Battery pack structure filled with phase change material

Abstract

The disclosed invention relates to a battery structure that forms at least a part of a battery case and includes a plurality of hollow channels therein, in which at least a part of the plurality of hollow channels is selectively filled with a phase change material that undergoes a phase change from a solid state to a liquid state when a preset temperature is exceeded.

Description

Technical Field

[0001] This disclosure relates to a battery pack structure included in a battery pack housing.

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2024-0086621, filed with the Korean Intellectual Property Office on July 2, 2024, the entire disclosure of which is incorporated herein by reference. Background Technology

[0003] Unlike primary batteries, secondary batteries are rechargeable and can be small in size and have large capacity. Therefore, much research and development has been conducted on secondary batteries in recent years. With technological advancements, increasing demand for mobile devices, and the growing focus on electric vehicles and energy storage systems in response to current environmental protection needs, the demand for secondary batteries as energy sources is rapidly increasing.

[0004] Based on the shape of the battery casing, secondary batteries are classified into coin-shaped, cylindrical, prismatic, and pouch-shaped batteries. In secondary batteries, the electrode assembly installed in the battery casing is a rechargeable power generation device with a stacked structure of electrodes and separators.

[0005] Since secondary batteries are used continuously for extended periods, it is necessary to effectively control the heat generated during the charging and discharging processes. See, for example, Korean Patent No. 10-2628603, granted on January 19, 2024. Summary of the Invention

[0006] Technical issues

[0007] This disclosure provides a battery pack structure that ensures sufficient thermal capacity to respond to thermal runaway occurring in a secondary battery, while maintaining the advantage of reduced weight.

[0008] The advantages of this disclosure are not limited to those described above, and other advantages will be readily apparent to those skilled in the art from the following description.

[0009] Technical solution

[0010] This disclosure relates to a battery pack structure configured to form at least a portion of a battery pack housing and having a plurality of hollow channels internally. At least a portion of the plurality of hollow channels is selectively filled with a phase change material that undergoes a phase change from solid to liquid at a temperature exceeding a preset temperature.

[0011] The specific gravity of the phase change material can be less than that of the material in the battery pack structure.

[0012] In one embodiment, the battery pack structure may form the bottom plate or side plate of the battery pack housing.

[0013] For example, the battery pack structure may be the base plate, and the base plate may be a heat sink, wherein a portion of the plurality of hollow channels is filled with the phase change material, and the remaining hollow channels are used as cooling channels.

[0014] The hollow channel filled with the phase change material is divided into multiple groups by the cooling channel.

[0015] In another embodiment, the battery pack structure may be the side plate, and the plurality of hollow channels in the side plate may be completely filled with the phase change material.

[0016] The battery pack structure including the hollow channel can be formed into a single piece by extrusion molding, and the hollow channel filled with the phase change material can maintain at least one end of it open to the outside.

[0017] The temperature set as the reference for the phase change material to undergo a phase change from solid to liquid can correspond to the upper limit of the temperature range for determining the normal operation of a battery pack, including the battery pack casing incorporating the battery pack structure.

[0018] For example, the upper limit of the temperature range for which the battery pack operates normally can be selected from a range of approximately 60°C to 80°C.

[0019] The phase change material can be a paraffin-based material.

[0020] 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.

[0021] The number and location of the hollow channels filled with the phase change material, as well as the number and location of the hollow channels used as cooling channels, can be determined by taking into account design factors such as cooling capacity, heat capacity, and weight.

[0022] Beneficial effects

[0023] According to the battery pack structure of this disclosure having the above-described structure, at least a portion of the plurality of hollow channels formed in the battery pack structure is filled with a phase change material undergoing a phase change from solid to liquid, and the phase change material absorbs ambient heat as sensible and latent heat until the phase change temperature is reached. Therefore, the overall heat capacity of the battery pack structure increases proportionally to the amount of phase change material filled.

[0024] Furthermore, when the phase change material is selected to have a smaller specific gravity than the material in the battery pack structure, the thermal capacity of the battery pack structure can be effectively increased while suppressing the increase in the overall weight of the battery pack structure.

[0025] The technical effects obtained from this disclosure are not limited to those described above, and other effects not described herein will be clearly understood by those skilled in the art based on the descriptions in the claims. Attached Figure Description

[0026] The accompanying drawings are merely illustrative of embodiments of this disclosure and, together with the description herein, serve to further facilitate understanding of the technical concept of this disclosure. Therefore, this disclosure should not be construed as limited to what is shown in the drawings.

[0027] Figure 1 This is a view showing the battery pack housing to which the battery pack structure according to an embodiment of the present disclosure can be applied.

[0028] Figure 2 It shows the application to Figure 1 A cross-sectional view of the bottom plate of the battery pack housing.

[0029] Figure 3 yes Figure 1 A magnified view of part of the letter "A".

[0030] Figure 4 It shows the application to Figure 1 A cross-sectional view of the side panel of the battery pack housing.

[0031] Figure 5 This is a view showing an example of applying a phase change material to the base plate of a battery pack housing to which the battery pack structure of this disclosure is applied.

[0032] In the various views of the accompanying drawings, corresponding reference numerals denote corresponding parts. The drawings presented are for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some elements in the drawings may be enlarged relative to other elements to aid in understanding the various embodiments. Furthermore, common but well-known elements that are useful or necessary in commercially viable embodiments are generally not depicted to facilitate less obstructive observation of these different embodiments. Detailed Implementation

[0033] Since this disclosure can be modified in various ways and includes various implementations, specific implementations of this disclosure will be described in detail below.

[0034] This disclosure is not limited to specific embodiments and should be interpreted as including all modifications, equivalents or substitutions that fall within the technical concept and scope of this disclosure.

[0035] In the following description, terms such as “comprising” and “having” are intended to indicate the presence of the features, numbers, steps, operations, components, parts and combinations thereof described herein, but should not be construed as excluding the presence or possible addition of one or more other features, numbers, steps, operations, components, parts and combinations thereof.

[0036] In the following description, when an element such as a layer, film, region, or plate is present "on" a particular portion, the description includes not only the case where the element is "directly" disposed on the particular portion, but also the case where another portion exists between the element and the particular portion. Similarly, when an element such as a layer, film, region, or plate is present "below" a particular portion, the description includes not only the case where the element is disposed "directly below" the particular portion, but also the case where another portion exists between the element and the particular portion. As used herein, the description "disposed of" can include not only the case where it is disposed on the upper side, but also the case where it is disposed on the lower side.

[0037] Secondary batteries are used for relatively long periods through repeated charging and discharging processes, and require effective control of the heat generated during use due to various reasons. For example, when secondary batteries cannot be effectively cooled, the temperature rises, leading to an increase in current, which in turn further increases the temperature, creating a positive feedback chain reaction that ultimately leads to a catastrophic state of thermal runaway.

[0038] To effectively dissipate the heat generated in secondary batteries, radiators (also known as cooling plates) in which coolant flows are widely used. Radiators form the bottom surface of an assembly of multiple secondary batteries, such as a battery pack comprising multiple secondary batteries, or are mounted on the bottom surface to perform a cooling function that absorbs the heat generated in the battery pack and dissipates it to the outside using coolant.

[0039] Based on their structure and manufacturing methods, radiators can be classified into brazed radiators and extruded radiators. Brazed radiators have a structure where two plates are brazed together to form a flow path. This provides high freedom in the design of the flow path, but it suffers from reduced structural rigidity due to the deterioration of the material's physical properties. Meanwhile, extruded radiators are manufactured as single units through extrusion molding. This ensures sufficient structural rigidity while achieving weight reduction, and the extrusion molding process simultaneously creates multiple hollow channels, effectively forming a coolant flow path. However, since extruded radiators may only form a straight flow path, appropriate design for providing the ports may be required to achieve efficient coolant flow.

[0040] Thus, while extruded radiators offer many advantages, including weight reduction, their light weight limits their heat absorption capacity in the event of thermal runaway, potentially making it difficult to control such situations solely through coolant circulation. To address this, filling in a portion of the hollow channels within the radiator can enhance resistance to thermal runaway; however, this significantly increases the weight of the battery pack casing, potentially leading to another problem, such as a loss of competitiveness.

[0041] This disclosure relates to a battery pack structure that forms at least a portion of a battery pack housing and includes a plurality of hollow channels, wherein at least a portion of the plurality of hollow channels is filled with a phase change material that undergoes a phase change from solid to liquid at a temperature exceeding a preset temperature.

[0042] Here, the phase change material can have a lower specific gravity than the materials used in the battery pack structure.

[0043] According to the battery pack structure of this disclosure having the above-described configuration, at least a portion of the plurality of hollow channels formed in the battery pack structure is filled with a phase change material undergoing a phase change from solid to liquid, and the phase change material absorbs ambient heat as sensible and latent heat until the phase change temperature is reached. Therefore, the overall thermal capacity of the battery pack structure increases proportionally to the amount of phase change material filled.

[0044] Furthermore, when the phase change material is selected to have a smaller specific gravity than the material of the battery pack structure, the heat capacity can be effectively increased while suppressing the increase in the overall weight of the battery pack structure.

[0045] Methods of implementing the present invention

[0046] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Here, directions such as front, back, up, down, left, and right (indicating relative positions) are used for ease of understanding the invention and, unless otherwise defined, refer to the directions shown in the drawings.

[0047] [First Implementation Method]

[0048] Figure 1This is a view illustrating a battery pack housing 300 to which a battery pack structure 100 according to an embodiment of the present disclosure can be applied. The battery pack housing 300 includes a base plate 101 forming a bottom surface and a plurality of side plates 102, which are walls surrounding all sides of the base plate 101. 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 may be mounted in the battery pack housing 300 in the form of modules (in which the plurality of battery cells are encapsulated in separate housings) or in the form of blocks (in which the plurality of battery cells are constrained by a plurality of frames).

[0049] The base plate 101 and the side plate 102 can be collectively referred to as the battery pack structure 100, which constitutes the frame structure of the battery pack housing 300. Figure 2 A cross-section of the base plate 101 according to an embodiment of the present disclosure is shown, and Figure 4 A cross-section of the side plate 102 according to an embodiment of the present disclosure is shown.

[0050] The base plate 101 corresponds to the battery pack structure 100 that forms the bottom surface of the battery pack housing 300. The base plate 101 includes a plurality of hollow channels 120 formed between a plurality of ribs 110, which are arranged to be spaced apart from each other along the entire length direction L. For example, as shown, the base plate 101 can be manufactured by extrusion molding. By extrusion molding, the entire base plate 101, including the ribs 110 and the hollow channels 120, can be formed as a single piece. Here, the length direction L indicates the direction of extrusion molding of the battery pack structure 100 (i.e., the direction in which the plurality of hollow channels 120 extend), and the width direction W indicates the direction perpendicular to the length direction L on the plane in which the plurality of hollow channels 120 are arranged to be spaced apart from each other.

[0051] A heat sink may be disposed on the bottom surface of the battery pack housing 300 to dissipate heat generated in the battery cells during charging and discharging. 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 such that a portion of a plurality of hollow channels 120 serves as a cooling channel 122, thereby acting as a heat sink.

[0052] See Figure 2 and Figure 3Port 130 is connected to a portion of a plurality of hollow channels 120, which are arranged to be spaced apart from each other in the width direction W. Each port 130 serves as a connector for connecting a pipe to each hollow channel 120, thereby serving as an inlet or outlet for cooling fluid. The hollow channels 120 connected to port 130 form cooling channels 122. The cooling channels 122 and the cooling fluid flowing therein suppress the temperature rise of the battery cells mounted on the base plate 101. Figure 2 The piping provided for configuring each port 130 as an inlet or outlet for cooling fluid is omitted.

[0053] Referring to the base plate 101 shown, port 130 is connected to only a portion of the plurality of hollow channels 120. For example, only a portion of the hollow channels 120 constitutes a cooling channel 122. In the prior art, the remaining hollow channels 120 are left as cavities to reduce the weight of the large base plate 101. However, as the weight of the base plate 101 decreases, the total heat capacity of the base plate 101 decreases. When the heat capacity of the base plate 101 decreases, the capacity to absorb heat generated in the battery cells and dissipate that heat to the outside decreases. In this case, no major problems will occur as long as the battery pack is operating normally, but in situations that could lead to thermal runaway, heat propagation, or fire hazards, the reduced capacity to absorb heat from the battery cells may be detrimental in suppressing temperature rise.

[0054] This disclosure addresses the problem of reduced heat capacity in a battery pack structure 100 comprising multiple hollow channels 120. To this end, at least a portion of the multiple hollow channels 120 is filled with a phase change material 200, which undergoes a phase change from solid to liquid when a preset temperature is exceeded. Furthermore, the phase change material 200 can be selected to have a lower specific gravity than the material of the battery pack structure 100 (e.g., aluminum alloy and stainless steel). Figure 3 yes Figure 1 An enlarged view of part “A” in the image shows a portion of the hollow channel 120 connected to port 130 to form cooling channel 122, and the remaining hollow channel 120 is filled with phase change material 200.

[0055] The phase change material 200, filled in the hollow channel 120, remains solid at a specific temperature or lower. For example, the phase change material 200 remains solid at room temperature or within a reference temperature range, within which the battery pack can be determined to be in normal operating condition. The solid phase change material 200 absorbs ambient heat (sensible heat) and undergoes a liquid phase change (latent heat) when a specific temperature is reached. When the specific temperature is exceeded, the phase change material 200 completely liquefies.

[0056] In this way, the phase change material 200 plays a role in absorbing heat introduced into the battery pack structure 100, and absorbs a large amount of heat in the form of latent heat during the phase change that occurs at a specific temperature. Therefore, by filling the hollow channel 120, which is kept as a cavity in the prior art, with the phase change material 200, the heat capacity of the battery pack structure 100 (e.g., the base plate 101) is significantly increased.

[0057] Refer to Figure 2 and Figure 3 Hollow channels 120 filled with phase change material 200 are connected to cooling channels 122 at port 130 and divided into multiple groups. For example, the number of hollow channels 120 constituting cooling channels 122 and the number of hollow channels 120 filled with phase change material 200 may not match one-to-one and may be different from each other. Furthermore, although the accompanying drawings show an example of phase change material 200 filling all hollow channels 120 that do not constitute cooling channels 122, a portion of such hollow channels 120 may remain as cavities unfilled with phase change material 200. In this way, in the base plate 101 serving as a heat sink, for example, the number and location of hollow channels 120 constituting cooling channels 122 and the number and location of hollow channels 120 filled with phase change material 200 can be appropriately determined taking into account various design factors such as cooling capacity, heat capacity, and weight.

[0058] Figure 4 This is a view showing another example of the battery pack structure 100, and illustrating its application to... Figure 1 The cross-section of the side plate 102 of the battery pack housing 300. Figure 4 The side panel 102 shown includes a plurality of hollow channels 120 divided by internal ribs 110 within the side panel 102, and all of the plurality of hollow channels 120 are filled with phase change material 200. For example, the side panel 102 shown does not include cooling channels 122, and in this case, all hollow channels 120 may be filled with phase change material 200. This embodiment is merely an example, and when cooling channels 122 are also formed in the side panel 102 to provide a cooling function, it is obvious that... Figure 2 and Figure 3 Similar to the base plate 101, a portion of the hollow channel 120 can form a cooling channel 122, and another portion of the hollow channel 120 can be filled with a phase change material 200.

[0059] Return to reference Figure 1Each hollow channel 120 filled with phase change material 200 remains open at at least one end. For example, by extrusion molding, the illustrated battery pack structure 100 can be manufactured with both ends open in the longitudinal direction L of the hollow channel 120, and the liquid phase change material 200 can be injected from one open end (while the other end is temporarily sealed) and solidified. After filling the hollow channel 120 of the battery pack structure 100 with phase change material 200, at least one end of the hollow channel 120 can be restored to or remain open. This is because the phase change material 200 is used to increase heat capacity; therefore, in the event of abnormal overheating of the battery pack, if the phase change material 200 retains the heat after absorbing a large amount of heat, the hot phase change material 200 could alternatively lead to the adverse effect of accelerating battery pack overheating. Therefore, the phase change material 200 liquefied after absorbing a large amount of heat can be removed by smoothly draining from the battery pack structure 100 to the outside via the open end. Furthermore, the phase change material 200 expands in volume upon liquefaction. Therefore, if the phase change material 200 remains in a liquid state for an extended period, the expanded phase change material 200 can exert continuous pressure on the sealed hollow channel 120, thereby adversely affecting the durability of the battery pack structure 100. In embodiments of this disclosure, the hollow channel 120 filled with the phase change material 200 can be configured to remain open to the outside, allowing the liquefied phase change material 200 to be smoothly discharged to the outside. For example, when abnormal heat is generated in the battery pack, including the battery cells, while the battery pack is installed in the battery pack structure 100, the phase change material 200 filled in the battery pack structure 100 can absorb the generated heat and liquefy and discharge to the outside when a certain phase change temperature is exceeded. In another embodiment of the invention, the phase change material 200 can be filled not only in the battery pack structure 100 but also in the battery cells and / or battery pack installed on the battery pack structure 100 to further increase the heat capacity.

[0060] Simultaneously, the reference temperature set for the phase change material 200 to undergo a phase change from solid to liquid can correspond to the following upper temperature limit: within the temperature range that determines the normal operation of the battery pack (including the battery pack housing 300 to which the battery pack structure 100 of this disclosure is applied), it warns of potential dangers such as thermal runaway, heat propagation, or fire in the battery cells. For example, the temperature range within which the battery pack is determined to operate normally can be set to approximately -40°C to 60°C. In this case, the phase change material 200 can have the physical property of undergoing a phase change from solid to liquid only when the temperature exceeds 60°C (which is the upper limit of the normal temperature range). In other words, the phase change material 200 remains stably solid within the normal temperature range and can undergo a phase change only when a specific temperature exceeding the upper temperature limit is reached. In this way, the liquefaction temperature of the phase change material 200 is set such that the phase change material 200 can liquefy and be discharged in an emergency situation where abnormally high temperatures occur in the battery pack.

[0061] The upper limit of the normal temperature range set for the battery pack can be appropriately selected. For example, the upper temperature limit can be set to a specific temperature in the range of approximately 60°C to 80°C, and the corresponding phase change material 200 can be a paraffin-based material. For example, the phase change material 200 suitable for this condition can be at least one material selected from paraffin 140, paraffin 145, paraffin 150, paraffin 155, and paraffin 160. The numbers 140 to 160, which distinguish paraffin-based materials, indicate temperatures in degrees Fahrenheit, and since paraffin-based materials of paraffin 140 to paraffin 160 liquefy at temperatures between approximately 60°C and 71°C, they can be appropriately applied to battery pack structures 100 in which the upper temperature limit is selected in the range of 60°C to 80°C.

[0062] "RT100HC," manufactured by Rubtherm Technologies GmbH in Berlin, Germany, is a phase change material 200 with a liquefaction point between approximately 99°C and 101°C and a high heat capacity of approximately 180 ± 7.5% (kJ / kg). By applying "RT100HC" to the battery pack structure 100 of this disclosure, the phase change material 200 can continuously absorb heat from the battery cells over a significantly extended period. However, since the liquefaction point of "RT100HC" is approximately 30°C to 40°C higher than that of the aforementioned paraffin-based materials, it may also be necessary to increase the cooling capacity of the battery pack.

[0063] [Second Implementation]

[0064] Figure 5 This is a view showing an example of phase change material 200 being applied to the base plate 101 of the battery pack housing 300 to which the battery pack structure 100 of the present invention is applied.

[0065] As described above, in the first embodiment, the battery pack structure 100 of this disclosure includes a plurality of hollow channels 120, and at least a portion of the hollow channels 120 is filled with a phase change material 200, which undergoes a phase change from solid to liquid when a certain temperature is exceeded. Figure 5 The embodiment shows a battery pack housing 300, wherein a base plate 101 and / or a side plate 102 serve as the battery pack structure 100 of this disclosure, and a phase change material 200 is not only filled in the battery pack structure 100, but also applied to a specific area on the base plate 101.

[0066] In the battery pack housing 300 shown, multiple battery cells are grouped and mounted on a base plate 101 in the form of modules or blocks, and the heat of the battery cells is transferred to the base plate 101 by thermal conduction. According to one embodiment, in order to improve the thermal conduction of these battery cells and enhance the tight contact and fixation of these battery modules or blocks, a thermal resin 310 is applied to the mounting area.

[0067] Since the thermosetting resin 310 is an expensive material, its application amount needs to be properly controlled to avoid over-application. Furthermore, insulation is required in areas where the thermosetting resin 310 is not applied; therefore, for example, a step of attaching a PET film is necessary. Taking these points into consideration, the phase change material 200 described in the first embodiment can be applied to the empty areas between the areas of the thermosetting resin 310. Applying the phase change material 200 to the substrate 101 helps increase the heat capacity of the substrate 101, and insulation can be easily performed compared to the step of attaching a film.

[0068] The present disclosure has been described in detail with reference to the accompanying drawings and embodiments. However, it is to be understood that the configurations described in the drawings and embodiments herein are merely examples of the present disclosure and do not represent the technical ideas of the present disclosure in detail, and various equivalents and modifications can be made in place of the present disclosure.

Claims

1. A battery pack structure, said battery pack structure being configured to form at least a portion of a battery pack housing and having a plurality of hollow channels inside, in, At least a portion of the plurality of hollow channels are selectively filled with a phase change material that undergoes a phase change from solid to liquid when the temperature exceeds a preset temperature.

2. The battery pack structure according to claim 1, wherein, The specific gravity of the phase change material is less than that of the material in the battery pack structure.

3. The battery pack structure according to claim 1, wherein, The battery pack structure forms the bottom plate or side plate of the battery pack housing.

4. The battery pack structure according to claim 3, wherein, The battery pack structure is the base plate, and The base plate is a heat sink, wherein a portion of the plurality of hollow channels is filled with the phase change material, and the remaining hollow channels are used as cooling channels.

5. The battery pack structure according to claim 4, wherein, The hollow channels filled with the phase change material are divided into multiple groups by the cooling channels.

6. The battery pack structure according to claim 4, wherein, The battery pack structure is the side plate, and In the side plate, all of the plurality of hollow channels are filled with the phase change material.

7. The battery pack structure according to claim 1, wherein, The battery pack structure, including the hollow channel, is formed into a single piece by extrusion molding, and At least one end of the hollow channel filled with the phase change material remains open to the outside.

8. The battery pack structure according to claim 1, wherein, The temperature set as the reference for the phase change material to undergo a phase change from solid to liquid corresponds to the upper limit of the temperature range that determines the normal operation of the battery pack, which includes the battery pack housing in which the battery pack structure is applied.

9. The battery pack structure according to claim 8, wherein, The upper limit of the temperature range for which the battery pack operates normally is selected from a range of approximately 60 °C to 80 °C.

10. The battery pack structure according to claim 9, wherein, The phase change material is a paraffin-based material.

11. The battery pack structure according to claim 10, wherein, The phase change material is at least one material selected from paraffin 140, paraffin 145, paraffin 150, paraffin 155 and paraffin 160.

12. The battery pack structure according to claim 4, wherein, The number and location of the hollow channels filled with the phase change material, as well as the number and location of the hollow channels used as cooling channels, are determined taking into account design factors such as cooling capacity, heat capacity, and weight.

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