Battery cell and battery pack

Abstract

The utility model relates to the technical field of batteries, and discloses a battery cell and a battery pack, and the battery cell comprises a shell and a cover plate, at least one pole group is arranged in the shell, and an opening is formed in one side of the shell; the cover plate covers one side of the opening of the shell, and a pole is arranged on the cover plate; a tab is arranged on one side, facing the cover plate, of the pole group, the tab is correspondingly welded with the pole column, the tab comprises a plurality of layers of sub-tabs which are stacked, and a welding printing area is reserved on the outer surface of the tab; in the length direction of the pole group, the size L1 of the welding and printing area is more than or equal to 15mm and less than or equal to 20mm; and in the width direction of the pole group, the size L2 of the welding and printing area is greater than or equal to 5mm and less than or equal to 10mm. According to the utility model, the tabs of the pole group are directly welded with the pole columns of the cover plate, an electric connecting piece is omitted, the space utilization rate and the energy density in the battery cell are improved, and the size of a welding area is limited, so that the structural strength requirement and the overcurrent requirement can be met.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to battery cells and battery packs. Background Technology

[0002] With the development of new energy technologies, battery packs are increasingly being used in various new energy products. As the core component of a battery pack, the battery cell mainly consists of a casing, a cover plate, electrode groups encapsulated within the casing, insulating components, and electrical connectors.

[0003] like Figure 1 and Figure 2 As shown, the battery cell casing typically contains multiple electrode groups 2', and the tabs 5' of each electrode group 2' are electrically connected to the posts 4' on the cover plate 3' via electrical connectors 7'. However, each electrode group 2' requires a separate electrical connector 7' to be electrically connected to the post 4', and multiple electrical connectors 7' occupy a lot of space inside the battery cell, resulting in a lower energy density of the battery cell. Utility Model Content

[0004] In view of this, the present invention provides a battery cell and battery pack to solve the problem that the battery cell has a low energy density because the battery cell is connected to the electrode group and the terminal post through electrical connectors inside the cell housing, and the electrical connectors occupy a lot of space inside the cell.

[0005] In a first aspect, this utility model provides a battery cell, comprising:

[0006] A housing containing at least one electrode assembly, with an opening on one side of the housing;

[0007] A cover plate is provided on one side of the opening of the housing, and the cover plate is provided with an pole post;

[0008] The electrode assembly has an electrode lug on the side facing the cover plate. The electrode lug is welded to the electrode post. The electrode lug includes multiple layers of stacked sub-electrodes. The outer surface of the electrode lug has a solder mark area.

[0009] Along the length of the electrode group, the dimension L1 of the solder area satisfies 15mm≤L1≤20mm;

[0010] In the width direction of the electrode group, the dimension L2 of the solder area satisfies 5mm≤L2≤10mm.

[0011] Beneficial effects: The battery cell of this utility model directly welds the tabs of the electrode assembly to the terminal posts of the cover plate, eliminating electrical connectors, reducing the space occupied by electrical connectors, improving the space utilization and energy density within the battery cell, reducing usage costs, and simplifying the battery cell structure. The tabs are formed by welding multiple layers of sub-tabs, forming a solder area after welding. By limiting the dimensions of the solder area in the length and width directions of the electrode assembly, a suitable solder area size is obtained, which can meet the structural strength and current requirements of the battery cell after omitting electrical connectors.

[0012] In one alternative embodiment, in the width direction of the electrode group, the distance L3 between the side of the solder area near the electrode group and the connection between the electrode group and the tab satisfies 8mm≤L3≤14mm.

[0013] Beneficial effects: By controlling the spacing L3 between the side of the solder area closest to the electrode assembly and the connection point between the electrode assembly and the tab within a suitable range in the width direction of the electrode assembly, the closing effect of the tab can be improved, avoiding interference between the soldering head and the tab's diaphragm. If the value of L3 is too small, the soldering head will be too close to the electrode assembly during soldering, and the soldering head is prone to interference with the tab's diaphragm. If the value of L3 is too large, defects such as folding and tearing of the tab are likely to occur.

[0014] In one alternative embodiment, in the length direction of the electrode group, the maximum distance L4 between one side of the solder area and the outer side of the adjacent electrode tab satisfies 2mm≤L4≤4mm.

[0015] Beneficial effects: By controlling the maximum distance L4 between one side of the solder area and the outer side of the adjacent tab along the length of the electrode assembly within a suitable range, the welding quality between the electrode assembly and the pole can be improved. If the value of L4 is too small, it is easy to misalign the solder joint and produce welding defects. If the value of L4 is too large, the edge of the tab is prone to warping defects.

[0016] In one alternative embodiment, in the length direction of the electrode group, the minimum distance L5 between one side of the solder area and the outer side of the adjacent electrode tab satisfies 1mm≤L5≤3mm.

[0017] Beneficial effects: By controlling the minimum distance L5 between one side of the solder area and the outer side of the adjacent tab along the length of the electrode assembly, the welding quality between the electrode assembly and the pole can be further improved. If the value of L5 is too small, it is easy to misalign the solder joint and produce welding defects. If the value of L5 is too large, the edge of the tab is prone to warping defects.

[0018] In one alternative embodiment, in the width direction of the electrode group, the size L6 of the electrode tab satisfies 26mm≤L6≤32mm.

[0019] Beneficial effects: By controlling the size of the tabs in the width direction of the electrode group, sufficient space can be reserved for processes such as welding and cutting to meet the usage requirements of these processes.

[0020] In one optional embodiment, the electrode tab includes a positive electrode tab and a negative electrode tab, the positive electrode tab and the negative electrode tab are spaced apart on the same side of the electrode group, and the number of sub-electrode tab layers of the negative electrode tab is greater than the number of sub-electrode tab layers of the positive electrode tab;

[0021] The number of layers N1 of the sub-electrodes of the positive electrode tab satisfies 70≤N1≤90;

[0022] The number of layers N2 of the sub-electrode of the negative electrode tab satisfies 71≤N2≤91.

[0023] Beneficial effects: By controlling the number of sub-tab layers of the positive and negative electrodes, the energy of the welding head is concentrated, forming a tight solder mark. At the same time, it prevents excessive positive electrode active material, ensures balanced discharge depth, and extends the life of the battery cell.

[0024] In one optional embodiment, the thickness H1 of the positive electrode tab satisfies 0.9mm ≤ H1 ≤ 1.2mm;

[0025] The thickness H2 of the negative electrode tab satisfies 0.3mm≤H2≤0.55mm.

[0026] Beneficial effects: By controlling the thickness of the positive and negative tabs within a suitable range, welding quality can be further improved. If the thickness of the positive tab is too large, the welding head is prone to excessive heat conduction, resulting in non-repeating fusion and a cold weld, as well as material waste. If the thickness of the positive tab is too small, the internal resistance is too high, easily leading to localized overheating. If the thickness of the negative tab is too large, the welding head is prone to excessive heat conduction, resulting in non-repeating fusion and a cold weld. If the thickness of the negative tab is too small, lithium dendrite growth can easily penetrate the tab, causing a short circuit.

[0027] In one optional embodiment, the electrode post includes a positive electrode post and a negative electrode post. When the electrode group is provided in pairs, the positive electrode tabs of the pair of electrode groups are respectively welded to the opposite ends of the positive electrode post, and the negative electrode tabs of the pair of electrode groups are respectively welded to the opposite ends of the negative electrode post.

[0028] Beneficial effects: By placing the positive tabs at opposite ends of the positive terminal and the negative tabs at opposite ends of the negative terminal, a pair of electrode groups can be placed on both sides of the cover plate. After bending the electrode groups, they can be stored inside the casing, which helps to make full use of the internal space of the cell and avoids the problem of redundant internal space caused by placing the electrode groups on the same side of the cover plate.

[0029] In one alternative embodiment, the electrode assembly is bent relative to the electrode tab and then housed within the housing.

[0030] Beneficial effects: Bending the electrode assembly and storing it inside the casing can further improve the space utilization of the casing and increase the energy density of the battery cell.

[0031] Secondly, the present invention also provides a battery pack, comprising: at least one of the above-mentioned battery cells.

[0032] Beneficial effects: Since the battery pack includes battery cells, it has the same effects as the battery cells, which will not be elaborated here. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a partial structural diagram of an existing battery cell before the electrode assembly is bent.

[0035] Figure 2 A partial cross-sectional view of the electrode assembly of an existing battery cell before bending.

[0036] Figure 3 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present utility model;

[0037] Figure 4 This is a partial structural diagram of the electrode assembly and electrode tabs of a battery cell according to an embodiment of the present utility model;

[0038] Figure 5 This is a partial structural diagram of a battery cell before the electrode assembly is bent, according to an embodiment of the present invention.

[0039] Figure 6 This is a partial cross-sectional view of a battery cell before the electrode assembly is bent, according to an embodiment of the present invention.

[0040] Figure 7 This is a schematic diagram of the electrode assembly and positive electrode tab of a battery cell according to an embodiment of the present invention;

[0041] Figure 8 This is a schematic diagram of the electrode assembly and negative electrode tab of a battery cell according to an embodiment of the present invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] Existing technology: 2', pole group; 3', cover plate; 4', pole post; 5', pole tab; 7', electrical connector;

[0044] This application includes: 1. Housing; 2. Electrode assembly; 3. Cover plate; 4. Electrode post; 401. Positive electrode post; 402. Negative electrode post; 5. Electrode tab; 501. Positive electrode tab; 502. Negative electrode tab; 503. Sub-electrode tab; 6. Soldering area. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0046] In this invention, a "cell" refers to a single battery cell capable of independent charging and discharging. The components of a cell may include a positive electrode, a negative electrode, a separator, an electrolyte, and a casing and cover for encapsulating the positive electrode, negative electrode, separator, and electrolyte. This invention does not impose particular limitations on the type or shape of the cell; it can be a lithium-ion cell, a potassium-ion cell, a sodium-ion cell, a lithium-sulfur cell, etc., with lithium-ion cells being particularly preferred. During the charging and discharging process, active ions repeatedly insert and extract between the positive and negative electrode plates. The electrolyte acts as a conductor of ions between the positive and negative electrode plates.

[0047] The inventors discovered that existing battery cells, employing a four-electrode configuration and four electrical connectors, suffer from complex manufacturing processes and high operating costs. For example... Figure 1 and Figure 2 As shown, the pre-welding process parameters for pole post 4', pole lug 5' and electrical connector 7' are wide-ranging, which can easily lead to welding defects such as incomplete welding and weld slag during the production process.

[0048] The following is combined Figures 3 to 8 The following describes embodiments of the present invention.

[0049] According to embodiments of the present invention, on the one hand, such as Figure 3 and Figure 4 As shown, a battery cell is provided, mainly comprising: a housing 1 and a cover plate 3. At least one electrode group 2 is disposed inside the housing 1, and an opening is provided on one side of the housing 1. The cover plate 3 covers the opening side of the housing 1, and an electrode post 4 is disposed on the cover plate 3. An electrode tab 5 is provided on the side of the electrode group 2 facing the cover plate 3. The electrode tab 5 is welded to the electrode post 4. The electrode tab 5 includes multiple layers of stacked sub-electrode tabs 503, which are welded using a welding head, and a solder mark area 6 is left on the outer surface of the electrode tab 5.

[0050] like Figure 4As shown, in the length direction of electrode group 2, the dimension L1 of solder area 6 satisfies 15mm≤L1≤20mm. In the width direction of electrode group 2, the dimension L2 of solder area 6 satisfies 5mm≤L2≤10mm.

[0051] Therefore, the battery cell provided in this embodiment of the present invention directly welds the tabs 5 of the electrode group 2 to the pole posts 4 of the cover plate 3, omitting electrical connectors, reducing the space occupied by electrical connectors, improving the space utilization and energy density within the battery cell, reducing usage costs, and simplifying the battery cell structure. The tabs 5 are formed by welding multiple layers of sub-tabs 503, forming a solder area 6 after welding. By limiting the dimensions of the solder area 6 in the length and width directions of the electrode group 2, a suitable solder area size is obtained, which can meet the structural strength and current requirements of the battery cell after omitting electrical connectors.

[0052] For example, in the embodiments of this utility model, L1 can be 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, etc., and L2 can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.

[0053] It should be noted that before welding the multi-layer sub-tab 503, the welding area on the sub-tab 503 should be determined in advance according to the size of the welding area 6, and then a welding head of the corresponding size should be selected. During welding, the electrode assembly 2 is fixed on the fixture, and by controlling the position of the welding head relative to the outer sub-tab 503, the welding head only needs to weld one side of the multi-layer sub-tab 503 to obtain the welding area 6 at the corresponding position. The multi-layer sub-tab 503 is welded and fixed in one go, forming a complete electrode 5.

[0054] In addition, after multiple sub-tabs 503 are welded into a whole by welding head, the side of the tab 5 away from the pole group 2 needs to be cut off, and then the tab 5 is welded to the pole post 4.

[0055] Specifically, the cover plate 3 has mounting holes, and the pole post 4 passes through the mounting holes of the cover plate 3. One end of the pole post 4 protrudes from the outside of the cover plate 3, and the other end of the pole post 4 is located on the inside of the cover plate 3 and welded to the pole lug 5. The length direction of the pole group 2 is as follows: Figure 4 As shown by arrow L in the diagram, the width direction of pole group 2 is as follows: Figure 4 As indicated by arrow W in the diagram. Electrode group 2 is fabricated using a lamination process.

[0056] In one embodiment, such as Figure 4As shown, in the width direction of electrode group 2, the distance L3 between the side of the solder area 6 closest to electrode group 2 and the connection point between electrode group 2 and electrode tab 5 satisfies 8mm ≤ L3 ≤ 14mm. By controlling the distance L3 between the side of the solder area 6 closest to electrode group 2 and the connection point between electrode group 2 and electrode tab 5 within a suitable range in the width direction of electrode group 2, the closing effect of electrode tab 5 can be improved, and interference between the soldering head and the diaphragm of electrode tab 5 can be avoided. If the value of L3 is less than 8mm, the soldering head will be too close to electrode group 2 during soldering, and the soldering head will easily interfere with the diaphragm of electrode tab 5. If the value of L3 is greater than 14mm, defects such as folding and tearing of electrode tab 5 are likely to occur.

[0057] Specifically, the distance L3 between the side of the soldering area 6 closest to the electrode group 2 and the connection between the electrode group 2 and the electrode tab 5 can be adjusted by controlling the size of the soldering head and the welding position of the soldering head relative to the electrode tab 5.

[0058] For example, in the embodiments of this utility model, L3 can be 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, etc.

[0059] In one embodiment, such as Figure 4 As shown, in the length direction of electrode group 2, the maximum distance L4 between one side of the solder area 6 and the outer side of the adjacent tab 5 satisfies 2mm≤L4≤4mm. By controlling the maximum distance L4 between one side of the solder area 6 and the outer side of the adjacent tab 5 in the length direction of electrode group 2 within a suitable range, the welding quality between electrode group 2 and pole post 4 can be improved. If the value of L4 is less than 2mm, it is easy to weld off-center, resulting in welding defects. If the value of L4 is greater than 4mm, the edge of tab 5 is prone to warping defects.

[0060] For example, in the embodiments of this utility model, L4 can be 2mm, 3mm, 4mm, etc.

[0061] Furthermore, in one embodiment, such as Figure 4 As shown, along the length of electrode group 2, the minimum distance L5 between one side of the solder area 6 and the outer side of the adjacent tab 5 satisfies 1mm ≤ L5 ≤ 3mm. By controlling the minimum distance L5 between one side of the solder area 6 and the outer side of the adjacent tab 5 along the length of electrode group 2 within a suitable range, the welding quality between electrode group 2 and pole post 4 can be further improved. If the value of L5 is less than 1mm, it is easy to weld off-center, resulting in welding defects. If the value of L5 is greater than 3mm, the edge of tab 5 is prone to warping defects.

[0062] Similarly, along the length of electrode group 2, the maximum spacing L4 and the minimum spacing L5 between one side of the solder area 6 and the outer side of the adjacent electrode tab 5 can be adjusted by controlling the welding fixture.

[0063] For example, in the embodiments of this utility model, L5 can be 1mm, 2mm, 3mm, etc.

[0064] In one embodiment, such as Figure 4 As shown, in the width direction of electrode group 2, the dimension L6 of electrode tab 5 satisfies 26mm≤L6≤32mm. By controlling the dimension of electrode tab 5 in the width direction of electrode group 2, sufficient space can be reserved for processes such as welding and cutting to meet the usage requirements of welding and cutting processes.

[0065] For example, in the embodiments of this utility model, L6 can be 26mm, 28mm, 30mm, 32mm, etc.

[0066] In one embodiment, such as Figure 4 and Figure 5 As shown, electrode 5 includes a positive electrode 501 and a negative electrode 502, which are spaced apart and located on the same side of electrode group 2. The number of sub-electrode layers 503 of the negative electrode 502 is greater than the number of sub-electrode layers 503 of the positive electrode 501. The number of sub-electrode layers N1 of the positive electrode 501 satisfies 70≤N1≤90. The number of sub-electrode layers N2 of the negative electrode 502 satisfies 71≤N2≤91. By controlling the number of sub-electrode layers 503 of each of the positive and negative electrodes 501, the energy of the welding head is concentrated, forming a tight solder joint, while preventing excessive positive electrode active material, ensuring balanced discharge depth, and extending the life of the battery cell.

[0067] For example, in this embodiment of the present invention, the number of sub-tabs 503 layers N2 of the negative electrode 502 is one more than the number of sub-tabs 503 layers N1 of the positive electrode 501. For example, N1 can be 70, and the corresponding N2 can be 71; N1 can be 80, and the corresponding N2 can be 81; N1 can be 90, and the corresponding N2 can be 91.

[0068] In one alternative implementation, such as Figure 7 As shown, the thickness H1 of the positive electrode tab 501 satisfies 0.9mm ≤ H1 ≤ 1.2mm. Figure 8 As shown, the thickness H2 of the negative electrode tab 502 satisfies 0.3mm≤H2≤0.55mm.

[0069] By controlling the thickness of the positive tab 501 and the negative tab 502 within a suitable range, the welding quality can be further improved. If the thickness of the positive tab 501 is too large, the welding head is prone to excessive heat conduction, resulting in non-repeating fusion and forming a cold weld, as well as material waste. If the thickness of the positive tab 501 is too small, the internal resistance is too high, which can easily lead to localized overheating. If the thickness of the negative tab 502 is too large, the welding head is prone to excessive heat conduction, resulting in non-repeating fusion and forming a cold weld. If the thickness of the negative tab 502 is too small, lithium dendrite growth can easily penetrate the tab 5, causing a short circuit.

[0070] Furthermore, the thickness of the single-layer sub-tab 503 of the positive electrode 501 is generally around 0.013 mm, and the thickness of the single-layer sub-tab 503 of the negative electrode 502 is generally between 0.0045 mm and 0.006 mm. Therefore, the thickness H1 of the positive electrode 501 satisfies 0.91 mm ≤ H1 ≤ 1.17 mm. The thickness H2 of the negative electrode 502 satisfies 0.3195 mm ≤ H2 ≤ 0.546 mm.

[0071] In one embodiment, such as Figure 5 and Figure 6 As shown, the electrode post 4 includes a positive electrode post 401 and a negative electrode post 402. When a pair of electrode groups 2 are provided, the positive electrode tabs 501 of the pair of electrode groups 2 are respectively welded to the opposite ends of the positive electrode post 401, and the negative electrode tabs 502 of the pair of electrode groups 2 are respectively welded to the opposite ends of the negative electrode post 402.

[0072] By placing the positive tab 501 at the opposite ends of the positive terminal 401 and the negative tab 502 at the opposite ends of the negative terminal 402, a pair of electrode groups 2 can be placed on both sides of the cover plate 3. After bending the electrode group 2, the electrode group 2 can be stored in the housing 1, which helps to make full use of the internal space of the cell and avoids the problem of redundant internal space of the cell caused by placing the electrode group 2 on the same side of the cover plate 3.

[0073] Compared to the traditional four-pole group and four electrical connector structure, the battery cell of this utility model embodiment adopts the form of a bipolar group, which simplifies the structure of the battery cell, makes the manufacturing process simpler, reduces the cost of use, and facilitates its promotion.

[0074] In one embodiment, such as Figure 3 and Figure 6 As shown, the electrode assembly 2 is bent relative to the tab 5 and stored inside the housing 1. Bending the electrode assembly 2 and storing it inside the housing 1 can further improve the space utilization of the housing 1 and increase the energy density of the battery cell.

[0075] According to an embodiment of the present invention, another aspect provides a battery pack comprising at least one of the aforementioned battery cells.

[0076] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be elaborated on here.

[0077] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: A housing containing at least one electrode assembly, with an opening on one side of the housing; A cover plate is provided on one side of the opening of the housing, and the cover plate is provided with an pole post; The electrode assembly has an electrode lug on the side facing the cover plate. The electrode lug is welded to the electrode post. The electrode lug includes multiple layers of stacked sub-electrodes. The outer surface of the electrode lug has a solder mark area. Along the length of the electrode group, the dimension L1 of the solder area satisfies 15mm≤L1≤20mm; In the width direction of the electrode group, the dimension L2 of the solder area satisfies 5mm≤L2≤10mm.

2. The battery cell according to claim 1, characterized in that, In the width direction of the electrode group, the distance L3 between the side of the solder area near the electrode group and the connection between the electrode group and the electrode tab satisfies 8mm≤L3≤14mm.

3. The battery cell according to claim 2, characterized in that, In the length direction of the electrode group, the maximum distance L4 between one side of the solder area and the outer side of the adjacent electrode tab satisfies 2mm≤L4≤4mm.

4. The battery cell according to claim 3, characterized in that, In the length direction of the electrode group, the minimum distance L5 between one side of the solder area and the outer side of the adjacent electrode tab satisfies 1mm≤L5≤3mm.

5. The battery cell according to any one of claims 1 to 4, characterized in that, In the width direction of the electrode group, the size L6 of the electrode tab satisfies 26mm≤L6≤32mm.

6. The battery cell according to any one of claims 1 to 4, characterized in that, The electrode tabs include a positive electrode tab and a negative electrode tab, which are spaced apart on the same side of the electrode group. The number of sub-electrode tabs of the negative electrode tab is greater than the number of sub-electrode tabs of the positive electrode tab. The number of layers N1 of the sub-electrodes of the positive electrode tab satisfies 70≤N1≤90; The number of layers N2 of the sub-electrode of the negative electrode tab satisfies 71≤N2≤91.

7. The battery cell according to claim 6, characterized in that, The thickness H1 of the positive electrode tab satisfies 0.9mm ≤ H1 ≤ 1.2mm; The thickness H2 of the negative electrode tab satisfies 0.3mm≤H2≤0.55mm.

8. The battery cell according to claim 6, characterized in that, The electrode includes a positive electrode and a negative electrode. When the electrode group is provided in pairs, the positive tabs of the pair of electrode groups are respectively welded to the opposite ends of the positive electrode, and the negative tabs of the pair of electrode groups are respectively welded to the opposite ends of the negative electrode.

9. The battery cell according to any one of claims 1 to 4, characterized in that, The electrode assembly is bent relative to the electrode tab and then housed inside the housing.

10. A battery pack, characterized in that, include: At least one battery cell according to any one of claims 1 to 9.

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