Battery, battery module and battery pack

Abstract

To provide a battery which can solve a conventional problem that torsion resistance of a welded body formed by welding and a bottom of a case is insufficient and twisting of the welded body and a steel shell occurs due to external force in subsequent assembly, resulting in fracture of welding spots and poor welding, and to provide a battery module and a battery pack.SOLUTION: The invention provides a battery, a battery module, and a battery pack. The battery includes a case, a current collector plate, and multiple first welding portions. The case includes a top and a bottom, and a cavity is formed in the case. The current collector plate is arranged in the cavity. The first welding portions are formed on a side, close to the bottom, of the current collector plate. The current collector plate is welded to the bottom through the first welding portions. The first welding portions are provided around a center of the current collector plate. A distance from each of the first welding portions to the center of the current collector plate is greater than a distance from the first welding portions to an edge of the current collector plate.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention claims the priority of a Chinese patent application filed with the China National Intellectual Property Administration on December 18, 2023, with the application number 202323459079.8, a Chinese patent application with the application number 202311750665.X, and an international application filed with the China National Intellectual Property Administration on July 31, 2024, with the application number PCT / CN2024 / 108930. All the contents of the above applications are incorporated into the present invention by reference.

[0002] The present invention relates to a battery, and specifically, to a battery, a battery module, and a battery pack.

Background Art

[0003] In a battery lead-out structure in which a battery case serves as one of the electrodes in a battery, usually, a current collector plate is used as a conductive medium to lead out the current from one of the electrodes of the cell to the battery case, thereby charging the case and making it serve as one of the electrodes in the battery. Specifically, one side surface of the current collector plate is welded to the cell, and the other side surface is welded to the bottom of the case. In the related art, in the welding method between the case and the current collector plate, the welding part between the current collector plate and the bottom of the case is arranged at the middle position of the current collector plate.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in such a welding method, the torsional resistance ability between the welded body formed by welding the cell and the current collector plate and the bottom of the case is insufficient, and in subsequent assembly, torsion is likely to occur between the welded body and the steel shell due to an external acting force, thereby causing the welding point between the current collector plate and the case to break and resulting in poor welding.

Means for Solving the Problems

[0005] In a first aspect, the present invention provides a battery. The battery includes a case, a current collector plate, and a plurality of first welding parts. The case has a top and a bottom, and a cavity is formed inside the case. The current collector plate is provided inside the cavity. A plurality of first welding parts are formed on the side of the current collector plate close to the bottom. The current collector plate is welded to the bottom through the plurality of first welding parts. The plurality of first welding parts are provided surrounding the center of the current collector plate, and the distance from each first welding part to the center of the current collector plate is greater than the distance from the first welding part to the edge of the current collector plate.

[0006] In a second aspect, the present invention further provides a battery module. The battery module includes a plurality of batteries and a connection sheet on which a plurality of connection parts are formed, and each connection part is connected to a corresponding battery. Each battery includes a case, a current collector plate, and a plurality of first welding parts. A cavity is formed inside the case. The current collector plate is provided inside the cavity. The plurality of first welding parts are formed on the side of the current collector plate close to the bottom of the case. The current collector plate is welded to the bottom of the case through the plurality of first welding parts. The plurality of first welding parts are provided surrounding the center of the current collector plate, and the distance from each first welding part to the center of the current collector plate is greater than the distance from the first welding part to the edge of the current collector plate.

[0007] In a third aspect, the present invention further provides a battery pack. The battery pack includes a housing and a battery module provided on the housing.

Advantages of the Invention

[0008] In the present invention, the current collector plate is welded and connected to the case via a plurality of first welding parts. By being connected via the plurality of first welding parts, the welding contact area between the current collector plate and the case is increased, the connection stability between the current collector plate and the case is improved, and it can resist a large torque. At the same time, the large welding area can also meet the requirements of rapid charging overcurrent of the battery and improve the performance of the battery. As can be seen from the relationship between distance and torque, when the first welding part is arranged at a position close to the edge of the current collector plate, the welding force received by the first welding part decreases. By limiting that the distance from the first welding part to the center of the current collector plate is greater than the distance from the first welding part to the edge of the current collector plate, the welding force received by the first welding part is decreased, the welding difficulty is reduced, the welding strength is improved, the torsional resistance ability between the current collector plate and the bottom of the case is improved, the detachment of the current collector plate from the case is avoided, and the safety rate of the battery is improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] In the related art, the welding method between the case and the current collector plate is such that the welding part between the current collector plate and the bottom of the case is arranged at the middle position of the current collector plate. Such a welding method has insufficient torsional resistance between the welded body formed by welding the cell and the current collector plate and the bottom of the case. In subsequent assembly, torsions are likely to occur in the welded body and the steel case due to external acting forces, resulting in breakage of the welding point between the current collector plate and the case and causing poor welding.

[0011] In view of this, the present invention provides a battery. FIGS. 1 to 6 are schematic structural diagrams of an embodiment of the battery according to the present invention. The battery according to the present invention has a stable structure, strong torque resistance, and high safety rate. The following will describe the battery in detail with reference to the drawings.

[0012] Referring to FIGS. 1, 2, and 3, the battery 100 includes a case 101, a current collector plate 106, and a plurality of first welding parts 109. A cavity 102 is formed in the case 101. The current collector plate 106 is provided in the cavity 102. The plurality of first welding parts 109 are formed on the side of the current collector plate 106 close to the bottom 103 of the case 101. The current collector plate 106 is welded to the bottom 103 of the case 101 via the plurality of first welding parts 109. The plurality of first welding parts 109 are provided surrounding the center of the current collector plate 106. The distance from each first welding part 109 to the center of the current collector plate 106 is greater than the distance from the first welding part 109 to the edge of the current collector plate 106.

[0013] In the present invention, the current collecting plate 106 is welded and connected to the case 101 via a plurality of first welding parts 109. By being connected by the plurality of first welding parts 109, the welding contact area between the current collecting plate 106 and the case 101 is increased, the connection stability between the current collecting plate 106 and the case 101 is improved, and it can resist large torque. At the same time, the large welding area can meet the requirements of rapid charging overcurrent of the battery 100 and improve the performance of the battery 100. As can be seen from the relationship between distance and torque, when the first welding part 109 is arranged at a position close to the edge of the current collecting plate 106, the welding force received by the first welding part 109 decreases. By limiting that the distance from the first welding part 109 to the center of the current collecting plate 106 is greater than the distance from the first welding part 109 to the edge of the current collecting plate 106, the welding force received by the first welding part 109 is reduced, the welding difficulty is lowered, the welding strength is improved, the torsional resistance ability between the current collecting plate 106 and the bottom 103 of the case 101 is improved, the current collecting plate 106 is prevented from detaching from the case 101, and the safety rate of the battery 100 is improved.

[0014] Specifically, in this embodiment, as shown in FIG. 4, the bottom 103 of the case 101 has two opposing side surfaces. Taking the length direction of the battery 100 as an example, the two side surfaces of the bottom 103 of the case 101 are the first side surface 104 and the second side surface 105 respectively. The first side surface 104 is the side surface located in the cavity 102, and the second side surface 105 is provided opposite to the first side surface 104 and is the side surface located outside the cavity 102. Similarly, the current collecting plate 106 has two opposing side surfaces, which are the third side surface 107 and the fourth side surface 108 respectively. The third side surface 107 is the side surface facing the bottom 103 of the case 101, and the fourth side surface 108 is the side surface away from the bottom 103 of the case 101. Specifically, the plurality of first welding parts 109 are formed on the third side surface 107.

[0015] In addition, during the process of using the battery 100, there may be displacements such as rotation and rocking. During the process of the battery 100 rotating and rocking, the current collector plate 106 and the case 101 may move in opposite directions. The jelly roll 122 inside the battery 100 forms a force couple due to inertia, and as a result, the welding between the current collector plate 106 and the bottom 103 of the case 101 is peeled off. Through testing, it was discovered that there is an inverse proportional relationship between the distance (here, the distance refers to the distance from the first welding part 109 to the center of the current collector plate 106) and the torque resistance. Therefore, the closer the first welding part 109 is to the center of the current collector plate 106, the greater the force received by the current collector plate 106. Specifically, in order to avoid the welding between the current collector plate 106 and the bottom 103 of the case 101 from being peeled off, in this embodiment, each first welding part 109 has a first side 110 close to the center of the current collector plate 106 and a second side 111 far from the center of the current collector plate 106. Define the radius of the current collector plate 106 as D1, define the shortest distance from the first side 110 to the center of the current collector plate 106 as D2, define the inertial force received by the current collector plate 106 as F1, define the welding force received by the first welding part 109 as F2, and define the number of the first welding parts 109 as n. Here, F1D1 < nF2D2. When limited in this way, during the process of the battery 100 rotating and rocking, it is possible to prevent the jelly roll 122 and the current collector plate 106 from rotating together, avoid the welding part between the current collector plate 106 and the bottom 103 of the case 101 from breaking, and improve the connection strength between the current collector plate 106 and the bottom 103 of the case 101.

[0016] In addition, when the first welding part 109 is arc-shaped, the shortest distance from the first side 110 to the center of the current collector plate 106 is the radius of the arc. When the first welding part 109 is linear, the shortest distance from the first side 110 to the center of the current collector plate 106 is the distance from the center point of the first side to the center of the current collector plate 106.

[0017] Specifically, in the actual application process, first, it is necessary to determine the shortest distance from the first side 110 to the center of the current collector plate 106 (i.e., D2), and the position of the first welding part 109 can be determined by D2. Next, the position of the second side 111 is determined based on the width of the first welding part 109. In this way, the position of the first welding part 109 is determined. Specifically, in this embodiment, the distance from the first side 110 to the center of the current collector plate 106 is D2, and 7.0 mm ≤ D2 ≤ 9.4 mm. More specifically, the distance from the first side 110 to the center of the current collector plate 106 may be 7.0 mm, 7.2 mm, 7.4 mm, 7.6 mm, 7.8 mm, 8.0 mm, 8.1 mm, 8.2 mm, 8.3 mm, 8.4 mm, 8.5 mm, 8.61 mm, 8.62 mm, 8.64 mm, 8.65 mm, 8.68 mm, 8.69 mm, 8.7 mm, 8.8 mm, 8.85 mm, 8.9 mm, 9.0 mm, 9.1 mm, 9.2 mm, 9.3 mm, 9.4 mm. In some embodiments, the distance between the first side 110 and the second side 111 is D3, and 0.1 mm ≤ D3 ≤ 0.3 mm. More specifically, the distance between the first side 110 and the second side 111 may be 0.1 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 m, 0.28 mm, 0.29 mm, 0.30 mm. In one embodiment, the distance from the first side edge 110 to the center of the current collector plate 106 is 8.7 mm, and the distance from the first side edge 110 to the second side edge 111 is 0.3 mm.

[0018] Referring to FIGS. 2 and 3, to ensure the uniformity of the forces received by the current collector plate 106 and the bottom 103 of the case 101, the distances between two adjacent first welding parts 109 are the same, that is, the plurality of first welding parts 109 are distributed at equal intervals. Such an arrangement is to improve the stability of the connection between the current collector plate 106 and the bottom 103 of the case 101, evenly distribute the torque, and avoid the torque concentrating at one point and causing excessive force at this point to cause breakage.

[0019] Note that the specific shape of the first welding part 109 is not limited. Specifically, in this embodiment, the shape of the first welding part 109 may be arc-shaped, annular, C-shaped, or spiral-shaped.

[0020] Referring to FIG. 1, the battery 100 further includes a jelly roll 122 and a plurality of second welding parts 116. In this embodiment, tabs are provided on the jelly roll 122, and the current collector plate 106 and the tabs are welded and connected via the plurality of second welding parts 116. Specifically, the plurality of second welding parts 116 are formed on the side away from the bottom 103 of the current collector plate 106 (the current collector plate 106 has a third side surface 107 and a fourth side surface 108, the fourth side surface 108 is the side surface away from the bottom of the current collector plate 106, the third side surface 107 is the side surface facing the bottom of the current collector plate 106, and the plurality of first welding parts 109 are formed on the third side surface 107, and the plurality of second welding parts 116 are formed on the fourth side surface 108), the current collector plate 106 is welded to the tabs via the plurality of second welding parts 116, and the tabs are provided on the jelly roll 122, that is, the current collector plate is welded to the jelly roll 122 via the plurality of second welding parts 116. Specifically, considering the connection stability, the plurality of second welding parts 116 are provided so as to surround the center of the current collector plate 106, and the distance between each two adjacent second welding parts 116 is the same, and the plurality of second welding parts 116 are evenly distributed, so as to evenly distribute the welding force between the current collector plate 106 and the tabs, and improve the connection stability between the current collector plate 106 and the tabs. More specifically, each second welding part 116 is provided alternately with each first welding part 109. Being provided alternately means that the orthographic projection of the first welding part 109 on the current collector plate 106 and the orthographic projection of the second welding part 116 on the current collector plate 106 do not overlap. By providing the first welding part 109 and the second welding part 116 offset from each other, mutual interference is avoided, the welding stability is improved, and the safety rate of the battery 100 is improved.

[0021] Note that the method in which the first welding part 109 and the second welding part 116 are displaced is not limited, as long as they do not interfere with each other. Specifically, in this embodiment, as shown in FIGS. 2 and 4, the current collecting plate 106 includes a first connection segment 117 and a second connection segment 119 provided to surround the first connection segment 117. The second connection segment 119 is recessed in the direction toward the bottom 103 of the case 101 to form an annular boss 118. The first connection segment 117 and the second connection segment 119 are integrally formed. In the actual processing process, the current collecting plate is placed on a press, and the annular boss 118 is formed by pressing a part of the second connection segment 119. In some embodiments, the annular boss 118 has a side surface close to the bottom 103 of the case 101, and the plurality of first welding parts 109 are all formed under the annular boss 118 (here, "under" refers to the side surface of the annular boss 118 close to the bottom 103 of the case 101). The first connection segment 117 has a side surface close to the jelly roll 122, and the plurality of second welding parts 116 are formed on the first connection segment 117 (here, "on" refers to the side surface of the first connection segment 117 close to the jelly roll 122). Specifically, in this embodiment, by providing the annular boss 118, the current collecting plate 106 itself is divided into different parts (i.e., the region of the annular boss 118 and the region of the second connection segment 119). The first welding part 109 is provided on the annular boss 118, and the second welding part 116 is provided on the second connection segment 119. By dividing the current collecting plate 106 into different regions and providing the first welding part 109 and the second welding part 116 in different regions, the first welding part 109 and the second welding part 116 are displaced. Specifically, the height at which the second welding part 116 protrudes from the current collecting plate 106 is smaller than the height of the annular boss 118. Thereby, good contact between the annular boss 118 and the inner side surface of the case 101 is ensured, and the stability of the connection between the bottom 103 of the case 101 and the current collecting plate 106 is improved.

[0022] Specifically, in this embodiment, since the bottom 103 of the case 101 serves as an electrode, the case 101 is charged. Considering the safety of the battery 100, the battery 100 further includes a housing 112. The housing 112 is externally fitted to the case 101, and an insulating film is coated on the housing 112. The purpose of providing the insulating film is to cover the outside of the case 101 with the housing 112 to isolate the case 101 from the outside, avoid the case 101 from being oxidized and corroded, protect the housing 112 with the insulating film, and avoid the housing 112 from being corroded. Also, it can avoid the current in the case 101 from being transmitted externally and improve the safety of the battery 100. Specifically, in this embodiment, referring to FIGS. 1 and 5, the end of the housing 112 close to the bottom 103 of the case 101 is folded back toward the bottom 103 of the case 101 to form an extending portion 113. The extending portion 113 is located below the bottom 103 of the case 101 (here, "below" refers to the second side surface 105, that is, the extending portion 113 covers the second side surface 105), and the orthographic projection of the extending portion 113 on the bottom 103 of the case 101 covers the orthographic projection of the plurality of first welding portions 109 on the bottom 103 of the case 101. Such an arrangement is to ensure that the extending portion 113 can wrap the first welding portion 109, protect the first welding portion 109, and avoid the first welding portion 109 from being oxidized and corroded, resulting in the disconnection between the current collecting plate 106 and the bottom 103 of the case 101. In one embodiment, the first welding portion 109 is located at the middle position of the extending portion 113.

[0023] Note that the length of the extending portion 113 is related to the dimensions and positions of the first welding portion 109. It is necessary to consider that the extending portion 113 can cover all of the first welding portion 109, avoid the exposure of the welding points on the first welding portion 109, and avoid the extending portion 113 from being too long to affect the current transmission by the bottom 103 of the case 101. Specifically, in this embodiment, the length of the extending portion 113 is D4, and 2 mm ≤ D4 ≤ D3 mm. More specifically, the length of the extending portion 113 may be 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, or 3.0 mm.

[0024] In another embodiment, the battery 100 further includes a protective layer, the protective layer is provided under the bottom 103 of the case 101 (where "under" here refers to the second side 105, that is, the protective layer covers the second side 105), and the orthographic projection of the protective layer on the bottom 103 of the case 101 covers the orthographic projection of the plurality of first welding parts 109 on the bottom 103 of the case 101. Specifically, the protective layer covers the plurality of first welding parts 109, isolates the plurality of first welding parts 109 from the outside, and avoids the oxidation and corrosion of the first welding parts 109.

[0025] Referring to FIG. 6, the current collector plate 106 includes a core material 114 and an outer layer 115 located outside the core material 114. The core material 114 is welded to the bottom 103 of the case 101 through the outer layer 115. The material of the core material 114 contains copper, and the material of the outer layer 115 contains nickel. In order to ensure the strength of the battery 100, generally steel is selected as the material of the case 101. Considering that the case 101 and the current collector plate 106 are connected by welding to achieve a reduction in electrical resistance, copper is selected as the material of the current collector plate 106. However, copper has poor reflectivity to laser welding, the welding process is complex and welding is difficult. Therefore, copper is selected as the material of the core material 114, and nickel is selected as the material of the outer layer 115. The outer layer 115 is wrapped outside the core material 114, and the outer material is nickel. Nickel can reduce the reflection of laser welding. On the other hand, by plating a layer of nickel on the outside of copper, the processability of copper can be improved, the current collector plate 106 can be more easily welded to the case 101, and the outer layer 115 is wrapped outside the outer layer 115 of the core material 114, which can protect the core material 114 and avoid the core material 114 from being exposed to the air and oxidized and corroded, thereby improving the service life of the current collector plate 106.

[0026] In actual applications, it is necessary to consider not only the resistance of the current collector plate 106, but also the strength of the current collector plate 106 itself and the size of the occupied space. If the thickness of the current collector plate 106 is thin, the connection strength is weak, and the current collector plate 106 is likely to break. If the thickness of the current collector plate 106 is thick, the occupied space of the current collector plate 106 becomes large, and the size of the entire battery 100 increases. The thickness of the core material 114 is D5, and the thickness of the outer layer 115 is D6, where D5≥0.15 mm and 0.3 μm≤D6≤3.5 μm. Specifically, the thickness of the core material 114 may be 0.15, 0.18, 0.2, 0.25, 0.3, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, and the thickness of the outer layer 115 may be 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 1.5 μm, 2.0 μm, 2.2 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.8 μm, 2.9 μm, 3.0 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, and it may be selected according to the actual situation.

[0027] An embodiment of the present invention further provides a battery module 1000. Referring to FIG. 7, the battery module 1000 includes a plurality of batteries 100 and a connection sheet 200. A plurality of connection portions 201 are formed on the connection sheet 200, and each connection portion 201 is connected to a corresponding battery 100.

[0028] Referring to FIGS. 5 and 7, each battery 100 further includes a third welding portion 120, and the third welding portion 120 is formed on the side of the bottom 103 of the case 101 away from the current collecting plate 106 (i.e., a plurality of third welding portions 120 are formed on the second side surface 105), and the battery 100 is welded and connected to the connection sheet 200 through the third welding portion 120. It should be noted that the orthographic projection of the third welding portion 120 on the bottom 103 of the case 101 does not overlap with the orthographic projection of the first welding portion 109 on the bottom 103 of the case 101. This arrangement is to avoid the first welding portion 109 and the third welding portion 120 interfering with each other and making welding difficult. In one embodiment, the third welding portion 120 is provided at the center of the bottom 103 of the case 101.

[0029] More specifically, within the same battery 100, the orthographic projections of the plurality of first welding portions 109, the plurality of second welding portions 116, and the third welding portion 120 on the current collecting plate 106 are alternately provided. The first welding portion 109, the second welding portion 116, and the third welding portion 120 do not interfere with each other, making welding easier and the strength of the welded connection more stable.

[0030] It should be noted that an annular boss 118 is formed on the current collecting plate 106. To avoid the case 101 interfering with the annular boss 118, the bottom 103 of the case 101 is recessed in a direction away from the current collecting plate 106 to form a welding track accommodating portion 123, and the welding track accommodating portion 123 avoids the annular boss 118 so as to accommodate the plurality of first welding portions 109.

[0031] The embodiment of the present invention further provides a battery pack including a housing and a battery module 1000 provided in the housing.

Description of Reference Numerals

[0032] 100 Battery 101 Case 102 Cavity 103 Bottom 104 First Side Surface 105 Second Side Surface 106 Current collector plate 107 Third side 108 Fourth side 109 First welding part 110 First side edge 111 Second side edge 112 Housing 113 Extension part 114 Core material 115 Outer layer 116 Second welding part 117 First connection segment 118 Annular boss 119 Second connection segment 1000 Battery module 200 Connection sheet 201 Connection part 120 Third welding part 122 Jelly roll 123 Welding track accommodation part

Claims

1. A battery, The battery includes a case (101), a current collecting plate (106), and a plurality of first welds (109); The case (101) has a top and a bottom (103), and a cavity (102) is formed within the case (101); The current collecting plate (106) is disposed within the cavity (102); the plurality of first welds (109) are formed on a side of the current collecting plate (106) close to the bottom (103), the current collecting plate (106) is welded to the bottom (103) via the plurality of first welds (109), the plurality of first welds (109) are provided surrounding a center of the current collecting plate (106), and a distance from each of the first welds (109) to the center of the current collecting plate (106) is greater than a distance from each of the first welds (109) to an edge of the current collecting plate (106); battery.

2. Each of the first welds (109) has a first side (110) close to the center of the current collecting plate (106) and a second side (111) far from the center of the current collecting plate (106), the radius of the current collecting plate (106) is D1, the shortest distance between the first side (110) and the center of the current collecting plate (106) is D2, the inertial force applied to the current collecting plate (106) is F1, the welding force applied to the first welds (109) is F2, and the number of the first welds (109) is n, satisfying the following formula (1): F1D1<nF2D2 Formula (1) 10. The battery of claim 1.

3. The distance between the first side (110) and the second side (111) is D3, where 7.0 mm≦D2≦9.4 mm, 0.1 mm≦D3≦0.3 mm; 3. The battery of claim 2.

4. The distance between two adjacent first welds (109) is the same; and / or The shape of the first weld (109) is arc-shaped, annular, C-shaped, or spiral.

10. The battery of claim 1.

5. the housing (112) is fitted onto the case (101), an end of the housing (112) close to the bottom (103) is folded inward to form an extension (113), the extension (113) covers a part of the bottom (103), and an orthogonal projection of the extension (113) on the bottom (103) covers an orthogonal projection of the first welds (109) on the bottom (103) of the case (101). The battery according to any one of claims 1 to 4.

6. The insulating film further includes an insulating film that is fitted to the housing.

6. The battery of claim 5.

7. The length of the extension (113) is D4, where 2.55 mm≦D4≦3.4 mm.

6. The battery of claim 5.

8. a protective layer is provided under the bottom (103) of the case (101), and an orthogonal projection of the protective layer on the bottom (103) of the case (101) covers an orthogonal projection of the first welds (109) on the bottom (103) of the case (101). The battery according to any one of claims 1 to 4.

9. The current collecting plate (106) includes a core material (114) and an outer layer (115) located outside the core material (114), the core material (114) is welded to the bottom (103) of the case (101) via the outer layer (115), the material of the core material (114) includes copper, and the material of the outer layer (115) includes nickel. The battery according to any one of claims 1 to 4.

10. The thickness of the core material (114) is D5, and the thickness of the outer layer (115) is D6, where D5≧0.15 mm, 0.3 μm≦D6≦3.5 μm.

10. The battery of claim 9.

11. the current collecting plate (106) is welded to the jelly roll (122) via the second welds (116), the second welds (116) being formed on a side of the current collecting plate (106) that faces away from the bottom (103) of the case (101); the current collecting plate (106) is welded to the jelly roll (122) via the second welds (116), the second welds (116) being arranged around a center of the current collecting plate (106), and each of the second welds (116) being arranged alternately with each of the first welds (109); The battery according to any one of claims 1 to 4.

12. The distance between two adjacent second welds (116) is the same. The battery of claim 11.

13. the current collecting plate (106) includes a first connecting segment (117) and a second connecting segment (119) surrounding the first connecting segment (117), the second connecting segment (119) being partially recessed in a direction toward the bottom (103) of the case (101) to form an annular boss (118), the first welds (109) are all formed below the annular boss (118), and the second welds (116) are formed on the first connecting segment (117); The battery of claim 11.

14. The bottom (103) of the case (101) is recessed in a direction away from the current collecting plate (106) to form a welding track accommodation portion (123), and the welding track accommodation portion (123) accommodates the plurality of first welds (109). The battery according to any one of claims 1 to 4.

15. A number of batteries; a connection sheet (200) having a plurality of connection portions (201) formed thereon, each of the connection portions (201) being connected to a corresponding one of the batteries; Each of the batteries is a battery according to any one of claims 1 to 4. Battery module.

16. Each of the batteries further includes a third weld (120), the third weld (120) being formed on a side of the bottom (103) away from the current collecting plate (106), and the battery is welded to the connection sheet (200) via the third weld (120). The battery module according to claim 15.

17. The battery further includes a plurality of second welds (116); Within the same battery, the orthogonal projections of the first welds (109), the second welds (116) and the third welds (120) on the current collecting plate (106) are alternated. The battery module according to claim 16.

18. A housing and The battery module (1000) according to claim 15 is provided in the housing. Battery pack.

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