A lithium-ion battery

Abstract

This utility model discloses a lithium-ion battery, including a terminal post, a tab, and an adapter plate. The terminal post has a bottom surface along the thickness direction of the adapter plate. The adapter plate includes a tab welding portion and a terminal post welding portion, with the tab welding portion welded to the tab. The terminal post welding portion is welded to the bottom surface, and the projection of the bottom surface onto the adapter plate along the thickness direction forms a first region. The set of lines connecting the center of the first region to any point on the tab welding portion constitutes a predetermined region. The projection of the predetermined region onto the adapter plate along the thickness direction forms a second region, and the overlapping portion of the first and second regions forms a third region. At least a portion of the terminal post welding portion is located within the third region. The area of ​​the first region is S1, the area of ​​the terminal post welding portion is S2, and 1 / 2*S1≥S2. Using the lithium-ion battery provided by this utility model, overcurrent requirements can be met while reducing the welding area between the terminal post and the adapter plate, thus improving production efficiency.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a lithium-ion battery. Background Technology

[0002] In the production process of lithium-ion batteries, the electrode assembly and the cover plate assembly need to be electrically connected via adapter plates to enable the conduction of the internal circuitry of the lithium-ion battery. The terminals of the cover plate assembly and the adapter plates are connected by welding. Since current flows through the adapter plates when the lithium-ion battery is operating, the area of ​​the welded connection significantly determines the current-carrying performance, and the welding time generally increases with the increase of the welded area. Therefore, how to improve production efficiency while meeting the current-carrying performance requirements between the terminals and the adapter plates has become a pressing problem for those skilled in the art. Utility Model Content

[0003] This invention provides a lithium-ion battery that improves production efficiency while meeting the overcurrent performance requirements between the terminals and the adapter.

[0004] This utility model provides a lithium-ion battery, including a terminal post, a tab, and an adapter plate. The terminal post has a bottom surface along the thickness direction of the adapter plate. The adapter plate includes a tab welding portion and a terminal post welding portion, the tab welding portion being electrically connected to the tab. The terminal post welding portion is electrically connected to the bottom surface, and the projection of the bottom surface onto the adapter plate along the thickness direction forms a first region. The set of lines connecting the center of the first region to any point on the tab welding portion constitutes a predetermined region. The projection of the predetermined region onto the adapter plate along the thickness direction forms a second region, and the overlapping portion of the first and second regions forms a third region. At least a portion of the terminal post welding portion is located within the third region. The area of ​​the first region is S1, the area of ​​the terminal post welding portion is S2, and S1 and S2 satisfy: 1 / 2*S1≥S2.

[0005] The lithium-ion battery provided by this invention has a predetermined region formed by the lines connecting the center of the first region to any point on the tab welding portion. The projection of this predetermined region onto the adapter plate along the thickness direction forms a second region. It is understood that during the operation of the lithium-ion battery, current flows through the adapter plate between the terminal and the tab. The second region roughly corresponds to the area with lower resistance between the terminal welding portion and the tab welding portion on the adapter plate. In other words, the resistance when current flows through the second region is generally lower than other connection areas of the adapter plate between the first region and the tab welding portion. At least a portion of the terminal welding portion is located in the overlapping part of the first and second regions (the third region), according to P=I... 2As shown by R, during the operation of a lithium-ion battery, the current passing through the adapter plate can flow directly from the second region to the electrode welding section, effectively reducing the heat generation of the adapter plate and thus ensuring the overcurrent performance of the lithium-ion battery. Furthermore, since the area of ​​the electrode welding section is less than or equal to half the total area of ​​the bottom surface of the electrode, during the welding process between the electrode and the adapter plate, it can effectively control the heat generation of the adapter plate while ensuring a certain level of overcurrent performance. It can also effectively shorten the welding time between the electrode and the adapter plate, thereby improving production efficiency.

[0006] In one possible implementation of this invention, the projection of a predetermined area along the thickness direction of the adapter piece completely falls within the adapter piece. This shortens the conduction path length of the current on the adapter piece while satisfying overcurrent performance, thereby reducing the heat generated by the adapter piece during lithium-ion battery operation.

[0007] In one possible implementation of this invention, the area of ​​the electrode welding portion in the third region is S3, and S2 and S3 satisfy: S2≥S3≥1 / 2*S2. Since the third region is the overlapping part of the first and second regions, placing most of the electrode welding portions in the third region can maintain a shorter current path between most of the electrode welding portions and the electrode tab welding portions, ensuring that the overall conduction path of the current on the adapter plate has a small resistance. At the same time, it also makes the electrode welding portions relatively concentrated, that is, the welding positions of the electrode and the adapter plate are not too dispersed, so as to improve the connection strength between the adapter plate and the electrode with a smaller welding area while satisfying the overcurrent performance.

[0008] In one possible implementation of this invention, the adapter piece further includes a first contour line, which encloses a first region. The overlapping portion of the first contour line and the third region is a contour segment, at least a portion of which is located within the electrode welding portion. Since the first contour line is the outer contour of the projection of the bottom surface of the electrode, by placing the contour segment of the overlapping portion of the first contour line and the third region within the electrode welding portion, a portion of the electrode welding portion can be located within the third region at the position closest to the tab welding portion. This is beneficial for further shortening the current path and improving the performance of the lithium-ion battery when the area of ​​the electrode welding portion is limited.

[0009] In one possible implementation of this utility model, the adapter plate further includes a first contour line and a second contour line. The first contour line encloses a first region, and the second contour line encloses a terminal welding portion. The minimum distance between the second contour line and the first contour line is D1, and D1 ≥ 1 mm. During the terminal welding process, when the molten area generated by the welding of the adapter plate and the terminal exceeds the outer contour of the bottom surface of the terminal and enters a region on the adapter plate that does not correspond to the terminal, since there is only the adapter plate at the position exceeding the outer contour of the bottom surface of the terminal and no corresponding bottom surface of the terminal, the excess part is not welded to the terminal and it is difficult to directly improve the current flow performance, ultimately becoming an ineffective welding area. Therefore, with the lithium-ion battery provided by this utility model, since the minimum distance between the second contour line and the first contour line is D1, and D1 ≥ 1 mm, the molten area exceeding the outer contour of the bottom surface of the terminal can be effectively reduced during the terminal welding process, thereby improving welding efficiency and welding quality.

[0010] In one possible implementation of this invention, the minimum distance between the center of the first region and the first contour line is D2, and D1 and D2 satisfy: D1≥1 / 10*D2. For poles of different shapes and sizes, by making the pole welding portion closer to the center of the first region relative to the outer contour of the first region, the current is mainly directly discharged through the pole body after passing through the adapter plate, thereby improving overcurrent performance.

[0011] In one possible implementation of this invention, the projection of the minimum cross-section of the electrode post onto the adapter plate along the thickness direction is a fourth region. The fourth region includes a fifth region, which is the overlapping portion of the fourth and second regions. The area of ​​the electrode post welding portion within the fifth region is S5, and S2 and S5 satisfy: S2 ≥ S5 ≥ 1 / 2 * S2. This is beneficial for further shortening the current conduction path between the adapter plate and the electrode post, reducing the internal resistance of the lithium-ion battery, thereby reducing the heat generated during use and improving the performance of the lithium-ion battery.

[0012] In one possible implementation of this invention, the center of the fourth region is located within the electrode welding portion. During the operation of the lithium-ion battery, the current is conducted to the electrode near the center of the fourth region, and then conducts from the center of the electrode to other parts of the electrode, further shortening the conduction path and thus further reducing the internal resistance of the lithium-ion battery.

[0013] In one possible implementation of this invention, the minimum cross-sectional area of ​​the electrode post along the thickness direction of the adapter piece is S4, and S2 and S4 satisfy: S2≤1 / 2*S4. This is beneficial for further reducing the area of ​​the electrode post welding part and reducing the total heat generated during welding, thereby reducing the thermal impact on the adapter piece and other components of the lithium-ion battery during the welding process, and thus extending the service life of the lithium-ion battery.

[0014] In one possible implementation of this invention, at least two tabs are included, and the adapter piece includes at least two tab welding portions. Along a predetermined direction, the at least two tab welding portions are located on the same side of the electrode welding portion. This ensures that as many second regions as possible are located on the same side of the electrode welding portion, allowing the welding head to traverse a shorter distance during welding, which further improves production efficiency.

[0015] Alternatively, along a predetermined direction, at least two tab welding portions are located on both sides of the pole welding portion, with the predetermined direction perpendicular to the thickness direction of the adapter piece, so that the second region is distributed as much as possible on both sides of the pole welding portion. In this way, during the welding process, the pole welding portions can be distributed on at least both sides of the corresponding area on the bottom surface of the pole, thereby increasing the connection strength between the adapter piece and the pole. Furthermore, by arranging the pole welding portion in a continuous manner, compared to separate pole welding portions, the welding head can operate continuously during the welding process without needing to cross areas between separate pole welding portions that do not require welding, which is beneficial for further improving production efficiency. Attached Figure Description

[0016] Figure 1 A partial cross-sectional view of the lithium-ion battery provided by this utility model;

[0017] Figure 2 A schematic diagram of the structure of the adapter plate provided by this utility model;

[0018] Figure 3 for Figure 2 A schematic diagram of the structure of the first region of the provided adapter plate;

[0019] Figure 4 Another structural schematic diagram of the adapter plate provided by this utility model;

[0020] Figure 5 Another structural schematic diagram of the adapter plate provided by this utility model;

[0021] Figure 6 A schematic diagram of the pole welding part provided by this utility model;

[0022] Figure 7 Another structural schematic diagram of the adapter plate provided by this utility model;

[0023] Figure 8 for Figure 7 A schematic diagram of the structure of the first region of the provided adapter plate;

[0024] Figure 9 for Figure 2 Another structural diagram of the first region of the provided adapter plate.

[0025] Reference numerals: 1-Pole post; 11-Bottom surface; 2-Adapter piece; 21-Electrode tab welding part; 22-Pole post welding part; 23-First region; 24-Second region; 25-Third region; 26-First outline; 27-Second outline; 28-Fourth region; 281-Fifth region; 3-Electrode tab. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted. The terms expressing position and direction described in the embodiments of this utility model are illustrative based on the accompanying drawings, but changes can be made as needed, and all such changes are included within the protection scope of this utility model. The accompanying drawings of the embodiments of this utility model are only for illustrating relative positional relationships and do not represent actual proportions.

[0027] It should be noted that specific details are set forth in the following description to facilitate understanding of this utility model. However, this utility model can be implemented in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0028] During the production of lithium-ion batteries, the electrode assembly and the cover plate assembly need to be electrically connected through an adapter plate. The electrode post of the cover plate assembly and the adapter plate are connected by welding. The area of ​​the welded connection part determines the current carrying capacity to a certain extent, and the welding time generally increases with the increase of the welding area.

[0029] In view of this, the lithium-ion battery provided by this utility model, by placing the welding part of the terminal and the adapter plate in the region of low resistance between the tab and the terminal, and at the same time reducing the area of ​​the welding part, effectively reduces the welding area between the terminal and the adapter plate while satisfying the overcurrent performance, thereby improving production efficiency. To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] A lithium-ion battery includes adapter tabs, electrode assemblies, and a housing. The electrode assembly includes stacked electrode sheets and a separator. Each electrode sheet includes a current collector and an active material layer, the active material layer being coated on the surface of the current collector. The tabs can be areas on the electrode sheet not coated with active material. The housing typically includes a cover assembly and sidewalls. The sidewalls can enclose an opening to form a receiving space within which the electrode assembly is disposed. The cover assembly can be used to close the opening. The terminal posts can be exemplaryly disposed in the cover assembly or the sidewalls. (Reference) Figure 1 , Figure 1 This is a partial cross-sectional view showing the lithium-ion battery at electrode 1 along the radial direction of the electrode. Electrode 1 is exemplary in a stepped columnar shape, along the thickness direction of the adapter piece 2 (axial direction of electrode 1). Figure 1 (As shown in the Z-axis direction), the pole post 1 is provided with a bottom surface 11, which is used for welding with the adapter piece 2. It should be noted that the pole post 1 can also be cylindrical, prismatic, or multi-segmented prism-shaped, and this utility model does not make any specific limitation.

[0031] When adapter plate 2 is configured, refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of the adapter plate 2 provided by this utility model. The adapter plate 2 includes a tab welding part 21 and a post welding part ( Figure 2 (Not shown in the diagram), wherein the tab welding part 21 is welded to the tab 3, and the post welding part is welded to the bottom surface 11, so as to realize the electrical connection between the electrode assembly and the post 1. The tab welding part 21 and the tab 3 can be laser welded or ultrasonic welded, and this utility model does not make a specific limitation.

[0032] It should be noted that, along the thickness direction of the adapter piece 2, the pole post 1 and the pole lug 3 can be located on the same side of the adapter piece 2, or on opposite sides of the adapter piece 2. Specifically, the pole lug welding portion 21 and the pole post welding portion can be located on the same side of the adapter piece 2 or on opposite sides. (Refer to...) Figure 3 , Figure 3 for Figure 2 A schematic diagram of the structure of the first region 23 of the provided adapter plate 2. The projection of the bottom surface 11 of the pole post 1 onto the adapter plate 2 forms the first region 23. The set of lines connecting the center of the first region 23 and any point on the electrode tab welding part 21 constitutes a predetermined region. It can be understood that, along the thickness direction of the adapter plate 2, when the pole post 1 and the electrode tab 3 are located on the same side of the adapter plate 2, the predetermined region is located on the same side surface of the adapter plate 2; while when the pole post 1 and the electrode tab 3 are located on opposite sides of the adapter plate 2, the predetermined region extends from one surface to the opposite surface along the thickness direction of the adapter plate 2.

[0033] Please refer to the above. Figure 2 and Figure 3Along the thickness direction of the adapter piece 2, the projection of the predetermined area onto the adapter piece 2 forms a second region 24. It should be noted that the second region 24 is not the portion overlapping the adapter piece 2 after the predetermined area is projected using the aforementioned method, but rather the region obtained by directly projecting the predetermined area along the thickness direction of the adapter piece 2, which may extend beyond the outline of the adapter piece 2. The overlapping portion of the first region 23 and the second region 24 forms the third region 25, meaning that the first region 23 and the second region 24 are located on the same side of the adapter piece 2. In other words, when projecting the predetermined area using the aforementioned method, the predetermined area can be projected onto the side where the first region 23 is located, so that the resulting second region 24 and the first region 23 are located on the same side of the adapter piece 2.

[0034] It should be noted that, along the thickness direction of adapter piece 2, due to the projection of the preset area (by... Figure 2 If the area enclosed by line segment M, line segment N and electrode welding part 21 can extend beyond the outer contour of adapter piece 2, then during the operation of lithium-ion battery, part of the current flowing between electrode 3 and electrode post 1 needs to pass through point P and point E (flowing along broken line segment or curved segment) before being conducted.

[0035] It is worth mentioning that, in one alternative implementation, such as Figure 4 As shown, Figure 4 This is another structural schematic diagram of the adapter plate 2 provided by this utility model. Along the thickness direction of the adapter plate 2, the projection of the predetermined area can fall completely within the adapter plate 2, so that the current between the tab welding portion 21 and the post welding portion 22 can flow in a straight line, i.e., without passing through the inflection point of the adapter plate 2 (e.g., ...). Figure 2 Points P and E in the connector can shorten the conduction path of the current on the adapter 2 while meeting the overcurrent performance requirements, thereby reducing the heat generated by the adapter 2 when the lithium-ion battery is working.

[0036] When specifically setting the pole welding part 22, at least a portion of the pole welding part 22 is located within the third region 25, and the area of ​​the first region 23 is S1, the area of ​​the pole welding part 22 is S2, and S1 and S2 satisfy: 1 / 2*S1≥S2.

[0037] Using the lithium-ion battery provided by this utility model, since the set of lines connecting the center of the first region 23 and any point on the tab welding part 21 constitutes a predetermined region, and the projection of the predetermined region onto the adapter piece 2 along the thickness direction of the adapter piece 2 forms a second region 24. It can be understood that during the operation of the lithium-ion battery, the current between the first region 23 and the tab welding part 21 flows through the second region 24, so the resistance value of the second region 24 is less than the resistance value of other connection regions of the adapter piece 2 between the first region 23 and the tab welding part 21. Simultaneously, at least a portion of the electrode welding part 22 is located in the overlapping part of the first region 23 and the second region 24 (the third region 25). The second region 24 roughly corresponds to the region on the adapter piece 2 where the current conduction path is shorter. Therefore, since at least a portion of the electrode welding part 22 is located within the third region 25, the current through the adapter piece 2 can flow directly from the second region 24 to the electrode welding part 22, where P = I. 2 As can be seen from *R, it can effectively reduce the heat generated by the lithium-ion battery during operation, thus ensuring the overcurrent performance of the lithium-ion battery. Furthermore, since the area of ​​the electrode welding part 22 is less than or equal to half the total area of ​​the bottom surface 11 of the electrode 1, during the welding process between the electrode 1 and the adapter piece 2, it can effectively control the heat generated by the adapter piece 2 while ensuring a certain level of overcurrent performance. It can also effectively shorten the welding time between the electrode 1 and the adapter piece 2, thereby improving production efficiency.

[0038] In addition, the cover plate assembly typically includes a cover plate body and an insulating component located between the cover plate body and the adapter piece 2. In some embodiments, the insulating component is made of plastic. Therefore, by reducing the welding area between the bottom surface 11 of the electrode post 1 and the adapter piece 2, the heat generated during the welding process can be effectively reduced, thereby reducing the thermal impact on the insulating component and preventing the insulation performance of the lithium-ion battery from being reduced due to thermal deformation or even melting of the insulating component, thus improving the safety of the lithium-ion battery.

[0039] In an optional embodiment, the area of ​​the electrode welding portion 22 can be S2, and the area of ​​the electrode welding portion 22 located in the third region 25 can be S3, and S2 and S3 satisfy: S2≥S3≥1 / 2*S2. Since the third region 25 is the overlapping part of the first region 23 and the second region 24, placing most of the electrode welding portions 22 in the third region 25 can maintain a shorter current path between most of the electrode welding portions 22 and the electrode tab welding portion 21, so as to ensure that the overall conduction path of the current on the adapter piece 2 has a small resistance. At the same time, it also makes the electrode welding portions 22 relatively concentrated, that is, the welding positions of the electrode 1 and the adapter piece 2 are not too dispersed, so as to improve the connection strength between the adapter piece 2 and the electrode 1 while satisfying the overcurrent performance and with a smaller welding area.

[0040] It is understandable that when S2 = S3, the pole post welding part 22 completely covers the third region 25, that is, as Figure 4 The shaded area is shown. Additionally, as... Figure 3 As shown, a portion of the electrode welding part 22 can also cover a portion of the third region 25, and another portion of the electrode welding part 22 can extend beyond the third region 25, so as to improve the connection strength between the adapter piece 2 and the electrode 1 while satisfying the overcurrent performance.

[0041] It should be noted that this utility model does not limit the position and number of the pole post 1, pole lug 3, pole lug welding part 21, and pole post welding part 22. For example, in an optional embodiment, such as Figure 2 As shown, the lithium-ion battery includes at least two tabs 3, and the adapter piece 2 includes at least two tab welding portions 21. Along a predetermined direction (perpendicular to the thickness direction of the adapter piece 2), the at least two tab welding portions 21 are located on the same side of the electrode welding portion 22 and are spaced apart. It should be noted that since the tab 3 can be an area on the electrode sheet that is not coated with active material, and the stacked electrodes in the lithium-ion battery can also have multiple layers of tabs, the tab 3 here can refer to a relatively tightly arranged cluster of tabs formed by multiple layers of tabs. It can be understood that "the lithium-ion battery includes at least two tabs 3" means that the lithium-ion battery includes at least two relatively tightly arranged clusters of tabs. The projection of the electrode welding portion 22 toward the two tab welding portions 21 is located between the two electrode welding portions 22. This ensures that the second region 24 is located as much as possible on the same side of the electrode welding portion 22, thus shortening the distance the welding head traverses during welding, which is beneficial for further improving production efficiency.

[0042] It is understandable that the aforementioned adapter piece 2 will form two second regions 24, and after the two second regions 24 intersect with the first region 23, there are two third regions 25. The two electrode tab welding portions 21 will correspondingly form two electrode post welding portions 22 within the two third regions 25, and the electrode post welding portions 22 are arranged in a continuous manner. On the one hand, forming a larger electrode post welding portion 22 is beneficial to improving the connection strength between the adapter piece 2 and the electrode post 1. On the other hand, compared to separate electrode post welding portions 22, during the welding process, the welding head will not cross the areas between the separate electrode post welding portions 22 that do not need to be welded, allowing the welding head to operate continuously to further improve production efficiency.

[0043] In one alternative implementation, such as Figure 5 As shown, Figure 5This is another structural schematic diagram of the adapter piece 2 provided by this utility model. Along a predetermined direction, at least two electrode tab welding portions 21 can also be located on both sides of the electrode post welding portion 22. This ensures that the second region 24 is distributed as much as possible on both sides of the corresponding region on the bottom surface 11 of the electrode post 1. Thus, during the welding process, the electrode post welding portions 22 can be distributed at least on both sides of the corresponding region on the bottom surface 11 of the electrode post 1. Overall, the distribution of the electrode post welding portions 22 on the adapter piece is relatively uniform, which is beneficial for increasing the connection strength between the adapter piece 2 and the electrode post 1.

[0044] It should be noted that this utility model does not limit the shape of the pole welding part 22; specifically, it can be circular, elliptical, spiral, triangular, polygonal, or rounded rectangle, etc. Figure 6 As shown, Figure 6 A schematic diagram illustrating the structure of the electrode welding section. For example, the electrode welding section 22 can be rectangular in shape, and multiple electrode welding sections 22 can be arranged radially at intervals along the first region 23, so as to effectively improve the connection strength between the adapter plate 2 and the electrode 1 while meeting the overcurrent requirements of the adapter plate 2.

[0045] In one particular embodiment, reference is made together with Figure 2 and Figure 3 The adapter plate 2 also includes a first contour line 26, which encloses a first region 23. The overlapping portion of the first contour line 26 and the third region 25 is a contour segment (line segment F), at least a portion of which is located within the electrode welding portion 22. Since the first contour line 26 is the outer contour of the projection of the bottom surface 11 of the electrode post 1, by setting the contour segment of the overlapping portion of the first contour line 26 and the third region 25 within the electrode welding portion 22, a portion of the electrode welding portion 22 can be located within the third region 25 at the position closest to the tab welding portion 21. This is beneficial for further shortening the current path and improving the performance of the lithium-ion battery when the area of ​​the electrode welding portion 22 is limited.

[0046] It should be noted that this utility model does not limit the shape of the first region 23; exemplary examples are also provided. Figure 7 and Figure 8 , Figure 7 Another structural diagram is used to illustrate adapter plate 2; Figure 8 For display Figure 7 A schematic diagram of the structure of the first region 23 of the provided adapter plate 2. The first region 23 can be rectangular in shape, resulting in a broken line segment F. When providing the electrode welding part 22, the electrode welding part 22 can be bent, and two electrode welding parts 22 can be connected to each other to reduce the welding difficulty between the adapter plate 2 and the electrode 1.

[0047] Furthermore, in the adapter piece 2 provided by this utility model, the first contour line 26 is equivalent to the outer contour line of the first region 23. It can be understood that the first region 23 can also be provided with an inner contour line, that is, the first region 23 is annular, in order to adapt to the welding requirements of different lithium-ion batteries.

[0048] In one alternative implementation, refer to Figure 8 or Figure 9 , Figure 9 for Figure 2 Another structural schematic diagram of the first region 23 of the provided adapter plate 2. The adapter plate 2 also includes a second contour line 27, wherein the second contour line 27 encloses and forms the pole welding part 22, and the minimum distance between the second contour line 27 and the first contour line 26 of the first region 23 is D1, and D1 ≥ 1mm, such as 1.5mm, 2mm, etc. During the welding process of the pole 1, when the molten area generated by the welding of the adapter plate 2 and the pole 1 crosses the outer contour of the bottom surface 11 of the pole 1 and enters the area on the adapter plate 2 that does not correspond to the pole 1, since there is only the adapter plate and no pole bottom surface corresponding to it at the position beyond the outer contour of the pole bottom surface, the area beyond is not welded together with the pole 1, and it is difficult to improve the current flow performance, thus becoming an ineffective welding area. Therefore, by using the lithium-ion battery provided by this utility model, the minimum distance between the second contour line 27 and the first contour line 26 is D1, and D1≥1mm. In this way, during the welding process of the electrode post 1, the outer contour of the electrode post welding part 22 can be spaced apart from the first contour line 26, which can effectively reduce the melting area from crossing the outer contour of the bottom surface 11 of the electrode post 1, thereby improving welding efficiency and welding quality.

[0049] It is worth mentioning that, optional, such as Figure 9 As shown, the minimum distance between the center of the first region 23 and the first contour line 26 can be set to D2, and D1 and D2 satisfy: D1≥1 / 10*D2, for example D1=1 / 8*D2, D1=1 / 7*D2, D1=1 / 6*D2, D1=1 / 5*D2, D1=1 / 4*D2, D1=1 / 3*D2 or D1=1 / 2*D2. For poles 1 of different shapes and sizes, the pole welding part 22 is made closer to the center of the first region 23 relative to the outer contour of the first region 23, so that the current is mainly directly discharged through the pole body after passing through the adapter piece 2, thereby improving the overcurrent performance. It can be understood that when the first region 23 enclosed by the first contour line 26 is circular, then D2 is the radius of the circle.

[0050] In one specific embodiment, reference is also made to Figure 1 and Figure 9 Along the thickness direction of the adapter piece 2, the projection of the minimum cross-section of the pole post 1 onto the adapter piece 2 is the fourth region 28. Figure 9The area enclosed by the dashed line). When specifically setting the fourth region 28, when the bottom surface 11 of the pole post 1 contacts the adapter piece 2, the fourth region 28 can be located within the outer contour line of the bottom surface 11 of the pole post 1, and the fourth region 28 includes a fifth region 281, which is the overlapping portion of the fourth region 28 and the second region 24. Figure 9 (At least part of the shaded area within the area enclosed by the dashed line). Therefore, at least a portion of the electrode welding portion 22 can be located within the fifth region 281. This allows the current to be directly conducted along the axial direction of the electrode 1 after reaching the electrode welding portion 22 located within the fifth region 281 during lithium-ion battery operation, further shortening the current conduction path between the adapter piece 2 and the electrode 1.

[0051] In addition, the area of ​​the electrode welding part 22 located in the fifth region 281 is S5, and the area of ​​the electrode welding part 22 is S2. S2 and S5 satisfy: S2≥S5≥1 / 2*S2, so that most of the electrode welding part 22 is located in the fifth region 281. This is beneficial to further shorten the length of the current conduction path between the adapter piece 2 and the electrode 1, reduce the internal resistance of the lithium-ion battery, thereby reducing the heat generation of the lithium-ion battery during use and improving the performance of the lithium-ion battery.

[0052] It is worth mentioning that the center of the fourth region 28 can also be located inside the electrode welding part 22. In this way, during the operation of the lithium-ion battery, the current is conducted to the electrode 1 through the vicinity of the center of the fourth region 28, and then conducted to other parts of the electrode 1 from the center of the electrode 1. This is used to further shorten the current conduction path, thereby further reducing the internal resistance of the lithium-ion battery and reducing heat generation.

[0053] In an optional embodiment, along the thickness direction of the adapter piece 2, the area of ​​the minimum cross-section of the terminal post 1 is S4, and the area of ​​the terminal post welding portion 22 is S2, and S2 and S4 satisfy: S2≤1 / 2*S4, so as to further reduce the area of ​​the terminal post welding portion 22 and reduce the total heat generated during the welding of the adapter piece 2 while satisfying the overcurrent performance, thereby reducing the thermal impact on the adapter piece 2 and other components of the lithium-ion battery during the welding process, so as to extend the service life of the lithium-ion battery.

[0054] In summary, using the lithium-ion battery provided by this utility model, since the set of lines connecting the center of the first region 23 and any point on the tab welding part 21 constitutes a predetermined region, and the projection of the predetermined region onto the adapter piece 2 along the thickness direction of the adapter piece 2 forms a second region 24, it can be understood that during the operation of the lithium-ion battery, the current between the first region 23 and the tab welding part 21 flows through the second region 24, and the resistance value of the second region 24 is less than that of other connection regions of the adapter piece 2 between the first region 23 and the tab welding part 21. Simultaneously, at least a portion of the electrode welding part 22 is located in the overlapping portion of the first region 23 and the second region 24 (the third region 25). The second region 24 roughly corresponds to the region on the adapter piece 2 where the current conduction path is shorter. Therefore, since at least a portion of the electrode welding part 22 is located within the third region 25, the current through the adapter piece 2 can flow directly from the second region 24 to the electrode welding part 22. According to P=I... 2 As can be seen from *R, it can effectively reduce the heat generation of the adapter piece 2, thus ensuring the overcurrent performance of the lithium-ion battery. Furthermore, since the area of ​​the electrode welding part 22 is less than or equal to half the total area of ​​the bottom surface 11 of the electrode 1, during the welding process between the electrode 1 and the adapter piece 2, it can effectively control the heat generation of the adapter piece 2 while effectively shortening the welding time between the electrode 1 and the adapter piece 2, thereby improving production efficiency.

[0055] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. A lithium-ion battery, characterized in that, The device includes a pole, a tab, and an adapter plate. Along the thickness direction of the adapter plate, the pole has a bottom surface, wherein: The adapter plate includes a tab welding portion and a post welding portion, the tab welding portion being welded to the tab; the post welding portion being welded to the bottom surface, and along the thickness direction of the adapter plate, the projection of the bottom surface onto the adapter plate forms a first region; The set of lines connecting the center of the first region to any point on the electrode welding part constitutes a predetermined region; along the thickness direction of the adapter piece, the projection of the predetermined region on the adapter piece forms a second region, and the overlapping part of the first region and the second region is a third region; At least a portion of the electrode welding part is located within the third region; the area of ​​the first region is S1, the area of ​​the electrode welding part is S2, and S1 and S2 satisfy: 1 / 2*S1≥S2.

2. The lithium-ion battery according to claim 1, characterized in that, Along the thickness direction of the adapter piece, the projection of the predetermined area falls completely within the adapter piece.

3. The lithium-ion battery according to claim 2, characterized in that, The area of ​​the pole welding part located in the third region is S3, and S2 and S3 satisfy: S2≥S3≥1 / 2*S2.

4. The lithium-ion battery according to any one of claims 1-3, characterized in that, The adapter plate also includes a first contour line, which encloses and forms the first region. The overlapping portion of the first contour line and the third region is a contour segment, and at least a portion of the contour segment is located within the pole welding portion.

5. The lithium-ion battery according to claim 1, characterized in that, The adapter plate also includes a first contour line and a second contour line. The first contour line encloses and forms the first region, and the second contour line encloses and forms the pole welding part. The minimum distance between the second contour line and the first contour line is D1, and D1 ≥ 1 mm.

6. The lithium-ion battery according to claim 5, characterized in that, The minimum distance between the center of the first region and the first contour line is D2, and D1 and D2 satisfy: D1≥1 / 10*D2.

7. The lithium-ion battery according to claim 1, characterized in that, Along the thickness direction of the adapter piece, the projection of the minimum cross-section of the pole post onto the adapter piece is the fourth region; The fourth region includes a fifth region, which is the overlapping part of the fourth region and the second region; the area of ​​the pole welding part located in the fifth region is S5, and S2 and S5 satisfy: S2≥S5≥1 / 2*S2.

8. The lithium-ion battery according to claim 7, characterized in that, The center of the fourth region is located within the pole welding section.

9. The lithium-ion battery according to claim 1, characterized in that, Along the thickness direction of the adapter piece, the area of ​​the minimum cross-section of the pole is S4, and S2 and S4 satisfy: S2≤1 / 2*S4.

10. The lithium-ion battery according to claim 1, characterized in that, The lithium-ion battery includes at least two tabs, and the adapter includes at least two tab welding portions. Along a preset direction, the at least two tab welding portions are located on the same side of the electrode welding portion. Alternatively, along a preset direction, the at least two electrode tab welding portions are located on both sides of the electrode post welding portion; The preset direction is perpendicular to the thickness direction of the adapter piece; The pole welding section is arranged in a continuous manner.

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