Battery cell and corner pressing seal head

Abstract

The invention discloses a battery cell and a corner pressing end socket, which are applied to the technical field of batteries, and comprise a battery cell body and a shell covering the battery cell body, the shell comprises a membrane shell for accommodating the battery cell body, and the membrane shell is provided with a bottom corner part; the shell is provided with a corner pressing structure, the corner pressing structure comprises an R corner part and a convex part, and a clearance part is formed between the convex part and the R corner part; the R corner part is arranged along one part of the edge of the bottom corner part, and the clearance part extends to the other part of the edge of the bottom corner part. The receding part is formed in the corner pressing structure, excessive extrusion of the protruding part on the membrane shell can be avoided, and therefore allowance is reserved for deformation of the membrane shell in the follow-up using process, and the corner breakage probability of the bottom corner of the membrane shell is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery cell and an angle pressing head. Background Art

[0002] With the continuous advancement of science and technology, people hope that electronic products will be lighter and more compact, which puts higher requirements on the energy density of battery cells. In the process of pursuing energy density, in addition to the continuous improvement of the gram capacity of the main material, the thickness of the auxiliary material is continuously reduced, and the volume of the membrane shell is compressed. Reducing the gap between the core and the membrane shell is also one of the important ways and means.

[0003] However, in the process of reducing the volume of the winding core / membrane shell, it is found that the pole piece will have a certain proportion of extension in the three directions of X / Y / Z. The extension of the pole piece itself will interfere with the membrane shell. The breathing effect will squeeze the membrane shell during the cycle. According to the analysis of the tensile stress-strain principle of metals, when the tensile stress / strain of the aluminum-plastic film passes through the plastic deformation stage and reaches the peak of the tensile strength, it will break and the battery cell corners will be broken, creating safety risks on the user side.

[0004] In the process of analyzing corner breakage, it is found that the ratio of bottom corner breakage is much higher than that of top corner breakage. Therefore, how to provide a battery cell that can reduce the ratio of bottom corner breakage is an urgent problem that technicians in this field need to solve. Summary of the invention

[0005] An object of the present invention is to provide a battery cell with a low probability of bottom corner breakage; another object of the present invention is to provide a corner pressing head that can reduce the probability of bottom corner breakage of the battery cell.

[0006] In order to solve the above technical problems, the present invention provides a battery cell, comprising a battery cell body and a shell covering the battery cell body; the shell comprises a film shell accommodating the battery cell body, and the film shell has a bottom corner portion;

[0007] The housing is provided with an angle-pressing structure, the angle-pressing structure comprises an R-angle portion and a convex portion, and a space-avoiding portion is formed between the convex portion and the R-angle portion;

[0008] The R corner portion is arranged along a portion of the edge of the bottom corner portion, and the avoidance portion extends to another portion of the edge of the bottom corner portion.

[0009] Optionally, the R angle of the R corner portion is greater than the R angle of the bottom corner portion.

[0010] Optionally, the housing further comprises a sealing area located outside the membrane shell, and an inner unsealed area located between the membrane shell and the sealing area;

[0011] The air-avoiding portion is arranged in the inner unsealed area.

[0012] Optionally, the width of the R corner portion ranges from 0.3 mm to 2 mm, the R angle size ranges from 1.5 mm to 2.5 mm, and the width of the air avoidance portion ranges from 0 mm to 3 mm.

[0013] Optionally, there is a back margin between the bottom corner portion and the back of the shell, and the back margin is not less than 1.4 mm.

[0014] Optionally, the back margin has a value range of 1.4 mm to 4.0 mm.

[0015] Optionally, the battery cell body includes a positive electrode sheet and a negative electrode sheet, the negative electrode sheet includes a negative electrode current collector and a negative electrode paste layer, and the negative electrode paste layer is a graphite paste layer or a silicon-based material paste layer or a mixed paste layer of graphite and silicon-based materials.

[0016] Optionally, the absolute strength of the negative electrode current collector ranges from 450 N / m to 1000 N / m.

[0017] Optionally, the thickness of the negative electrode current collector ranges from 1 μm to 15 μm.

[0018] The present invention also provides a corner pressing head for forming a corner pressing structure in a battery cell as described in any one of the above items, comprising:

[0019] A corner pressing body, a corner pressing R corner portion located at one side edge of the corner pressing body, and a corner pressing convex portion protruding from one side edge of the corner pressing body; the corner pressing convex portion is arranged close to one end portion of the corner pressing R corner portion, and a preset interval is arranged between the corner pressing convex portion and one end portion of the corner pressing R corner portion to form a corner pressing avoidance portion.

[0020] A battery cell provided by the present invention comprises a battery cell body and a shell covering the battery cell body; the shell comprises a film shell accommodating the battery cell body, the film shell having a bottom corner portion; the shell is provided with a pressure angle structure, the pressure angle structure comprises an R corner portion and a convex portion, a gap avoidance portion is formed between the convex portion and the R corner portion; the R corner portion is provided along a portion of the edge of the bottom corner portion, and the gap avoidance portion extends to another portion of the edge of the bottom corner portion.

[0021] The formation of the avoidance portion in the angle pressing structure can prevent the convex portion from excessively squeezing the membrane shell, thereby leaving a margin for deformation of the membrane shell during subsequent use, thereby reducing the probability of breakage of the bottom corner of the membrane shell.

[0022] The present invention also provides a corner pressing head, which can also achieve the above-mentioned beneficial effects, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] FIG1 is a schematic diagram of a partial structure of a battery cell in the prior art;

[0025] 2 and 3 are electron microscope scanning images of a battery cell provided by an embodiment of the present invention;

[0026] FIG4 is a schematic diagram of the overall structure of a battery cell provided by an embodiment of the present invention;

[0027] Figure 5 A schematic diagram of the structure of a specific battery cell provided by an embodiment of the present invention.

[0028] In the figure: 1. membrane shell, 11. bottom corner, 21. R corner, 22. convex part, 23. air avoidance part, 3. inner unsealed area, 4. sealing area, 5. battery cell body. DETAILED DESCRIPTION

[0029] The core of the present invention is to provide a battery cell. Please refer to Figure 1, which is a schematic diagram of the partial structure of the battery cell in the prior art. Referring to Figure 1, in the prior art, the outer shell of the battery cell is usually a shell formed by first pressing two pits in a piece of material, and then folding it in half and sealing the edges. The membrane shell 1 is formed after the two pits are aligned, and the corner of the membrane shell 1 facing the folded position is the bottom corner 11. When the folding edge is not completed, the bottom corner 11 will generate a manual inspection process, and the process will add a corner pressing process next to the bottom corner 11 to form a corner pressing structure. When the angle pressing goes too deep into the shell volume, it will cause interference with the volume of the membrane shell space, affecting the expansion of the membrane shell space, thereby making the probability of the bottom corner breaking higher.

[0030] The present invention provides a battery cell, comprising a battery cell body and a shell covering the battery cell body; the shell comprises a film shell accommodating the battery cell body, the film shell having a bottom corner portion; the shell is provided with a pressure angle structure, the pressure angle structure comprises an R corner portion and a convex portion, a gap portion is formed between the convex portion and the R corner portion; the R corner portion is provided along a portion of the edge of the bottom corner portion, and the gap portion extends to another portion of the edge of the bottom corner portion.

[0031] The formation of the avoidance portion in the angle pressing structure can prevent the convex portion from excessively squeezing the membrane shell, thereby leaving a margin for deformation of the membrane shell during subsequent use, thereby reducing the probability of breakage of the bottom corner of the membrane shell.

[0032] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] Embodiment 1

[0034] Please refer to Figures 2 to Figure 5 , FIG. 2 and FIG. 3 are electron microscope scanning images of a battery cell provided in an embodiment of the present invention; FIG. 4 is a schematic diagram of the overall structure of a battery cell provided in an embodiment of the present invention; Figure 5 A schematic diagram of the structure of a specific battery cell provided by an embodiment of the present invention.

[0035] Referring to Figures 2 and 3, in an embodiment of the present invention, a battery cell includes a battery cell body 5 and a shell covering the battery cell body 5; the shell includes a membrane shell 1 for accommodating the battery cell body 5, and the membrane shell 1 has a bottom corner portion 11; the shell is provided with a pressure angle structure, and the pressure angle structure includes an R corner portion 21 and a convex portion 22, and a gap 23 is formed between the convex portion 22 and the R corner portion 21; the R corner portion 21 is arranged along a portion of the edge of the bottom corner portion 11, and the gap 23 extends to another portion of the edge of the bottom corner portion 11.

[0036] The above-mentioned battery cell body 5 is a structure in which the battery cell is mainly used for power generation, and its specific content will be described in detail in the following invention embodiments, and will not be repeated here. The above-mentioned shell will wrap the battery cell body 5, and the shell is formed with a membrane shell 1, and the space formed by the membrane shell 1 is used to accommodate the battery cell body 5. Since the shell is formed by folding in half and then sealing the edges, the membrane shell 1 is composed of two pits combined after folding in half. In this embodiment, the cross-section of the above-mentioned membrane shell 1 along the thickness direction is usually a rounded rectangle, and one side of the corresponding membrane shell 1 faces the bending position of the shell, and the other three sides face the edge sealing position of the shell, that is, the above-mentioned edge sealing process usually seals the three sides of the non-bending edge of the shell to form the above-mentioned shell.

[0037] Referring to Fig. 4, Fig. 1 and Fig. 2 are enlarged views of the area A circled in Fig. 4. Accordingly, in this embodiment, in addition to the membrane shell 1, the housing also includes a sealing area 4 located outside the membrane shell 1 and an inner unsealed area located between the membrane shell 1 and the sealing area 4. That is, in this embodiment, the housing is provided with the membrane shell 1, the inner unsealed area 3, and the sealing area 4 in sequence from the center to the edge seal; and the housing is provided with the membrane shell 1 and the inner unsealed area 3 in sequence from the center to the bending edge.

[0038] In this embodiment, the corner of the membrane shell 1 facing the bent edge is the bottom corner 11, and a pressing structure is formed in the shell based on the pressing process. The pressing structure is arranged near the bottom corner 11. The shape of the pressing structure corresponds to the shape of the pressing head used in the pressing process. In this embodiment, the pressing head usually has a pressing convex portion and a pressing R corner portion, wherein the pressing convex portion is arranged near one end of the pressing R corner portion, and between the pressing convex portion and the pressing R corner portion, the pressing convex portion is arranged near one end of the pressing R corner portion. There is a gap between the parts to form an angle-pressing space-avoiding portion. Correspondingly, in this embodiment, based on the above-mentioned angle-pressing head, an angle-pressing structure including an R-corner portion 21, a convex portion 22 and a space-avoiding portion 23 will be formed on the shell, wherein the head portion 22 of the angle-pressing structure corresponds to the angle-pressing convex portion of the angle-pressing head, the R-corner portion 21 of the angle-pressing structure corresponds to the angle-pressing R-corner portion of the angle-pressing head, the space-avoiding portion 23 of the angle-pressing structure corresponds to the angle-pressing space-avoiding portion of the angle-pressing head, and the above-mentioned space-avoiding portion 23 is located between the R-corner portion 21 of the angle-pressing structure and its convex portion 22.

[0039] In this embodiment, the R corner portion 21 of the angle pressing structure will be arranged along a portion of the edge of the bottom corner portion 11 of the membrane shell 1, and the above-mentioned avoidance portion 23 will extend to another portion of the edge of the bottom corner portion 11. That is, in the angle pressing process, the R corner portion of the angle pressing seal will be tangent to the bottom corner portion 11 of the membrane shell 1, and accordingly, the R corner portion 21 of the angle pressing structure will be arranged along a portion of the edge of the bottom corner portion 11, and the edge of the R corner portion 21 will be tangent to a portion of the edge of the bottom corner portion 11. In this embodiment, the above-mentioned R corner portion 21 will not be arranged along the entire edge of the bottom corner portion 11, but will only be arranged along a portion of the edge, and the above-mentioned avoidance portion 23 will be formed on the outside of another portion of the edge of the bottom corner portion 11.

[0040] In the present embodiment, the avoidance portion 23 is a structure formed in the shell that is not pressed by the angle pressing head. Since the avoidance portion 23 extends to a portion of the edge of the bottom corner portion 11 in the present embodiment, the angle pressing structure will not affect the morphology of the membrane shell 1 too much, and the avoidance portion 23 can be used as a reserved space for the bottom corner portion 11 to expand outward. Based on the setting of the avoidance portion 23, the probability of the bottom corner of the membrane shell 1 being broken can be effectively reduced.

[0041] Specifically, the R angle size of the R corner portion 21 usually needs to be larger than the R angle size of the bottom corner portion 11. At this time, it can be ensured that the R corner portion 21 of the corner pressing head cannot completely cover the edge of the entire bottom corner portion 11 during the corner pressing process, but a part of the space between the R corner portion 21 and the bottom corner portion 11 will inevitably be left to form a clearance portion 23 to reduce the probability of the bottom corner of the membrane shell 1 being broken. Of course, in this embodiment, the R angle size of the above-mentioned R corner portion 21 can also be equal to the R angle size of the bottom corner portion 11, but at this time, the length of the R corner portion 21 along the edge of the membrane shell 1 needs to be less than the length of the edge of the bottom corner portion 11, so that part of the edge of the bottom corner portion 11 can be reserved to be adjacent to the clearance portion 23.

[0042] In this embodiment, the above-mentioned avoidance portion 23 is usually arranged in the inner unsealed area 3. Of course, the above-mentioned avoidance portion 23 can also extend from the inner unsealed area 3 to the sealing area 4. The size of the above-mentioned avoidance portion 23 usually depends on the position of the above-mentioned convex portion 22. When the convex portion 22 is arranged in the sealing area 4, the avoidance portion 23 will extend from the inner unsealed area 3 to the sealing area 4; when the convex portion 22 is arranged along the edge of the sealing area 4 and the inner unsealed area 3 or is arranged to extend into the inner unsealed area 3, the avoidance portion 23 will only be arranged in the inner unsealed area 3.

[0043] In this embodiment, the width of the R corner portion 21 is in the range of 0.3 mm to 2 mm, the R angle of the R corner portion 21 is in the range of 1.5 mm to 2.5 mm, and the width of the gap portion 23 is in the range of 0 mm to 3 mm. As shown in FIG4 , assuming that the width of the R corner portion 21 is d, the R angle of the R corner portion 21 is e, and the width of the gap portion 23 is f, then 2mm≥d≥0.3mm, 2.5mm≥e≥1.5mm, and 3mm≥f≥0mm exist.

[0044] The above d, e, and f are the size parameters of the angle pressing structure, which together determine the angle pressing volume. The larger the angle pressing volume, the larger the interference volume between the core and the core after the core expands, which will continue to interfere with the core during the cycle, eventually leading to corner breakage. When the size parameters d, e, and f of the angle pressing structure are within the above range, the probability of corner breakage at the bottom corner of the membrane shell 1 can be significantly reduced. Of course, in this embodiment, the specific size of the angle pressing structure is not specifically limited, depending on the specific situation.

[0045] The battery cell provided in the present embodiment forms a void portion 23 in the corner pressing structure, which can prevent the convex portion 22 from excessively squeezing the membrane shell 1, thereby leaving a margin for deformation of the membrane shell 1 during subsequent use, thereby reducing the probability of the bottom corner of the membrane shell 1 being broken.

[0046] The specific structure of a battery cell provided by the present invention will be described in detail in the following embodiments of the invention and will not be described in detail here.

[0047] Embodiment 2

[0048] Different from the above embodiment, this embodiment further defines the specific structure of the battery cell on the basis of the above embodiment. The rest of the contents have been described in detail in the above invention embodiment and will not be repeated here.

[0049] Referring to Figure 4, in this embodiment, there is a back margin between the bottom corner portion 11 and the back of the shell, and the back margin is not less than 1.4mm. The above-mentioned back margin is the distance between the side of the membrane shell 1 facing the bending position of the shell and the bending position of the shell. When the back margin is small, stress concentration is easily formed, resulting in an increased probability of bottom corner breakage. In this embodiment, stress concentration can be avoided and the probability of bottom corner breakage can be reduced by increasing the above-mentioned back margin. In this embodiment, the above-mentioned back margin is usually not less than 1.4mm to ensure that the shell has sufficient back margin to avoid stress concentration. Specifically, in this embodiment, the value range of the back margin is between 1.4mm and 4.0mm. That is, if the back margin is g, it is usually necessary to satisfy g between 1.4mm-4.0mm.

[0050] In this embodiment, the battery cell body 5 generally includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet generally includes a positive electrode collector and a positive electrode paste layer. The negative electrode sheet includes a negative electrode collector and a negative electrode paste layer. The negative electrode paste layer is a graphite paste layer or a silicon-based material paste layer or a mixed paste layer of graphite and silicon-based materials.

[0051] Specifically, in this embodiment, the absolute strength of the negative electrode current collector is generally in the range of 450 N / m to 1000 N / m, preferably 450 N / m to 700 N / m. The thickness of the negative electrode current collector is generally in the range of 1 μm to 15 μm, preferably 3 μm to 7 μm. In this embodiment, the silicon-based material paste layer contains a general formula of M y SiO x One or more silicon-oxygen materials in the components represented by, wherein 0≤y≤4, 0≤x≤4, and M is at least one of Li, Mg, Ti and Al. The weight ratio of the above silicon-based materials based on the total weight of the negative electrode paste layer is usually 0% to 20%. In the above negative electrode paste layer, the OI value of graphite is a, the strength of copper foil is b N / m, and the thickness of copper foil is cμm, then the above values ​​are usually within the following ranges:

[0052] 30≥a≥8, 700 N / m≥b≥450 N / m, 7μm≥c≥3μm.

[0053] In this embodiment, the smaller the graphite OI value a, the greater the extension of the pole piece, and the higher the risk of corner breakage; the smaller the copper foil strength, the greater the extension of the pole piece, and the higher the risk of corner breakage. When the above parameters are set within the above range, the probability of corner breakage at the bottom corner of the membrane shell 1 can be significantly reduced.

[0054] In this embodiment, the above-mentioned negative electrode paste layer is mainly artificial graphite, natural graphite, mesophase carbon microspheres, soft carbon, hard carbon, organic polymer compound carbon, lithium titanate, silicon oxygen, silicon carbon, any one or a combination of two or more; and the positive electrode paste layer can be one or a combination of lithium cobalt oxide, ternary material, lithium iron phosphate, lithium manganese oxide, lithium titanate.

[0055] The preparation method of the battery cell provided in this embodiment is as follows:

[0056] The first step is to prepare a coating slurry: a mixture of artificial graphite and silicon carbon is used as a negative electrode active material; conductive carbon black is used as a conductive agent, styrene-butadiene rubber is used as a binder, and sodium carboxymethyl cellulose is used as a thickener. The negative electrode active material: conductive agent: binder: thickener are added into a stirring tank in a mass ratio of 96.9:1.5:1.3:13, and deionized water solvent is added. The mixture is fully stirred according to the batching process of the prior art, and filtered through a 150-mesh sieve to prepare a slurry with a solid content of 40% to 45%.

[0057] The second step is negative electrode coating and sheeting: use a coating machine to coat the above negative electrode slurry on the copper foil current collector, dry it at 100°C to prepare the initial negative electrode sheet; cut the above initial sheet according to actual needs to prepare the negative electrode sheet.

[0058] The third step is to prepare the positive electrode slurry: lithium cobalt oxide is used as the positive electrode active material, and then added into a stirring tank with a conductive agent and polyvinylidene fluoride in a mass ratio of 97.2:1.5:1.3, and NMP (N-methylpyrrolidone) solvent is added for thorough stirring, and passed through a 200-mesh sieve to prepare the positive electrode slurry. The solid content of the positive electrode slurry is 70% to 75%.

[0059] The fourth step is positive electrode coating and sheeting: use a coating machine to coat the above positive electrode slurry on the aluminum foil current collector, dry it at 120°C to prepare the initial positive electrode sheet; cut the above initial sheet according to actual needs to prepare the positive electrode sheet.

[0060] Step 5: Assemble the battery cell: Wind the positive electrode sheet, negative electrode sheet and separator together to form a core, wrap it with aluminum-plastic film, bake it to remove moisture, inject electrolyte, and use hot pressing process to form the battery cell. The aluminum-plastic film after packaging will form the shell.

[0061] The test methods corresponding to the above parameters are as follows:

[0062] OI value test method: The OI value of the powder of the negative electrode active material and the OI value of the negative electrode paste layer can be obtained by using an X-ray powder diffractometer. According to the general rules of X-ray diffraction analysis and the method for determining the lattice parameters of graphite JIS K0131-1996 and JB / T4220-2011, an X-ray diffraction spectrum is obtained, and the OI value = C004 / C110, wherein C004 is the peak area of ​​the 004 characteristic diffraction peak, and C110 is the peak area of ​​the 110 characteristic diffraction peak. Specifically, the OI value test method of the powder of the negative electrode active material is as follows: a certain mass of the negative electrode active material powder is placed in an X-ray powder diffractometer, and the peak area of ​​the 004 crystal plane diffraction peak and the peak area of ​​the 110 crystal plane diffraction peak are obtained by X-ray diffraction analysis, thereby obtaining the powder OI value of the negative electrode active material particles. Specifically, the OI value test method of the negative electrode paste layer is: directly placing the prepared negative electrode plate in an X-ray powder diffractometer, and obtaining the peak area of ​​the 004 crystal plane diffraction peak and the peak area of ​​the 110 crystal plane diffraction peak by X-ray diffraction analysis, and then obtaining the OI value of the negative electrode paste layer.

[0063] Copper foil strength and thickness test method: Use a tensile testing machine with a range of 0N to 1000N and an indication error of ±1%, and a vernier caliper with a range of 0mm to 300mm and a minimum graduation value of 0.02mm or a measuring tool of corresponding accuracy. Cut the sample to be tested with a length of 200±0.5mm and a width of 15±0.25mm. Take 2 samples in the longitudinal and transverse directions of the width direction of the sample to be tested. Then, place the sample to be tested in a tensile testing machine, where the chuck distance is 125±0.1mm, the chuck stretching speed is 50mm / min, and the test temperature is 20±10℃. Continuously apply load to the sample to be tested in the length direction until it breaks, read the maximum load F from the force measuring disk or the tensile curve, and calculate the absolute strength: σ=F / L, where L is the width of the sample to be tested. Take the arithmetic mean of the test results of 3-5 samples to obtain the absolute strength of the sample to be tested.

[0064] Elongation test method: disassemble the electrode under full charge state, test the electrode width a and record it. The designed electrode width is a0, and the elongation = (a-a0) / a0*100%.

[0065] 45℃-1000T test method: According to the charge and discharge method in the battery specification, the battery cell is tested for 1000 cycles in a 45℃±2 environment.

[0066] Method for measuring the size of the angle-pressing structure: magnify the local area under a 2.5D microscope, and take point-dash line measurements of the size parameters of the angle-pressing structure.

[0067] Embodiment 3

[0068] A corner pressing head provided in an embodiment of the present invention is introduced below. The corner pressing head described below and the battery cell described above can refer to each other.

[0069] See also Figure 5 In this embodiment, the angle pressing head is used to form an angle pressing structure in the battery cell as described in any of the above embodiments, including: an angle pressing body, an angle pressing R corner portion located at one side edge of the angle pressing body, and an angle pressing convex portion protruding from one side edge of the angle pressing body; the angle pressing convex portion is arranged close to one end portion of the angle pressing R corner portion, and a preset interval is arranged between the angle pressing convex portion and one end portion of the angle pressing R corner portion to form an angle pressing avoidance portion.

[0070] The above-mentioned angle pressing body is the main structure of the angle pressing head, and the angle pressing R corner portion, the angle pressing convex portion and the angle pressing gap portion are structures arranged at the edge of the angle pressing body. The angle pressing structure formed in the battery cell during use is a corresponding structure mainly formed based on the above-mentioned angle pressing R corner portion, the angle pressing convex portion and the angle pressing gap portion. The specific correspondence between the above-mentioned angle pressing head and the angle pressing structure has been introduced in detail in the above-mentioned embodiments, and will not be repeated here. The specific structure of the angle pressing head corresponds to the specific structure of the angle pressing structure.

[0071] The angle pressing head provided in this embodiment is specifically used to form the above-mentioned angle pressing structure, which can leave a margin for the deformation of the membrane shell 1 during subsequent use, so as to reduce the probability of the bottom corner of the membrane shell 1 being broken.

[0072] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0073] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0074] The above is a detailed introduction to a battery cell and an angled head provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A battery cell, characterized in that: It comprises a battery cell body and a shell covering the battery cell body; the shell comprises a film shell accommodating the battery cell body, and the film shell has a bottom corner portion; The housing is provided with an angle-pressing structure, the angle-pressing structure comprises an R-angle portion and a convex portion, and a space-avoiding portion is formed between the convex portion and the R-angle portion; The R corner portion is arranged along a portion of the edge of the bottom corner portion, and the avoidance portion extends to another portion of the edge of the bottom corner portion.

2. The battery cell according to claim 1, characterized in that: The R angle size of the R corner portion is greater than the R angle size of the bottom corner portion.

3. The battery cell according to claim 1, characterized in that: The housing further comprises a sealing area located outside the membrane shell, and an inner unsealed area located between the membrane shell and the sealing area; The air-avoiding portion is arranged in the inner unsealed area.

4. The battery cell according to claim 3, characterized in that: The width of the R corner portion ranges from 0.3 mm to 2 mm, the R angle size of the R corner portion ranges from 1.5 mm to 2.5 mm, and the width of the gap avoidance portion ranges from 0 mm to 3 mm.

5. The battery cell according to claim 1, characterized in that: There is a back margin between the bottom corner portion and the back of the shell, and the back margin is not less than 1.4 mm.

6. The battery cell according to claim 5, characterized in that: The back margin has a value range of 1.4 mm to 4.0 mm.

7. The battery cell according to claim 1, characterized in that: The battery cell body comprises a positive electrode sheet and a negative electrode sheet, the negative electrode sheet comprises a negative electrode current collector and a negative electrode paste layer, and the negative electrode paste layer is a graphite paste layer or a silicon-based material paste layer or a mixed paste layer of graphite and silicon-based materials.

8. The battery cell according to claim 7, characterized in that: The absolute strength of the negative electrode current collector ranges from 450 N / m to 1000 N / m.

9. The battery cell according to claim 7, characterized in that: The thickness of the negative electrode current collector ranges from 1 μm to 15 μm.

10. A corner pressing head, characterized in that: The method for forming the angle-pressing structure in the battery cell according to any one of claims 1 to 9 comprises: A corner pressing body, a corner pressing R corner portion located at one side edge of the corner pressing body, and a corner pressing convex portion protruding from one side edge of the corner pressing body; the corner pressing convex portion is arranged close to one end portion of the corner pressing R corner portion, and a preset interval is arranged between the corner pressing convex portion and one end portion of the corner pressing R corner portion to form a corner pressing avoidance portion.

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