Battery cell, battery module and battery pack

Abstract

A battery cell, a battery module and a battery pack. The battery cell comprises a battery casing (100) and an electrode assembly, wherein the battery casing (100) is provided with an accommodating cavity (110); the electrode assembly is arranged in the accommodating cavity (110); the electrode assembly comprises tabs (210) and electrode sheets (220); each tab (210) comprising a first connecting strip (211) and a second connecting strip (212); a first end of the first connecting strip (211) is connected to a second end of the second connecting strip (212), a second end of the first connecting strip (211) is welded to one electrode sheet (220), and the first connecting strip (211) and the electrode sheet (220) are made of the same material; and a first end of the second connecting strip (212) is welded to the battery casing (100), and the second connecting strip (212) and the battery casing (100) are made of the same material, thereby improving the welding effect between the tabs and the electrode sheets and the welding effect between the tabs and the battery casing.

Description

Battery cells, battery modules and battery packs

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 23, 2024, with application number 202423185798.X. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, for example, to a battery cell, a battery module and a battery pack. Background Art

[0003] A battery cell usually includes a battery shell and an electrode group. The battery shell is provided with a closed cavity, and the electrode group is arranged in the cavity. The electrode group usually includes a pole ear and a pole piece. One end of the pole ear is welded to the pole piece, and the other end of the pole ear is welded to the battery shell.

[0004] When the electrode is made of aluminum and the battery shell is made of stainless steel, the tab is usually made of stainless steel, and the tab is fixedly connected to the battery shell by resistance welding or laser welding, and the tab is fixedly connected to the electrode by ultrasonic metal welding.

[0005] Ultrasonic metal welding is a special method of joining similar or dissimilar metals using mechanical vibration energy at ultrasonic frequencies. When ultrasonic welding metals, neither current nor high-temperature heat source is applied to the workpieces. Instead, under static pressure, mechanical energy is converted into internal energy, deformation energy and a limited temperature rise, so that the two welding base materials reach the recrystallization temperature to achieve solid-phase welding. Technical issues

[0006] The recrystallization temperature of aluminum material is about 350℃~420℃, and the recrystallization temperature of stainless steel is about 500℃~1000℃. The recrystallization temperatures of the two materials are quite different. Therefore, when ultrasonic metal welding is performed on the stainless steel tab and the aluminum pole piece, the pole piece is prone to breakage or poor welding between the pole piece and the tab, thereby reducing the output rate of the battery cell and even shortening the service life of the battery cell. Solution

[0007] The present application provides a battery cell, comprising:

[0008] A battery shell, wherein the battery shell is provided with a cavity;

[0009] The electrode group is arranged in the cavity, the electrode group includes a pole ear and a pole piece, the pole ear includes a first connecting belt and a second connecting belt, the first end of the first connecting belt is connected to the second end of the second connecting belt, the second end of the first connecting belt is welded to the pole piece, and the first connecting belt and the pole piece are made of the same material, the first end of the second connecting belt is welded to the battery shell, and the second connecting belt and the battery shell are made of the same material.

[0010] Optionally, the battery case includes a shell cover structure and a shell, the shell cover structure includes a cover plate, a conductive member, and a pole, the cover plate is snap-fitted to the shell, the cover plate and the shell cooperate to form a cavity, the conductive member is located in the cavity, and one end of the pole passes through the cover plate and is connected to the conductive member;

[0011] The electrode tab includes a positive electrode tab, the first connecting band of the positive electrode tab is a positive electrode first connecting band, the second connecting band of the positive electrode tab is a positive electrode second connecting band, the first end of the positive electrode second connecting band is welded to the conductive member, and the positive electrode second connecting band and the conductive member are made of the same material, and the second end of the positive electrode second connecting band is connected to the first end of the positive electrode first connecting band;

[0012] The electrode sheet includes a positive electrode sheet. The second end of the positive electrode first connecting strip is welded to the positive electrode sheet, and the positive electrode first connecting strip and the positive electrode sheet are made of the same material.

[0013] Optionally, the electrode tab further includes a negative electrode tab, the first connecting band of the negative electrode tab is a negative electrode first connecting band, the second connecting band of the negative electrode tab is a negative electrode second connecting band, the first end of the negative electrode second connecting band is welded to the inner wall of the shell, and the negative electrode second connecting band and the shell are made of the same material, and the second end of the negative electrode second connecting band is connected to the first end of the negative electrode first connecting band;

[0014] The electrode sheet further includes a negative electrode sheet. The second end of the negative electrode first connecting strip is welded to the negative electrode sheet, and the negative electrode first connecting strip and the negative electrode sheet are made of the same material.

[0015] Optionally, the material of the negative electrode plate is one of copper, aluminum, nickel and nickel-plated.

[0016] Optionally, the material is set to at least one of the following:

[0017] The material of the positive electrode is aluminum;

[0018] Alternatively, the conductive member is made of one of stainless steel, carbon steel and aluminum;

[0019] Alternatively, the shell is made of one of stainless steel, carbon steel and aluminum.

[0020] Optionally, the first end of the first connecting belt is welded to the second end of the second connecting belt, and the number of first welding points between the first end of the first connecting belt and the second end of the second connecting belt is at least two.

[0021] Optionally, the thickness of the first connecting belt and the second connecting belt are both greater than 0.05 mm.

[0022] Optionally, the second end of the first connecting strip is fixed to the pole piece via a second welding point, and insulating tape is attached to the pole piece, covering the second welding point.

[0023] The present application also provides a battery module, comprising a plurality of battery cells and a bus bar.

[0024] The present application also provides a battery pack, comprising a box and a battery module arranged in the box. Beneficial effects

[0025] The battery cell provided in this application has a tab comprising a first connecting strap and a second connecting strap. The first end of the first connecting strap is connected to the second end of the second connecting strap, and the second end of the first connecting strap is welded to the electrode. The first connecting strap and the electrode are made of the same material, thereby reducing the probability of poor welding between the first connecting strap and the electrode, and also reducing the probability of the first connecting strap and the electrode breaking during welding. The first end of the second connecting strap is welded to the battery shell, and the second connecting strap and the battery shell are made of the same material, thereby reducing the probability of poor welding between the second connecting strap and the battery shell, and also reducing the probability of the second connecting strap and the battery shell breaking during welding. This structural design is therefore beneficial for improving the output rate of the battery cell and extending the service life of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic cross-sectional view of a battery cell provided by some implementations of the present application;

[0027] FIG2 is a schematic diagram of the structure of a tab provided by some implementations of the present application;

[0028] FIG3 is a schematic diagram of the connection structure between the tab and the pole piece provided in some implementations of the present application;

[0029] FIG4 is a schematic structural diagram of a tab semi-finished product provided by some implementations of the present application;

[0030] FIG5 is a schematic diagram of the structure of a battery pack provided by some implementations of the present application.

[0031] In the picture:

[0032] 100, battery case; 110, cavity; 120, shell cover structure; 121, cover plate; 122, conductive member; 123, pole; 130, housing;

[0033] 210, electrode tab; 211, first connecting band; 212, second connecting band; 213, positive electrode tab; 2131, first positive electrode connecting band; 2132, second positive electrode connecting band; 214, negative electrode tab; 2141, first negative electrode connecting band; 2142, second negative electrode connecting band; 220, electrode sheet; 221, positive electrode sheet; 222, negative electrode sheet; 230, separator;

[0034] 310, first welding point; 320, second welding point;

[0035] 400, insulation ring;

[0036] 500, insulating tape;

[0037] 1. Battery cell; 2. Busbar; 3. Box. Modes for Carrying Out the Invention

[0038] In the description of this application, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0039] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in contact with the second feature through another feature between them instead of being in direct contact. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may indicate that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may indicate that the first feature is at a lower level than the second feature.

[0040] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings. They are used for ease of description and simplified operation, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and do not have any special meanings.

[0041] This embodiment provides a battery cell having a high welding effect between the electrode tab and the electrode sheet, and a high welding effect between the electrode tab and the battery shell.

[0042] Exemplarily, as shown in Figures 1 and 2, the battery cell includes a battery shell 100 and a pole group, wherein the battery shell 100 is provided with a cavity 110, the pole group is arranged in the cavity 110, the pole group includes a pole ear 210 and a pole piece 220, the pole ear 210 includes a first connecting band 211 and a second connecting band 212, the first end of the first connecting band 211 is connected to the second end of the second connecting band 212, the second end of the first connecting band 211 opposite to the first end of the first connecting band 211 is welded to the pole piece 220, and the first connecting band 211 and the pole piece 220 are made of the same material, the first end of the second connecting band 212 opposite to the second end of the second connecting band 212 is welded to the battery shell 100, and the second connecting band 212 is made of the same material as the battery shell 100.

[0043] Based on the above design, the tab 210 includes a first connecting strap 211 and a second connecting strap 212. The first end of the first connecting strap 211 is connected to the second end of the second connecting strap 212, and the second end of the first connecting strap 211 is welded to the electrode 220. The first connecting strap 211 and the electrode 220 are made of the same material. This reduces the probability of poor welding between the first connecting strap 211 and the electrode 220, and also reduces the probability of breakage during welding between the first connecting strap 211 and the electrode 220. The first end of the second connecting strap 212 is welded to the battery shell 100, and the second connecting strap 212 and the battery shell 100 are made of the same material. This reduces the probability of poor welding between the second connecting strap 212 and the battery shell 100, and also reduces the probability of breakage during welding between the second connecting strap 212 and the battery shell 100. It can be seen that this structural design is conducive to improving the output rate of the battery cell and extending the service life of the battery cell.

[0044] As shown in Figure 2, the first end of the first connecting band 211 is welded to the second end of the second connecting band 212, and the number of first welding points 310 between the first end of the first connecting band 211 and the second end of the second connecting band 212 is two or more. For example, the number of first welding points 310 can be two, six or eight, etc., to improve the stability of the connection between the first connecting band 211 and the second connecting band 212.

[0045] The two or more first welding points 310 are evenly distributed in the overlapping area of ​​the first connecting strip 211 and the second connecting strip 212 to improve the stability of the connection between the first connecting strip 211 and the second connecting strip 212 .

[0046] Optionally, as shown in Figure 3, the second end of the first connecting band 211 is fixed to the pole piece 220 through a second welding point 320, and the number of the second welding points 320 is two or more. Exemplarily, the number of the second welding points 320 can be two, three or five, etc., to improve the connection stability between the first connecting band 211 and the pole piece 220.

[0047] The two or more second welding points 320 are evenly distributed in the overlapping area of ​​the first connecting strip 211 and the pole piece 220 to improve the connection stability between the first connecting strip 211 and the pole piece 220 .

[0048] Optionally, insulating tape 500 is attached to the pole piece 220, and the insulating tape 500 covers the second welding point 320. When the pole piece 220 is welded to the first connecting strip 211, burrs and protrusions are easily generated at the welding point of the pole piece 220 (i.e., the position of the second welding point 320). Covering the second welding point 320 with insulating tape 500 can prevent burrs and protrusions from piercing other pole pieces 220 adjacent to the pole piece 220, thereby reducing the probability of internal short circuit of the battery cell.

[0049] Optionally, the thickness of the first connecting strip 211 and the second connecting strip 212 is greater than 0.05 mm. For example, the thickness of the first connecting strip 211 can be 0.05 mm, 0.1 mm, or 0.15 mm, and the thickness of the second connecting strip 212 can be 0.05 mm, 0.1 mm, or 0.15 mm, to ensure that the first connecting strip 211 and the second connecting strip 212 have sufficient structural strength and reduce the probability of breakage of the first connecting strip 211 and the second connecting strip 212. Optionally, the thickness of the first connecting strip 211 and the second connecting strip 212 is less than 0.3 mm to improve the welding effect between the first connecting strip 211 and the electrode 220, and the welding effect between the second connecting strip 212 and the battery case 100.

[0050] In actual production, multiple first connecting strips 211 and multiple second connecting strips 212 can be alternately arranged and welded in sequence to form the semi-finished pole tab 210 as shown in Figure 4, and then the semi-finished pole tab 210 can be cut according to usage requirements to obtain the finished pole tab 210 as shown in Figure 2.

[0051] Optionally, as shown in FIG1 , the battery shell 100 includes a shell cover structure 120 and a shell 130, the shell cover structure 120 includes a cover plate 121, a conductive member 122 and a pole 123, the cover plate 121 is snap-fitted to the shell 130, the cover plate 121 and the shell 130 cooperate to form a cavity 110, the conductive member 122 is located in the cavity 110, and one end of the pole 123 is connected to the conductive member 122 through the cover plate 121; the pole ear 210 includes a positive pole ear 213, and the first connecting band 211 of the positive pole ear 213 is the positive first connecting band 213 1. The second connecting band 212 of the positive electrode ear 213 is a positive second connecting band 2132. The first end of the positive second connecting band 2132 is welded to the conductive member 122, and the positive second connecting band 2132 and the conductive member 122 are made of the same material. The second end of the positive second connecting band 2132 is connected to the first end of the positive first connecting band 2131. The electrode sheet 220 includes a positive electrode sheet 221. The second end of the positive first connecting band 2131 is welded to the positive electrode sheet 221, and the positive first connecting band 2131 and the positive electrode sheet 221 are made of the same material.

[0052] In one embodiment, the positive electrode sheet 221 is made of aluminum, and therefore, the positive electrode first connecting strip 2131 is also made of aluminum. The conductive member 122 is made of stainless steel, and therefore, the positive electrode second connecting strip 2132 is also made of stainless steel. In other embodiments, the conductive member 122 may also be made of carbon steel or aluminum, depending on the application.

[0053] Optionally, the electrode tab 210 also includes a negative electrode tab 214, the first connecting band 211 of the negative electrode tab 214 is a negative electrode first connecting band 2141, the second connecting band 212 of the negative electrode tab 214 is a negative electrode second connecting band 2142, the first end of the negative electrode second connecting band 2142 is welded to the inner wall of the shell 130, and the negative electrode second connecting band 2142 is made of the same material as the shell 130, and the second end of the negative electrode second connecting band 2142 is connected to the first end of the negative electrode first connecting band 2141; the electrode sheet 220 also includes a negative electrode sheet 222, the second end of the negative electrode first connecting band 2141 is welded to the negative electrode sheet 222, and the negative electrode first connecting band 2141 is made of the same material as the negative electrode sheet 222.

[0054] In one embodiment, the negative electrode sheet 222 is made of nickel, and therefore, the negative electrode first connecting strip 2141 is made of nickel. In other embodiments, the negative electrode sheet 222 may also be made of copper, aluminum, or nickel-plated, depending on the application.

[0055] In one embodiment, the material of the housing 130 is stainless steel, and therefore the material of the negative electrode second connecting strip 2142 is stainless steel. In other embodiments, the material of the housing 130 can also be carbon steel or aluminum, etc., depending on the application situation.

[0056] The stainless steel material is not limited to austenitic, ferritic, martensitic stainless steel materials, etc. The aluminum material is not limited to pure aluminum or alloy aluminum materials.

[0057] In this embodiment, the shell 130, the negative second connecting strip 2142, the conductive member 122 and the positive second connecting strip 2132 are all made of stainless steel, which can prevent the shell 130, the negative second connecting strip 2142, the conductive member 122 and the positive second connecting strip 2132 from producing unstable chemical reactions with the electrolyte in the cavity 110, thereby improving the reliability of the battery cell.

[0058] The battery cells provided in this embodiment are suitable for cylindrical cells, prismatic cells, and special-shaped cells. The electrode assembly can be either a wound electrode assembly or a non-wound electrode assembly. The following briefly describes the production process of the battery cells provided in this embodiment, using a wound electrode assembly as an example:

[0059] Please refer to Figure 1. Prepare the positive electrode ear 213 and the negative electrode ear 214. Ultrasonic welding is used to weld the end of the positive electrode first connecting tape 2131 away from the positive electrode second connecting tape 2132 to the positive electrode sheet 221. The end of the negative electrode first connecting tape 2141 away from the negative electrode second connecting tape 2142 is welded to the negative electrode sheet 222. The positive electrode sheet 221, the separator 230 and the negative electrode sheet 222 are stacked in sequence and wound into a roll. The rolled electrode assembly is then assembled into the housing 130. The negative electrode second connecting tape 2142 is welded away from the negative electrode first connecting tape 2142. 1 is laser welded or resistance welded to the inner wall of the shell 130; an insulating ring 400 is placed on the side of the electrode group away from the inner bottom wall of the shell 130, and the end of the positive electrode second connecting belt 2132 away from the positive electrode first connecting belt 2131 is passed through the through hole on the insulating ring 400, and the end of the positive electrode second connecting belt 2132 away from the positive electrode first connecting belt 2131 is laser welded or resistance welded to the conductive member 122; electrolyte is injected into the shell 130, and the cover plate 121 is sealed and fastened to the opening of the shell 130.

[0060] This embodiment also provides a battery module, as shown in FIG5 . The battery module includes a plurality of battery cells 1 and a busbar 2, wherein the plurality of battery cells 1 are electrically connected via the busbar 2. The ends of the tab 210 of the battery cell 1 are welded to the electrode sheet 220 and the battery shell 100, respectively. The first connecting band 211 of the tab 210 (i.e., the portion of the tab 210 welded to the electrode sheet 220) is made of the same material as the electrode sheet 220, and the second connecting band 212 of the tab 210 (i.e., the portion of the tab 210 welded to the battery shell 100) is made of the same material as the battery shell 100. As a result, the welding performance between the tab 210 and the electrode sheet 220, and between the tab 210 and the battery shell 100, is high, thereby improving the output rate of the battery cells and extending the service life of the battery cells. Therefore, a battery module using the battery cells of the embodiment of the present application has a high output rate and a long service life.

[0061] This embodiment further provides a battery pack, as shown in FIG5 . The battery pack includes a box body 3 and a battery module disposed in the box body 3 . Therefore, the battery pack has a high output rate and a long service life.

Claims

1. A battery cell, comprising: A battery shell (100), wherein the battery shell (100) is provided with a cavity (110); A pole group, wherein the pole group is arranged in the cavity (110), the pole group includes a pole ear (210) and a pole piece (220), the pole ear (210) includes a first connecting belt (211) and a second connecting belt (212), the first end of the first connecting belt (211) is connected to the second end of the second connecting belt (212), the second end of the first connecting belt (211) is welded to the pole piece (220), and the first connecting belt (211) and the pole piece (220) are made of the same material, the first end of the second connecting belt (212) is welded to the battery shell (100), and the second connecting belt (212) and the battery shell (100) are made of the same material.

2. The battery cell according to claim 1, wherein: The battery shell (100) includes a shell cover structure (120) and a shell (130), wherein the shell cover structure (120) includes a cover plate (121), a conductive member (122) and a pole (123), wherein the cover plate (121) is snap-fitted with the shell (130), and the cover plate (121) and the shell (130) cooperate to form the cavity (110), wherein the conductive member (122) is located in the cavity (110), and one end of the pole (123) passes through the cover plate (121) and is connected to the conductive member (122); The electrode tab (210) includes a positive electrode tab (213), the first connecting band (211) of the positive electrode tab (213) is a positive electrode first connecting band (2131), the second connecting band (212) of the positive electrode tab (213) is a positive electrode second connecting band (2132), the first end of the positive electrode second connecting band (2132) is welded to the conductive member (122), and the positive electrode second connecting band (2132) and the conductive member (122) are made of the same material, and the second end of the positive electrode second connecting band (2132) is connected to the first end of the positive electrode first connecting band (2131); The electrode sheet (220) comprises a positive electrode sheet (221), the second end of the positive electrode first connecting strip (2131) is welded to the positive electrode sheet (221), and the positive electrode first connecting strip (2131) and the positive electrode sheet (221) are made of the same material.

3. The battery cell according to claim 2, wherein: The electrode tab (210) further comprises a negative electrode tab (214); the first connecting band (211) of the negative electrode tab (214) is a negative electrode first connecting band (2141); the second connecting band (212) of the negative electrode tab (214) is a negative electrode second connecting band (2142); a first end of the negative electrode second connecting band (2142) is welded to the inner wall of the shell (130); the negative electrode second connecting band (2142) and the shell (130) are made of the same material; and a second end of the negative electrode second connecting band (2142) is connected to the first end of the negative electrode first connecting band (2141); The electrode sheet (220) further includes a negative electrode sheet (222), the second end of the negative electrode first connecting strip (2141) is welded to the negative electrode sheet (222), and the negative electrode first connecting strip (2141) and the negative electrode sheet (222) are made of the same material.

4. The battery cell according to claim 3, wherein: The material of the negative electrode sheet (222) is one of copper, aluminum, nickel and nickel plating.

5. The battery cell according to any one of claims 2 to 4, wherein: The material is set to at least one of the following: The material of the positive electrode plate (221) is aluminum; Alternatively, the conductive member (122) is made of one of stainless steel, carbon steel and aluminum; Alternatively, the shell (130) is made of one of stainless steel, carbon steel and aluminum.

6. The battery cell according to any one of claims 1 to 4, wherein: The first end of the first connecting belt (211) and the second end of the second connecting belt (212) are welded, and the number of first welding points (310) between the first end of the first connecting belt (211) and the second end of the second connecting belt (212) is at least two.

7. The battery cell according to any one of claims 1 to 4, wherein: The thickness of the first connecting belt (211) and the second connecting belt (212) are both greater than 0.05 mm.

8. The battery cell according to any one of claims 1 to 4, wherein: The second end of the first connecting band (211) is fixed to the pole piece (220) via a second welding point (320); an insulating tape (500) is attached to the pole piece (220); and the insulating tape (500) covers the second welding point (320).

9. A battery module comprising a plurality of battery cells (1) and a busbar (2) according to any one of claims 1 to 8.

10. A battery pack comprising a box (3) and the battery module according to claim 9 arranged in the box (3).

Images