An electric cell

Abstract

The application discloses an electric core and relates to the technical field of batteries. The electric core comprises a first pole piece, a diaphragm and a second pole piece opposite to the first pole piece in polarity; the diaphragm is attached to both sides of the first pole piece in the thickness direction and is arranged in a laminated mode with the first pole piece; the diaphragm comprises an extension part beyond the first pole piece in a first direction of the first pole piece, the extension parts on both sides of the first pole piece are bonded to each other, and the first pole piece and the diaphragm are both continuous structures; the first pole piece comprises a plurality of bending sections and a plurality of first laminated sections arranged in a laminated mode, and the bending sections are connected to adjacent first laminated sections; and the first pole piece comprises a plurality of thinning areas, and the thickness of the thinning areas is smaller than the thickness of other areas of the first pole piece. By arranging the first pole piece and the diaphragm as continuous structures, the first pole piece is prevented from being cut, thereby avoiding the situation that active substances fall on the diaphragm to damage the diaphragm and cause the positive pole piece and the negative pole piece to be in contact to form internal short circuits, and the self-discharge rate of the electric core is protected from being affected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, more particularly, to a battery cell. BACKGROUND

[0002] With the wide application of lithium ion batteries, higher requirements are put forward for their performance, which gradually promotes the development of lithium ion batteries towards high energy density and high rate. The laminated battery cell is widely used in fast charging and high energy density battery field due to its small internal resistance, high energy density and long cycle life.

[0003] When the thickness of the battery cell is constant, the thinner the thickness of the foil, the more the active material content can be increased, so using high-strength thin foil can effectively improve the energy density of the battery cell, but the active material on the edge of the pole piece is easy to fall off when cutting the pole piece, and the active material falling on the separator will cause the separator to be damaged after hot pressing, so that the positive and negative poles of the battery cell are directly contacted, which is easy to form internal short circuit, thereby increasing the voltage decay, and ultimately leading to the increase of the K value of the battery cell and the badness. The K value of the battery cell is a key indicator for measuring the self-discharge rate of the battery cell, which usually represents the proportion of the capacity loss of the self-discharge of the battery cell per unit time to the initial capacity, and is generally calculated in terms of the percentage of the self-discharge capacity loss per day. The increase of the K value of the battery cell will affect the self-discharge rate of the battery cell.

[0004] In summary, how to provide a battery cell that avoids affecting the self-discharge rate of the battery cell due to cutting the pole piece is a problem that needs to be solved by the technical personnel in the field at present. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a battery cell, by setting the first pole piece and the separator as a continuous whole structure, the cutting of the first pole piece can be avoided, thereby avoiding the situation that the active material falls on the separator and damages the separator when cutting, causing the positive pole piece to contact the negative pole piece to form internal short circuit, and protecting the self-discharge rate of the battery cell from being affected.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] A battery cell, comprising a first pole piece, a separator and a second pole piece opposite in polarity to the first pole piece;

[0008] The separator is attached to both sides of the thickness direction of the first pole piece and is stacked with the first pole piece, the separator comprises an extension part beyond the first pole piece along the first direction of the first pole piece, and the extension parts on both sides of the first pole piece are adhered to each other; the first pole piece and the separator are a continuous structure;

[0009] The first pole piece comprises a plurality of bending segments and a plurality of first laminated segments arranged in layers, the bending segments connecting adjacent first laminated segments; the first pole piece comprises a thinning area formed on the bending segment, the thickness of the thinning area being less than the thickness of other regions of the first pole piece; the second pole piece comprises a plurality of second laminated segments, the second laminated segments being located between two adjacent first laminated segments; along the length direction of the first pole piece, the size of the thinning area is greater than or equal to the size of the bending segment, and both ends of the thinning area exceed the bending segment.

[0010] Optionally, the first pole piece is a negative pole piece, and the second pole piece is a positive pole piece.

[0011] Optionally, the thickness of the positive pole piece is H1, the maximum distance between the end of the positive pole piece and the inside of the bending segment is a first distance H2, and the coverage distance of the thinning area in the part of the first laminated segment is a second distance H3, the second distance H3 being less than or equal to the difference between the first distance H2 and the thickness H1 of the positive pole piece minus 1 mm.

[0012] And / or, the length of the thinning area is greater than or equal to the length of a semicircle with a diameter of the thickness H1 of the positive pole piece, and the length of the thinning area is less than or equal to the sum of the length of the semicircle with a diameter of the thickness H1 of the positive pole piece and twice the second distance H3.

[0013] Optionally, the first pole piece is a positive pole piece, the second pole piece is a negative pole piece, the first pole piece comprises a first current collector and a tab formed outward from the first current collector; an insulating area is arranged between two adjacent tabs, both sides of the part of the first pole piece located in the insulating area in the thickness direction are provided with an insulating layer, and the thickness of the insulating area is greater than or equal to the thickness of the thinning area; along the length direction of the first pole piece, the insulating area covers at least part of the thinning area.

[0014] Optionally, the insulating area covers all the bending segments and part of the first laminated segments connected with the bending segments.

[0015] Optionally, the thickness of the negative pole piece is H4, the maximum distance between the end of the negative pole piece and the inside of the bending segment is a third distance H5, the coverage distance of the insulating area in the first laminated segment is a fourth distance H6, the third distance H5 is greater than or equal to 0 and less than or equal to 1 mm, and the fourth distance H6 is greater than or equal to the sum of the third distance H5 and 0.1 mm and less than or equal to the sum of the third distance H5 and 1 mm.

[0016] And / or, the length of the insulating region is greater than or equal to the length of a semicircular arc with the thickness H4 of the negative electrode tab as a diameter, and the length of the thinning region is less than or equal to the sum of the length of a semicircular arc with the thickness H4 of the negative electrode tab as a diameter and twice the fourth distance H6.

[0017] Optionally, one side of the thickness direction of the first electrode tab is provided with a concave-convex region, and the concave-convex region is provided with a plurality of concave portions.

[0018] Optionally, the edge of the concave-convex region has a first gap T1 with one end of the first electrode tab provided with a tab, and the edge of the concave-convex region has a second gap T2 with one end of the second electrode tab in the length direction; the pitch between adjacent concave portions in the first direction in the concave-convex region is greater than the second gap T2, and / or the pitch between adjacent concave portions in the second direction in the concave-convex region is greater than the first gap T1.

[0019] Optionally, in the second direction, the concave-convex region at least partially covers one end of the first electrode tab provided with a tab; the ceramic region of the tab for connecting with the first electrode tab is provided with the concave portion, and the concave depth of the concave portion in the tab is less than the concave depth of the concave portion in the first electrode tab.

[0020] Optionally, the depth of the concave portion is less than the thickness of the first electrode tab, and the side of the first electrode tab away from the concave portion is a plane.

[0021] The application provides an electric core, which comprises a first electrode tab, a diaphragm, and a second electrode tab opposite in polarity to the first electrode tab; the diaphragm is attached to both sides of the thickness direction of the first electrode tab and is stacked with the first electrode tab; the diaphragm comprises an extension part beyond the first electrode tab in the first direction of the first electrode tab, and the extension parts on both sides of the first electrode tab are bonded to each other; the first electrode tab and the diaphragm are continuous structures; the first electrode tab comprises a plurality of bending sections and a plurality of first stacked sections stacked, and the bending sections connect adjacent first stacked sections; the first electrode tab comprises a thinning region formed on the bending section, and the thickness of the thinning region is less than the thickness of other regions of the first electrode tab; the second electrode tab comprises a plurality of second stacked sections, and the second stacked sections are located between adjacent first stacked sections.

[0022] The first pole piece and the separator in the battery cell provided in the application are both continuous structures, avoiding cutting the first pole piece, thereby avoiding the case that active material falls on the separator to damage the separator and make the positive pole piece and the negative pole piece contact to form internal short circuit, which can effectively protect the K value and the self-discharge rate of the battery cell from being affected. In addition, the thinning area covering the entire bending section and part of the first layer section connected with the bending section is arranged in the application, the bending section of the first pole piece is convenient to bend, and the curvature of the bending section can be effectively increased to avoid the active material of the bending section falling on the separator and also to avoid the separator from being wrinkled or bubbled; the internal resistance of the battery cell can also be avoided from being increased, and the black spots in the battery cell after cycling can be prevented. In addition, the thinning area also covers part of the first layer section connected with the bending section, the width of the thinning area is greater than the width of the bending section, and the thinning area is cleaned by laser or a scraper, that is, the bending section is cleaned, and the first layer section is also cleaned, which can prevent the active material on the first pole piece at the bending section from falling on the separator during the lamination of the pole pieces, thereby avoiding affecting the K value of the battery cell; furthermore, in the length direction, the size of the thinning area is greater than or equal to the size of the bending section, and the two ends of the thinning area both exceed the bending section, which can effectively prevent the case that when the junction between the thinning area and the non-thinning area is located in the circular arc area, the junction in the circular arc area is subjected to a large extrusion stress during the charging and discharging process, thereby causing the active particles at the junction to fall off, thereby causing the short circuit phenomenon. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on the provided drawings.

[0024] Figure 1 The structure schematic diagram of the first pole piece and the separator in the application;

[0025] Figure 2 The structure schematic diagram of the first pole piece being a negative pole piece;

[0026] Figure 3 The structure schematic diagram of the first pole piece being a negative pole piece; Figure 2 The structure schematic diagram of the battery cell composed of the first pole piece in the application in the folded state;

[0027] Figure 4 The structure schematic diagram of the first pole piece being a positive pole piece;

[0028] Figure 5 The structure schematic diagram of the battery cell composed of the first pole piece in the application in the folded state; Figure 4 The structure schematic diagram of the battery cell composed of the first pole piece in the application in the folded state;

[0029] Figure 6A schematic diagram of a structure with concave and convex areas in the first electrode plate;

[0030] Figure 7 for Figure 6 Cross-sectional schematic diagram of the concave-convex region;

[0031] Figure 8 A schematic diagram of a structure with a long strip-shaped recess in the negative electrode plate;

[0032] Figure 9 for Figure 8 A cross-sectional schematic diagram of the concave-convex region.

[0033] Figures 1-9 middle:

[0034] 1 is the first electrode, 11 is the thinning area, 12 is the first stacked section, 13 is the bending section, 2 is the positive electrode, 21 is the insulating area, 3 is the negative electrode, 4 is the diaphragm, 5 is the tab, 6 is the concave-convex area, and 61 is the concave part. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] The core of this application is to provide a battery cell that, by setting the first electrode and the separator as a continuous integral structure, avoids cutting the first electrode, thereby preventing the active material from falling onto the separator during cutting and damaging the separator, which could cause the positive electrode and negative electrode to come into contact and form an internal short circuit, thus protecting the self-discharge rate of the battery cell from being affected.

[0037] Example 1

[0038] This specific embodiment discloses a battery cell, such as Figure 1 As shown, the battery cell includes a first electrode 1, a separator 4, and a second electrode with the opposite polarity to the first electrode 1. The separator 4 is attached to both sides of the first electrode 1 in the thickness direction and is stacked with the first electrode 1. The separator 4 includes an extension portion extending beyond the first electrode 1 in a first direction. The extension portions on both sides of the first electrode 1 are bonded to each other. The first electrode 1 and the separator 4 are both continuous integral structures. The first electrode 1 includes multiple bent sections 13 and multiple stacked first stacked sections 12. The bent sections 13 connect adjacent first stacked sections 12. The first electrode 1 includes a thinned region 11 formed on the bent section 13. The thickness of the thinned region 11 is less than the thickness of other areas of the first electrode 1. The second electrode includes multiple second stacked sections. The second stacked sections are located between two adjacent first stacked sections 12.

[0039] Specifically, the thinning area 11 can cover the entire bending section 13 and part of the first laminated section 12 connected with the bending section 13.

[0040] Specifically, as shown in Figure 1 , the first direction can be the length direction from left to right at the angle shown in Figure 1 .

[0041] The first pole piece 1 and the diaphragm 4 in the battery cell provided by the embodiment are both continuous whole structures, avoiding cutting the first pole piece 1, thereby avoiding the situation that the active material falls on the diaphragm 4 to damage the diaphragm 4 and make the positive pole piece 2 and the negative pole piece 3 contact to form internal short circuit when cutting, which can effectively protect the K value and the self-discharge rate of the battery cell from being affected. In addition, the thinning area 11 covering the entire bending section 13 and part of the first laminated section 12 connected with the bending section 13 is arranged in the first pole piece 1, which facilitates bending of the bending section 13 and can effectively increase the curvature of the bending section 13, avoiding that the active material of the bending section 13 falls on the diaphragm 4 and also avoiding that the diaphragm 4 is wrinkled or bubbled; the internal resistance of the battery cell can also be avoided from being increased, and black spots can be prevented from appearing in the battery cell after cycling.

[0042] In addition, the thinning area 11 also covers part of the first laminated section 12 connected with the bending section 13, as shown in Figure 2 , the widths of the two thinning areas 11 are S1 and S2 respectively, and the widths of the two adjacent bending sections are L1 and L2 respectively. The width of the thinning area 11 is greater than the width of the bending section, and the thinning area 11 is cleaned by laser or scraper, that is, the bending section is cleaned, and the first laminated section 12 is also cleaned, that is, S1>L1 and S2>L2 are satisfied. The width of the thinning area 11 is greater than the width of the bending section, and the thinning area 11 is cleaned by laser or scraper, that is, the bending section 13 is cleaned, and the first laminated section 12 is also cleaned, which can prevent the active material on the first pole piece 1 at the bending section 13 from falling on the diaphragm 4 when the laminated section is laminated, thereby avoiding affecting the K value of the battery cell.

[0043] The battery cell further includes a second pole piece, the polarity of the second pole piece is opposite to that of the first pole piece 1, and the second pole piece includes a plurality of second laminated sections, the second laminated sections are located between the adjacent two first laminated sections 12 when the battery cell is in a laminated state.

[0044] The second pole piece is wrapped by the bending section 13 of the first pole piece 1, when the first pole piece 1 is the negative pole piece 3, the positive pole piece 2 has no risk of poor coverage at both ends, and special management and control is not needed, which can significantly improve the process efficiency; and the two ends of the positive pole piece 2 in the width direction are protected by the circular arc, and are not easy to be damaged by the outside.

[0045] As shown in Figure 3As shown, the position of the thinning area 11 directly opposite the second tab can be set as the thinnest area, and the thickness of the thinning area 11 gradually increases from the thinnest area to the first layer segment at both ends. The thickness of the thinnest area of the thinning area 11 is W1. The thinning area 11 gradually increasing in thickness from the middle to both ends can better bend the bending segment 13, maximize the bending radius of the bending segment 13, and avoid wrinkles of the diaphragm 4 when bending.

[0046] In the actual setting process, the size of the thinning area 11 is greater than or equal to the size of the bending segment 13 along the length direction of the first tab 1 to completely cover the bending segment 13. This can effectively prevent the phenomenon of short circuit caused by the active particles falling off at the junction of the thinning area and the non-thinning area when the junction is located in the circular arc area and the junction area in the circular arc area is subjected to a large extrusion stress during charging and discharging. Of course, the size of the thinning area 11 can also be greater than the size of the bending segment 13 along the length direction of the first tab 1, and both ends of the thinning area 11 can exceed the bending segment 13 to cover part of the first layer segment 12.

[0047] Embodiment 2

[0048] As shown in Figure 2 , Figure 3 , the first tab 1 is a negative tab 3, and the second tab is a positive tab 2. The thickness of the positive tab 2 is H1, the maximum distance between the end of the positive tab 2 and the inner side of the bending segment 13 is a first distance H2, and the coverage distance of the thinning area 11 on the first layer segment 12 is a second distance H3. The second distance H3 is less than or equal to the difference between the first distance H2 and the thickness H1 of the positive tab 2 minus 1 mm. This can avoid the tab falling off at the bending segment 13 while the negative tab 3 can cover the positive tab 2. The edge of the positive tab 2 away from the inner side of the bending segment 13 is reserved a certain distance H2, which can avoid the transverse burr of the positive tab 2 piercing the diaphragm 4 and causing short circuit of the battery cell, and can also reserve more energy density of the battery cell. In this specific embodiment, the thickness H1 of the positive tab 2 is in the range of 30 μm-150 μm; the first distance H2 is in the range of 0.1 mm-2 mm; and the second distance H3 is in the range of 0 mm-0.97 mm.

[0049] In addition, the length of the thinning area 11 can also be greater than or equal to the length of a semicircular arc with a diameter of the thickness H1 of the positive tab 2, and the length of the thinning area 11 is less than or equal to the sum of the length of the semicircular arc with a diameter of the thickness H1 of the positive tab 2 and twice the second distance H3. Specifically, the length of the thinning area 11 is S1. This effectively ensures that the width of the thinning zone 11 is greater than the width of the bending section 13, preventing the active material on the first electrode 1 at the bending section 13 from falling onto the separator 4 during stacking, thus affecting the K value of the cell, and also preserving more of the cell's energy density.

[0050] Example 3

[0051] Combination Figure 4 , Figure 5 As shown, the first electrode 1 is the positive electrode 2, and the second electrode is the negative electrode 3. The first electrode 1 includes a first current collector and a tab 5 extending outward from the first current collector. An insulating region 21 is provided between two adjacent tabs 5, and an insulating layer is provided on both sides of the portion of the first electrode 1 located in the insulating region 21 in the thickness direction. The insulating region 21 can be achieved by coating the surface of the positive electrode 2 with ceramic, applying adhesive paper, or other methods. Two adjacent insulating regions 21 are respectively located on one side and the other side of the first electrode 1. By providing the insulating region 21, the active material on the positive electrode 2 at the bending section 13 during stacking can be prevented from falling onto the separator 4, thus avoiding affecting the K value of the cell. Simultaneously, it ensures that the negative electrode 3 can cover the positive electrode 2, preventing lithium plating in the cell.

[0052] To ensure insulation performance, the thickness of the insulation region 21 is greater than or equal to the thickness of the thinned region 11.

[0053] Furthermore, for Figure 4 In the actual processing of the first electrode 1, a thinning area 11 can be formed between the two tabs 5 before insulation treatment. This can better prevent the active material on the electrode from falling onto the separator 4 during stacking, thus avoiding affecting the K value of the cell.

[0054] like Figure 4 As shown, the insulating region 21 covers the entire bent section 13 and part of the first stacked section 12 connected to the bent section 13. The widths of two adjacent insulating regions 21 are S3 and S4, respectively, and the widths of two adjacent bent sections 13 are L3 and L4, respectively. The width of the insulating region 21 is greater than the width of the bent section 13, i.e., S3 > L3 and S4 > L4. Simultaneously, the insulating region 21 needs to reach the first stacked section 12 of the positive electrode 2. This prevents the active material on the electrode at the bent section 13 from falling onto the separator 4, while the negative electrode 3 can cover the positive electrode 2, preventing lithium plating in the cell.

[0055] like Figure 5 As shown, the thickness of the negative electrode 3 is H4, and the maximum distance between the end of the negative electrode 3 and the inner side of the bent section 13 is the third distance H5. This minimizes energy loss in the battery cell due to insulation, while ensuring that the negative electrode 3 covers the positive electrode 2, thus preventing lithium plating in the battery cell.

[0056] The insulating area 21 covers a fourth distance H6 on the first layering section 12, the third distance H5 is greater than or equal to 0 and less than or equal to 1 mm, and the fourth distance H6 is greater than or equal to the sum of the third distance H5 and 0.1 mm and less than or equal to the sum of the third distance H5 and 1 mm. ; under the condition of ensuring the least loss of the energy density of the battery cell, the negative electrode sheet 3 can cover the positive electrode.

[0057] In the embodiment, the thickness H4 of the negative electrode sheet 3 ranges from 30 μm to 150 μm, the third distance H5 ranges from 0 mm to 1 mm, and the fourth distance H6 ranges from 0.1 mm to 1.1 mm.

[0058] The length of the insulating area 21 is S3, the length of the insulating area 21 is greater than or equal to the length of a semicircular arc with the thickness H4 of the negative electrode sheet 3 as the diameter, and the length of the thinning area 11 is less than or equal to the sum of the length of a semicircular arc with the thickness H4 of the negative electrode sheet 3 as the diameter and twice the fourth distance H6; ; the width of the insulating area 21 can be ensured to be greater than the width of the bending section 13, so as to avoid the active material on the electrode sheet at the bending section 13 from falling onto the separator 4 during the lamination, and the negative electrode sheet 3 can cover the positive electrode sheet 2, so as to avoid the lithium precipitation of the battery cell.

[0059] Embodiment 4

[0060] The first electrode sheet 1 can be provided with a concave-convex area 6 on one side in the thickness direction, and the concave-convex area 6 is provided with a plurality of concave portions 61.

[0061] As shown in Figure 6 , the edge of the concave-convex area 6 has a first gap T1 with one end of the first electrode sheet 1 provided with the tab 5, and the edge of the concave-convex area 6 has a second gap T2 with one end in the length direction of the second electrode sheet; the spacing L1, L2 between the adjacent concave portions 61 in the first direction in the concave-convex area 6 is greater than the second gap T2, and the spacing W1, W2 between the adjacent concave portions 61 in the second direction in the concave-convex area 6 is greater than the first gap T1. In order to ensure that the first layering section 12 and the bending section 13 of the first electrode sheet 1 have more concave portions 61, the paste on the electrode sheet at the bending section 13 can be prevented from falling off during the lamination, and the bubbles between the separator 4 and the electrode sheet during the compounding can also be prevented.

[0062] As shown in Figure 6 , the first spacing between the adjacent concave portions 61 in the first direction is different, specifically, the first spacing can be I1 or I2; and the ratio of the different first spacing ranges from 0.6 to 1.4, . The second spacing between the adjacent concave portions 61 in the second direction is different, and the second spacing can be W1 or W2; and the ratio of the different second spacing ranges from 0.6 to 1.4, .

[0063] The interval between the adjacent recesses 61 in the first direction and the second direction is not limited to be the same in the specific embodiment. In actual processing, the interval between the adjacent recesses 61 does not need to be the same, which can effectively improve the die cutting efficiency and quality.

[0064] In actual processing, as shown in Figure 7 The thickness of the position without the recess 61 in the first tab 1 is H1, the depth of the recess 61 is h2, the thickness of the position with the recess 61 in the first tab 1 is h1, and the interval between the centers of the adjacent two recesses 61 is L1. The depth of the recess 61 can be less than the thickness H1 of the position without the recess 61 in the first tab 1, and the side of the first tab 1 away from the recess 61 is a plane.

[0065] When the side of the first tab 1 away from the recess 61 is a plane, the thickness H1 of the position without the recess 61 in the first tab 1 is the sum of the thickness h1 of the position with the recess 61 in the first tab 1 and the depth h2 of the recess 61. When the side of the first tab 1 away from the recess 61 is a protrusion, the thickness H1 of the position without the recess 61 in the first tab 1 is less than the sum of the thickness h1 of the position with the recess 61 in the first tab 1 and the depth h2 of the recess 61.

[0066] Further, the The recess 61 of the first tab 1 can have sufficient depth, which can increase the wettability of the electrolyte and further increase the cycle life of the battery. At the same time, the consistency of the overall adhesion of the step battery can be improved, and the lithium ion transport path tends to be consistent, which meets the uniform distribution of lithium ions on the negative tab 3 in the charging and discharging process and prevents lithium precipitation during the cycle process.

[0067] In addition, in the second direction, the concave-convex area 6 at least partially covers one end of the first tab 1 provided with the tab 5. The ceramic area in the tab 5 for connecting with the first tab 1 is provided with the recess 61, and the recess depth of the recess 61 in the tab 5 is less than the recess depth of the recess 61 in the first tab 1.

[0068] The ceramic area is mainly used to avoid the direct contact between the aluminum foil in the tab 5 and the graphite in the tab, and the ceramic area can also play a role in avoiding burrs.

[0069] As shown in Figure 8As shown, the first tab 1 can be a negative tab 3, and the recess 61 can be a long strip-shaped recess 61 provided on the negative tab 3. The distance between the edge of the long strip-shaped recess 61 in the second direction and the edge of the negative tab 3 is T3, the distance between the edge of the concave-convex area 6 in the first direction and the edge of the negative tab 3 is T4, the distance between the adjacent two long strip-shaped recesses 61 is L3 or L4, and the distance between the adjacent two long strip-shaped recesses 61 is L3 or L4, which is greater than the distance T4 between the edge of the concave-convex area 6 in the first direction and the edge of the negative tab 3. This can ensure that the first tab 1 has more recesses 61 in the first layer 12 and the bending section 13, the recesses 61 are provided in the bending section 13, the thickness of the bending section 13 is reduced, the falling of the paste on the tab at the bending section 13 can be avoided, and the bubbles between the tab and the diaphragm 4 during the compounding can also be avoided. In addition, the distance between the adjacent recesses in the first direction can be equal or not equal, that is to ensure the die cutting efficiency and quality.

[0070] As shown in FIG. 9, the thickness of the negative tab 3 is H4, the thickness of the negative tab 3 at the recess 61 is h4, and the depth of the recess 61 is h3. Wherein, H4≤h4+h3, 0≤ <1, 0≤ <1, to ensure that the tab has sufficient depth at the recess 61, thereby reducing the thickness of the bending section 13, avoiding the falling of the paste on the tab at the bending section 13, and preventing the bubbles between the tab and the diaphragm 4 during the compounding.

[0071] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. Any combination of the embodiments provided in the present application is within the protection scope of the present application, which is not described here.

[0072] The above describes the battery cell provided by the present application in detail. The principles and implementation manners of the present application are described by applying specific examples, and the above embodiment is only used to help understand the method and core idea of the present application. It should be pointed out that the ordinary skilled in the art can make some improvements and modifications to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A battery cell, characterized in that, It includes a first electrode (1), a diaphragm (4) and a second electrode with the opposite polarity to the first electrode (1), wherein the first electrode (1) is a positive electrode (2) and the second electrode is a negative electrode (3). The diaphragm (4) is attached to both sides of the first electrode (1) in the thickness direction and is stacked with the first electrode (1). The diaphragm (4) includes an extension portion that extends beyond the first electrode (1) along a first direction. The extension portions on both sides of the first electrode (1) are bonded to each other. The first electrode (1) and the diaphragm (4) are a continuous structure. The first electrode (1) includes a plurality of bent segments (13) and a plurality of stacked first stacked segments (12), wherein the bent segments (13) connect adjacent first stacked segments (12); the first electrode (1) includes a thinned region (11) formed on the bent segment (13), wherein the thickness of the thinned region (11) is less than the thickness of other regions of the first electrode (1); the second electrode includes a plurality of second stacked segments, wherein the second stacked segments are located between two adjacent first stacked segments (12); along the length direction of the first electrode (1), the size of the thinned region (11) is greater than or equal to the size of the bent segment (13), and both ends of the thinned region (11) extend beyond the bent segment (13). The thickness of the positive electrode (2) is H1, the maximum distance between the end of the positive electrode (2) and the inner side of the bent section (13) is the first distance H2, the coverage distance of the thinned area (11) in the first stacked section (12) is the second distance H3, and the second distance H3 is less than or equal to the difference between the first distance H2 and the thickness H1 of the positive electrode (2) minus 1 mm; And / or, the length of the thinned region (11) is greater than or equal to the length of a semicircular arc with the thickness H1 of the positive electrode (2) as its diameter, and the length of the thinned region (11) is less than or equal to the sum of the length of the semicircular arc with the thickness H1 of the positive electrode (2) as its diameter and twice the second distance H3.

2. The battery cell according to claim 1, characterized in that, The first electrode (1) includes a first current collector and an electrode tab (5) extending outward from the first current collector; an insulating region (21) is provided between two adjacent electrodes (5), and an insulating layer is provided on both sides of the portion of the first electrode (1) located in the insulating region (21) in the thickness direction, and the thickness of the insulating region (21) is greater than or equal to the thickness of the thinned region (11); along the length direction of the first electrode (1), the insulating region (21) at least covers part of the thinned region (11).

3. The battery cell according to claim 2, characterized in that, The insulating area (21) covers the bent section (13) and the first stacked section (12) that is partially connected to the bent section (13).

4. The battery cell according to claim 2, characterized in that, The thickness of the negative electrode (3) is H4, the maximum distance between the end of the negative electrode (3) and the inner side of the bent section (13) is the third distance H5, the coverage distance of the insulating area (21) in the first stacked section (12) is the fourth distance H6, the third distance H5 is greater than or equal to 0 and less than or equal to 1 mm, and the fourth distance H6 is greater than or equal to the sum of the third distance H5 and 0.1 mm and less than or equal to the sum of the third distance H5 and 1 mm; And / or, the length of the insulating region (21) is greater than or equal to the length of a semicircular arc with the thickness H4 of the negative electrode (3) as its diameter, and the length of the thinned region (11) is less than or equal to the sum of the length of a semicircular arc with the thickness H4 of the negative electrode (3) as its diameter and twice the fourth distance H6.

5. The battery cell according to any one of claims 1-4, characterized in that, The first electrode (1) has a concave-convex region (6) on one side of its thickness direction, and the concave-convex region (6) has a plurality of recesses (61).

6. The battery cell according to claim 5, characterized in that, The edge of the concave-convex region (6) has a first gap T1 with the end of the first electrode (1) where the tab (5) is provided, and the edge of the concave-convex region (6) has a second gap T2 with the end of the second electrode in the length direction; the distance between adjacent concave portions (61) in the first direction of the concave-convex region (6) is greater than the second gap T2, and / or the distance between adjacent concave portions (61) in the second direction of the concave-convex region (6) is greater than the first gap T1.

7. The battery cell according to claim 5, characterized in that, In the second direction, the concave-convex region (6) at least partially covers one end of the first electrode (1) where the tab (5) is provided; the ceramic region of the tab (5) is provided with the recess (61), and the recess (61) in the tab (5) is less than the recess (61) in the first electrode (1).

8. The battery cell according to claim 5, characterized in that, The depth of the recess (61) is less than the thickness of the first electrode (1), and the side of the first electrode (1) facing away from the recess (61) is a plane.

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