Pole group, battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a pole group, a battery cell and a battery pack. Wherein the pole group comprises a first pole piece, a diaphragm and a second pole piece which are stacked in sequence, and the polarity of the first pole piece is opposite to that of the second pole piece; in the thickness direction of the pole group, the orthographic projection of the second pole piece towards the first pole piece falls into the first pole piece, and the orthographic projection of the first pole piece towards the diaphragm is located in the diaphragm; wherein the surface area S1 of the first pole piece and the surface area S2 of the second pole piece meet the condition that S1 / S2 is greater than or equal to 1.05 and less than or equal to 1.15; and the surface area S of the diaphragm and the surface area S1 of the first pole piece meet the condition that 1.1 < = S / S1 < = 1.3. The first pole piece, the diaphragm and the second pole piece are arranged according to the parameters, so that material waste can be avoided, and the overall weight of the pole group and the production cost of the pole group are reduced. And meanwhile, the condition of lamination dislocation between the first pole piece and the second pole piece can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a pole group, a battery cell, and a battery pack. Background Art

[0002] In the field of the structural design of lithium-ion batteries, the coating method of the electrode plays an important role, which is directly related to the performance, safety and reliability of the battery, as well as the difficulty and cost of the manufacturing process. At present, there are mainly two common coating methods for the electrode: coating the negative electrode on the positive electrode and coating the positive electrode on the negative electrode. However, whether the method of coating the negative electrode on the positive electrode or the method of coating the positive electrode on the negative electrode is adopted, it will inevitably lead to the waste of the electrode material. This material waste will not only increase the weight of the battery itself, but also increase the production cost of the battery accordingly. Summary of the Invention

[0003] In view of this, the present invention provides a pole group, a battery cell, and a battery pack to solve the problem that the existing electrode wrapping method will cause material waste, resulting in an increase in the weight of the battery itself and the production cost.

[0004] In a first aspect, the present invention provides a pole group, including: a first electrode, a separator, and a second electrode that are sequentially stacked, wherein the polarity of the first electrode is opposite to that of the second electrode; along the thickness direction of the pole group, the positive projection of the second electrode facing the first electrode falls within the first electrode, and the positive projection of the first electrode facing the separator is located within the separator;

[0005] wherein, the surface area S1 of the first electrode and the surface area S2 of the second electrode satisfy: 1.05 ≤ S1 / S2 ≤ 1.15;

[0006] The surface area S of the separator and the surface area S1 of the first electrode satisfy: 1.1 ≤ S / S1 ≤ 1.3; wherein, the value range of S1 is: 4950mm 2 ≤ S1 ≤ 75600mm 2 ; the value range of S2 is: 4250mm 2 ≤ S2 ≤ 66000mm 2 ; the value range of S is: 5700mm 2 ≤ S ≤ 90000mm 2 .

[0007] Beneficial effects: In the present invention, the first electrode plate, the separator, and the second electrode plate are sequentially stacked, and by controlling the surface area ratio between the first electrode plate and the second electrode plate and the surface area ratio between the separator and the first electrode plate, it is possible to effectively improve the space utilization rate and energy density of the electrode group while ensuring good electrochemical performance of the electrode group, and reduce the edge effect between the electrode plates. In addition, this structural design can also save materials, achieving the purpose of reducing the production cost of the electrode group and the overall weight of the electrode group.

[0008] In an optional embodiment, along the thickness direction of the electrode group, the cross-sectional shapes of the first electrode plate, the separator, and the second electrode plate are all square; the length directions and width directions of the first electrode plate, the separator, and the second electrode plate are the same.

[0009] Beneficial effects: In the present invention, keeping the shapes and directions of the first electrode plate, the second electrode plate, and the separator consistent can make the overall structure of the electrode group more regular, which is beneficial to the uniform transmission of ions through the separator between the first electrode plate and the second electrode plate, making the charge and discharge performance of the battery cell more stable and prolonging the service life of the battery cell. Secondly, keeping the shapes and directions of the first electrode plate, the second electrode plate, and the separator consistent can also enable operators to quickly assemble and align, reducing the assembly difficulty and error probability. In this way, not only the assembly efficiency is improved, but also the stability of the product quality is ensured.

[0010] In an optional embodiment, along the length direction of the electrode group, the size L of the separator and the size L1 of the first electrode plate satisfy: 1.01 ≤ L / L1 ≤ 1.2; the size L1 of the first electrode plate and the size L2 of the second electrode plate satisfy: 1.01 ≤ L1 / L2 ≤ 1.2; where, the value range of L is: 95mm ≤ L ≤ 450mm; the value range of L1 is: 90mm ≤ L1 ≤ 420mm; the value range of L2 is: 85mm ≤ L2 ≤ 400mm.

[0011] Beneficial effects: In the present invention, by setting the first electrode plate, the second electrode plate, and the separator according to the above parameters, it can be ensured that the separator can effectively cover the first electrode plate and the second electrode plate in the length direction, preventing the first electrode plate and the second electrode plate from directly contacting and causing a short circuit, thereby improving the safety of the battery cell. Secondly, the setting of the above size ratio helps to avoid the separator from shrinking and becoming smaller during the baking process of battery cell manufacturing, resulting in its inability to completely cover the first electrode plate, ensuring that the separator can effectively isolate the first electrode plate and the second electrode plate. In addition, this setting can also avoid waste of separator and first electrode plate materials, reducing production costs. At the same time, in the length direction of the electrode group, the size of the first electrode plate is slightly larger than that of the second electrode plate, which can enable the first electrode plate to better accommodate the lithium ions released from the second electrode plate, avoiding excessive accumulation of lithium ions on the surface of the first electrode plate to form lithium dendrites, and further reducing the risk of internal short circuit in the battery cell.

[0012] In an alternative embodiment, along the width direction of the electrode group, the following relationships are satisfied between the size W of the separator and the size W1 of the first electrode sheet: 1.01 ≤ W / W1 ≤ 1.2; and between the size W1 of the first electrode sheet and the size W2 of the second electrode sheet: 1.01 ≤ W1 / W2 ≤ 1.2; where the value range of W is: 60 mm ≤ W ≤ 200 mm; the value range of W1 is: 55 mm ≤ W1 ≤ 180 mm; and the value range of W2 is: 50 mm ≤ W2 ≤ 165 mm.

[0013] Advantageous effects: By setting the first electrode sheet, the second electrode sheet, and the separator according to the above parameters, the present invention can ensure that the separator can effectively cover the first electrode sheet and the second electrode sheet in the width direction, preventing the first electrode sheet and the second electrode sheet from directly contacting and causing a short circuit, thereby improving the safety of the battery cell. Secondly, the setting of the above size ratios helps to avoid the separator being unable to completely cover the first electrode sheet due to size shrinkage during the baking process of battery cell manufacturing, ensuring that the separator can effectively isolate the first electrode sheet and the second electrode sheet. In addition, this setting can also avoid waste of separator and first electrode sheet materials, reducing production costs. At the same time, in the width direction of the electrode group, the size of the first electrode sheet is slightly larger than that of the second electrode sheet, which can enable the first electrode sheet to better accommodate the lithium ions released from the second electrode sheet, preventing the excessive accumulation of lithium ions on the surface of the first electrode sheet to form lithium dendrites, and further reducing the risk of internal short circuit in the battery cell.

[0014] In an alternative embodiment, the electrode group further includes a first internal tab provided on the first electrode sheet and a second internal tab provided on the second electrode sheet. The first internal tab and the second internal tab are oppositely arranged along the length direction or the width direction of the electrode group and partially located outside the separator.

[0015] Advantageous effects: By providing the first internal tab and the second internal tab, the present invention can not only enable external current to be transmitted into the electrode group through the first internal tab and the second internal tab, but also enable the electrode group to release current to the outside through the first internal tab and the second internal tab. Secondly, arranging the first internal tab and the second internal tab oppositely can promote the uniform distribution of current on the first electrode sheet and the second electrode sheet, avoiding local overheating caused by uneven current distribution during high-current charge and discharge, thereby improving the high-current charge and discharge performance of the battery cell and extending the service life of the battery cell. Moreover, having part of the first internal tab and the second internal tab located outside the separator can facilitate the subsequent assembly of the electrode group with other components of the battery cell, improving production efficiency.

[0016] In an alternative embodiment, the first inner tab and the second inner tab are respectively located at two ends in the length direction of the electrode group; along the length direction of the electrode group, the distance A between the end of the first electrode plate and the corresponding end of the separator satisfies: 1.5 mm ≤ A ≤ 3 mm; the distance B between the end of the first electrode plate and the corresponding end of the second electrode plate satisfies: 0.75 mm ≤ B ≤ 2 mm.

[0017] Advantageous effects: The first inner tab and the second inner tab are respectively located at two ends in the length direction of the electrode group. Such a layout optimizes the current conduction path within the electrode group, enabling the current to flow more evenly through the first electrode plate and the second electrode plate, effectively reducing the internal resistance of the battery cell and enhancing the charge and discharge performance of the battery cell. At the same time, along the length direction of the electrode group, the distance A between the end of the first electrode plate and the corresponding end of the separator satisfies 1.5 mm ≤ A ≤ 3 mm. This distance can not only ensure that the separator fully wraps the first electrode plate to prevent direct contact between the first electrode plate and the second electrode plate, thus avoiding short circuits, but also prevent material waste and increased production costs caused by an overly long separator. The distance B between the end of the first electrode plate and the corresponding end of the second electrode plate satisfies 0.75 mm ≤ B ≤ 2 mm. This distance not only ensures the smooth transmission of ions between the first electrode plate and the second electrode plate but also avoids an increased short-circuit risk due to too small a spacing or a reduction in the energy density of the battery cell due to too large a spacing.

[0018] In an alternative embodiment, along the width direction of the electrode group, the distance C between the end of the first electrode plate and the corresponding end of the separator satisfies: 1 mm ≤ C ≤ 2.5 mm; the distance D between the end of the first electrode plate and the corresponding end of the second electrode plate satisfies: 1 mm ≤ D ≤ 2.5 mm.

[0019] Advantageous effects: Along the width direction of the electrode group, the distance C between the end of the first electrode plate and the corresponding end of the separator satisfies 1 mm ≤ C ≤ 2.5 mm. This distance ensures that the separator can fully wrap the first electrode plate in the width direction, preventing direct contact between the first electrode plate and the second electrode plate and avoiding short circuits, as well as preventing material waste and increased production costs caused by an overly long separator. The distance D between the end of the first electrode plate and the corresponding end of the second electrode plate satisfies 1 mm ≤ D ≤ 2.5 mm. This distance can not only ensure the smooth transmission of ions between the first electrode plate and the second electrode plate, promoting the normal charge and discharge reactions of the battery cell, but also avoid potential short-circuit hazards caused by too small a spacing and the problem of reduced battery energy density caused by too large a spacing.

[0020] In an alternative embodiment, the number of the first electrode plates, the separators, and the second electrode plates is multiple. Along the thickness direction of the electrode group, the first electrode plates and the second electrode plates are alternately arranged, and the separators are arranged between adjacent first electrode plates and second electrode plates.

[0021] Beneficial effects: By alternately arranging a plurality of first electrode plates and second electrode plates, the present invention can increase the electrode reaction area of the battery cell, improve the capacity and energy density of the battery cell. Secondly, a separator is arranged between adjacent first electrode plates and second electrode plates, which can prevent the first electrode plate and the second electrode plate from directly contacting, reduce the risk of internal short circuit of the battery cell, and improve the safety and reliability of the battery cell.

[0022] Second, the present invention also provides a battery cell, including:

[0023] The above-mentioned electrode assembly;

[0024] A packaging film, which is wrapped outside the electrode assembly.

[0025] Beneficial effects: The battery cell equipped with the above-mentioned electrode assembly has a lower self-weight and a lower production cost compared with the existing battery cell. In addition, the battery cell of the present invention also has other advantages of the above-mentioned electrode assembly, which will not be elaborated here.

[0026] Third, the present invention also provides a battery pack, including:

[0027] A housing;

[0028] A plurality of the above-mentioned battery cells, which are arranged in the housing in sequence along its thickness direction.

[0029] Beneficial effects: The battery pack equipped with the above-mentioned battery cell has a lower self-weight and a lower production cost compared with the existing battery pack. In addition, the battery pack of the present invention also has other advantages of the above-mentioned battery cell, which will not be elaborated here. Description of the Drawings

[0030] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required to be used in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is a schematic structural diagram of an electrode assembly according to an embodiment of the present invention.

[0032] Description of the reference numerals in the drawings:

[0033] 1. First electrode plate; 2. Separator; 3. Second electrode plate; 4. First internal tab; 5. Second internal tab. Detailed Embodiments

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] In view of the problem that the existing method of wrapping the electrode sheet will cause material waste, resulting in an increase in the weight of the battery itself and the production cost, the present invention provides a pole group, an electric core, and a battery pack.

[0036] The following will describe the embodiments of the present invention in conjunction with Figure 1 , and describe the embodiments of the present invention.

[0037] According to an embodiment of the present invention, on the one hand, as Figure 1 shown, a pole group is provided, including: a first electrode sheet 1, a separator 2, and a second electrode sheet 3 that are sequentially stacked, and the polarity of the first electrode sheet 1 is opposite to that of the second electrode sheet 3; along the thickness direction of the pole group, the positive projection of the second electrode sheet 3 facing the first electrode sheet 1 falls within the first electrode sheet 1, and the positive projection of the first electrode sheet 1 facing the separator 2 is located within the separator 2;

[0038] Among them, the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 satisfy: 1.05 ≤ S1 / S2 ≤ 1.15;

[0039] The surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 satisfy: 1.1 ≤ S / S1 ≤ 1.3; where the value range of S1 is: 4950mm 2 ≤ S1 ≤ 75600mm 2 ; the value range of S2 is: 4250mm 2 ≤ S2 ≤ 66000mm 2 ; the value range of S is: 5700mm 2 ≤ S ≤ 90000mm 2 .

[0040] The present invention stacks the first electrode sheet 1, the separator 2, and the second electrode sheet 3 in sequence, and by controlling the surface area ratio of the first electrode sheet 1 to the second electrode sheet 3 and the surface area ratio of the separator 2 to the first electrode sheet 1, it can effectively improve the space utilization rate and energy density of the pole group while ensuring good electrochemical performance of the pole group, and reduce the edge effect between the electrode sheets. In addition, this structural design can also save materials, achieving the purpose of reducing the production cost of the pole group and the overall weight of the pole group.

[0041] Specifically, in this embodiment, the surface area of the first electrode sheet 1 is made larger than that of the second electrode sheet 3, which enables the first electrode sheet 1 to better accommodate the lithium ions released from the second electrode sheet 3, avoids the excessive accumulation of lithium ions on the surface of the first electrode sheet 1 to form lithium dendrites, reduces the risk of internal short circuit of the battery cell, and improves the safety of the battery cell. Secondly, since the surface area of the first electrode sheet 1 is larger than that of the second electrode sheet 3, the first electrode sheet 1 can better wrap the second electrode sheet 3, reducing the misalignment problem between the first electrode sheet 1 and the second electrode sheet 3, thereby simplifying the manufacturing process of the battery cell and improving production efficiency. Moreover, by setting the surface area ratio between the first electrode sheet 1 and the second electrode sheet 3 according to the above parameters, not only can the waste of materials of the first electrode sheet 1 be avoided, achieving the purpose of reducing the production cost of the battery cell and the overall weight of the battery cell; at the same time, it can also avoid occupying too much installation space, ensuring that the battery cell can store more electrical energy in a limited space, thereby improving the energy density of the battery cell.

[0042] Similarly, in this embodiment, the surface area of the separator 2 is made larger than that of the first electrode sheet 1. On the one hand, it can prevent the first electrode sheet 1 and the second electrode sheet 3 from directly contacting to cause a short circuit; on the other hand, it can avoid the separator 2 from shrinking in size during the baking process of battery cell manufacturing, resulting in its inability to completely wrap the first electrode sheet 1. In addition, by setting the surface area between the separator 2 and the first electrode sheet 1 according to the above parameters, it can also avoid wasting the material of the separator 2 and reduce the production cost. At the same time, it can also avoid the separator 2 occupying too much internal space of the battery cell.

[0043] It should be noted that the first electrode sheet 1 in this embodiment can be a positive electrode sheet with a positive polarity or a negative electrode sheet with a negative polarity. Therefore, if the first electrode sheet 1 is a positive electrode sheet, the second electrode sheet 3 is a negative electrode sheet; conversely, if the first electrode sheet 1 is a negative electrode sheet, the second electrode sheet 3 is a positive electrode sheet. It can be seen that the structure of the electrode group in this embodiment can be either a positive electrode sheet wrapping a negative electrode sheet or a negative electrode sheet wrapping a positive electrode sheet, as long as the first electrode sheet 1, the second electrode sheet 3, and the separator 2 are reasonably set according to the above parameters. In this regard, the present invention does not make special limitations.

[0044] The technical effects of this embodiment will be described below in conjunction with the following examples and comparative examples. The specific results are shown in Table 1.

[0045] Example 1

[0046] The relationship between the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 is 1.05, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 is 1.2;

[0047] Example 2

[0048] The relationship between the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 is 1.1, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 is 1.15;

[0049] Example 3

[0050] The relationship between the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 is 1.15, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 is 1.2;

[0051] Example 4

[0052] The relationship between the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 is 1.08, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 is 1.1;

[0053] Example 5

[0054] The relationship between the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 is 1.12, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 is 1.3.

[0055] Comparative Example 1

[0056] The relationship between the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 is 1.05, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 is 1.0;

[0057] Comparative Example 2

[0058] The relationship between the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 is 1.1, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 is 1.05;

[0059] Comparative Example 3

[0060] The relationship between the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 is 1.15, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 is 1.35;

[0061] Comparative Example 4

[0062] The relationship between the surface area S1 of the first electrode sheet 1 and the surface area S2 of the second electrode sheet 3 is 1.0, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode sheet 1 is 1.1;

[0063] Comparative Example 5

[0064] The relationship between the surface area S1 of the first electrode tab 1 and the surface area S2 of the second electrode tab 3 is 1.2, and the relationship between the surface area S of the separator 2 and the surface area S1 of the first electrode tab 1 is 1.3.

[0065] Table 1

[0066]

[0067]

[0068] According to an embodiment of the present invention, as Figure 1 shown, along the thickness direction of the electrode assembly, the cross-sectional shapes of the first electrode tab 1, the separator 2, and the second electrode tab 3 are all square; the length direction and the width direction of the first electrode tab 1, the separator 2, and the second electrode tab 3 are the same. In this embodiment, keeping the shapes and directions of the first electrode tab 1, the second electrode tab 3, and the separator 2 consistent can make the overall structure of the electrode assembly more regular, which is beneficial to the uniform transmission of ions through the separator 2 between the first electrode tab 1 and the second electrode tab 3, making the charge and discharge performance of the battery cell more stable and extending the service life of the battery cell. Secondly, keeping the shapes and directions of the first electrode tab 1, the second electrode tab 3, and the separator 2 consistent can also enable the operator to quickly assemble and align, reducing the assembly difficulty and the probability of errors. In this way, not only the assembly efficiency is improved, but also the stability of the product quality is ensured.

[0069] According to an embodiment of the present invention, as Figure 1 shown, along the length direction of the electrode assembly, the size L of the separator 2 and the size L1 of the first electrode tab 1 satisfy: 1.01 ≤ L / L1 ≤ 1.2; the size L1 of the first electrode tab 1 and the size L2 of the second electrode tab 3 satisfy: 1.01 ≤ L1 / L2 ≤ 1.2; wherein, the value range of L is: 95 mm ≤ L ≤ 450 mm; the value range of L1 is: 90 mm ≤ L1 ≤ 420 mm; the value range of L2 is: 85 mm ≤ L2 ≤ 400 mm. In this embodiment, setting the first electrode tab 1, the second electrode tab 3, and the separator 2 according to the above parameters can ensure that the separator 2 can effectively cover the first electrode tab 1 and the second electrode tab 3 in the length direction, preventing the first electrode tab 1 and the second electrode tab 3 from directly contacting and causing a short circuit, thereby improving the safety of the battery cell. Secondly, the setting of the above size ratio helps to avoid the separator 2 from shrinking and becoming smaller during the baking process of the battery cell manufacturing, resulting in its inability to completely cover the first electrode tab 1, ensuring that the separator 2 can effectively isolate the first electrode tab 1 and the second electrode tab 3. In addition, this setting can also avoid wasting the materials of the separator 2 and the first electrode tab 1, reducing the production cost. At the same time, the size of the first electrode tab 1 is slightly larger than that of the second electrode tab 3, which can enable the first electrode tab 1 to better accommodate the lithium ions released from the second electrode tab 3, avoiding the excessive accumulation of lithium ions on the surface of the first electrode tab 1 to form lithium dendrites, and further reducing the risk of internal short circuit in the battery cell.

[0070] The technical effects of this embodiment will be described below in conjunction with the following examples and comparative examples. The specific results are shown in Table 2.

[0071] Example 6

[0072] The relationship between the size L of the separator 2 and the size L1 of the first electrode sheet 1 is 1.01, and the relationship between the size L1 of the first electrode sheet 1 and the size L2 of the second electrode sheet 3 is 1.2;

[0073] Example 7

[0074] The relationship between the size L of the separator 2 and the size L1 of the first electrode sheet 1 is 1.2, and the relationship between the size L1 of the first electrode sheet 1 and the size L2 of the second electrode sheet 3 is 1.01;

[0075] Example 8

[0076] The relationship between the size L of the separator 2 and the size L1 of the first electrode sheet 1 is 1.1, and the relationship between the size L1 of the first electrode sheet 1 and the size L2 of the second electrode sheet 3 is 1.1;

[0077] Comparative Example 6

[0078] The relationship between the size L of the separator 2 and the size L1 of the first electrode sheet 1 is 0.9, and the relationship between the size L1 of the first electrode sheet 1 and the size L2 of the second electrode sheet 3 is 1.1;

[0079] Comparative Example 7

[0080] The relationship between the size L of the separator 2 and the size L1 of the first electrode sheet 1 is 1.1, and the relationship between the size L1 of the first electrode sheet 1 and the size L2 of the second electrode sheet 3 is 0.9;

[0081] Comparative Example 8

[0082] The relationship between the size L of the separator 2 and the size L1 of the first electrode sheet 1 is 1.1, and the relationship between the size L1 of the first electrode sheet 1 and the size L2 of the second electrode sheet 3 is 1.3;

[0083] Comparative Example 9

[0084] The relationship between the size L of the separator 2 and the size L1 of the first electrode sheet 1 is 1.35, and the relationship between the size L1 of the first electrode sheet 1 and the size L2 of the second electrode sheet 3 is 1.05.

[0085] Table 2

[0086]

[0087]

[0088] According to an embodiment of the present invention, as Figure 1 shown, along the width direction of the electrode group, the dimension W of the separator 2 and the dimension W1 of the first electrode tab 1 satisfy: 1.01 ≤ W / W1 ≤ 1.2; the dimension W1 of the first electrode tab 1 and the dimension W2 of the second electrode tab 3 satisfy: 1.01 ≤ W1 / W2 ≤ 1.2; wherein, the value range of W is: 60 mm ≤ W ≤ 200 mm; the value range of W1 is: 55 mm ≤ W1 ≤ 180 mm; the value range of W2 is: 50 mm ≤ W2 ≤ 165 mm. By setting the first electrode tab 1, the second electrode tab 3 and the separator 2 according to the above parameters in this embodiment, it can be ensured that the separator 2 can effectively cover the first electrode tab 1 and the second electrode tab 3 in the width direction, preventing the first electrode tab 1 and the second electrode tab 3 from directly contacting and causing a short circuit, thereby improving the safety of the battery cell. Secondly, the setting of the above size ratio helps to avoid the separator 2 from shrinking in size during the baking process of battery cell manufacturing and thus being unable to completely cover the first electrode tab 1, ensuring that the separator 2 can effectively isolate the first electrode tab 1 and the second electrode tab 3. In addition, this setting can also avoid waste of the materials of the separator 2 and the first electrode tab 1, reducing the production cost. At the same time, in the width direction of the electrode group, the size of the first electrode tab 1 is slightly larger than that of the second electrode tab 3, which can enable the first electrode tab 1 to better accommodate the lithium ions released from the second electrode tab 3, avoiding excessive accumulation of lithium ions on the surface of the first electrode tab 1 to form lithium dendrites, and further reducing the risk of internal short circuit in the battery cell.

[0089] The technical effects of this embodiment will be described below in conjunction with the following examples and comparative examples. The specific results are shown in Table III.

[0090] Example 9

[0091] The relationship between the dimension W of the separator 2 and the dimension W1 of the first electrode tab 1 is 1.01, and the relationship between the dimension W1 of the first electrode tab 1 and the dimension W2 of the second electrode tab 3 is 1.2;

[0092] Example 10

[0093] The relationship between the dimension W of the separator 2 and the dimension W1 of the first electrode tab 1 is 1.2, and the relationship between the dimension W1 of the first electrode tab 1 and the dimension W2 of the second electrode tab 3 is 1.01;

[0094] Example 11

[0095] The relationship between the dimension W of the separator 2 and the dimension W1 of the first electrode tab 1 is 1.15, and the relationship between the dimension W1 of the first electrode tab 1 and the dimension W2 of the second electrode tab 3 is 1.06;

[0096] Comparative Example 10

[0097] The relationship between the dimension W of the separator 2 and the dimension W1 of the first electrode tab 1 is 0.85, and the relationship between the dimension W1 of the first electrode tab 1 and the dimension W2 of the second electrode tab 3 is 1.12;

[0098] Comparative Example 11

[0099] The relationship between the dimension W of the separator 2 and the dimension W1 of the first electrode tab 1 is 1.08, and the relationship between the dimension W1 of the first electrode tab 1 and the dimension W2 of the second electrode tab 3 is 0.8;

[0100] Comparative Example 12

[0101] The relationship between the dimension W of the separator 2 and the dimension W1 of the first electrode tab 1 is 1.16, and the relationship between the dimension W1 of the first electrode tab 1 and the dimension W2 of the second electrode tab 3 is 1.25;

[0102] Comparative Example 13

[0103] The relationship between the dimension W of the separator 2 and the dimension W1 of the first electrode tab 1 is 1.3, and the relationship between the dimension W1 of the first electrode tab 1 and the dimension W2 of the second electrode tab 3 is 1.05.

[0104] Table III

[0105]

[0106]

[0107] According to an embodiment of the present invention, as Figure 1 shown, the electrode group further includes a first inner tab 4 provided on the first electrode tab 1 and a second inner tab 5 provided on the second electrode tab 3. The first inner tab 4 and the second inner tab 5 are oppositely arranged along the length direction or the width direction of the electrode group and partially located outside the separator 2. In this embodiment, by providing the first inner tab 4 and the second inner tab 5, not only can the external current be transmitted into the electrode group through the first inner tab 4 and the second inner tab 5, but also the electrode group can release current to the outside through the first inner tab 4 and the second inner tab 5. Secondly, by arranging the first inner tab 4 and the second inner tab 5 oppositely, it can promote the uniform distribution of current on the first electrode tab 1 and the second electrode tab 3, avoid local overheating caused by uneven current distribution during large-current charging and discharging, thereby improving the large-current charging and discharging performance of the battery cell and extending the service life of the battery cell. Furthermore, by arranging part of the first inner tab 4 and the second inner tab 5 outside the separator 2, it is convenient for the subsequent assembly of the electrode group with other accessories of the battery cell and improves the production efficiency.

[0108] According to an embodiment of the present invention, as Figure 1As shown, the first inner tab 4 and the second inner tab 5 are respectively located at both ends in the length direction of the electrode assembly; along the length direction of the electrode assembly, the distance A between the end of the first electrode tab 1 and the end of the corresponding separator 2 satisfies: 1.5 mm ≤ A ≤ 3 mm; the distance B between the end of the first electrode tab 1 and the end of the corresponding second electrode tab 3 satisfies: 0.75 mm ≤ B ≤ 2 mm. The first inner tab 4 and the second inner tab 5 are respectively located at both ends in the length direction of the electrode assembly. Such a layout optimizes the current conduction path within the electrode assembly, enabling the current to flow more evenly through the first electrode tab 1 and the second electrode tab 3, effectively reducing the internal resistance of the battery cell and improving the charge and discharge performance of the battery cell. At the same time, along the length direction of the electrode assembly, the distance A between the end of the first electrode tab 1 and the end of the corresponding separator 2 satisfies 1.5 mm ≤ A ≤ 3 mm. This distance can not only ensure that the separator 2 fully wraps the first electrode tab 1 to prevent direct contact between the first electrode tab 1 and the second electrode tab 3, thus avoiding short circuits, but also avoid material waste and increased production costs caused by an overly long separator 2. And the distance B between the end of the first electrode tab 1 and the end of the corresponding second electrode tab 3 satisfies 0.75 mm ≤ B ≤ 2 mm, which not only ensures the smooth transmission of ions between the first electrode tab 1 and the second electrode tab 3 but also avoids an increased short - circuit risk due to too small a distance or a reduction in the energy density of the battery cell due to too large a distance.

[0109] According to an embodiment of the present invention, as Figure 1 shown, along the width direction of the electrode assembly, the distance C between the end of the first electrode tab 1 and the end of the corresponding separator 2 satisfies: 1 mm ≤ C ≤ 2.5 mm; the distance D between the end of the first electrode tab 1 and the end of the corresponding second electrode tab 3 satisfies: 1 mm ≤ D ≤ 2.5 mm. Along the width direction of the electrode assembly, the distance C between the end of the first electrode tab 1 and the end of the corresponding separator 2 satisfies 1 mm ≤ C ≤ 2.5 mm. This distance ensures that the separator 2 can fully wrap the first electrode tab 1 in the width direction, preventing direct contact between the first electrode tab 1 and the second electrode tab 3 and avoiding short circuits, as well as material waste and increased production costs caused by an overly long separator 2. And the distance D between the end of the first electrode tab 1 and the end of the corresponding second electrode tab 3 satisfies 1 mm ≤ D ≤ 2.5 mm. This distance can not only ensure the smooth transmission of ions between the first electrode tab 1 and the second electrode tab 3, promoting the normal charge and discharge reaction of the battery cell, but also avoid potential short - circuit hazards caused by too small a distance and problems such as a reduction in the battery energy density caused by too large a distance.

[0110] According to an embodiment of the present invention, the number of the first electrode plates 1, the separator 2, and the second electrode plates 3 is multiple. Along the thickness direction of the electrode group, the first electrode plates 1 and the second electrode plates 3 are arranged alternately, and the separator 2 is arranged between adjacent first electrode plates 1 and second electrode plates 3. In this embodiment, by arranging the multiple first electrode plates 1 and second electrode plates 3 alternately, the electrode reaction area of the battery cell can be increased, and the capacity and energy density of the battery cell can be improved. Secondly, arranging the separator 2 between adjacent first electrode plates 1 and second electrode plates 3 can prevent the first electrode plates 1 and the second electrode plates 3 from directly contacting, reduce the risk of internal short circuit of the battery cell, and improve the safety and reliability of the battery cell.

[0111] According to an embodiment of the present invention, on the other hand, a battery cell is further provided, including: the above-mentioned electrode group and a packaging film. Specifically, the packaging film wraps the outside of the electrode group.

[0112] The battery cell installed with the above-mentioned electrode group has a lower self-weight and a lower production cost compared with the existing battery cell. In addition, the battery cell of the embodiment of the present invention also has other advantages of the above-mentioned electrode group, which will not be elaborated here.

[0113] According to an embodiment of the present invention, on the other hand, a battery pack is further provided, including: a housing and multiple above-mentioned battery cells. Specifically, the multiple above-mentioned battery cells are arranged in sequence along their thickness direction in the housing.

[0114] The battery pack installed with the above-mentioned battery cells has a lower self-weight and a lower production cost compared with the existing battery pack. In addition, the battery pack of the embodiment of the present invention also has other advantages of the above-mentioned battery cells, which will not be elaborated here.

[0115] Although the 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 pole group, characterized in that: include: A first pole piece, a diaphragm and a second pole piece are stacked in sequence, wherein the polarity of the first pole piece is opposite to the polarity of the second pole piece; Along the thickness direction of the electrode group, the orthographic projection of the second electrode piece toward the first electrode piece falls into the first electrode piece, and the orthographic projection of the first electrode piece toward the diaphragm is located inside the diaphragm; Wherein, the surface area S1 of the first pole piece and the surface area S2 of the second pole piece satisfy: 1.05≤S1 / S2≤1.15; The surface area S of the diaphragm and the surface area S1 of the first pole piece satisfy: 1.1≤S / S1≤1.3; wherein the value range of S1 is: 4950mm 2 ≤S1≤75600mm 2 ; The value range of S2 is: 4250mm 2 ≤S2≤66000mm 2 ; The value range of S is: 5700mm 2 ≤S≤90000mm 2 .

2. The pole group according to claim 1, characterized in that: Along the thickness direction of the pole group, the cross-sectional shapes of the first pole piece, the diaphragm and the second pole piece are all square; the length direction and width direction of the first pole piece, the diaphragm and the second pole piece are consistent.

3. The pole group according to claim 2, characterized in that: Along the length direction of the pole group, the size L of the diaphragm and the size L1 of the first pole piece satisfy: 1.01≤L / L1≤1.2; the size L1 of the first pole piece and the size L2 of the second pole piece satisfy: 1.01≤L1 / L2≤1.2; wherein, the value range of L is: 95mm≤L≤450mm; the value range of L1 is: 90mm≤L1≤420mm; the value range of L2 is: 85mm≤L2≤400mm.

4. The pole group according to claim 3, characterized in that: Along the width direction of the pole group, the size W of the diaphragm and the size W1 of the first pole piece satisfy: 1.01≤W / W1≤1.2; the size W1 of the first pole piece and the size W2 of the second pole piece satisfy: 1.01≤W1 / W2≤1.2; wherein, the value range of W is: 60mm≤W≤200mm; the value range of W1 is: 55mm≤W1≤180mm; the value range of W2 is: 50mm≤W2≤165mm.

5. The pole group according to claim 1, characterized in that: The pole group further includes a first inner pole ear arranged on the first pole piece and a second inner pole ear arranged on the second pole piece. The first inner pole ear and the second inner pole ear are arranged opposite to each other along the length direction or the width direction of the pole group and are partially located outside the diaphragm.

6. The pole group according to claim 5, characterized in that: The first inner pole ear and the second inner pole ear are respectively located at the two ends of the pole group in the length direction; along the length direction of the pole group, the distance A between the end of the first pole piece and the corresponding end of the diaphragm satisfies: 1.5mm≤A≤3mm; the distance B between the end of the first pole piece and the corresponding end of the second pole piece satisfies: 0.75mm≤B≤2mm.

7. The pole group according to claim 6, characterized in that: Along the width direction of the electrode group, the distance C between the end of the first electrode piece and the corresponding end of the diaphragm satisfies: 1mm≤C≤2.5mm; the distance D between the end of the first electrode piece and the corresponding end of the second electrode piece satisfies: 1mm≤D≤2.5mm.

8. The pole group according to any one of claims 1 to 7, characterized in that: The number of the first pole pieces, the diaphragms and the second pole pieces are all multiple. The first pole pieces and the second pole pieces are alternately arranged along the thickness direction of the pole group, and the diaphragms are arranged between adjacent first pole pieces and second pole pieces.

9. A battery cell, characterized in that: include: The pole group according to any one of claims 1 to 8; The packaging film is wrapped around the outside of the electrode group.

10. A battery pack, characterized in that: include: case; A plurality of battery cells according to claim 9 are arranged sequentially in the casing along the thickness direction thereof.

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