A battery cell and a battery pack thereof

Abstract

The present application relates to the technical field of battery cell design, and provides a battery cell and its battery pack, which mainly include a pole structure, a connecting tab and a plurality of winding cores; the pole structure includes a battery cell pole and a conductive block, and the battery cell pole is arranged on one side of the conductive block; the end of the winding core is provided with a conductive connection part, one end of the connecting tab is welded to the conductive connection part, and the other end of the connecting tab is welded to the other side of the conductive block. In the present application, the connecting tab is directly welded to the winding core and the conductive block, so compared with the form of the prior art that requires the provision of a connecting piece, the present application can save at least one welding operation, reducing the difficulty of welding processing; at the same time, the winding core and the conductive block are electrically connected through the connecting tab, which can also effectively reduce the internal resistance of the battery cell, thereby improving the temperature rise phenomenon under special working conditions.

Description

Technical Field

[0001] The present application relates to the technical field of battery cell design, and in particular to a battery cell and a battery pack thereof. Background Art

[0002] Currently, mainstream new energy vehicles, both domestically and internationally, use battery packs with a conventional modular layout. Within these modules, the cells are arranged vertically. For these vertically arranged cells, the polarity contacts and explosion-proof valves are located on the top surface of the cells. However, the conductive tabs on the winding core are typically located on either side of the core, necessitating the use of connecting tabs to connect the polarity contacts and the conductive tabs, ensuring electrical connectivity between the polarity contacts and the winding core.

[0003] However, in actual applications, the inventors found that in the traditional technology of setting up connecting plates for conductive connection, it is usually necessary to first complete the welding between the winding core and the conductive electrode ear, and then weld between the connecting plate and the conductive electrode ear, and weld between the connecting plate and the polarity contact. There are at least three welding operations, the operation process is complicated and the cost is high. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a battery cell and a battery pack thereof, which can simplify the connection operation between the winding core and the polarity contacts in the battery cell, so as to reduce production costs.

[0005] The technical means adopted by this application to solve the above technical defects are:

[0006] The present application provides a battery cell, comprising a pole structure, connecting tabs and a plurality of winding cores;

[0007] The pole structure comprises a cell pole and a conductive block, wherein the cell pole is arranged on one side of the conductive block;

[0008] A conductive connection portion is provided at the end of the winding core, one end of the connecting tab is welded to the conductive connection portion, and the other end of the connecting tab is welded to the other side surface of the conductive block.

[0009] In the above implementation process, the present application provides a new battery cell structure, in which the connecting tabs are directly welded to the winding core and the conductive block. Compared with the prior art form that requires the setting of connecting plates, the present application can save at least one welding operation, thereby reducing the difficulty of welding processing; at the same time, the winding core and the conductive block are conductively connected through the connecting tabs, which can also effectively reduce the internal resistance of the battery cell, thereby improving the temperature rise phenomenon under special working conditions.

[0010] Furthermore, a bending section is provided on the connecting electrode tab, and the bending section extends to one end portion of the connecting electrode tab and is bent at the end portion of the connecting electrode tab to form a welding plane.

[0011] In the above implementation process, the bending section is set so that the connecting electrode ear can have a certain elastic expansion and contraction, so that a certain dimensional error can be absorbed during the welding installation between the connecting electrode ear and the winding core and the conductive block; and the welding plane is set to effectively increase the contact area of ​​the connecting electrode ear to ensure the welding connection effect.

[0012] Furthermore, a reinforcing sheet is provided on the side facing away from the welding plane.

[0013] In the above implementation process, the reinforcement sheet is provided to strengthen the welding plane, thereby avoiding the impact caused by over-welding of the welding plane, so as to ensure the current-carrying capacity of the connecting tab after welding.

[0014] Furthermore, it also includes a battery cell housing and a first end cover and a second end cover arranged in a cylindrical structure;

[0015] The battery cell shell is wrapped around the outer periphery of the plurality of winding cores, and the first end cover and the second end cover are respectively arranged to cover the two ends of the battery cell shell.

[0016] In the above implementation process, by setting the battery cell housing, the first end cover and the second end cover, during installation, the winding core can be set in the battery cell housing, and the pole structure can be set on the first end cover and the second end cover, and the outer shape assembly of the battery cell can be completed by covering and installing the first end cover, the second end cover and the battery cell housing.

[0017] Furthermore, a mylar film layer is provided between the plurality of winding cores and the battery cell shell, and the surface structure of the mylar film layer is honeycomb-shaped.

[0018] In the above implementation process, the mylar film layer can be used to wrap and heat-seal the roll core; at the same time, the outer surface of the mylar film layer is set to be in a honeycomb form, which can play a role in structural reinforcement.

[0019] Furthermore, only one of the pole structure is provided on the first end cover and the second end cover; and a liquid injection hole is also provided on the first end cover and / or the second end cover.

[0020] In the above implementation process, the present application is provided with only one of the pole structural members on the first end cover and the second end cover, so that the positive and negative poles of the battery cell are not on the same side. For example, the present solution is provided on two opposite sides to realize the long strip structural design of the battery cell, so as to improve the applicability of the battery cell.

[0021] Furthermore, a mounting bracket is provided between the first end cover and / or the second end cover and the battery cell housing, and a plurality of hollow holes are provided on the mounting bracket.

[0022] In the above implementation process, the installation bracket is provided to facilitate the installation and connection of various structural parts in the battery cell; at the same time, a number of hollow holes are also provided on the installation bracket, so that when the battery cell is injected with liquid, the impact force caused by the injection can be buffered to prevent the structural stress concentration problem, thereby improving the structural protection capability of the battery cell.

[0023] Furthermore, a contact block is provided at one end of the battery cell pole away from the conductive block, and an insulating protective pad is provided between the contact block and the first end cover or the second end cover;

[0024] The outer dimensions of the insulating protective pad are larger than those of the contact block.

[0025] In the above implementation process, the insulating protective pad is provided to avoid the risk of burrs and other metal foreign objects falling and overlapping with the pole to form a short circuit.

[0026] Furthermore, an explosion-proof valve is provided on the first end cover or the second end cover.

[0027] In the above implementation process, the explosion-proof valve is provided to facilitate the centralized discharge and treatment of thermal runaway reactants when thermal runaway occurs in the battery cell.

[0028] The present application also provides a battery pack, comprising the battery cell described above.

[0029] In the above implementation process, by applying a battery cell provided by the present application in a battery pack, the difficulty of welding operation of the battery pack can be effectively reduced, which facilitates the control of the production cost of the battery pack; at the same time, it can facilitate the extension of the service life of the battery cell in the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a structural schematic diagram of the battery cell of the present application with one end thereof looking downward.

[0032] Figure 2 This is a schematic structural diagram of the battery cell of this application looking downward from the other end.

[0033] Figure 3 This is a schematic diagram of the structure of the battery cell of this application after removing the battery cell shell.

[0034] Figure 4 This is a schematic diagram of the structure of the pole structure of this application.

[0035] Figure 5 This is a structural diagram of the first end cover or the second end cover of this application.

[0036] Figure 6 This is a schematic diagram of the connection structure between the winding core and the connecting tabs of this application.

[0037] Figure 7 This is a schematic diagram of the structure of the connection tab of this application looking downward.

[0038] Figure 8 This is another schematic diagram of the structure of the connection tab of this application looking downward.

[0039] Figure 9 This is a schematic diagram of the structure of the connection tabs of this application looking downward.

[0040] Figure 10 This is a schematic diagram of the connection structure between the tab and the conductive block in this application.

[0041] Figure 11 This is a schematic diagram of the structure of the mounting bracket for this application.

[0042] Marking Description:

[0043] 1-pole structure, 11-cell pole, 12-conductive block, 13-contact block, 14-insulating protective pad;

[0044] 2-connecting tab, 21-bending section, 22-welding plane, 23-reinforcement sheet;

[0045] 3- core, 31- mylar film layer; 4- cell shell;

[0046] 5-first end cover, 51-liquid injection hole, 52-explosion-proof valve; 6-second end cover;

[0047] 7-mounting bracket, 71-hollow hole. DETAILED DESCRIPTION

[0048] In order to be able to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth in order to fully understand the present invention. The embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention.

[0049] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. Similar reference numerals and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures. At the same time, in the description of this application, the terms "first", "second", etc. are used only to distinguish descriptions and are not to be understood as indicating or implying relative importance.

[0050] like Figure 1-11 As shown, this embodiment provides a battery cell, including a pole structure 1, a plurality of connecting tabs 2, a plurality of winding cores 3, a battery cell housing 4, a first end cap 5, and a second end cap 6. The specific structure of the winding core 3 can be found in the prior art and will not be described in detail here.

[0051] In this embodiment, the pole structure 1 is provided in two groups, corresponding to the positive and negative poles of the battery cell respectively. Each group of the pole structure 1 mainly includes a battery cell pole 11, a conductive block 12 and a contact block 13. The battery cell pole 11 is connected to one side of the conductive block 12, and the contact block 13 is provided at the end of the battery cell pole 11 away from the conductive block 12. During installation and use, the conductive block 12 is used to achieve internal electrical connection with the winding core 3, and the contact block 13 is used to achieve external electrical connection of the battery cell.

[0052] Furthermore, a conductive connection portion is provided at the end of the winding core 3. One end of the connecting tab 2 is welded to the conductive connection portion, and the other end of the connecting tab 2 is welded to the other side surface of the conductive block 12. This welding connection can be performed using ultrasonic welding. In this embodiment, the connecting tab 2 is directly welded to the winding core 3 and the conductive block 12, providing a welding structure without a connecting plate, which can reduce the material cost directly incurred by the need for a connecting plate in traditional technologies.

[0053] At the same time, in traditional technology, it is necessary to pre-weld the connecting tabs using ultrasonic welding first, and then ultrasonically weld the pre-welded connecting tabs to the connecting pieces, which then need to be laser welded to the battery cell poles. That is, at least two ultrasonic weldings and one laser welding are required. The second ultrasonic welding in this way often requires a larger welding power, so not only is the process complicated, but the welding cost is also relatively high. Therefore, compared to the welding form with connecting pieces in the prior art, in this application, only ultrasonic welding is needed to achieve conductive connection between the winding core 3, the connecting tabs 2 and the conductive block 12, and the welding process is simpler and more convenient. Since the welding step between the connecting piece and the connecting tab 2 is eliminated, the welding equipment can also be low-power, and the applicable scenarios are more extensive.

[0054] Furthermore, the welded structure of this embodiment can effectively reduce the internal resistance of the battery cell and mitigate temperature rise under special operating conditions. In some specific application examples, it was found that compared to conventional solutions with connecting plates, the welded structure of this embodiment can reduce the internal resistance by approximately 5%, and the temperature rise during overcharging is also reduced by approximately 5%.

[0055] As a preferred solution, the number of the connecting tabs 2 corresponds to the number of the winding cores 3. In this embodiment, two winding cores 3 are hot-pressed for illustration; in this case, a connecting tab 2 is welded to the conductive connection portion of each winding core 3, and the other ends of several connecting tabs 2 are welded to the same conductive block 12.

[0056] Furthermore, in this embodiment, a bending section 21 is provided on the connecting tab 2 . The bending section 21 extends to one end of the connecting tab 2 and is bent at the end of the connecting tab 2 to form a welding plane 22 .

[0057] As one application example, the bending section 21 extends from one end of the connecting tab 2 to the other end thereof, and the bending section 21 is wavy in shape. In this embodiment, the crest of the wavy shape is preferably gradually enlarged, so that the connecting tab 2 can have better elastic deformation performance, thereby absorbing certain dimensional errors during the welding and installation between the connecting tab 2 and the winding core 3 and the conductive block 12. At the same time, the welding plane 22 is provided at the end where the crest becomes larger, so as to increase the welding area between the connecting tab 2 and the winding core 3 or the conductive block 12, thereby ensuring the welding connection effect.

[0058] Furthermore, a reinforcing sheet 23 is provided on the side of the connecting tab 2 facing away from the welding plane 22. The welding deformation of the reinforcing sheet 23 is smaller than that of the connecting tab 2. As an application example, the length of the reinforcing sheet 23 in this embodiment is adapted to the height of the connecting tab 2, and the reinforcing sheet 23 and the connecting tab 2 are connected by laser welding.

[0059] In this embodiment, the reinforcing sheet 23 is provided. The outer surface of the reinforcing sheet 23 can contact the laser welding head, absorbing laser energy to protect the connecting tab 2, thereby preventing over-welding on the welding plane 22 and reducing the impact of over-welding. This can strengthen the welding plane 22. At the same time, the inner surface of the reinforcing sheet 23 is in contact with the back side of the welding plane 22, flattening the connecting tab 2 after pre-welding, thereby ensuring the current-carrying capacity of the connecting tab 2 after welding.

[0060] In addition, the battery cell shell 4 in this embodiment is set in a cylindrical structure, such as a cylindrical structure with a rectangular cross-section. At this time, the battery cell shell 4 is wrapped around the outer periphery of several of the winding cores 3, and the first end cover 5 and the second end cover 6 are respectively covered at both ends of the battery cell shell 4 to form a package for the winding core 3.

[0061] As a preferred solution, in this embodiment, a mylar film layer 31 is provided between the plurality of the cores 3 and the cell housing 4 , and the hot-pressed cores 3 are wrapped and heat-sealed by the mylar film layer 31 to provide insulation protection for the cores 3 .

[0062] Furthermore, the surface structure of the Mylar film layer 31 in this embodiment is honeycomb-shaped, and its thermal conductivity is preferably set to greater than 5 W / (m·K). This honeycomb-shaped surface structure can provide structural reinforcement for cores 3 longer than 350 mm, while also restraining their expansion, thereby preventing undesirable phenomena such as core collapse at the end of the battery cell's life. Furthermore, this honeycomb structure can provide a buffer for particles, especially those generated during welding, that fall between the battery cell casing 4 and the Mylar film layer 31, thereby improving the core 3's resistance to puncture during expansion.

[0063] As a preferred solution, in this embodiment, the shapes of the first end cap 5 and the second end cap 6 are adapted to the cross-sectional shape of the battery cell housing 4. At the same time, only one of the pole structure members 1 is provided on each of the first end cap 5 and the second end cap 6. In this case, the positive and negative electrodes of the battery cell are respectively provided at the two ends of the battery cell, so that the battery cell can be designed to be oblong.

[0064] In one of the application examples, the height of the oblong battery cell in this embodiment is only about 90mm, which is far lower than the industry level of 130mm. It can fully meet the space height requirements of vehicles on different platforms, greatly improving the adaptability of the battery pack layout and the ground clearance indicators of the whole vehicle. It supports upright, lying and CTB (CELL TO BODY) structural layouts of battery cells, which can bring higher space utilization and is expected to reach more than 75%; when combined with battery cells with higher energy density, it can also facilitate the realization of a higher energy-to-weight ratio.

[0065] In addition, a number of through holes are provided on the first end cover 5 and / or the second end cover 6, and the through holes include a first through hole for the battery cell pole 11 to pass through. When the battery cell pole 11 passes through the first through hole and is provided on the first end cover 5 or the second end cover 6, the conductive block 12 and the contact block 13 are respectively provided on both sides of the end cover.

[0066] As a preferred solution, in this embodiment, an insulating protective pad 14 is provided between the contact block 13 and the first end cap 5 or the second end cap 6. The outer dimensions of the insulating protective pad 14 are larger than the outer dimensions of the contact block 13. For example, the length and width of the insulating protective pad 14 are both 2-5 mm larger than the length and width of the contact block 13. The provision of the insulating protective pad 14 can prevent the risk of falling metal foreign matter such as burrs from contacting the battery cell pole 11 and causing a short circuit.

[0067] Furthermore, the via hole further includes an injection hole 51, through which electrolyte can be injected into the battery cell housing 4. In this embodiment, the injection hole 51 can be provided only on the first end cover 5 or the second end cover 6.

[0068] Furthermore, the via also includes an explosion-proof valve mounting hole. In this embodiment, the explosion-proof valve 52 can be installed only on the first end cap 5 or the second end cap 6. The installation of the explosion-proof valve 52 facilitates the centralized discharge of thermal runaway reactants in the event of thermal runaway. Other functions of the explosion-proof valve 52 can be referenced in the prior art.

[0069] In addition, in this embodiment, a mounting bracket 7 is provided between the first end cover 5 and / or the second end cover 6 and the cell housing 4 , and a plurality of hollow holes 71 are provided on the mounting bracket 7 .

[0070] As a preferred solution, the mounting bracket 7 is made of plastic to provide insulation and resistance to electrolyte corrosion. The ends of the mylar film layer 31 are fixed to the mounting bracket 7 by heat-melting. The mounting bracket 7 facilitates the installation and connection of various structural components within the battery cell. Furthermore, the mounting bracket 7 is provided with a number of hollow holes 71. This buffers the structural stress concentration caused by the impact of the injection during liquid injection, prevents undesirable phenomena such as powder loss caused by direct electrolyte injection, and improves the structural protection of the battery cell.

[0071] Moreover, in this embodiment, when the liquid injection hole 51 and the explosion-proof valve 52 are provided on the same end cover, the mounting bracket 7 may not be provided on the other end cover side, thereby facilitating further cost control.

[0072] In addition, this application also provides a battery pack, which mainly benefits from the above-mentioned battery cell. By using the battery cell provided in this embodiment in the battery pack, the difficulty of the battery pack welding operation can be effectively reduced, which facilitates the control of the battery pack production cost; at the same time, it can also facilitate the extension of the service life of the battery cell in the battery pack.

[0073] The above description is only a specific embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in the present application, which should also be included in the scope of protection of the present application. Therefore, the scope of protection of the present application shall be based on the scope of protection of the claims.

[0074] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

Claims

1. A battery cell, characterized in that: It includes pole structure, connecting tabs and several winding cores; The pole structure comprises a cell pole and a conductive block, wherein the cell pole is arranged on one side of the conductive block; The end of the winding core is provided with a conductive connection portion, one end of the connecting tab is welded to the conductive connection portion, and the other end of the connecting tab is welded to the other side surface of the conductive block; It also includes a battery cell shell with a cylindrical structure, which is wrapped around the outer periphery of the plurality of winding cores. A mylar film layer is provided between the plurality of winding cores and the battery cell shell, and the surface structure of the mylar film layer is honeycomb-shaped.

2. The battery cell according to claim 1, characterized in that The connecting tab is provided with a bending section, which extends to one end of the connecting tab and is bent at the end of the connecting tab to form a welding plane.

3. The battery cell according to claim 2, characterized in that A reinforcing sheet is arranged on the side facing away from the welding plane.

4. The battery cell according to claim 1 or 3, characterized in that: It also includes a first end cover and a second end cover, wherein the first end cover and the second end cover are respectively arranged to cover the two ends of the battery cell shell, and the battery cell is configured as a cylindrical structure with a rectangular cross section.

5. The battery cell according to claim 4, characterized in that: Only one of the pole structure components is provided on the first end cover and the second end cover; The first end cover and / or the second end cover is also provided with a liquid injection hole.

6. The battery cell according to claim 5, characterized in that A mounting bracket is provided between the first end cover and / or the second end cover and the battery cell housing, and a plurality of hollow holes are provided on the mounting bracket.

7. The battery cell according to claim 5, characterized in that A contact block is provided at one end of the battery cell pole away from the conductive block, and an insulating protective pad is provided between the contact block and the first end cover or the second end cover; The outer dimensions of the insulating protective pad are larger than those of the contact block.

8. The battery cell according to any one of claims 5 to 7, characterized in that: The first end cover or the second end cover is provided with an explosion-proof valve.

9. A battery pack, characterized in that: A battery cell comprising any one of claims 1 to 8.

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