Battery cell, cylindrical battery and battery pack
By using a current collector with high elongation and high tensile strength, the problem of pole fracture is solved, and the safety and stability of the battery is improved.
Patent Information
- Application Number
- CN202422288363.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-19
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-09-19
AI Technical Summary
In existing cylindrical batteries, the electrode segments are broken due to the expansion stress of the electrode group, which affects the stability and safety of the battery.
The negative and positive electrode current collectors with high elongation and high tensile strength are used to disperse the expansion stress by increasing the elongation and tensile strength of the current collector to prevent the electrode segment from breaking.
Effectively prevent pole pieces from breaking, improve the safety and stability of the battery, and avoid the problem of short-circuit contact of positive and negative pole pieces.
Smart Images
Figure CN223181183U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of batteries, and in particular to a battery core, a cylindrical battery and a battery pack. Background Art
[0002] Cylindrical batteries have the advantages of high capacity, high output voltage, good charge and discharge cycle performance, stable output voltage, ability to discharge at large currents, high electrochemical stability, and high safety. They can operate within a wide temperature range and have little impact on the environment during use.
[0003] In cylindrical batteries, the steel casing restrains the expansion of the electrode group (also known as the core), and the expansion stress of the electrode group is theoretically isotropic in the radial direction of the cylindrical cell. Therefore, more Si-based materials can be incorporated into the negative electrode system to increase the negative electrode capacity and improve the energy density of the cell. However, in actual production, due to factors such as material selection and the fact that the electrode group is not a perfect cylinder, the stress in the radial direction of the cylindrical cell varies. Due to excessive stress in a single direction, the positive and negative electrodes often break during the expansion of the electrode group during charging and discharging, affecting the stability of the cell.
[0004] To achieve high energy density in existing cylindrical batteries, a Si-based negative electrode is often incorporated into the large cylindrical system. Due to the significant expansion of Si-based materials, foil with high tensile strength is often used to resist the expansion stress of the electrode assembly. However, this is not ideal and can easily lead to electrode breakage. A broken electrode can puncture the separator between the positive and negative electrodes, causing a short circuit between the positive and negative electrodes and rapid heating of the battery. This can lead to thermal runaway and explosion, compromising safety.
[0005] Therefore, there is an urgent need for a battery cell, a cylindrical battery and a battery pack to solve the above problems existing in the prior art. Utility Model Content
[0006] The purpose of the utility model is to provide a battery cell, a cylindrical battery and a battery pack to solve the problem of electrode breakage caused by electrode group expansion stress and improve the safety and stability of the battery.
[0007] To achieve this purpose, the present invention adopts the following technical solutions:
[0008] In a first aspect, a battery cell is provided, comprising a negative electrode sheet, a positive electrode sheet, and a separator that are stacked and wound together;
[0009] The negative electrode plate includes a negative electrode current collector and a negative electrode active layer disposed on the negative electrode current collector, wherein the elongation of the negative electrode current collector is greater than 5.2%, and the tensile strength of the negative electrode current collector is greater than or equal to 300 MPa;
[0010] The positive electrode tab includes a positive current collector and a positive active layer disposed on the positive current collector. The elongation rate of the positive current collector is greater than or equal to 3%, and the tensile strength of the positive current collector is greater than or equal to 230 MPa;
[0011] The separator is clamped between the positive active layer and the negative active layer.
[0012] In some embodiments of the battery cell provided by the present invention, the negative current collector is a copper foil; or the negative current collector includes a first polymer layer and a copper alloy layer, and the copper alloy layers are disposed on both sides of the first polymer layer in the thickness direction;
[0013] And / or, the positive current collector is an aluminum foil; or the positive current collector includes a second polymer layer and an aluminum alloy layer, and the aluminum alloy layers are disposed on both sides of the second polymer layer in the thickness direction.
[0014] In some embodiments of the battery cell provided by the present invention, the negative current collector is a copper foil;
[0015] The copper foil is a first general anti - and general elongation copper foil, the thickness of the first general anti - and general elongation copper foil is 6 μm, the elongation rate of the first general anti - and general elongation copper foil is greater than 5.2%, and the tensile strength of the first general anti - and general elongation copper foil is greater than or equal to 300 MPa; or,
[0016] The copper foil is a second general anti - and general elongation copper foil, the thickness of the second general anti - and general elongation copper foil is 8 μm, the elongation rate of the second general anti - and general elongation copper foil is greater than or equal to 5.5%, and the tensile strength of the second general anti - and general elongation copper foil is greater than or equal to 300 MPa.
[0017] In some embodiments of the battery cell provided by the present invention, the negative current collector is a copper foil;
[0018] The copper foil is a first general anti - and high elongation copper foil, the thickness of the first general anti - and high elongation copper foil is 6 μm, the elongation rate of the first general anti - and high elongation copper foil is greater than 6%, and the tensile strength of the first general anti - and high elongation copper foil is greater than or equal to 300 MPa; or,
[0019] The copper foil is a second general anti - and high elongation copper foil, the thickness of the second general anti - and high elongation copper foil is 8 μm, the elongation rate of the second general anti - and high elongation copper foil is greater than 8%, and the tensile strength of the second general anti - and high elongation copper foil is greater than or equal to 300 MPa.
[0020] In some embodiments of the battery cell provided by the present invention, the negative current collector is a copper foil;
[0021] The copper foil is a first high anti - high elongation copper foil; the thickness of the first high anti - high elongation copper foil is 6μm, the elongation rate of the first high anti - high elongation copper foil is greater than 6%, and the tensile strength of the first high anti - high elongation copper foil is greater than or equal to 400MPa; or,
[0022] The copper foil is a second high anti - high elongation copper foil; the thickness of the second high anti - high elongation copper foil is 8μm, the elongation rate of the second high anti - high elongation copper foil is greater than 8%, and the tensile strength of the second high anti - high elongation copper foil is greater than or equal to 400MPa.
[0023] As some embodiments of the battery cell provided by the present utility model, the positive current collector is an aluminum foil;
[0024] The aluminum foil is a first high anti - aluminum foil, the thickness of the first high anti - aluminum foil is 12μm, and the tensile strength of the first high anti - aluminum foil is greater than or equal to 230MPa and less than or equal to 270MPa; or,
[0025] The aluminum foil is a second high anti - aluminum foil, the thickness of the second high anti - aluminum foil is 15μm, and the tensile strength of the second high anti - aluminum foil is greater than or equal to 240MPa and less than or equal to 280Mpa.
[0026] As some embodiments of the battery cell provided by the present utility model, the thickness value of the negative current collector is greater than or equal to 6μm and less than or equal to 8μm; and / or, the thickness value of the positive current collector is greater than or equal to 12μm and less than or equal to 16μm.
[0027] As some embodiments of the battery cell provided by the present utility model, the negative electrode plate, the positive electrode plate and the separator are stacked and wound together to form a core assembly, and the battery cell further includes a core encapsulation, and the core assembly is provided with the core encapsulation outside.
[0028] In a second aspect, a cylindrical battery is provided, including a housing and the battery cell as described above, and the battery cell is located inside the housing.
[0029] In a third aspect, a battery pack is provided, including a box body and a plurality of cylindrical batteries as described above.
[0030] Advantages of the present utility model:
[0031] The present utility model provides a battery cell, a cylindrical battery, and a battery pack. Since the elongation rate of the negative current collector is greater than 5.2% and the tensile strength is greater than or equal to 300 MPa, and the elongation rate of the positive current collector is greater than or equal to 3% and the tensile strength is greater than or equal to 230 MPa, both the negative current collector and the positive current collector have relatively high elongation rates and certain tensile strengths. When stress is generated due to the expansion inside the battery cell, the negative current collector and the positive current collector with relatively high elongation rates can better disperse the stress generated by the expansion, prevent the negative electrode sheet and the positive electrode sheet from breaking, and further avoid the problem of piercing the separator between the positive and negative electrode sheets due to the breakage of the electrode sheets, resulting in contact short - circuit between the positive and negative electrode sheets, thereby improving the safety and stability of the battery. Moreover, since the negative current collector and the positive current collector have certain tensile strengths, they can also prevent breakage to a certain extent due to the expansion stress. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for use in the embodiments of the present utility model. Obviously, the following described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.
[0033] Figure 1 It is a stacked schematic diagram of a positive electrode sheet, a separator, and a negative electrode sheet provided by the specific embodiment of the present utility model;
[0034] Figure 2 It is a structural schematic diagram of a negative current collector provided by the specific embodiment of the present utility model;
[0035] Figure 3 It is a structural schematic diagram of a positive current collector provided by the specific embodiment of the present utility model.
[0036] In the figure:
[0037] 1, negative electrode sheet; 2, positive electrode sheet; 3, separator;
[0038] 11, negative current collector; 12, negative active layer;
[0039] 21, positive current collector; 22, positive active layer;
[0040] 111, first polymer layer; 112, copper alloy layer;
[0041] 211, second polymer layer; 212, aluminum alloy layer. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0042] The present utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present utility model, rather than limiting the present utility model. In addition, it should be noted that for the sake of convenience of description, only the parts related to the present utility model are shown in the drawings, rather than all the structures.
[0043] In the description of the present utility model, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.
[0044] In the present utility model, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over", and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature has a higher horizontal height than the second feature. The first feature being "below", "under", and "beneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower horizontal height than the second feature.
[0045] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "left", and "right" are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meanings.
[0046] The term "and / or" in this embodiment is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present utility model generally represents an "or" relationship between the associated objects before and after.
[0047] In the embodiments of the present utility model, the same reference numerals represent the same components, and for the sake of simplicity, in different embodiments, the detailed description of the same components is omitted.
[0048] Such as Figure 1As shown in the figure, an embodiment of the present application provides an electric core, which includes a negative electrode tab 1, a positive electrode tab 2, and a separator 3 that are stacked and wound together.
[0049] Specifically, the negative electrode tab 1 includes a negative electrode current collector 11 and a negative electrode active layer 12 provided on the negative electrode current collector 11. The elongation rate of the negative electrode current collector 11 is greater than 5.2%, and the tensile strength of the negative electrode current collector 11 is greater than or equal to 300 MPa. The positive electrode tab 2 includes a positive electrode current collector 21 and a positive electrode active layer 22 provided on the positive electrode current collector 21. The elongation rate of the positive electrode current collector 21 is greater than or equal to 3%, and the tensile strength of the positive electrode current collector 21 is greater than or equal to 230 MPa. The separator 3 is sandwiched between the positive electrode active layer 22 and the negative electrode active layer 12.
[0050] The negative electrode tab 1, the positive electrode tab 2, and the separator 3 are stacked and wound together to form a core assembly, which is also called a pole group. In a cylindrical battery, the core assembly is cylindrical.
[0051] Furthermore, the material composition of the negative electrode active layer 12 includes a silicon-based material. The presence of the silicon-based material can improve the energy density of the battery, but the negative electrode active layer 12 containing the silicon-based material has a large expansion factor, which generates a large expansion stress in the core assembly during charge and discharge, easily causing the negative electrode tab 1 to break. Affected by the expansion of the negative electrode active layer 12, the positive electrode tab 2 also has a risk of breaking.
[0052] In the electric core provided by the embodiment of the present application, since the elongation rate of the negative electrode current collector 11 is greater than 5.2% and the tensile strength is greater than or equal to 300 MPa, and the elongation rate of the positive electrode current collector 21 is greater than or equal to 3% and the tensile strength is greater than or equal to 230 MPa, both the negative electrode current collector 11 and the positive electrode current collector 21 have a relatively high elongation rate and a certain tensile strength. When stress is generated due to internal expansion of the electric core, the negative electrode current collector 11 and the positive electrode current collector 21 with relatively high elongation rates can better disperse the stress generated by the expansion, prevent the negative electrode tab 1 and the positive electrode tab 2 from breaking, and further avoid the problem of the separator 3 between the positive and negative electrode tabs being punctured due to the breakage of the electrode tabs, resulting in contact short circuit between the positive and negative electrode tabs, thereby improving the safety and stability of the battery. Moreover, since the negative electrode current collector 11 and the positive electrode current collector 21 have a certain tensile strength, it can also prevent breakage due to expansion stress to a certain extent.
[0053] Furthermore, the elongation rate of the negative electrode current collector 11 is greater than or equal to 6%, which more effectively prevents the negative electrode tab 1 and the positive electrode tab 2 from breaking. Further, the elongation rate of the negative electrode current collector 11 is greater than or equal to 8%.
[0054] Furthermore, the elongation rate of the positive electrode current collector 21 is greater than or equal to 4%. Further, the elongation rate of the positive electrode current collector 21 is greater than or equal to 5%.
[0055] In some embodiments, the negative electrode current collector 11 is a copper foil, which has good electrical conductivity, is soft in texture, has a relatively low cost, and can remain stable in air.
[0056] In some embodiments, referring to Figure 2 , the negative electrode current collector 11 includes a first polymer layer 111 and a copper alloy layer 112, and copper alloy layers 112 are provided on both sides of the first polymer layer 111 in the thickness direction. The first polymer layer 111 is exemplarily a plastic film made of materials such as PET, PP, or PI. The thickness of the copper alloy layer 112 is exemplarily greater than or equal to 1 μm and less than or equal to 2 μm. That is, the negative electrode current collector 11 is a sandwich composite copper foil structure with the first polymer layer 111 in the middle and copper alloys on both sides, which has better effects of inhibiting dendrite growth, inhibiting internal short - circuit ignition in the negative electrode current collector 11, and inhibiting the spread of ignition compared with copper foil.
[0057] In some embodiments, the positive electrode current collector 21 is an aluminum foil. The aluminum foil has good electrical conductivity, flexibility, ductility, and stability, and the price of the aluminum foil is relatively cheap, which helps to control the production cost of the battery.
[0058] In some embodiments, referring to Figure 3 , the positive electrode current collector 21 includes a second polymer layer 211 and an aluminum alloy layer 212, and aluminum alloy layers 212 are provided on both sides of the second polymer layer 211 in the thickness direction. The second polymer layer 211 is exemplarily a plastic film made of materials such as PET, PP, or PI. The thickness of the aluminum alloy layer 212 is exemplarily greater than or equal to 1 μm and less than or equal to 2 μm. That is, the positive electrode current collector 21 is a sandwich composite aluminum foil structure with the second polymer layer 211 in the middle and aluminum alloys on both sides, which has better effects of inhibiting dendrite growth, inhibiting internal short - circuit ignition in the positive electrode current collector 21, and inhibiting the spread of ignition compared with aluminum foil.
[0059] The positive electrode potential of the lithium - ion battery is relatively high. Using aluminum foil or composite aluminum foil as the positive electrode current collector 21 can remain stable at high potentials, while copper foil or composite copper foil is easily oxidized at high potentials. Therefore, the positive electrode current collector 21 uses aluminum foil or composite aluminum foil, and the negative electrode current collector 11 uses copper foil or composite copper foil to ensure the stability of the battery.
[0060] As some embodiments, the negative electrode current collector 11 is a copper foil, and this copper foil is a first general - purpose anti - corrosion and general - purpose elongation copper foil. The thickness of the first general - purpose anti - corrosion and general - purpose elongation copper foil is 6 μm, the elongation rate of the first general - purpose anti - corrosion and general - purpose elongation copper foil is greater than 5.2%, and the tensile strength of the first general - purpose anti - corrosion and general - purpose elongation copper foil is greater than or equal to 300 MPa. The relatively high elongation rate and tensile strength of the first general - purpose anti - corrosion and general - purpose elongation copper foil can prevent the pole piece from breaking.
[0061] As some embodiments, the negative electrode current collector 11 is a copper foil, and this copper foil is a second general anti-extension copper foil. The thickness of the second general anti-extension copper foil is 8 μm, the elongation rate of the second general anti-extension copper foil is greater than or equal to 5.5%, and the tensile strength of the second general anti-extension copper foil is greater than or equal to 300 MPa. The elongation rate of the second general anti-extension copper foil is relatively high compared to the first general anti-extension copper foil, and combined with its tensile strength, it can achieve a better effect of preventing the electrode sheet from breaking.
[0062] As some embodiments, the negative electrode current collector 11 is a copper foil, and this copper foil is a first general anti-high-elongation copper foil. The thickness of the first general anti-high-elongation copper foil is 6 μm, the elongation rate of the first general anti-high-elongation copper foil is greater than 6%, and the tensile strength of the first general anti-high-elongation copper foil is greater than or equal to 300 MPa. The elongation rate of the first general anti-high-elongation copper foil is relatively high compared to the elongation rate of the second general anti-extension copper foil, and combined with its tensile strength, it can achieve a better effect of preventing the electrode sheet from breaking.
[0063] As some embodiments, the negative electrode current collector 11 is a copper foil, and this copper foil is a second general anti-high-elongation copper foil. The thickness of the second general anti-high-elongation copper foil is 8 μm, the elongation rate of the second general anti-high-elongation copper foil is greater than 8%, and the tensile strength of the second general anti-high-elongation copper foil is greater than or equal to 300 MPa. The elongation rate of the second general anti-high-elongation copper foil is relatively high compared to the elongation rate of the first general anti-high-elongation copper foil, and combined with its tensile strength, it can achieve a better effect of preventing the electrode sheet from breaking.
[0064] As some embodiments, the negative electrode current collector 11 is a copper foil, and this copper foil is a first high anti-high-elongation copper foil; the thickness of the first high anti-high-elongation copper foil is 6 μm, the elongation rate of the first high anti-high-elongation copper foil is greater than 6%, and the tensile strength of the first high anti-high-elongation copper foil is greater than or equal to 400 MPa. The elongation rate and tensile strength of the first high anti-high-elongation copper foil are higher than those of the first general anti-extension copper foil, and it can resist greater expansion stress, achieving a better effect of preventing the electrode sheet from breaking.
[0065] As some embodiments, the negative electrode current collector 11 is a copper foil, and this copper foil is a second high anti-high-elongation copper foil; the thickness of the second high anti-high-elongation copper foil is 8 μm, the elongation rate of the second high anti-high-elongation copper foil is greater than 8%, and the tensile strength of the second high anti-high-elongation copper foil is greater than or equal to 400 MPa. The elongation rate of the second high anti-high-elongation copper foil is higher than that of the first high anti-high-elongation copper foil, and combined with its tensile strength, it can achieve a better effect of preventing the electrode sheet from breaking.
[0066] As some embodiments, the positive current collector 21 is an aluminum foil, and the aluminum foil is a first high-resistant aluminum foil. The thickness of the first high-resistant aluminum foil is 12 μm, and the tensile strength of the first high-resistant aluminum foil is greater than or equal to 230 MPa and less than or equal to 270 MPa. The elongation rate of the first high-resistant aluminum foil is ≥3%, which is beneficial to dispersing the expansion stress inside the core assembly. Cooperating with its tensile strength, it effectively avoids the fracture of the positive electrode tab 2. Exemplarily, the alloy grade of the first high-resistant aluminum foil is 1N00-H18.
[0067] As some embodiments, the positive current collector 21 is an aluminum foil, and the aluminum foil is a second high-resistant aluminum foil. The thickness of the second high-resistant aluminum foil is 15 μm, and the tensile strength of the second high-resistant aluminum foil is greater than or equal to 240 MPa and less than or equal to 280 Mpa. The elongation rate of the second high-resistant aluminum foil is ≥3%, which is beneficial to dispersing the expansion stress inside the core assembly. Cooperating with its tensile strength, it effectively avoids the fracture of the positive electrode tab 2. Exemplarily, the alloy grade of the second high-resistant aluminum foil is 1N00-H18.
[0068] In the embodiments of the present application, the thickness value of the negative current collector 11 is greater than or equal to 6 μm and less than or equal to 8 μm; and / or, the thickness value of the positive current collector 21 is greater than or equal to 12 μm and less than or equal to 16 μm. The negative current collector 11 and the positive current collector 21 with the above thickness dimensions are of appropriate thickness, which not only have sufficient strength but also help to miniaturize the battery cell, thereby realizing the light weight of the battery.
[0069] In the embodiments of the present application, the battery cell further includes a core encapsulation. There is a core encapsulation outside the core assembly, which helps to protect the core assembly and reduce the probability of battery short circuit.
[0070] The present application also provides a cylindrical battery, including a housing and the battery cell as described above. The battery cell is located inside the housing. Further, a pole is provided outside the housing, and the pole is electrically connected to the battery cell to achieve current transmission. For the cylindrical battery with the above battery cell, when stress is generated due to the expansion inside the battery cell, the negative current collector 11 and the positive current collector 21 with relatively high elongation rates can better disperse the stress generated by the expansion, prevent the negative electrode tab 1 and the positive electrode tab 2 from breaking, and further avoid the problem of piercing the separator 3 between the positive and negative electrode tabs and causing contact short circuit between the positive and negative electrode tabs due to the fracture of the electrode tabs, thereby improving the safety and stability of the battery.
[0071] The present application also provides a battery pack, including a box body and a plurality of the above cylindrical batteries. This battery pack can effectively prevent the internal electrode tabs from breaking and has higher safety and stability.
[0072] The advantages of the battery cell provided in this embodiment are described below with reference to Examples 1 to 5 and Comparative Examples 1 to 4.
[0073] Example 1
[0074] This embodiment provides an electric core, which includes a negative electrode tab 1, a positive electrode tab 2 and a separator 3 that are stacked and wound together.
[0075] The negative electrode tab 1 includes a negative electrode current collector 11 and a negative electrode active layer 12 disposed on the negative electrode current collector 11. The positive electrode tab 2 includes a positive electrode current collector 21 and a positive electrode active layer 22 disposed on the positive electrode current collector 21. The separator 3 is sandwiched between the positive electrode active layer 22 and the negative electrode active layer 12.
[0076] The material components of the negative electrode active layer 12 include a negative electrode active material, wherein the negative electrode active material is a composite material of a silicon-based material and artificial graphite; the material components of the positive electrode active layer 22 include a positive electrode active material, and the positive electrode active material is a high-nickel ternary material.
[0077] The negative electrode current collector 11 is made of a general-purpose anti-corrosion and general-purpose elongation copper foil with a thickness of 6 μm, its elongation rate > 5.2%, and its tensile strength ≥ 300 Mpa.
[0078] The positive electrode current collector 21 is made of a high-anti-aluminum foil with a thickness of 12 μm, its elongation rate ≥ 3%, and its tensile strength is 230 MPa - 270 MPa.
[0079] This electric core is applied in a cylindrical battery, and the assembly ratio during assembly is 96.4%. The assembly ratio is the ratio of the diameter of the core assembly (also called the electrode group) to the inner diameter of the cylindrical battery case (such as a steel case). The core is wrapped with an expansion tape of 78 mm.
[0080] Embodiment 2
[0081] This embodiment provides an electric core, and the difference from Embodiment 1 is as follows:
[0082] The negative electrode current collector 11 is made of a general-purpose anti-corrosion and high-elongation copper foil with a thickness of 6 μm, its elongation rate > 6%, and its tensile strength ≥ 300 Mpa. The assembly ratio is 97.6%, and the core is wrapped with a 10 mm PET tape.
[0083] Embodiment 3
[0084] This embodiment provides an electric core, and the difference from Embodiment 1 is as follows:
[0085] The negative electrode current collector 11 is made of a high-anti and high-elongation copper foil with a thickness of 6 μm, its elongation rate > 6%, and its tensile strength ≥ 400 Mpa. The assembly ratio is 98.4%, and the core is wrapped with a 12 mm expansion tape, and it is pasted at both ends of the core assembly.
[0086] Embodiment 4
[0087] This embodiment provides an electric core, and the difference from Embodiment 1 is as follows:
[0088] The negative current collector 11 uses a composite copper foil with a thickness of 6 μm (the structure is as Figure 2 shown), its elongation rate > 5.2%, and its tensile strength ≥ 300 Mpa. The assembly ratio is 99.1%, and the core wrapping uses a 56 mm expansion tape to cover the core assembly.
[0089] Example 5
[0090] This example provides a battery cell, and the difference from Example 1 is that:
[0091] The negative current collector 11 uses a high - resistance and high - elongation copper foil with a thickness of 8 μm, its elongation rate > 8%, and its tensile strength ≥ 400 Mpa. The positive current collector 21 uses a composite aluminum foil with a thickness of 12 μm (the structure is as Figure 3 shown), and its elongation rate ≥ 3%. The assembly ratio is 98.8%, and the core wrapping uses a PET tape to cover the core assembly.
[0092] Comparative Example 1
[0093] This comparative example provides a battery cell, and the difference from Example 1 is that:
[0094] The negative current collector 11 uses a high - resistance and ordinary - elongation copper foil with a thickness of 6 μm, its elongation rate ≤ 5.2%, and its tensile strength > 400 Mpa. The assembly ratio is 96.4%, and the core wrapping uses a 12 mm expansion tape and is pasted at both ends of the core assembly.
[0095] Comparative Example 2
[0096] This comparative example provides a battery cell, and the difference from Comparative Example 1 is that:
[0097] The assembly ratio is 98.4%, and the core wrapping uses a 56 mm expansion tape to cover the core assembly.
[0098] Comparative Example 3
[0099] This comparative example provides a battery cell, and the difference from Comparative Example 1 is that:
[0100] The assembly ratio is 99.1%, and the core wrapping uses a PET tape to cover the core assembly.
[0101] Comparative Example 4
[0102] This comparative example provides a battery cell, and the difference from Comparative Example 1 is that: no core wrapping is used.
[0103] The battery cells provided in Examples 1 - 5 and Comparative Examples 1 - 4 are tested to analyze whether the electrode sheets are broken, and the test results are as follows in the table.
[0104]
[0105] As can be seen from the above table, the non-polar plate fracture situation in the battery cells provided in Examples 1 to 5 can improve the safety and stability of the battery.
[0106] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.
Claims
1. A battery cell, characterized in that, It includes a negative electrode tab (1), a positive electrode tab (2), and a separator (3) that are stacked and wound together; The negative electrode tab (1) includes a negative electrode current collector (11) and a negative electrode active layer (12) provided on the negative electrode current collector (11). The elongation rate of the negative electrode current collector (11) is greater than 5.2%, and the tensile strength of the negative electrode current collector (11) is greater than or equal to 300 MPa; The positive electrode tab (2) includes a positive electrode current collector (21) and a positive electrode active layer (22) provided on the positive electrode current collector (21). The elongation rate of the positive electrode current collector (21) is greater than or equal to 3%, and the tensile strength of the positive electrode current collector (21) is greater than or equal to 230 MPa; The separator (3) is sandwiched between the positive electrode active layer (22) and the negative electrode active layer (12).
2. The battery cell according to claim 1, characterized in that, The negative electrode current collector (11) is a copper foil; or the negative electrode current collector (11) includes a first polymer layer (111) and a copper alloy layer (112), and the copper alloy layer (112) is provided on both sides of the first polymer layer (111) in the thickness direction; And / or, the positive electrode current collector (21) is an aluminum foil; or the positive electrode current collector (21) includes a second polymer layer (211) and an aluminum alloy layer (212), and the aluminum alloy layer (212) is provided on both sides of the second polymer layer (211) in the thickness direction.
3. The battery cell according to claim 2, wherein The negative electrode current collector (11) is a copper foil; The copper foil is a first general anti - general elongation copper foil. The thickness of the first general anti - general elongation copper foil is 6 μm, the elongation rate of the first general anti - general elongation copper foil is greater than 5.2%, and the tensile strength of the first general anti - general elongation copper foil is greater than or equal to 300 MPa; or, The copper foil is a second general anti - general elongation copper foil. The thickness of the second general anti - general elongation copper foil is 8 μm, the elongation rate of the second general anti - general elongation copper foil is greater than or equal to 5.5%, and the tensile strength of the second general anti - general elongation copper foil is greater than or equal to 300 MPa.
4. The battery cell according to claim 2, wherein, The negative electrode current collector (11) is a copper foil; The copper foil is a first general anti - high elongation copper foil. The thickness of the first general anti - high elongation copper foil is 6 μm, the elongation rate of the first general anti - high elongation copper foil is greater than 6%, and the tensile strength of the first general anti - high elongation copper foil is greater than or equal to 300 MPa; or, The copper foil is a second general anti - high elongation copper foil. The thickness of the second general anti - high elongation copper foil is 8 μm, the elongation rate of the second general anti - high elongation copper foil is greater than 8%, and the tensile strength of the second general anti - high elongation copper foil is greater than or equal to 300 MPa.
5. The battery cell according to claim 2, characterized in that, The negative electrode current collector (11) is a copper foil; The copper foil is a first high anti - high elongation copper foil; the thickness of the first high anti - high elongation copper foil is 6 μm, the elongation rate of the first high anti - high elongation copper foil is greater than 6%, and the tensile strength of the first high anti - high elongation copper foil is greater than or equal to 400 MPa; Or, The copper foil is a second high anti - high elongation copper foil; the thickness of the second high anti - high elongation copper foil is 8 μm, the elongation rate of the second high anti - high elongation copper foil is greater than 8%, and the tensile strength of the second high anti - high elongation copper foil is greater than or equal to 400 MPa.
6. The battery cell according to claim 2, wherein, The positive electrode current collector (21) is an aluminum foil; The aluminum foil is a first high-barrier aluminum foil with a thickness of 12 μm, and the tensile strength of the first high-barrier aluminum foil is greater than or equal to 230 MPa and less than or equal to 270 MPa; or, The aluminum foil is a second high-barrier aluminum foil with a thickness of 15 μm, and the tensile strength of the second high-barrier aluminum foil is greater than or equal to 240 MPa and less than or equal to 280 MPa.
7. The battery cell according to claim 1, characterized in that, The thickness value of the negative current collector (11) is greater than or equal to 6 μm and less than or equal to 8 μm; and / or, the thickness value of the positive current collector (21) is greater than or equal to 12 μm and less than or equal to 16 μm.
8. The battery cell according to claim 1, wherein The negative electrode plate (1), the positive electrode plate (2), and the separator (3) are stacked and wound together to form a core assembly, and the battery cell further includes core encapsulation, and the core encapsulation is provided outside the core assembly.
9. A cylindrical battery, characterized in that, It includes a housing and the battery cell according to any one of claims 1-8, and the battery cell is located inside the housing.
10. A battery pack, characterized in that, It includes a box body and a plurality of cylindrical batteries according to claim 9.