Battery cell and battery

Abstract

The utility model relates to the technical field of batteries, and discloses a battery cell and a battery. The battery cell comprises a battery cell body which is provided with a first surface and a second surface which are arranged at intervals in the thickness direction of the battery cell body, and the battery cell body comprises a positive plate, a diaphragm and a negative plate which are sequentially stacked in the thickness direction; the soft tab comprises a first tab section, a first bending section, a second tab section, a second bending section and a welding section which are arranged in sequence, one end of the first tab section is connected with one end, in the length direction, of the battery cell body, the first bending section is arranged close to the second surface, the second bending section is arranged close to the first surface, and the welding section is arranged in the length direction; and the hard tab is arranged along the length direction, and one end of the hard tab forms a welding end welded with the welding section. The hard tabs do not need to be bent in the height direction, and only the soft tabs are bent in the height direction, so that the space of the bent parts of the hard tabs can be saved, the occupied head space in the battery cavity is reduced, and the space utilization rate of the battery cell is improved.

Description

Technical Field

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

[0002] Lithium-ion batteries are widely used in consumer electronics, new energy vehicles, and energy storage power stations due to their advantages such as high specific energy, low discharge rate, and good cycle performance. With the deepening of the "dual carbon" policy, lithium-ion batteries are developing rapidly, gradually moving towards fast charging, long lifespan, high energy density, and high safety.

[0003] Currently, the tabs of laminated battery cells include soft tabs and hard tabs. After the soft tabs and hard tabs are welded, both soft tabs and hard tabs are bent. The bent tabs have a certain thickness, which occupies a lot of space at the head of the battery cell, resulting in a waste of overall space. Utility Model Content

[0004] In view of this, the present invention provides a battery cell and battery to solve the problem that bending the tabs occupies a large amount of head space of the battery cell, resulting in overall space waste and reduced energy density of the battery cell.

[0005] In a first aspect, this utility model provides a battery cell having a thickness direction and a length direction perpendicular to the thickness direction. The battery cell includes: a battery cell body having a first surface and a second surface spaced apart in its thickness direction, the battery cell body including a positive electrode sheet, a separator, and a negative electrode sheet stacked sequentially along the thickness direction; a soft electrode tab including a first electrode tab segment, a first bending segment, a second electrode tab segment, a second bending segment, and a welding segment arranged sequentially, one end of the first electrode tab segment being connected to one end of the battery cell body along the length direction, the first bending segment being disposed near the second surface, the second bending segment being disposed near the first surface, and the welding segment being disposed along the length direction; and a hard electrode tab being disposed along the length direction, one end of the hard electrode tab forming a welding end for welding to the welding segment.

[0006] Beneficial effects: By bending the soft tab twice to form two bending segments, and with the welding end set along the length direction, the hard tab is also set along the length direction. The hard tab does not need to be bent in the length direction. Compared with the existing technology, only the soft tab occupies the head space in the length direction, which can save the space of the bending part of the hard tab and the welding end, reduce the head space occupied in the length direction of the battery cavity, and improve the space utilization of the cell. In addition, in the thickness direction, compared with the existing technology, only the soft tab occupies the head space. By setting the welding end along the length direction, there is no need to consider the influence of the area of ​​the solder end on the thickness direction, further reducing the required head space and improving the space utilization of the cell.

[0007] In one alternative embodiment, one end of the diaphragm extends along the surface of the first tab section to a position close to the first bending section, and the projection of the hard tab on the first surface and the projection of the diaphragm on the first surface have a first overlapping area, the length L1 of the first overlapping area along the length direction being greater than or equal to 0.3 mm; and / or, the projection of the weld mark at the weld joint of the welding section and the welding end on the first surface and the projection of the diaphragm on the first surface have a second overlapping area, the length L2 of the second overlapping area along the length direction being greater than or equal to 0.1 mm.

[0008] Beneficial effects: Setting the length L1 of the first overlapping region along the longitudinal direction to be greater than or equal to 0.3 mm fully utilizes the space on one side of the separator to accommodate the rigid tabs, further reducing the head space occupied in the longitudinal direction. This allows for full utilization of the internal space of the casing to place the rigid tabs, improving the space utilization rate of the cell. Setting the length L2 of the second overlapping region along the longitudinal direction to be greater than or equal to 0.1 mm further utilizes the space on one side of the separator to accommodate the welding ends. This allows for full utilization of the internal space of the casing to place the welding ends of the rigid tabs, improving the space utilization rate of the cell.

[0009] In one alternative embodiment, the weld protrusion of the welded segment does not exceed the first surface; and / or, the angle formed between the second tab segment and the plane containing the positive or negative electrode is less than 90°.

[0010] Beneficial effects: The weld protrusion not exceeding the first surface prevents the second bending section from shifting upwards due to rebound force during formation, thus avoiding bulging of the casing at the weld end, affecting the cell's flatness, and reducing its energy density. An angle of less than 90° between the second tab section and the plane containing the positive or negative electrode prevents the stress generated by electrode expansion during charging and discharging from causing the bending section of the soft tab to shift upwards, potentially leading to contact between the soft tab and the aluminum-plastic film, causing electrochemical corrosion, or bulging of the casing corresponding to the tab.

[0011] In one optional embodiment, a first insulating member is provided on the side of the soft tab facing the cell body. The projection of the first insulating member on the first surface and the projection of the separator on the first surface have a third overlapping area. A second insulating member is provided on the first surface of the hard tab and the cell body. The projection of the second insulating member on the first surface and the projection of the negative electrode sheet on the first surface have a fourth overlapping area. The second insulating member covers the entire solder mark at the welding joint between the welding section and the welding end. The length L3 of the third overlapping area along the length direction is greater than or equal to 0.1 mm. And / or, the length L4 of the fourth overlapping area along the length direction is greater than or equal to 2 mm. And / or, the end of the second insulating member away from the cell body protrudes from the end of the welding section away from the cell body, and the distance D2 between the end of the second insulating member away from the cell body and the end of the welding section away from the cell body is greater than or equal to 0.1 mm.

[0012] Beneficial effects: By setting a first insulating element on the flexible tab, the first insulating element ensures insulation of the battery body after bending. Furthermore, compared to existing technologies, only one first insulating element is used along the length, reducing the cumulative thickness along the length. The overlap between the first insulating element and the separator allows part of the first insulating element to be hidden within the separator, saving thickness space. Setting the length L4 of the fourth overlapping area along the length direction to be greater than or equal to 2mm increases the contact area between the second insulating element and the battery cell body, ensuring the reliability of the second insulating element's fixation to the battery cell body. Burrs or protrusions may exist at the solder joints; by completely covering the solder joints with the second insulating element, it is possible to prevent burrs on the tab from contacting other conductive materials, reducing the risk of internal short circuits and thus improving battery safety. Setting the dimension of the second insulating element extending beyond the flexible tab to be greater than or equal to 0.1mm effectively protects against protrusions and burrs on the tab, preventing contact with the aluminum-plastic film and avoiding the risk of damage and corrosion to the aluminum-plastic film.

[0013] In one optional embodiment, the battery cell further has a width direction perpendicular to both the thickness direction and the length direction; the flexible tab has a blank area with an edge extending along the width direction close to the battery cell body, a portion of the blank area forming a solder area, the distance between the edge and the solder area along the length direction being L, and the thickness of the battery cell body along the thickness direction being H; after the flexible tab is bent, the battery cell further includes a sheathing component, which wraps around the outside of the battery cell body and the flexible tab, the sheathing component having a side portion located away from the battery cell body from the flexible tab, the distance between the side portion close to the battery cell body and the edge being D; the flexible tab includes multiple tab pieces, the sum of the thicknesses of all tab pieces being h1, the sum of the thicknesses of all separators being h2, and the thickness of the first insulating component being h3, wherein, L 2 ≥((1+k)+H) 2 +D 2 D≥h1+h2+2h3, where k is the cell expansion coefficient.

[0014] Beneficial effects: By setting the length of the flexible tabs to be greater than the hypotenuse of the right triangle formed by H and D, it ensures that even when the cell expands to its maximum, the flexible tabs are long enough to avoid stretching, thus avoiding the risk of breakage due to stretching and improving the overall reliability of the battery. D≥h1+h2+2h3 ensures that the head space can accommodate the two layers of bent flexible tabs, adhesive tape, and separator, allowing for a more compact and rational internal battery layout, maximizing the use of limited space, and preventing deformation of the aluminum-plastic film due to compression, or even encroachment on the top sealing space.

[0015] In one alternative embodiment, the welding section is positioned away from the cell body relative to the second bending section, and the second bending section wraps around the end of the welding end.

[0016] Beneficial effects: After bending, the soft tab wraps around the end of the hard tab, which can prevent the tab from being subjected to excessive force when moving into the cell under extreme conditions, thus preventing it from puncturing the separator and electrode and causing a short circuit, thereby improving the safety performance of the battery. At the same time, in the thickness direction of the cell, the thickness of the hard tab and the welded end are hidden within the length of the second bending section of the soft tab, further reducing the head space occupied by the folded tab and increasing the energy density.

[0017] In one optional embodiment, the end of the first insulating member near the first surface is spaced apart from the hard electrode tab, and along the length direction, the distance D1 between the end of the first insulating member near the first surface and the end of the hard electrode tab near the cell body is greater than or equal to 0.1 mm.

[0018] Beneficial effect: The first insulating element does not overlap with the hard electrode tab, which can reduce the accumulation of thickness and save thickness space.

[0019] In one alternative implementation, the welding section is positioned close to the cell body relative to the second bending section.

[0020] In one alternative embodiment, the end of the first insulating member near the first surface forms a protrusion that extends beyond the end of the soft electrode near the cell body. The protrusion is bonded to the second insulating member. The length D3 of the protrusion along the length direction is greater than or equal to 0.1 mm, and the length L5 of the bonding area at the bonding point of the first and second insulating members along the length direction is greater than or equal to 0.1 mm.

[0021] Beneficial effects: By bonding the first and second insulating components together, the ends of the hard and soft tabs are wrapped, preventing excessive force from puncturing the separator and electrode sheets and causing short circuits when the tabs move into the cell under extreme conditions, thus improving battery safety. Both D3 and L5 are greater than or equal to 0.1mm, ensuring sufficient bonding between the first and second insulating components and improving the reliability and stability of their fixation.

[0022] Secondly, this utility model also provides a battery, including the aforementioned battery cell. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present utility model;

[0025] Figure 2 for Figure 1 A schematic diagram of the right side of the battery cell shown;

[0026] Figure 3 for Figure 1 The diagram shows the structure of the battery cell during the welding of the soft and hard tabs.

[0027] Figure 4 for Figure 3 The diagram shows the structure of the battery cell when the first insulating component is attached.

[0028] Figure 5 for Figure 4 A schematic diagram of the structure of a European-style battery cell after the soft tabs have been bent.

[0029] Figure 6 for Figure 1 The diagram shows the structure of the positive electrode tab after it has been unfolded.

[0030] Figure 7 for Figure 1 The diagram shows the structure of the negative electrode tab after it has been unfolded.

[0031] Figure 8 This is a schematic diagram of the structure of another battery cell according to an embodiment of the present invention;

[0032] Figure 9 for Figure 8The diagram shows the structure of the battery cell before bending.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Cell body; 101. Positive electrode plate; 102. Negative electrode plate; 103. Separator; 104. First surface; 105. Second surface;

[0035] 2. Soft tab; 201. First tab section; 202. First bending section; 203. Second tab section; 204. Second bending section; 205. Welding section; 206. Blank area; 2061. Edge; 2062. Welding area; 207. Tab piece;

[0036] 3. Hard electrode tab; 301. Welding end; 302. Weld mark; 303. Electrode tab protective adhesive;

[0037] 4. First insulating component;

[0038] 5. Second insulating component;

[0039] 6. Covering component; 601. Side part. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0041] In related technologies, after the soft and hard tabs are welded, both the soft and hard tabs are bent. The bent tabs occupy a large space in both the length and thickness directions of the cell. The solder mark at the weld between the soft and hard tabs extends along the thickness direction. From the length direction, the length occupied in the head space is mainly the sum of the thickness of the hard tab, the thickness of the soft tab, the thickness of the solder mark protrusion, and the thickness of the protective adhesive on both sides of the solder mark. From the thickness direction, the thickness occupied in the head space is mainly the sum of the thickness of the soft tab, the length of the solder mark, and the thickness of the hard tab. It should be noted that the area required for welding results in a relatively long solder mark length.

[0042] The following is combined Figures 1 to 9 The following describes embodiments of the present invention.

[0043] According to an embodiment of the present invention, in one aspect, a battery cell is provided, having a thickness direction and a length direction perpendicular to the thickness direction. The battery cell includes: a battery cell body 1, a soft electrode tab 2, and a hard electrode tab 3. The battery cell body 1 has a first surface 104 and a second surface 105 spaced apart in its thickness direction. The battery cell body 1 includes a positive electrode sheet 101, a separator 103, and a negative electrode sheet 102 stacked sequentially along the thickness direction. The soft electrode tab 2 includes a first electrode tab section 201, a first bending section 202, a second electrode tab section 203, a second bending section 204, and a welding section 205 arranged sequentially. One end of the first electrode tab section 201 is connected to one end of the battery cell body 1 along the length direction. The first bending section 202 is disposed near the second surface 105, the second bending section 204 is disposed near the first surface 104, and the welding section 205 is disposed along the length direction. The hard electrode tab 3 is disposed along the length direction, and one end of the hard electrode tab 3 forms a welding end 301 welded to the welding section 205. The thickness direction refers to the stacking direction of the battery cell, and the length direction refers to the height direction of the battery cell.

[0044] In some exemplary embodiments, the positive electrode sheet may include a positive current collector and a positive active material layer disposed on the surface of the positive current collector. Exemplarily, the positive current collector may be aluminum foil; however, other positive current collectors commonly used in the art may also be used, and the thickness of the positive current collector may be from 1 μm to 200 μm. The positive active material layer may be disposed on one or both opposing surfaces of the positive current collector. Further, in the thickness direction of the positive electrode sheet, the positive active material layer may be coated only on a portion of the positive current collector, and the thickness of the positive active material layer may be from 10 μm to 500 μm.

[0045] The positive electrode active material layer includes positive electrode active materials, such as LiCoO2, LiNiO2, LiMn2O4, and LiCo. 1-y M y O2, LiNi 1-y M y O2, LiMn 2-y M y O4, LiNi x Co y Mn z M 1-x-y-zO2, wherein M is selected from at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, or Ti, and 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1. Exemplarily, the positive electrode active material may include at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or lithium nickel manganese oxide, and the above positive electrode active materials may be doped and / or coated. The positive electrode active material layer also includes a binder and a conductive agent. For example, the binder in the positive electrode active material layer may include at least one of polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and hexafluoropropylene, a styrene-acrylate copolymer, a styrene-butadiene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene; the conductive agent in the positive electrode active material layer may include at least one of conductive carbon black, acetylene black, Ketjen black, sheet graphite, graphene, carbon nanotubes, or carbon fibers.

[0046] In some exemplary embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer disposed on the surface of the negative electrode current collector. Exemplarily, the negative electrode current collector may be at least one of copper foil, aluminum foil, nickel foil, or carbon-based current collector; the thickness of the negative electrode current collector may be from 1 μm to 200 μm. The negative electrode active material layer may be disposed on one or both opposing surfaces of the negative electrode current collector. Further, in the thickness direction of the negative electrode sheet, the negative electrode active material layer may be coated only on a portion of the negative electrode current collector. Exemplarily, the thickness of the negative electrode active material layer may be from 10 μm to 500 μm.

[0047] The negative electrode active material layer includes a negative electrode active material. Exemplarily, the negative electrode active material includes at least one of lithium metal, natural graphite, artificial graphite, or a silicon-based material. The silicon-based material includes at least one of silicon, silicon oxides, silicon carbide compounds, or silicon alloys. The negative electrode active material layer may also include a conductive agent and / or a binder. Exemplarily, the conductive agent in the negative electrode active material layer may include at least one of carbon black, acetylene black, Ketjen black, sheet graphite, graphene, carbon nanotubes, carbon fibers, or carbon nanowires; the binder in the negative electrode active material layer may include at least one of carboxymethyl cellulose (CMC), polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyaniline, polyimide, polyamide-imide, polysiloxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin, or polyfluorene.

[0048] In some exemplary embodiments, the diaphragm 103 comprises at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, polyethylene comprises at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene. Polyethylene and polypropylene, in particular, are effective in preventing short circuits and can improve the stability of the electrode assembly through a turn-off effect. The thickness of the separator 50 is in the range of about 3 μm to 500 μm.

[0049] The battery cell using this embodiment forms two bent segments through two bends of the soft tab, with the welding end positioned along the length direction. The hard tab is also positioned along the length direction, eliminating the need for bending in the length direction. Compared to existing solutions, only the soft tab occupies the head space in the length direction, saving space from the bending portion of the hard tab and the welding end, reducing the head space occupied in the battery cavity in the length direction, and improving the space utilization of the battery cell. Furthermore, in the thickness direction, compared to existing solutions, only the soft tab occupies the head space. By positioning the welding end along the length direction, the influence of the solder area on the thickness direction is eliminated, further reducing the required head space and improving the space utilization of the battery cell.

[0050] It should be noted that soft tab 2 refers to a tab that can be bent or flexed, while hard tab 3 refers to a tab that is not easily bent or flexed.

[0051] In one embodiment, such as Figure 1 and Figure 2 As shown, one end of the separator 103 extends along the surface of the first tab section 201 to near the first bending section 202. The projection of the rigid tab 3 on the first surface 104 and the projection of the separator 103 on the first surface 104 have a first overlapping area, and the length L1 of the first overlapping area along the length direction is greater than or equal to 0.3 mm. By setting the length L1 of the first overlapping area along the length direction to be greater than or equal to 0.3 mm, the space on one side of the separator 103 is fully utilized to accommodate the rigid tab, further reducing the head space occupied in the length direction. This allows for full utilization of the space inside the casing to place the rigid tab 31, improving the space utilization rate of the battery cell.

[0052] In one embodiment, such as Figure 1 and Figure 2As shown, the projection of the weld mark 302 at the weld joint between the welding segment 205 and the welding end 301 on the first surface 104 and the projection of the diaphragm 103 on the first surface 104 have a second overlapping area. The length L2 of the second overlapping area along the length direction is greater than or equal to 0.1 mm. Setting the length L2 of the second overlapping area along the length direction to be greater than or equal to 0.1 mm further makes full use of the space on one side of the diaphragm 103 to accommodate the welding end 301, thereby making full use of the space inside the housing to place the welding end 301 of the hard tab 3, and improving the space utilization rate of the cell.

[0053] In one embodiment, the weld protrusion of the welding section does not exceed the first surface. The weld protrusion not exceeding the first surface can prevent the position of the second bending section from being moved upward by the rebound force during the formation process, thereby causing the shell at the welding end position to bulge, affecting the flatness of the cell and reducing the energy density of the cell.

[0054] In one embodiment, the angle between the second tab section and the plane containing the positive or negative electrode is less than 90°. An angle of less than 90° between the second tab section and the plane containing the positive or negative electrode prevents the stress generated by electrode expansion during charging and discharging from causing the bent section of the soft tab to shift upwards, which could lead to contact between the soft tab and the aluminum-plastic film, resulting in electrochemical corrosion, or the risk of bulging in the casing corresponding to the bent tab.

[0055] In one embodiment, such as Figure 1 and Figure 4 As shown, a first insulating member 4 is provided on the side of the flexible tab 2 facing the battery cell body. The projection of the first insulating member 4 on the first surface 104 and the projection of the separator 103 on the first surface 104 have a third overlapping area. The length L3 of the third overlapping area along the length direction is greater than or equal to 0.1 mm. By providing the first insulating member 4 on the flexible tab 2, after the flexible tab 2 and the first insulating member 4 are bent, the first insulating member 4 plays a role in ensuring the insulation of the body. Moreover, compared with the prior art, there is only one first insulating member in the length direction, which reduces the thickness accumulation in the length direction. Furthermore, by overlapping the first insulating member and the separator, part of the first insulating member is hidden inside the separator, saving thickness space.

[0056] Furthermore, the first insulating component 4 is adhesive tape, etc. The adhesive tape is directly attached to the soft electrode tab 2, which is easy to install. The adhesive tape also has the advantages of good insulation performance, excellent mechanical properties, and easy processing.

[0057] In one embodiment, such as Figure 1As shown, a second insulating member 5 is provided on the first surface 104 of the rigid tab 3 and the cell body 1. The projection of the second insulating member 5 on the first surface 104 and the projection of the negative electrode 102 on the first surface 104 have a fourth overlapping area. The length L4 of the fourth overlapping area along the length direction is greater than or equal to 2 mm. Setting the length L4 of the fourth overlapping area along the length direction to be greater than or equal to 2 mm makes the contact area between the second insulating member 5 and the cell body 1 large, ensuring the reliability of the second insulating member 5 being fixed on the cell body 1.

[0058] Furthermore, the first insulating component 4 is adhesive tape, which is directly attached to the battery cell body 1 and the rigid tab 3, making it easy to install. The adhesive tape also has advantages such as good insulation performance, excellent mechanical properties, and ease of processing. L4 is greater than or equal to 2mm, ensuring that the adhesive tape is fully bonded to the battery cell body 1, making the fixation of the second insulating component 5 more secure and reliable.

[0059] In one embodiment, such as Figure 1 As shown, the second insulating component 5 covers the entire solder mark 302 at the weld joint between the welding section 205 and the welding end 301. The solder mark 302 may contain burrs or protrusions. By completely covering the solder mark 302 with the second insulating component 5, it is possible to effectively prevent burrs on the electrode tab from contacting other conductive materials, reducing the risk of internal short circuits and thus improving battery safety.

[0060] In one embodiment, such as Figure 1 and Figure 2 As shown, the end of the second insulating member 5 away from the cell body 1 protrudes beyond the end of the welding section 205 away from the cell body 1, and the distance D2 between the end of the second insulating member 5 away from the cell body 1 and the end of the welding section 205 away from the cell body 1 is greater than or equal to 0.1 mm. Setting the dimension of the end of the second insulating member 5 extending beyond the soft electrode tab 2 to be greater than or equal to 0.1 mm can effectively protect against protrusions and burrs on the electrode tab, prevent contact with the aluminum-plastic film, and avoid the risk of damage and corrosion to the aluminum-plastic film.

[0061] In one embodiment, such as Figure 1 , Figure 6 and Figure 7As shown, the battery cell also has a width direction that is perpendicular to both the thickness direction and the length direction; after the flexible tab 2 is unfolded along the length direction, the flexible tab 2 has a blank area 206, the blank area 206 has an edge 2061 that is close to the battery cell body 1 and extends along the width direction, and part of the blank area 206 forms a soldering area 2062. Along the length direction, the distance between the edge 2061 and the soldering area 2062 is L, and the thickness of the battery cell body 1 along the thickness direction is H; after the flexible tab 2 is bent, the battery cell also includes a covering 6, which wraps around the outside of the battery cell body 1 and the flexible tab 2. The covering 6 has a side 601 located on the flexible tab 2 away from the battery cell body 1, and the distance between the side of the side 601 close to the battery cell body 1 and the edge 2061 is D; wherein, L 2 ≥((1+k)+H) 2 +D 2 Where k is the cell expansion coefficient. By setting the length of the soft tab 2, the length of the soft tab is greater than the length of the hypotenuse of the right triangle formed by H and D. This ensures that even if the cell expands to its maximum, the length of its soft tab is sufficient to prevent stretching, thus avoiding the risk of breakage after the soft tab 2 is stretched, thereby improving the overall reliability of the battery.

[0062] In one embodiment, such as Figure 1 and Figure 4 As shown, the soft tab 2 includes multiple tab pieces 207, the sum of the thicknesses of all tab pieces 207 is h1, the sum of the thicknesses of all separators 103 is h2, and the thickness of the first insulating member 4 is h3. Wherein, D≥h1+h2+2h3, which can ensure that the head space can accommodate the two layers of soft tab 2 after bending, the adhesive paper and the separator 103, making the internal layout of the battery more compact and reasonable, maximizing the use of limited space, and also avoiding the deformation of the appearance caused by the aluminum-plastic film being squeezed or even occupying the top sealing space.

[0063] In one embodiment, such as Figure 5As shown, the welding section 205 is positioned away from the cell body 1 relative to the second bending section 204, and the second bending section 204 wraps around the end of the welding end 301. After bending, the soft tab 2 wraps around the end of the hard tab 3, which can prevent the tab from being subjected to excessive force when moving into the cell under extreme conditions, thus preventing it from puncturing the separator 103 and the electrode sheet and causing a short circuit, thereby improving the safety performance of the battery. At the same time, in the thickness direction of the cell, the thickness of the hard tab and the welding end are hidden within the length of the second bending section of the soft tab, further reducing the head space occupied by the folded tab and improving the energy density. After the cell is stacked, multiple tab sheets 207 are gathered together towards the side where the second surface 105 is located to form the soft tab 2 before bending. Then, the end of the soft tab 2 away from the cell body 1 is bent towards the side of the first surface 104 and then bent along the length direction towards the side away from the cell body 1, so that the first bending section, the second tab section 203, the second bending section and the welding section 205 are roughly "S" shaped.

[0064] Furthermore, such as Figure 4 As shown, the end of the first insulating member 4 near the first surface 104 is spaced apart from the rigid tab 3. Along the length direction, the distance D1 between the end of the first insulating member 4 near the first surface 104 and the end of the rigid tab 3 near the cell body 1 is greater than or equal to 0.1 mm. The first insulating member 4 does not overlap with the rigid tab 3, which can reduce the accumulation of thickness and save thickness space.

[0065] It is understood that in another embodiment, such as Figure 8 and Figure 9 As shown, the welding section 205 is positioned close to the cell body 1 relative to the second bending section 204. After the cell is stacked, multiple tabs 207 are gathered together toward the side where the second surface 105 is located to form a soft tab 2 before bending. Then, the end of the soft tab 2 away from the cell body 1 is bent toward the side of the first surface 104 and then bent toward the cell body 1 along the length direction, so that the first bending section, the second tab section 203, the second bending section and the welding section 205 are roughly "U" shaped.

[0066] Furthermore, the end of the first insulating member 4 near the first surface forms a protrusion that extends beyond the end of the soft tab 2 away from the cell body 1, and the protrusion is bonded to the second insulating member 5. By bonding the first insulating member 4 to the second insulating member 5, the ends of the hard tab 3 and the soft tab 2 are wrapped, which can also prevent the tab from being subjected to excessive force when moving into the cell under extreme conditions, which could cause it to puncture the separator 103 and the electrode sheet and cause a short circuit, thereby improving the safety performance of the battery.

[0067] Specifically, such as Figure 8 and Figure 9As shown, the length D3 of the protrusion along the length direction is greater than or equal to 0.1 mm, and the length L5 of the bonding area at the joint between the first insulating member 4 and the second insulating member 5 along the length direction is greater than or equal to 0.1 mm. Both D3 and L5 are greater than or equal to 0.1 mm, ensuring sufficient bonding between the first insulating member 4 and the second insulating member 5, and improving the fixing reliability and stability between the first insulating member 4 and the second insulating member 5.

[0068] In one embodiment, the portion of the hard tab 3 near the welding end 301 is provided with tab protective adhesive 303. Tab protective adhesive 303 is used to protect the tab and prevent the tab from contacting the metal casing or other conductive components, which could cause a short circuit.

[0069] According to an embodiment of the present invention, another aspect provides a battery comprising the aforementioned battery cell.

[0070] In one embodiment, the battery further includes a housing and a cover, the housing having an open receiving cavity in which the battery cell is disposed, and the cover covering the opening. Specifically, the battery cell is a laminated battery cell.

[0071] In related technologies, the production process of laminated battery cells often requires processes such as transfer welding and bending with adhesive. After the soft and hard tabs are welded, both the soft and hard tabs are bent. The bent tabs have a certain thickness, occupying a large amount of space at the head of the battery cell, resulting in wasted overall space. Furthermore, with the application of foldable screen phones, the traditional tab bending method can no longer meet the thickness requirements due to the size limitations of the welding section of the hard tab.

[0072] In this application, the battery cell employs a method of bending the soft tab 2 and not bending the hard tab 3, thus overcoming the thickness limitations of bending thin battery cells and reducing wasted head space. Furthermore, the length of the soft tab 2 is designed to mitigate the risk of breakage due to cell expansion during cycling. In the length direction, the head space occupies the sum of the thickness of the soft tab and the thickness of a protective adhesive layer; in the thickness direction, the head space occupies the sum of the thickness of the soft tab, the thickness of the hard tab, and the thickness of the welding section of the soft tab. Figure 1 In the process, the thickness of the hard tab is hidden within the welding section of the soft tab.

[0073] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electric cell, characterized by, The battery cell has a thickness direction and a length direction perpendicular to the thickness direction, and comprises: a battery cell body (1) having a first surface (104) and a second surface (105) arranged at intervals in the thickness direction, the battery cell body (1) comprising a positive electrode sheet (101), a separator (103) and a negative electrode sheet (102) arranged in sequence in the thickness direction; a soft tab (2) comprising a first tab section (201), a first bending section (202), a second tab section (203), a second bending section (204) and a welding section (205) arranged in sequence, one end of the first tab section (201) being connected to one end of the battery cell body (1) along the length direction, the first bending section (202) being arranged close to the second surface (105), the second bending section (204) being arranged close to the first surface (104), and the welding section (205) being arranged along the length direction; a hard tab (3) arranged along the length direction, one end of the hard tab (3) forming a welding end (301) welded with the welding section (205).

2. The electric cell of claim 1, wherein, The separator (103) extends along the surface of the first tab section (201) to be arranged close to the first bending section (202) at one end along the length direction, the projection of the hard tab (3) on the first surface (104) and the projection of the separator (103) on the first surface (104) have a first overlapping area, and the length L1 of the first overlapping area along the length direction is greater than or equal to 0.3mm; and / or, the projection of the welding mark (302) where the welding section (205) is welded with the welding end (301) on the first surface (104) and the projection of the separator (103) on the first surface (104) have a second overlapping area, and the length L2 of the second overlapping area along the length direction is greater than or equal to 0.1mm.

3. The electric cell of claim 1, wherein, The welding mark of the welding section (205) does not protrude more than the first surface (104); and / or, the included angle between the second tab section (203) and the plane where the positive electrode sheet or the negative electrode sheet is located is less than 90°.

4. The electric cell of claim 1, wherein, The first surface (104) of the battery cell body (1) is provided with a second insulating member (5), and the projection of the second insulating member (5) on the first surface (104) and the projection of the negative electrode sheet (102) on the first surface (104) have a fourth overlapping area, and the second insulating member (5) covers all of the welding mark (302) where the welding section (205) is welded with the welding end (301); the length L3 of the third overlapping area along the length direction is greater than or equal to 0.1mm; And / or, a length L4 of the fourth overlapping region along the length direction is greater than or equal to 2 mm; And / or, an end of the second insulating piece (5) away from the battery body (1) protrudes from an end of the welding section (205) away from the battery body (1), and a distance D2 between the end of the second insulating piece (5) away from the battery body (1) and the end of the welding section (205) away from the battery body (1) is greater than or equal to 0.1 mm.

5. The electric cell of claim 4, wherein, The battery cell further has a width direction perpendicular to the thickness direction and the length direction; The soft tab (2) has a blank area (206) with an edge (2061) close to the battery body (1) and extending in the width direction, and part of the blank area (206) forms a welding mark area (2062), and along the length direction, a distance between the edge (2061) and the welding mark area (2062) is L, and a thickness of the battery body (1) along the thickness direction is H; The battery cell further includes a cladding piece (6) wrapped outside the battery body (1) and the soft tab (2), and the cladding piece (6) has a side portion (601) away from the battery body (1) of the soft tab (2), and a distance between a side of the side portion (601) close to the battery body (1) and the edge (2061) is D; The soft tab (2) comprises a plurality of tab pieces (207), the sum of thicknesses of all the tab pieces (207) is h1, the sum of thicknesses of all the diaphragms (103) is h2, the thickness of the first insulating member (4) is h3, wherein, L 2 ≥((1+k)+H) 2 +D 2 , D≥h1+h2+2h3, k is the expansion coefficient of the battery cell.

6. The electric cell of any one of claims 4-5, wherein, The welding section (205) is arranged away from the battery body (1) relative to the second bending section (204), and the second bending section (204) wraps an end of the welding end (301).

7. The electric cell of claim 6, wherein, An end of the first insulating piece (4) close to the first surface (104) is arranged away from the hard tab (3), and along the length direction, a distance D1 between the end of the first insulating piece (4) close to the first surface (104) and an end of the hard tab (3) close to the battery body (1) is greater than or equal to 0.1 mm.

8. The electric cell of any one of claims 4-5, wherein, The welding section (205) is arranged close to the battery body (1) relative to the second bending section (204).

9. The electric cell of claim 8, wherein, An end of the first insulating piece (4) close to the first surface (104) forms a protruding portion protruding from an end of the soft tab (2) close to the battery body (1), the protruding portion is bonded to the second insulating piece (5), a length D3 of the protruding portion along the length direction is greater than or equal to 0.1 mm, and a length L5 of a bonding area of the first insulating piece (4) and the second insulating piece (5) along the length direction is greater than or equal to 0.1 mm.

10. A battery, characterized by The battery cell includes: The battery cell of any one of claims 1 to 9.

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