Heat transfer device, secondary battery comprising same, and secondary battery module

Abstract

A heat transfer device, a secondary battery including the same, and a secondary battery module are provided. The heat transfer device includes a main body mounted between a case of the secondary battery and a junction between a current collector and a daughter board in the secondary battery. The main body includes a first contact surface in contact with the joint portion to receive heat from the joint portion, and a second contact surface formed opposite the first contact surface, the second contact surface being in contact with the housing to transfer heat from the first contact surface to the housing. A secondary battery may include the heat transfer device, and a vehicle may include the secondary battery.

Description

[0001] This application claims the priority and benefit of Korean Patent Application No. 10-2024-0013052, filed with the Korean Intellectual Property Office on January 29, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] The present disclosure relates to a secondary battery, and more particularly, to a secondary battery including a heat transfer device for directly transferring heat inside the secondary battery to a case. Background Art

[0003] Unlike a primary battery that is not designed to be charged, a secondary battery is designed to be discharged and recharged. Low-capacity secondary batteries are used in small portable electronic devices such as smart phones, feature phones, laptop computers, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for driving motors of hybrid vehicles or electric vehicles, batteries for power storage, and the like.

[0004] A secondary battery generally includes an electrode assembly composed of a positive electrode and a negative electrode, a case for accommodating the electrode assembly, a terminal part connected to the electrode assembly, various components connecting the terminal part and the electrode assembly, etc., and the various components generate a large amount of heat.

[0005] The above information is only intended to improve the understanding of the prior art of the present disclosure, and thus may also include information that does not constitute the prior art. Summary of the Invention

[0006] Various components connecting the terminal part and the electrode assembly of the secondary battery, particularly the joint between the current collector and the sub-board in the secondary battery, generate a large amount of heat, which may cause the secondary battery to rupture. In addition, the temperature rise in the secondary battery affects the performance of the secondary battery. Therefore, various embodiments describe herein a heat transfer structure provided inside the secondary battery to prevent the temperature rise and thus prevent the performance degradation of the secondary battery.

[0007] The present disclosure is not limited to the above object, and other objects of the present disclosure will be clearly understood by those skilled in the art from the following description.

[0008] In an embodiment, a heat transfer device is provided, which includes a main body configured to be mounted between a case of the secondary battery and a joint between a current collector and a sub-board in the secondary battery. The main body includes a first contact surface configured to contact the joint to receive heat from the joint and a second contact surface formed opposite to the first contact surface, and the second contact surface is configured to contact the case to transfer heat from the first contact surface to the case.

[0009] In another embodiment, a secondary battery is provided. The secondary battery includes a case configured to accommodate an electrode assembly, a terminal portion connected to the electrode assembly, a sub-board connecting the electrode assembly and the terminal portion, a current collector, and a heat transfer device installed between the case and a joint portion between the current collector and the sub-board. The joint portion is between the current collector and the sub-board, and the heat transfer device is configured to transfer heat from the joint portion to the case.

[0010] In another embodiment, a vehicle including a secondary battery pack is provided. The secondary battery pack is manufactured by using a secondary battery having a heat transfer device with the above-described configuration.

[0011] According to an embodiment of the present disclosure, the heat transfer device is installed between the case of the secondary battery and the joint portion between the current collector and the sub-board in the secondary battery to transfer heat generated at the joint portion to the case. Therefore, it is possible to prevent deterioration of the performance of the secondary battery due to an increase in the temperature in the secondary battery.

[0012] In addition, in a vehicle using a secondary battery including the heat transfer device according to the present disclosure, deterioration of the performance of the secondary battery can be prevented, thereby improving the performance of the vehicle (such as mileage and output). Furthermore, safety can be improved by preventing gas emissions and fires caused by an increase in the temperature inside the secondary battery.

[0013] The present disclosure is not limited to the above effects, and those skilled in the art will clearly understand other effects of the present disclosure from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings illustrate preferred embodiments of the present disclosure and are used, together with the detailed description of the present disclosure, to further describe aspects and features of the present disclosure. Therefore, the present disclosure should not be construed as being limited to the drawings, in which: Figure 1A is a top perspective view of a prismatic secondary battery; Figure 1B is a cross-sectional view taken along line I-I’ of Figure 1A ; Figure 2A is an enlarged cross-sectional view showing a main part of a secondary battery to which a heat transfer device according to an embodiment of the present disclosure can be applied; Figure 2B is a perspective view showing a main part of a secondary battery without a case to which a heat transfer device according to an embodiment of the present disclosure can be applied; Figure 3 is a diagram schematically showing a heat transfer device according to a first embodiment of the present disclosure; Figure 4 is a diagram showing a state in which a heat transfer device according to an embodiment of the present disclosure is applied to a secondary battery; Figure 5is a diagram showing heat transfer without applying the heat transfer device according to an embodiment of the present disclosure; Figure 6 is a diagram showing heat transfer when applying the heat transfer device according to an embodiment of the present disclosure; Figure 7 is a graph showing the relationship between the maximum temperature and the heat flux with respect to the thermal conductivity of the heat transfer device according to an embodiment of the present disclosure; Figure 8A and Figure 8B is a diagram showing the dimensions to be considered in the heat transfer device according to an embodiment of the present disclosure; Figure 9 is a diagram schematically showing a heat transfer device according to a second embodiment of the present disclosure; Figure 10 is a diagram schematically showing a heat transfer device according to a third embodiment of the present disclosure; Figure 11 is an exemplary diagram of a secondary battery module in which a secondary battery is arranged according to an embodiment of the present disclosure; Figure 12 is including Figure 11 an exemplary diagram of a secondary battery pack including the secondary battery module shown in; and Figure 13 is including Figure 12 a conceptual diagram of a vehicle including the secondary battery pack shown in. Detailed Description of the Embodiment

[0015] Exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Before the description, it is worth noting that the terms or words used in this specification and the claims should not be construed as being limited to the ordinary meaning or dictionary meaning, but should be understood as having a meaning and concept consistent with the spirit of the present disclosure based on the principle that the inventor can appropriately define each term so as to describe his / her own invention in the best possible way. Therefore, since the embodiments described in this specification and the configurations shown in the drawings are only examples of the present disclosure and do not cover all the technical concepts of the present disclosure, it should be understood that various changes and modifications can be made.

[0016] It will also be understood that when the terms "comprising / including" and / or their variants are used herein, it indicates the presence of the stated features, integers, steps, operations, elements, components, and / or groups thereof, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0017] To facilitate the understanding of the present disclosure, the accompanying drawings are not drawn to scale and some components may be exaggerated in size. It should be noted that in different embodiments, the same reference numerals denote the same components.

[0018] Referring to two compared elements, features, etc. as "the same" means that they are "substantially the same". Thus, the phrase "substantially the same" can include deviations that are considered low in the art, e.g., deviations of 5% or less. The uniformity of any parameter in a given area can mean that it is uniform from an average perspective.

[0019] Although terms such as "first" and / or "second" are used to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, unless specifically stated to the contrary, the first component can be referred to as the second component without departing from the teachings of the exemplary embodiments.

[0020] Throughout the specification, unless otherwise stated, each element can be single or multiple.

[0021] Arranging any component "above (or below)" or "on (or under)" a component can mean setting any such component in contact with the upper (or lower) surface of the component, and other components can be placed between the component and any such component disposed on (or under) the component.

[0022] It will be understood that when a component is referred to as being "connected", "coupled", or "joined" to another component, it can not only be directly "connected", "coupled", or "joined" to the other component, but can also be indirectly "connected", "coupled", or "joined" to the other component with other elements disposed therebetween.

[0023] As used herein, the term "and / or" includes any combination and all combinations of one or more of the associated listed items. When describing embodiments of the present disclosure, the use of "may" relates to "one or more embodiments of the present disclosure". Expressions such as "at least one of...", "one or more", after / before a list of elements, modify the entire list of elements rather than individual elements in the list.

[0024] Throughout the specification, unless otherwise stated, when stating "A and / or B", this means A, B, or A and B. Additionally, unless specifically stated to the contrary, when stating "C to D", this means C or greater and D or less.

[0025] When phrases such as "at least one of A, B, and C", "at least one of A, B, or C", "at least one selected from the group consisting of A, B, and C", or "at least one selected from among A, B, and C" are used to indicate a list of elements A, B, and C, the phrase can refer to any suitable combination and all suitable combinations.

[0026] The term "use" may be considered synonymous with the term "utilization". As used herein, the terms "substantially", "about" and similar terms are used as approximate terms and not as terms of degree, and are intended to account for the inherent variations of measured or calculated values that would be recognized by a person of ordinary skill in the art.

[0027] It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, first component, first region, first layer or first section discussed below may be referred to as a second element, second component, second region, second layer or second section without departing from the teachings of the exemplary embodiments.

[0028] For ease of explanation, when describing the relationship of one element or feature to another element or feature as shown in the drawings, spatial relative terms such as "under", "below", "beneath", "above" and "on" may be used herein. It will be understood that the spatial relative positions are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawings is turned over, any element described as "under" or "beneath" another element will then be oriented "above" or "on" the other element. Thus, the term "under" can include both upward and downward directions.

[0029] The terms used herein are for the purpose of describing embodiments of the present disclosure and are not intended to limit the present disclosure.

[0030] Examples of secondary batteries include coin-type, cylindrical, prismatic and pouch-type. The present disclosure is substantially applicable to prismatic secondary batteries. Therefore, before describing embodiments of the present disclosure, prismatic secondary batteries will be briefly described first.

[0031] Figure 1A is a top perspective view of a prismatic secondary battery. Figure 1B is a cross-sectional view taken along line I-I' of Figure 1A

[0032] First, the appearance of the secondary battery shown in Figure 1A will be described.

[0033] A case 51 defines the overall appearance of the prismatic secondary battery and may be made of a conductive metal such as aluminum, aluminum alloy or nickel-plated steel. In addition, the case 51 can provide a space for accommodating an electrode assembly therein.

[0034] The lid assembly 60 may include a cover plate 61 that covers an opening of the housing 51, and the lid assembly 60 and the cover plate 61 may be made of a conductive material. Here, the first terminal 62 and the second terminal 63 may be electrically connected to the corresponding positive electrode and negative electrode (or negative electrode and positive electrode) inside the housing, and may be mounted to protrude outward through the cover plate 61.

[0035] The cover plate 61 may be provided with an electrolyte injection port 64 formed to mount a sealing plug and an exhaust port 66 formed with a notch 65. The exhaust port 66 is used for exhausting the secondary battery, that is, for discharging the gas generated inside the secondary battery.

[0036] Referring Figure 1B , the internal structure of the prismatic secondary battery and the coupling structure with the lid assembly 60 will be described.

[0037] As Figure 1B shown in, the prismatic secondary battery may include an electrode assembly 40, a first current collector part 41, a first terminal 62, a second current collector part 42, a second terminal 63, and a lid assembly 60.

[0038] The electrode assembly 40 may be formed by winding or stacking a laminate of a first electrode plate, a separator, and a second electrode plate in the form of a sheet or film. When the electrode assembly 40 is a wound laminate, it may have a winding axis parallel to the length direction of the housing. The electrode assembly 40 may be a stacked type instead of a wound type, but the shape of the electrode assembly 40 is not limited in the present disclosure. Additionally, the electrode assembly 40 may be a Z-stack electrode assembly in which the first electrode plate and the second electrode plate are inserted on both sides of a separator bent into a Z-stack. Further, the electrode assembly 40 may include one or more electrode assemblies that are stacked such that their long sides are adjacent to each other and are accommodated in the housing, and the number of electrode assemblies is not limited in the present disclosure. The electrode assembly 40 may have a first electrode plate serving as a negative electrode and a second electrode plate serving as a positive electrode, or vice versa.

[0039] The first electrode plate may be formed by coating a first electrode active material such as graphite or carbon onto a first electrode current collector plate made of a metal foil such as copper, copper alloy, nickel, or nickel alloy. The first electrode plate may include a first electrode tab (or first uncoated part) 43 as an area where the first electrode active material is not coated. The first electrode tab 43 may serve as a current flow path between the first electrode plate and the first current collector part 41. In some examples, the first electrode tab 43 may be formed by pre-cutting the first electrode plate during the manufacture of the first electrode plate so that it protrudes to one side, and may protrude further to one side compared to the separator without separate cutting.

[0040] The second electrode plate can be formed by coating a second electrode active material such as a transition metal oxide onto a substrate made of a metal foil such as aluminum or an aluminum alloy. The second electrode plate can include a second electrode tab (or second uncoated portion) 44 that is an area where the second electrode active material is not coated. The second electrode tab 44 can serve as a current flow path between the second electrode plate and the second current collector portion 42. In some examples, the second electrode tab 44 can be formed by pre-cutting the second electrode plate during the manufacture of the second electrode plate so that it protrudes to the other side, and can protrude further to the other side compared to the separator without separate cutting.

[0041] In some embodiments, the first electrode tab 43 can be located on the right end side of the electrode assembly 40, and the second electrode tab 44 can be located on the left end side of the electrode assembly 40. Alternatively, the first electrode tab 43 and the second electrode tab 44 can be located on one end side of the electrode assembly 40 in the same direction. Here, for ease of explanation, based on Figure 1B the secondary battery shown in, the left and right are represented. When the secondary battery rotates left and right or up and down, the position of the secondary battery can change.

[0042] The separator is used to prevent a short circuit between the first electrode plate and the second electrode plate while allowing lithium ions to migrate between the first electrode plate and the second electrode plate. The separator can be made of, for example, a polyethylene film, a polypropylene film, a polyethylene - polypropylene film, etc.

[0043] As described above, the first electrode tab 43 of the first electrode plate and the second electrode tab 44 of the second electrode plate extend from both ends of the electrode assembly 40. In some embodiments, the electrode assembly 40 can be housed in a housing 51 together with an electrolyte.

[0044] In the electrode assembly 40, the first current collector portion 41 and the second current collector portion 42 can be respectively welded and connected to the first electrode tab 43 extending from the first electrode plate and the second electrode tab 44 extending from the second electrode plate.

[0045] As referred to Figure 1A described, the first current collector portion 41 and the second current collector portion 42 are respectively connected to the first terminal 62 and the second terminal 63 through terminal pins 67. In some embodiments, the terminal pins 67 can each have an outer peripheral surface that is threaded and can be fastened to the first terminal 62 and the second terminal 63 by tightening. However, the present disclosure is not limited thereto. For example, the terminal pins 67 can also be joined to the first terminal 62 and the second terminal 63 by riveting or welding.

[0046] Figure 2A is an enlarged cross-sectional view showing the main part of a secondary battery to which a heat transfer device according to an embodiment of the present disclosure can be applied.Figure 2B is a perspective view showing a main part of a secondary battery without a case to which a heat transfer device according to an embodiment of the present disclosure can be applied.

[0047] Referring to Figure 2A and Figure 2B , the secondary battery may include an electrode assembly 100, a case 200 for accommodating the electrode assembly 100, and a cover assembly 300 coupled to the case 200.

[0048] The cover assembly 300 may include a cover plate 310 coupled to the case 200, a terminal portion 320, an insulating member 330, and a current collector portion 340.

[0049] The cover plate 310 is in the form of a substantially rectangular plate. The cover plate 310 may be made of the same material as the case 200. As an example, the size of the cover plate 310 may correspond to the inner size of the opening in the case 200. The cover plate 310 may be coupled to the case 200 by, for example, laser welding. The cover plate 310 may be formed with a terminal hole and a groove for coupling to the terminal portion 320, a liquid injection hole, an exhaust hole for coupling to an exhaust port, etc. The exhaust port is for discharging gas by breaking when the internal pressure of the secondary battery increases, and a typical exhaust port structure may be applied to the exhaust port.

[0050] The terminal portion 320 may include a terminal pin 322 and a terminal plate 324. The terminal portion 320 may have a positive polarity or a negative polarity. The terminal portion 320 may have the same structure as Figure 2A and Figure 2B regardless of the polarity.

[0051] The terminal pin 322 has a substantially cylindrical shape. The terminal pin 322 is electrically connected to a current collector 342 of the current collector portion 340 (to be described later) to be electrically connected to a first electrode plate or a second electrode plate of the electrode assembly 100. During manufacturing, with the pin insulator 334 of the insulating member 330 (to be described later) inserted into the cover plate 310, the lower portion of the terminal pin 322 may be sequentially inserted through the cover plate 310, the insulating plate 332, and the current collector 342. Then the terminal plate 324 may be placed on the terminal pin 322, and the upper and lower ends of the terminal pin 322 may be pressed and deformed to fix the terminal pin 322 and the terminal plate 324 and to fix the terminal pin 322 and the current collector 342. If necessary, the terminal pin 322 and the current collector 342 may be fixed by welding the lower end of the terminal pin 322 to a part of the lower surface of the current collector 342.

[0052] The terminal plate 324 is disposed at the top of the terminal portion 320 and is made of a conductive material to electrically connect the secondary battery to the outside of the secondary battery. The terminal plate 324 has a substantially plate shape and may be disposed parallel to the top of the electrode assembly 100. The terminal plate 324 has a terminal hole formed therethrough for inserting the terminal pin 322 therethrough. The terminal plate 324 is seated on the terminal pin 322, and the terminal pin 322 is inserted into the cover plate 310. Then, by pressing the upper end of the terminal pin 322 and deforming it, the terminal plate 324 can be coupled and fixed to the terminal pin 322.

[0053] The insulating member 330 includes an insulating plate 332, a pin insulator 334, and an upper insulator 336. The components of the insulating member may all be made of an insulating material and may be manufactured, for example, by injection molding.

[0054] The insulating plate 332 is in the form of a substantially rectangular plate. The insulating plate 332 is in close contact with the lower surface of the cover plate 310 to insulate the cover plate 310 and the electrode assembly 100 from each other. In addition, the insulating plate 332 is for insulating the current collecting structure (described later) and the cover plate 310 from each other. Thus, the insulating plate 332 may have side surfaces extending downward along its edges. The side surfaces may be formed along the entire edge of the insulating plate 332 or may be formed only on a part of the edge of the insulating plate 332. The insulating plate 332 may have a shape of a surface or a side surface different from the shape of the components that need to be insulated. The insulating plate 332 may have one or more through holes formed corresponding to the positions of the terminal holes and the vent holes of the cover plate 310. A part of the current collector portion 340 may be disposed below the insulating plate 332.

[0055] The pin insulator 334 is for insulating the terminal pin 322 of the terminal portion 320 and the cover plate 310 from each other and has a substantially cylindrical shape.

[0056] The upper insulator 336 is disposed between the terminal plate 324 and the cover plate 310. The upper insulator 336 may be in the form of a rectangular plate corresponding to the shape of the terminal plate 324. The upper insulator 336 is larger than the terminal plate 324 and has a groove for seating the terminal plate 324. The upper insulator 336 has a hole formed therethrough at a position corresponding to the terminal hole of the cover plate 310. The terminal pin 322 is placed in the hole.

[0057] The current collector portion 340 is for electrically connecting the first electrode plate or the second electrode plate to the terminal portion 320. The current collector portion 340 may include a current collector 342 electrically connected to the terminal portion 320 and a sub-plate 344 electrically connected to the current collector 342 and the electrode assembly 100.

[0058] The current collector 342 is made of a conductive material having a preset thickness and can be formed by vertically bending a plate. The current collector 342 has through holes formed at positions corresponding to the terminal holes of the cover plate 310 and the through holes of the insulating plate 332. The terminal pins 322 are inserted into the through holes of the current collector 342. Based on the bent portion of the current collector 342, the upper side of the bent portion is defined as the upper part, and the portion extending downward from the bent portion is defined as the lower part. A part of the upper part of the current collector 342 is insulated by contacting the lower surface of the insulating plate 332. The outer surface of the lower part of the current collector 342 contacts one side of the daughter board 344. The current collector 342 and the daughter board 344 can be connected by laser welding or the like.

[0059] The daughter board 344 is made of a conductive material having a preset width and length, and the daughter board 344 can have a substantially plate shape. One end (upper end) of the daughter board 344 can be welded while contacting the lower part of the current collector 342. If the surface of the daughter board 344 facing the electrode assembly 100 is defined as the inner surface, and the surface of the daughter board 344 facing the short side of the housing 200 is defined as the outer surface, then the positive electrode tab (or negative electrode tab) 110 of the electrode assembly 100 can be connected to the inner surface. The connection portion of the daughter board 344 with the current collector 342 can be defined as the first connection portion 344a, and the connection portion of the daughter board 344 with the electrode tab 110 can be defined as the second connection portion 344b. The daughter board 344 can be configured such that the first connection portion 344a and the second connection portion 344b are bent at a predetermined angle. As an example, the second connection portion 344b can be arranged such that its inner surface bends from the first connection portion 344a toward the electrode assembly 100 and lies in the same plane as the inner surface of the current collector 342. Optionally, the second connection portion 344b can be arranged such that its inner surface is closer to the electrode assembly 100 than the inner surface of the current collector 342. The inner surface of the second connection portion 344b can be connected to the electrode tab 110 by welding. Therefore, the vertical length of the second connection portion 344b can correspond to or be slightly greater than the vertical length of the electrode tab 110. The width of the second connection portion 344b can also correspond to or be slightly greater than the width of a single electrode tab 110 welded together. Additionally, the second connection portion 344b can have a plurality of concave welding grooves 344c formed on its outer surface. The plurality of welding grooves 344c can be formed in Figure 2A and Figure 2B the width direction of the second connection portion 344b in. The welding between the second connection portion 344b and the electrode tab 110 can be formed on each of the welding grooves 344c.

[0060] As described above, the secondary battery includes various components that connect the terminal portion 320 and the electrode assembly 100, and these components generate a large amount of heat.

[0061] Specifically, a large amount of heat is generated at the joint where the current collector 342 and the sub-board 344 of the current collector part 340 are joined to each other. This joint is a region with increased resistance due to welding and geometric features (bending), which inevitably generates heat. The generation of heat can cause damage to the current collector part 340. When the temperature inside the secondary battery reaches about 80 degrees Celsius, the electrolyte begins to decompose, which affects the performance of the secondary battery.

[0062] Therefore, the heat transfer device according to an embodiment of the present disclosure can be arranged to prevent rupture or performance degradation caused by the generation of heat in the secondary battery. Hereinafter, the heat transfer device according to an embodiment of the present disclosure and the secondary battery including the heat transfer device will be described.

[0063] Figure 3 is a diagram schematically showing a heat transfer device according to a first embodiment of the present disclosure.

[0064] Refer to Figure 3 , the heat transfer device denoted by reference numeral 350 according to a first embodiment of the present disclosure may include a first body 352, a second body 354, and a fastener 356. The first body 352 is installed between the housing 200 and the joint between the current collector 342 and the sub-board 344 in the secondary battery. The second body 354 extends from the first body 352 to surround the joint. The fastener 356 fastens the first body 352 and the second body 354 to prevent the first body 352 and the second body 354 from separating from the joint.

[0065] The first body 352 may include a first contact surface 352a and a second contact surface 352b. The first contact surface 352a contacts the joint to receive heat from the joint, and the second contact surface 352b is formed to face the first contact surface 352a and contacts the housing 200 to transfer heat from the first contact surface 352a to the housing 200.

[0066] Figure 4 is a diagram showing a state in which the heat transfer device according to an embodiment of the present disclosure is applied to a secondary battery.

[0067] Refer to Figure 4 , the heat transfer device 350 according to an embodiment of the present disclosure is applied to a secondary battery to surround the joint between the current collector 342 and the sub-board 344. The heat transfer device 350 can be fixed in such a way that the first body 352 and the second body 354 surround the joint and are fastened by the fastener 356.

[0068] Figure 5 is a diagram showing heat transfer in the case where the heat transfer device according to an embodiment of the present disclosure is not applied. Figure 6FIG. is a view showing heat transfer in a case where a heat transfer device according to an embodiment of the present disclosure is applied.

[0069] Referring to Figure 5 , if the heat transfer device 350 according to the embodiment of the present disclosure is not applied, the heat generated at the joint between the current collector 342 and the sub-board 344 is transferred back to the terminal portion 320 through the current collector 342, or is transferred to the electrode assembly 100 through the electrode tab 110 via the sub-board 344, which may not allow the heat to radiate to the outside accordingly. Eventually, it may cause breakage due to heat generation and / or deterioration of the performance of the secondary battery due to decomposition of the electrolyte.

[0070] On the other hand, referring to Figure 6 , if the heat transfer device 350 according to the embodiment of the present disclosure is applied, the heat generated at the joint between the current collector 342 and the sub-board 344 is transferred to the housing 200 through the first contact surface 352a of the heat transfer device 350 in contact with the joint and the second contact surface 352b in contact with the housing 200, which can significantly reduce the heat transferred to the current collector 342 and the electrode assembly 100 accordingly. Since the housing 200 is made of a material having a high thermal conductivity such as aluminum, aluminum alloy or nickel-plated steel, it can effectively release the heat from the joint to the air around the battery.

[0071] Figure 7 FIG. is a graph showing the relationship between the maximum temperature and the heat flux with respect to the thermal conductivity of the heat transfer device according to the embodiment of the present disclosure.

[0072] The heat transfer device 350 according to the embodiment of the present disclosure may be made of at least one material selected from polycarbonate (PC) and polyphenylene sulfide (PPS) in order to effectively transfer heat. If the heat transfer device 350 is made of PC, it may have a thermal conductivity of 0.2 W / mK to 2 W / mK, and if the heat transfer device 350 is made of PPS, it may have a thermal conductivity of 0.3 W / mK to 10 W / mK.

[0073] Table 1 below shows the results of measuring the temperature change during rapid charging of the secondary battery according to whether the heat transfer device 350 is applied and the thermal conductivity of the heat transfer device 350, and Figure 7 is a graphical representation of Table 1 below.

[0074] [Table 1] Referring to Table 1 and Figure 7 , it is expected that the dissipation of the total heat inside the secondary battery through the heat transfer device 350 stabilizes at a thermal conductivity of 10 W / mK or more. For the maximum temperature, it can be seen that stability is observed at a thermal conductivity of 5 W / mK.

[0075] As can be confirmed from Table 1 and Figure 7 it is confirmed that by attaching the heat transfer device 350 to the secondary battery, the internal temperature of the secondary battery can be reduced. Accordingly, the heat transfer device 350 may have a thermal conductivity of 2 W / mK or more and may be made of PC or PPS having low reactivity with the electrolyte.

[0076] Figure 8A and Figure 8B FIG. shows dimensions to be considered in the heat transfer device according to an embodiment of the present disclosure.

[0077] Seven dimensions may be considered in manufacturing the heat transfer device 350 according to an embodiment of the present disclosure, which are shown by numbers in Figure 8A and Figure 8B FIG.

[0078] Referring to Figure 8A FIG., number ① refers to the thickness dimension of the second body 354. Since the separator should not be pressed in consideration of safety, the thickness dimension of the second body 354 may be less than the distance between the separator of the electrode assembly 100 and the joint between the current collector 342 and the sub-plate 344. Number ② refers to the thickness dimension of the first body 352, which may precisely match the distance between the housing 200 and the joint between the current collector 342 and the sub-plate 344 to effectively transfer heat from the joint to the housing. Number ③ refers to the dimension of the distance between the joint at the connection part between the first body 352 and the second body 354 and the heat transfer device 350. This connection part does not contact the housing 200, which may interfere with heat dissipation and cause a risk of breakage. Accordingly, some gaps may be provided in this area. Number ④ refers to the dimension of the thickness of the connection part between the first body 352 and the second body 354, which may be set not to contact the housing 200. Number ⑤ refers to the fastener of the heat transfer device 350. Like the dimension of number ④, it may have a thickness set not to contact the housing 200. Number ⑥ refers to the length dimension of the part of the first body 352 that contacts the housing 200, which may be less than the length of the straight part of the housing 200 in the cross-section of the housing 200 so that this dimension is not affected by the curved surface of the housing 200.

[0079] Referring to Figure 8B FIG., number ⑦ refers to the height dimension of the first body 352, which may be less than the length of the joint at the welded part of the current collector 342 and the sub-plate 344.

[0080] Among the seven dimensions of the heat transfer device 350 according to an embodiment of the present disclosure, the factors related to the heat conduction performance are the dimensions numbered ②, ⑥, and ⑦. The amount of heat conduction Q may be represented by the following equation: [Equation 1] where Q is the amount of heat conduction during 1 hour [kcal / h], F is the heat transfer area [m 2 , λ is the thermal conductivity [kcal / mhC], Δt is the temperature difference [C], and is the length (thickness) [m].

[0081] According to the above equation, the larger the sizes of numbers ⑥ and ⑦, and the smaller the size of number ②, the greater the amount of heat conduction. The size of number ② is determined at the stage of battery design, but the heat conduction performance increases by N times as the cross-sectional area of ⑥×⑦ increases by N times. Therefore, when manufacturing the heat transfer device 350, the heat conduction can be maximized by maximizing the sizes of numbers ⑥ and ⑦.

[0082] A method of manufacturing a secondary battery including the heat transfer device 350 having the above structure will now be described.

[0083] According to an embodiment of the method of manufacturing a secondary battery, an electrode assembly 100 is manufactured, a housing 200 for accommodating the electrode assembly 100 is manufactured, and a terminal portion 320 connected to the electrode assembly 100 is manufactured. Then, a current collector 342 and a sub-board 344 connecting the electrode assembly 100 and the terminal portion 320 are joined. In this case, the current collector 342 and the sub-board 344 can be joined by laser welding or the like. Then, the heat transfer device 350 can be installed between the housing 200 and the joint between the current collector 342 and the sub-board 344 to transfer the heat generated at the joint to the housing 200.

[0084] In one embodiment, the heat transfer device 350 may be in the form of a clip including Figure 3 shown and referred to in Figure 3 a first body 352, a second body 354, and a fastener 356. In this case, the method of manufacturing a secondary battery may include a process of installing the heat transfer device 350, which can be achieved by manufacturing the heat transfer device 350 in the form of a clip around the joint between the current collector 342 and the sub-board 344 and fastening the heat transfer device 350 to the joint.

[0085] Figure 9 and Figure 10 A heat transfer device according to other embodiments of the present disclosure is shown, and a method of manufacturing a secondary battery including the heat transfer device will be described.

[0086] Figure 9 is a diagram schematically showing a heat transfer device according to a second embodiment of the present disclosure.

[0087] In the present embodiment, the heat transfer device denoted by reference numeral 350 may be manufactured by insert injection molding between the joint between the housing 200 and the current collector 342 and the daughter board 344.

[0088] Referring to Figure 9 , the heat transfer device 350 is manufactured by joining the current collector 342 and the daughter board 344 and then performing insert injection molding between the joint between the current collector 342 and the daughter board 344 and the housing 200. Accordingly, the heat transfer device 350 includes only the first body 352 and the second body 354 and does not include the fastener 356 as described in the above embodiment.

[0089] Figure 10 is a diagram schematically showing a heat transfer device according to a third embodiment of the present disclosure.

[0090] Referring to Figure 10 , the heat transfer device according to the third embodiment of the present disclosure includes only the first body 352 and does not include the second body 354 and the fastener 356 described in the above embodiment.

[0091] In this case, the method of manufacturing a secondary battery may include a process of installing the heat transfer device 350, which may be achieved by manufacturing the heat transfer device 350, applying a thermally conductive adhesive to the heat transfer device 350, and attaching the heat transfer device 350 to the joint between the current collector 342 and the daughter board 344.

[0092] Since the method of manufacturing other components, the method of joining the current collector 342 and the daughter board 344, etc. correspond to the method of manufacturing a secondary battery described above, their descriptions will be omitted.

[0093] Hereinafter, examples of materials that can be used to manufacture a secondary battery according to the present disclosure will be described.

[0094] A compound capable of reversibly inserting / extracting lithium (e.g., a lithiated insertion compound) may be used as the positive electrode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from the group consisting of cobalt, manganese, nickel, and combinations thereof may be used.

[0095] Examples of the composite oxide may include lithium transition metal composite oxides such as lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel manganese-based oxides, or combinations thereof.

[0096] As an example, a compound represented by any of the following formulas may be used: Li a A 1-b X b O 2-c D c(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Mn 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 < α < 2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 < α < 2); Li a Ni b Co c L 1 d G e O2 (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.1); Li a NiG b O2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn 1-b G b O2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn 1-g G g PO4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3 (0 ≤ f ≤ 2); and Li a FePO4 (0.90 ≤ a ≤ 1.8).

[0097] In the above formula, A is Ni, Co, Mn, or a combination thereof, X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, D is O, F, S, P, or a combination thereof, G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, and L 1 is Mn, Al, or a combination thereof.

[0098] The positive electrode for a lithium secondary battery may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer may include a positive electrode active material and may further include a binder and / or a conductive material.

[0099] Based on 100 wt% of the positive electrode active material layer, the positive electrode active material may be included in an amount of about 90 wt% to about 99.5 wt%. Based on 100 wt% of the positive electrode active material layer, the binder and the conductive material may each be included in an amount of about 0.5 wt% to about 5 wt%.

[0100] The current collector may be made of aluminum (Al), but the present disclosure is not limited thereto.

[0101] The negative electrode active material may include a material capable of reversibly inserting / extracting lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and de-doping lithium, or a transition metal oxide.

[0102] Examples of the material capable of reversibly inserting / extracting lithium ions may include carbonaceous negative electrode active materials such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon may include graphite such as natural graphite or artificial graphite. Examples of amorphous carbon may include soft carbon or hard carbon, mesophase pitch carbide, and calcined coke.

[0103] Si-based negative electrode active materials or Sn-based negative electrode active materials may be used as the material capable of doping and de-doping lithium. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiO x (0 < x < 2), a Si-based alloy, or a combination thereof.

[0104] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to an embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0105] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer on the surface of the core.

[0106] The negative electrode for a lithium secondary battery may include a current collector and a negative electrode active material layer formed on the current collector. The negative electrode active material layer may include a negative electrode active material, and may further include a binder and / or a conductive material.

[0107] For example, the negative electrode active material layer may include from about 90 wt% to about 99 wt% of a negative electrode active material, from about 0.5 wt% to about 5 wt% of a binder, and from about 0 wt% to about 5 wt% of a conductive material.

[0108] The binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof. When an aqueous binder is used as the negative electrode binder, it may further include a cellulose-based compound capable of imparting viscosity.

[0109] The negative electrode current collector may be selected from the group consisting of a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0110] The electrolyte for a lithium secondary battery may include a non-aqueous organic solvent and a lithium salt.

[0111] The non-aqueous organic solvent serves as a medium through which ions participating in the electrochemical reaction of the battery can migrate.

[0112] The non-aqueous organic solvent may be a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, or an alcohol solvent, an aprotic solvent, or a combination thereof. The non-aqueous organic solvent may be used alone or in combination of two or more.

[0113] When a carbonate solvent is used as the non-aqueous organic solvent, a mixture of a cyclic carbonate and a linear carbonate may be used.

[0114] Depending on the type of the lithium secondary battery, a separator may be present between the positive electrode and the negative electrode. The separator may be a polyethylene film, a polypropylene film, a polyvinylidene fluoride film, or a multilayer film of two or more layers thereof.

[0115] The separator may include a porous substrate and a coating layer containing an organic material, an inorganic material, or a combination thereof on one or both surfaces of the porous substrate.

[0116] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic acid-based polymer.

[0117] The inorganic material may include inorganic particles selected from the group consisting of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof, but the present disclosure is not limited thereto.

[0118] The organic material and the inorganic material may be mixed in a coating layer, or may be in a form in which a coating layer containing the organic material and a coating layer containing the inorganic material are stacked on each other.

[0119] Figure 11 is an exemplary view of a secondary battery module in which a secondary battery (as shown in Figure 4 ) is arranged according to an embodiment of the present disclosure. As the capacity of the secondary battery for driving an electric vehicle increases, a secondary battery module is manufactured by arranging and connecting a plurality of secondary battery cells horizontally and / or vertically.

[0120] A plurality of secondary batteries are arranged in a space defined by a pair of opposing end plates 71a, 71b and a pair of opposing side plates 72a, 72b. The secondary batteries can be appropriately designed in terms of arrangement (direction) and quantity to obtain desired voltage and current specifications.

[0121] Figure 12 is an exemplary view of a secondary battery pack 80 configured to apply the secondary battery module shown in Figure 11 to an actual product (e.g., a vehicle).

[0122] The secondary battery pack can be manufactured by embedding a plurality of secondary battery modules in a battery pack housing designed to be mounted on an actual product. The battery pack housing may include fasteners and power sockets necessary for mounting to the product. For ease of illustration, associated elements such as bus bars, cooling units, and external terminals for electrical connection of the secondary battery are not shown in Figure 12 .

[0123] The secondary battery pack can be mounted in a vehicle. The vehicle can be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle can be a four-wheeled vehicle or a two-wheeled vehicle.

[0124] Figure 13 is a view for explaining a vehicle V including the secondary battery pack shown in Figure 12 . Figure 13 shows the secondary battery pack 80 according to an embodiment of the present disclosure mounted on the bottom of the vehicle V. The vehicle V can be operated by the power supplied from the secondary battery pack 80 according to an embodiment of the present disclosure.

[0125] Although the present disclosure has been described above with respect to embodiments of the present disclosure, the present disclosure is not limited thereto. Various modifications and variations can be made by those skilled in the art within the spirit of the present disclosure and the scope of the equivalents of the appended claims.

Claims

1. A heat transfer device, the heat transfer device comprising: A main body configured to be mounted between a housing of a secondary battery and a joint between a current collector and a sub-board in the secondary battery; Wherein the main body includes: a first contact surface configured to contact the joint to receive heat from the joint; and a second contact surface formed opposite to the first contact surface, the second contact surface being configured to contact the housing to transfer heat from the first contact surface to the housing.

2. The heat transfer device according to claim 1, wherein, The main body is a first main body, and the heat transfer device further includes a second main body extending from the first main body and configured to surround the joint.

3. The heat transfer device according to claim 2, the heat transfer device further comprising a fastener configured to fasten the first main body and the second main body to prevent the first main body and the second main body from separating from the joint.

4. The heat transfer device according to claim 1, wherein, The heat transfer device is made of at least one material selected from polycarbonate and polyphenylene sulfide.

5. A secondary battery, the secondary battery comprising: A housing configured to accommodate an electrode assembly; A terminal portion connected to the electrode assembly; A sub-board connecting the electrode assembly and the terminal portion; A current collector; And A heat transfer device mounted between the housing and a joint between the current collector and the sub-board, the heat transfer device being configured to transfer heat from the joint to the housing.

6. The secondary battery according to claim 5, Among them, The heat transfer device includes a main body mounted between the joint and the housing, and Wherein the main body includes: a first contact surface contacting the joint and configured to receive heat from the joint; and a second contact surface formed opposite to the first contact surface, the second contact surface contacting the housing and configured to transfer heat from the first contact surface to the housing.

7. The secondary battery according to claim 6, wherein, The main body is a first main body, and the secondary battery further includes a second main body extending from the first main body to surround the joint.

8. The secondary battery according to claim 7, the secondary battery further comprising a fastener fastening the first main body and the second main body to prevent the first main body and the second main body from separating from the joint.

9. The secondary battery according to claim 5, wherein, The heat transfer device is made of at least one material selected from polycarbonate and polyphenylene sulfide.

10. The secondary battery according to claim 5, wherein, The secondary battery is a prismatic secondary battery.

11. A secondary battery module, the secondary battery module including a plurality of secondary batteries according to claim 5, Among them, The plurality of secondary batteries are arranged and connected horizontally or vertically.

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