in close contact with each other on both sides of the partition wall 130. If one of the cell stack assemblies A experiences thermal runaway and expands, releasing high-temperature heat and gas, the hollow portion 131 and truss beam 140 inside the partition wall 130 prevent or reduce the transfer of the generated explosive pressure and heat to the cell stack assembly A on the opposite side.

[0074] The battery pack of the present invention may further include an upper case (not shown) coupled to the pack case 100 to cover an upper portion of the cell stack assembly A housed inside the pack case 100.

[0075] The upper case is not a main feature of the present invention, and therefore a description thereof will be omitted.

[0076] (Second embodiment) FIG. 12 shows a plan view of a partition wall 130 of a battery pack according to a second embodiment of the present invention and a cut-away view of the partition wall 130. As shown in FIG.

[0077] As shown in FIG. 12, the truss beam 140 includes a plurality of bent portions 141, and the bent portions 141 serve to support the partition walls 130.

[0078] The truss beam 140 is formed by an extension of a bent portion 141 and two support portions 142 extending in opposite directions from the bent portion 141. At this time, each support portion 142 connects one side of the partition wall 130 of the hollow portion 131 to the other side while alternately forming a vertical line and a diagonal line.

[0079] Specifically, one of the support portions 142 extending from the bent portion 141 connects one side and the other side of the partition wall 130 vertically, and the other support portion 142 connects one side and the other side of the partition wall 130 diagonally.

[0080] In this way, by varying the length of the support portions 142 included in the truss beam 140, the force and heat are transferred in an unbalanced direction.

[0081] (Third embodiment) FIG. 13 shows a plan view of a partition wall 130 of a battery pack according to a third embodiment of the present invention and a cut-away view of the partition wall 130. As shown in FIG.

[0082] The truss beam 140 includes a plurality of bent portions 141 as shown in FIG. 13, and serves to support the partition wall 130 at the bent portions 141 .

[0083] The truss beam 140 is formed by an extension of a bent portion 141 and two support portions 142 extending in opposite directions from the bent portion 141. At this time, each support portion 142 connects one side of the partition wall 130 of the hollow portion 131 to the other side while alternately forming a vertical line and a diagonal line.

[0084] Specifically, one of the support portions 142 extending from the bent portion 141 connects one side and the other side of the partition wall 130 vertically, and the other support portion 142 connects one side and the other side of the partition wall 130 diagonally.

[0085] In this way, by varying the length of the support portions 142 included in the truss beam 140, the force and heat are transferred in an unbalanced direction.

[0086] (Fourth embodiment) FIG. 14 shows a plan view of a partition wall 130 of a battery pack according to a fourth embodiment of the present invention and a cut-away view of the partition wall 130. As shown in FIG.

[0087] The truss beam 140 includes a plurality of bent portions 141 as shown in FIG. 14, and serves to support the partition wall 130 at the bent portions 141 .

[0088] The truss beam 140 is formed by extending a bending portion 141 and two support portions 142 extending in opposite directions from the bending portion 141. A pair of support portions 142 extending in a diagonal direction is connected to any one of the bending portions 141, and the support portions 142 connected to the remaining bending portions 141 connect one side of the partition wall 130 of the hollow portion 131 to the other side while alternately forming vertical and diagonal lines.

[0089] In the truss beam 140 having such a structure, the force and pressure are spread toward both ends from the center of the bent portion 141 connected to the two diagonal support portions 142 .

[0090] (Fifth embodiment) FIG. 15 shows a partial cross section of a pack case 100 included in a battery pack according to a fifth embodiment of the present invention and a base plate 110 included in the pack case 100. As shown in FIG.

[0091] The base plate 110 has a hollow structure similar to the partition wall 130. That is, the base plate 110 includes a lower hollow portion therein, and the pack case 100 of the present invention is characterized in that it further includes a lower truss beam 150 inserted to define the lower hollow portion of the base plate 110.

[0092] Referring to FIG. 15, the lower truss beam 150 includes a plurality of bent portions 141, and supports the base plate 110 at the bent portions 141.

[0093] The lower truss beam 150 is provided inside the lower hollow portion of the base plate 110 in an upside-down shape of the truss beam 140 applied to the partition wall 130. That is, the lower truss beam 150 is bent along the horizontal direction.

[0094] The inner surface of the base plate 110 may be coated with a thin metal film having high reflectivity, and the thin metal film may also be coated on the surface of the lower truss beam 150 .

[0095] The lower truss beam 150 may be made of any one of plastic and steel, and is preferably made of the same material as the base plate 110 for ease of joining.

[0096] The lower truss beam 150 shown in Figure 15 supports the weight of the cell stack assemblies A located on the base plate 110. In particular, when any one of the cell stack assemblies A expands or explodes due to thermal runaway, it can disperse the explosion pressure. It also absorbs and cools the high temperature generated by the thermal runaway.

[0097] The present invention has been described in more detail above through the drawings and embodiments, etc. However, the configurations shown in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, and therefore, various equivalents and modifications may exist at the time of filing this application. [Explanation of symbols]

[0098] 10: (Conventional technology) Pack case 20: (Conventional technology) Base plate 30: (Prior Art) Sidewall 40: (Conventional) Partition 50: (Prior art) Reinforcement rib 100: Pack case 110: Base plate 120: Side wall 130: Bulkhead 131: Hollow part 140: Truss beam 141: Bent part 142: Support part 150: Lower truss beam A: Cell stack assembly F: External force

Claims

1. A battery pack including a pack case that houses a cell stack assembly including a plurality of cells, The pack case is a base plate that supports a lower portion of the cell stack assembly; a sidewall coupled to an edge of the base plate to support a side of the cell stack assembly; a partition wall interposed between any pair of adjacently arranged cell stack assemblies and coupled to the base plate, The battery pack further includes a truss beam inserted to define a hollow portion inside the partition wall, the pack case including: a truss beam;

2. The battery pack according to claim 1 , wherein the partition wall has an inner surface coated with a thin metal film.

3. The battery pack according to claim 1 , wherein the truss beam includes a plurality of bent portions, and the bent portions support the partition walls.

4. The battery pack according to claim 1 , wherein the truss beam is bent along a longitudinal direction of the partition wall.

5. The battery pack according to claim 1 , wherein the truss beam extends along a height direction of the partition wall.

6. The battery pack according to claim 1 , wherein a surface of the truss beam is coated with a thin metal film.

7. The battery pack of claim 1 , wherein the truss beam includes any one of the following materials: plastic, aluminum, and steel.

8. The battery pack according to claim 1 , wherein the pack case includes a hollow portion inside the base plate, and further includes a lower truss beam inserted to define the hollow portion.

9. The battery pack according to claim 8 , wherein the lower truss beam includes a plurality of bent portions, and the bent portions support the base plate.

10. The battery pack according to claim 8 , wherein the lower truss beam is bent along a horizontal direction.

11. The battery pack according to claim 8 , wherein a surface of the lower truss beam is coated with a thin metal film having high reflectivity.

12. The battery pack of claim 8 , wherein the lower truss beam includes one of the following materials: plastic and steel.

Images