Pack structure filled with phase change material

Abstract

The disclosed invention relates to a pack structure forming at least a part of a pack case and having a plurality of hollow passages therein, wherein at least some of the plurality of hollow passages are filled with a phase change material that undergoes a phase change from solid to liquid when the temperature rises above a preset temperature.

Description

Pack structure filled with phase change material

[0001] The present invention relates to a pack structure included in a pack case.

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0086621, dated July 2, 2024, the entire contents of which are incorporated herein by reference.

[0003] Unlike primary batteries, secondary batteries are rechargeable and have the potential for miniaturization and large capacity, leading to extensive research and development in recent years. With increasing technological development and demand for mobile devices, and the emergence of electric vehicles and energy storage systems in response to the era's growing environmental concerns, demand for secondary batteries as an energy source is rapidly increasing.

[0004] Secondary batteries are classified into coin-shaped, cylindrical, square, and pouch-shaped batteries, depending on the shape of their battery cases. In secondary batteries, the electrode assembly mounted inside the battery case is a rechargeable, power-generating element comprised of a laminated structure of electrodes and a separator.

[0005] Because secondary batteries require continuous, long-term use, effective control of the heat generated during charging and discharging is essential. See Korean Patent No. 10-2628603 (registered January 19, 2024).

[0006] The purpose of the present invention is to provide a pack structure that can maintain the advantage of light weight while securing sufficient heat capacity to cope with thermal runaway of a secondary battery.

[0007] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0008] The present invention relates to a pack structure that forms at least a portion of a pack case and has a plurality of hollow passages therein, wherein at least a portion of the plurality of hollow passages is selectively filled with a phase change material that undergoes a phase change from solid to liquid when a temperature rises above a preset temperature.

[0009] The above phase change material may have a smaller specific gravity than the material forming the pack structure.

[0010] In one embodiment, the pack structure may form a base plate or a side plate of the pack case.

[0011] For example, the pack structure may be a base plate, and the base plate may be a heat sink in which some of the plurality of hollow passages are filled with the phase change material while the remaining hollow passages form a cooling path.

[0012] And, the hollow passage filled with the phase change material can form a plurality of groups divided by the cooling channel.

[0013] In another example, the pack structure is a side plate, and the side plate can be filled with the phase change material for all of the plurality of hollow passages.

[0014] Meanwhile, the pack structure may be formed integrally with the hollow passage through extrusion molding, and the hollow passage filled with the phase change material may be maintained in a state in which at least one end thereof is open to the outside.

[0015] In addition, the temperature set as a standard for causing the phase change material to change from solid to liquid may correspond to an upper limit value of a temperature range at which a battery pack including a pack case to which the pack structure is applied is determined to be in a normal operating state.

[0016] For example, the upper limit of the temperature range at which the battery pack is judged to be in a normal operating state may be a temperature selected from the range of about 60°C to 80°C.

[0017] And, the phase change material may be a paraffin-based material.

[0018] For example, the phase change material may be at least one material selected from paraffin 140, paraffin 145, paraffin 150, paraffin 155, and paraffin 160.

[0019] In addition, the number and position of the hollow passages filled with the phase change material among the plurality of hollow passages, and the number and position of the hollow passages forming the cooling path are determined by considering design factors such as cooling capacity, heat capacity, and weight.

[0020] According to the pack structure of the present invention having the above configuration, at least some of the plurality of hollow passages formed inside are filled with a phase change material that undergoes a phase change from solid to liquid, and the phase change material absorbs heat from the surroundings in the form of sensible heat and latent heat until the phase change temperature is reached. Therefore, the overall heat capacity of the pack structure increases as the phase change material is filled.

[0021] In addition, if the specific gravity of the phase change material is selected to be smaller than that of the material forming the pack structure, the heat capacity can be effectively increased while suppressing the increase in the weight of the entire pack structure.

[0022] However, the technical effects that can be obtained through the present invention are not limited to the above-described effects, and other effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0023] The following drawings attached to this specification illustrate embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0024] FIG. 1 is a drawing exemplarily showing a pack case to which a pack structure according to one embodiment of the present invention can be applied.

[0025] Fig. 2 is a cross-sectional drawing of a base plate applied to the pack case of Fig. 1.

[0026] Figure 3 is an enlarged view of part “A” of Figure 1.

[0027] Fig. 4 is a cross-sectional drawing of a side plate applied to the pack case of Fig. 1.

[0028] FIG. 5 is a drawing showing an example in which a phase change material is applied on a base plate of a pack case to which the pack structure of the present invention is applied.

[0029] In some of the accompanying drawings, corresponding components are designated by the same reference numerals. Those skilled in the art will appreciate that the drawings illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to facilitate understanding of various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated relative to other elements. Furthermore, elements of known technology that are useful or essential in commercially feasible embodiments may often not be depicted so as not to obscure the spirit of various embodiments of the present invention.

[0030] The present invention can be modified in various ways and has many embodiments, and specific embodiments will be described in detail below.

[0031] However, this is not intended to limit the present invention to a specific embodiment, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

[0032] In the present invention, it should be understood that terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0033] Additionally, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "directly above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "directly below" the other part, but also cases where there is another part in between. Furthermore, in the present application, "being placed on" may include cases where it is placed below as well as above.

[0034]

[0035] Secondary batteries are used for relatively long periods through repeated charging and discharging, and the heat generated during use for various reasons requires effective control. For example, if a secondary battery's cooling is not properly maintained, a rise in temperature can lead to an increase in current, which in turn causes a rise in temperature, resulting in a positive feedback chain reaction, ultimately leading to a catastrophic condition known as thermal runaway.

[0036] To effectively dissipate heat generated by secondary batteries, heat sinks (also called cooling plates) with flowing coolant are widely used. These heat sinks form the bottom of a battery pack, or are mounted on the bottom of a group of secondary batteries, such as a battery pack containing multiple secondary batteries. They perform a cooling function by absorbing heat generated within the battery pack through coolant and dissipating it to the outside.

[0037] Heat sinks can be categorized into brazed heat sinks and extruded heat sinks based on their structure and manufacturing method. Brazed heat sinks form a flow path by brazing two plates together. While they offer a high degree of freedom in flow path design, they suffer from structural rigidity issues due to the deterioration of the material properties. In contrast, extruded heat sinks, manufactured as a continuous body through extrusion, can achieve lightweight performance while also ensuring sufficient structural rigidity. Furthermore, they efficiently create refrigerant flow paths by forming multiple hollow channels simultaneously during the extrusion process. However, because extruded heat sinks can only achieve straight flow paths, appropriate port design is required to ensure effective refrigerant flow.

[0038] While extruded heat sinks offer numerous advantages, including lightweight design, their low weight limits their heat capacity in the event of thermal runaway, making it difficult to suppress the event solely through refrigerant circulation. To address this issue, filling in some of the heat sink's hollow passages can improve thermal runaway resistance. However, this can also lead to additional issues, such as excessive weight gain for the pack case, potentially compromising its competitiveness.

[0039] The present invention relates to a pack structure that forms at least a portion of a pack case and has a plurality of hollow passages therein, wherein at least a portion of the plurality of hollow passages is filled with a phase change material that undergoes a phase change from solid to liquid when a temperature rises above a preset temperature.

[0040] Here, the phase change material may have a smaller specific gravity than the material forming the pack structure.

[0041] According to the pack structure of the present invention having such a configuration, at least some of the plurality of hollow passages formed inside the pack structure are filled with a phase change material that undergoes a phase change from solid to liquid, and the phase change material absorbs heat from the surroundings in the form of sensible heat and latent heat until the phase change temperature is reached. Therefore, the overall heat capacity of the pack structure increases as the phase change material is filled.

[0042] In addition, if the specific gravity of the phase change material is selected to be smaller than that of the material forming the pack structure, the heat capacity can be effectively increased while suppressing the increase in the weight of the entire pack structure.

[0043] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Here, the directions of front, back, up, down, left, and right used to designate relative positions in the following description are intended to aid understanding of the invention, and unless otherwise specified, the directions depicted in the drawings are taken as the reference.

[0044]

[0045] [First Embodiment]

[0046] FIG. 1 is a drawing exemplarily illustrating a pack case (300) to which a pack structure (100) according to one embodiment of the present invention can be applied. The pack case (300) includes a base plate (101) forming a bottom surface, and a plurality of side plates (102) which are walls surrounding the base plate (101) on all sides. The space formed by the base plate (101) and the plurality of side plates (102) corresponds to a space for accommodating a plurality of battery cells. The plurality of battery cells can be mounted on the pack case (300) in the form of a module in which a plurality of battery cells are concentrated in a separate case, or in the form of a block in which a plurality of battery cells are restrained by a plurality of frames.

[0047] These base plates (101) and side plates (102) can be collectively referred to as a pack structure (100) that forms the frame structure of the pack case (300). Fig. 2 shows a cross-section of a base plate (101) according to one embodiment of the present invention, and Fig. 4 shows a cross-section of a side plate (102) according to one embodiment of the present invention.

[0048] The base plate (101) corresponds to the pack structure (100) forming the bottom surface of the pack case (300). The base plate (101) includes a plurality of hollow passages (120) formed between a plurality of ribs (110) spaced apart from each other along the entire longitudinal direction (L). For example, as illustrated, the base plate (101) may be manufactured by extrusion molding. By extrusion molding, the base plate (101) including the ribs (110) and the hollow passages (120) may be formed integrally. Here, the longitudinal direction (L) refers to the extrusion molding direction of the pack structure (100), that is, the direction in which the plurality of hollow passages (120) extend, and the width direction (W) refers to the direction orthogonal to the longitudinal direction (L) on a plane in which the plurality of hollow passages (120) are spaced apart from each other.

[0049] A heat sink may be placed on the bottom of the pack case (300) to discharge heat generated from battery cells during charging and discharging to the outside. The heat sink may be manufactured separately and attached to the base plate (101), or the base plate (101) itself may be configured as a heat sink. In the illustrated embodiment, the base plate (101) is configured to function as a heat sink by having some of the plurality of hollow passages (120) function as cooling channels (122).

[0050] Referring to FIGS. 2 and 3, ports (130) are connected to some of the plurality of hollow passages (120) spaced apart from each other along the width direction (W). The ports (130) serve as joints for connecting pipes for the hollow passages (120) to serve as inlets or outlets for cooling fluid. The hollow passages (120) to which the ports (130) are connected form cooling channels (122). The temperature rise of the battery cells mounted on the base plate (101) is suppressed by the cooling channels (122) and the cooling fluid flowing therethrough. However, in FIG. 2, the pipes for configuring each port (130) as an inlet or outlet for cooling fluid are omitted.

[0051] Referring to the illustrated base plate (101), ports (130) are coupled only to some of the plurality of hollow passages (120). For example, only some of the entire hollow passages (120) constitute cooling channels (122). The remaining hollow passages (120) were previously left as space to reduce the weight of the large base plate (101). However, as weight reduction is achieved, the overall thermal capacity of the base plate (101) decreases. As the thermal capacity of the base plate (101) decreases, the capacity to absorb heat generated from the battery cells and release it to the outside decreases. Therefore, there may not be a major problem when the battery pack is in a normal operating state, but in a dangerous state where thermal runaway, heat propagation, or ignition may occur, the reduced capacity to absorb heat from the battery cells is disadvantageous in suppressing temperature rise.

[0052] The present invention is to solve the problem of insufficient heat capacity of a pack structure (100) having a plurality of hollow passages (120), and to this end, at least some of the plurality of hollow passages (120) are filled with a phase change material (200) that causes a phase change from solid to liquid when the temperature rises above a preset temperature. Furthermore, the phase change material (200) may be selected to have a smaller specific gravity than the material (e.g., aluminum alloy, stainless steel, etc.) forming the pack structure (100). FIG. 3 is an enlarged view of part "A" of FIG. 1, showing a structure in which some of the hollow passages (120) are connected to ports (130) to form a cooling channel (122), and the remaining hollow passages (120) are filled with the phase change material (200).

[0053] The phase change material (200) filled in the hollow passage (120) maintains a solid state below a certain temperature. For example, at room temperature or within a certain reference temperature range where the battery pack can be determined to be in a normal operating state, the phase change material (200) is in a solid state. Then, the solid phase change material (200) absorbs heat from the surroundings (sensible heat) and, when it reaches a certain temperature, undergoes a phase change into a liquid (latent heat), and is ultimately completely liquefied when the certain temperature is exceeded.

[0054] In this way, the phase change material (200) plays a role in absorbing heat flowing into the pack structure (100), and absorbs a large amount of heat in the form of latent heat during the phase change process that occurs at a specific temperature. Therefore, the heat capacity of the pack structure (100), for example, the base plate (101), is greatly increased due to the phase change material (200) filling the hollow passage (120) that was previously empty.

[0055] Referring again to FIGS. 2 and 3, the hollow passages (120) filled with the phase change material (200) form a plurality of groups divided by cooling channels (122) coupled with ports (130). For example, the number of hollow passages (120) forming the cooling channels (122) and the number of hollow passages (120) filled with the phase change material (200) may not correspond one-to-one and may be different. In addition, although the drawing shows that the phase change material (200) is filled in all hollow passages (120) that do not form the cooling channels (122), some hollow passages (120) may be left as spaces in which the phase change material (200) is not filled. In this way, the base plate (101), which is a heat sink, can appropriately determine the number and location of the hollow passages (120) forming the cooling path (122) and the hollow passages (120) filled with the phase change material (200) by considering various design factors such as cooling capacity, heat capacity, and weight.

[0056] FIG. 4 is a cross-sectional view of a side plate (102) applied to the pack case (300) of FIG. 1 as another example of a pack structure (100). The side plate (102) exemplarily illustrated in FIG. 4 has a plurality of hollow passages (120) divided by internal ribs (110), and all of the plurality of hollow passages (120) are filled with a phase change material (200). For example, the illustrated side plate (102) does not have a cooling channel (122), in which case the phase change material (200) can be filled in all of the hollow passages (120). However, this is an exemplary embodiment, and if a cooling passage (122) is configured to provide a cooling function to the side plate (102), similar to the base plate (101) of FIGS. 2 and 3, some of the hollow passages (120) may be filled with cooling passages (122), and some of the hollow passages (120) may be filled with phase change materials (200).

[0057] And, referring again to FIG. 1, the hollow passage (120) filled with the phase change material (200) is maintained in a state in which at least one end is open to the outside. For example, the illustrated pack structure (100) is manufactured by extrusion molding in a state in which both ends of the hollow passage (120) in the longitudinal direction (L) are open, and the phase change material (200) in a liquid state can be injected and solidified through one open end (the other end is temporarily sealed). In this way, after filling the hollow passage (120) of the pack structure (100) with the phase change material (200), at least one end of the open hollow passage (120) can be restored or maintained in the open state. This is because the phase change material (200) is intended to increase heat capacity, but if the battery pack is abnormally overheated and the phase change material (200) remains in a state in which it has absorbed a large amount of heat, the high-temperature phase change material (200) may have the adverse effect of promoting overheating of the battery pack. Therefore, once the phase change material (200) has absorbed a large amount of heat and become liquefied, it can be naturally discharged and removed from the pack structure (100) through the open end. In addition, since the phase change material (200) expands as it liquefies, if the phase change material (200) remains in a liquid state for a long time, it may have a negative effect on the durability of the pack structure (100) by continuously applying pressure to the sealed hollow passage (120). In this respect, in one embodiment of the present invention, the hollow passage (120) filled with the phase change material (200) can be configured to be maintained in an open state toward the outside, so that the phase change material (200) that has been phase-changed into a liquid can be naturally discharged to the outside. For example, when a battery pack including a battery cell is installed in a pack structure (100) and abnormal heat is generated in the battery pack, the generated heat is absorbed by the phase change material (200) filled inside the pack structure (100), and when it exceeds a specific phase transition temperature, the phase change material (200) can be liquefied and discharged to the outside.Meanwhile, in another embodiment, the heat capacity can be additionally increased by filling the phase change material (200) not only in the pack structure (100) but also in the battery cell and / or battery pack installed in the pack structure (100).

[0058] Meanwhile, the temperature set as the standard for causing the phase change material (200) to change from solid to liquid may correspond to an upper temperature limit that indicates a dangerous state in which thermal runaway, heat propagation, or ignition of the battery cell may occur in a temperature range in which a battery pack including a pack case (300) to which the pack structure (100) of the present invention is applied is determined to be in a normal operating state. For example, the temperature range in which the battery pack is determined to be in a normal operating state may be set to a range of approximately -40°C to 60°C. In this case, the phase change material (200) can have a property of causing a phase change from solid to liquid only when it exceeds 60°C, which is the upper limit of the normal temperature range. In other words, the phase change material (200) stably maintains a solid state in the normal temperature range, and can cause a phase change only when it reaches a certain temperature exceeding the upper temperature limit. By setting the liquefaction temperature of the phase change material (200) in this way, the phase change material (200) can be liquefied and discharged only in an emergency state where an abnormally high temperature occurs in the battery pack.

[0059] The upper limit of the normal temperature range set for the battery pack can be appropriately selected. For example, the upper limit of the temperature can be selected as a temperature in the range of about 60°C to 80°C, and a paraffin-based material can be selected as the phase change material (200) corresponding thereto. For example, the phase change material (200) suitable for these conditions can be at least one material selected from paraffin 140, paraffin 145, paraffin 150, paraffin 155, and paraffin 160. The numbers (140 to 160) distinguishing the paraffin-based materials indicate the temperature in Fahrenheit, and paraffin-based materials between paraffin 140 and paraffin 160 liquefy at a temperature of about 60°C to 71°C, and therefore are suitable for application to the pack structure (100) in which the upper limit of the temperature is selected as a range of about 60°C to 80°C.

[0060] Alternatively, the product name "RT100HC" manufactured by "Rubitherm Technologies GmbH", a company located in Berlin, Germany, is a phase change material (200) with a liquefaction point of approximately 99°C to 101°C, and a high heat capacity phase change material (200) with a heat capacity of approximately 180±7.5% (kJ / kg). Therefore, by applying "RT100HC" to the pack structure (100) of the present invention, the phase change material (200) can be configured to continuously absorb the heat of the battery cell for a considerably long period of time. However, since the liquefaction point of "RT100HC" is approximately 30°C to 40°C higher than that of the paraffin-based material described above, it may be necessary to increase the cooling capacity of the battery pack accordingly.

[0061]

[0062] [Second Embodiment]

[0063] FIG. 5 is a drawing showing an example in which a phase change material (200) is applied on a base plate (101) of a pack case (300) to which a pack structure (100) of the present invention is applied.

[0064] As described above in the first embodiment, the pack structure (100) of the present invention has a plurality of hollow passages (120) therein, and at least some of the hollow passages (120) are filled with a phase change material (200) that causes a phase change from solid to liquid when a specific temperature is exceeded. The embodiment of FIG. 5 illustrates a pack case (300) in which the pack structure (100) of the present invention is applied as a base plate (101) and / or a side plate (102), and not only is the phase change material (200) filled inside the pack structure (100), but the phase change material (200) is also applied to some areas on the base plate (101).

[0065] In the illustrated pack case (300), a plurality of battery cells are bundled in the form of a module or a block and mounted on a base plate (101), and the heat of the battery cells is transferred to the base plate (101) in the form of heat conduction. In order to improve the heat conduction of the battery cells and to ensure close contact and fixation of the battery module or battery block, a thermal resin (310) is applied to the mounting area according to one embodiment.

[0066] Since the thermal resin (310) is an expensive material, it is necessary to manage it so as not to over-apply it in an appropriate amount. In addition, since insulation treatment is required in areas where the thermal resin (310) is not applied, a process of attaching a PET film, for example, is required. Considering this, the phase change material (200) described in the first embodiment can be applied to the empty areas between the thermal resins (310). The phase change material (200) applied on the base plate (101) helps increase the heat capacity of the base plate (101) and allows insulation treatment to be performed more easily compared to the process of attaching a film.

[0067]

[0068] The present invention has been described in more detail through the drawings and examples. However, the configurations described in the drawings or examples described in this specification are merely embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

Claims

1. In a pack structure that forms at least a portion of a pack case and has a plurality of hollow passages therein, A pack structure, wherein at least some of the plurality of hollow passages are selectively filled with a phase change material that causes a phase change from solid to liquid when the temperature rises above a preset temperature.

2. In paragraph 1, The above phase change material is, A pack structure having a specific gravity smaller than that of the material forming the pack structure.

3. In paragraph 1, The above pack structure is, A pack structure that forms the base plate or side plate of a pack case.

4. In paragraph 3, The above pack structure is a base plate, The above base plate is a pack structure in which some of the plurality of hollow passages are filled with the phase change material, while the remaining hollow passages are heat sinks forming cooling channels.

5. In paragraph 4, The hollow passage filled with the above phase change material is A pack structure comprising a plurality of groups divided by the above cooling channels.

6. In paragraph 4, The above pack structure is a side plate, The above side plate is a pack structure in which the phase change material is filled for all of the plurality of hollow passages.

7. In paragraph 1, The above pack structure is formed integrally with the hollow passage by extrusion molding, A pack structure in which the hollow passage filled with the above phase change material is maintained in a state in which at least one end is open to the outside.

8. In paragraph 1, The temperature set as the standard for the above phase change material to change from solid to liquid is A pack structure corresponding to the upper limit of the temperature range at which a battery pack including a pack case to which the above pack structure is applied is judged to be in a normal operating state.

9. In paragraph 8, The upper limit of the temperature range at which the above battery pack is judged to be in normal operation is A pack structure having a temperature selected in the range of approximately 60°C to 80°C.

10. In paragraph 9, The above phase change material is, A pack structure made of paraffin-based material.

11. In paragraph 10, The above phase change material is, A pack structure comprising at least one material selected from paraffin 140, paraffin 145, paraffin 150, paraffin 155, and paraffin 160.

12. In paragraph 4, A pack structure in which the number and position of the hollow passages filled with the phase change material among the plurality of hollow passages and the number and position of the hollow passages forming the cooling path are determined in consideration of design factors such as cooling capacity, heat capacity, and weight.

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