A tab, a pole piece and a lithium ion battery

Abstract

The application provides a tab, a pole piece and a lithium ion battery. The tab provided by the application comprises a current collector, an active material layer and a tab, the active material layer is arranged on the front and back surfaces of the current collector and / or one of the front and back surfaces of the current collector, at least one end of the length direction of the current collector is left with an empty foil area without the active material layer, the tab is arranged on the empty foil area at one end of the length direction of the current collector, the tab comprises a first section and a second section connected with the first section, and the top surface of the first section is provided with recesses concaved downward on both sides. The tab, the pole piece and the lithium ion battery are used to at least solve the technical problem that the flatness of the pole piece surface processed into the lithium ion battery is not ideal due to the structure of the tab.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium ion batteries, in particular to a tab, a pole piece and a lithium ion battery. BACKGROUND

[0002] At present, with the vigorous support of the state to new energy, lithium ion batteries as green and environmentally friendly new energy have been rapidly developed and widely used in digital products, electric vehicles and military products. People have higher requirements for the energy density, fast charging capacity and charge-discharge rate of lithium ion batteries. Fast charging lithium batteries are also the development trend of consumer lithium ion batteries.

[0003] Formation is an extremely important process in the manufacturing process of lithium ion batteries, which is an important link to ensure the service life of the battery. Formation has a crucial influence on the performance of the battery. Whether the pressure borne by the lithium ion battery during formation is uniform affects the interface bonding performance of the lithium ion battery. When fast charging, whether the interface bonding of the lithium ion battery is good will significantly affect the long cycle life of the lithium ion battery, and also relates to the swelling phenomenon of the lithium ion battery during the cycle charging and discharging process, and even can cause deformation of the lithium ion battery during use.

[0004] The key to whether the pressure borne by the lithium ion battery during formation is uniform lies in whether the flatness of the whole battery cell is good. The smaller the difference between the highest point and the lowest point on the surface of the battery cell, the better the flatness of the battery cell. During formation, poor flatness of the battery cell will cause uneven pressure on the pole piece, eventually leading to problems such as uneven surface, depression and even wave deformation of the battery cell. During long cycle, the uneven stress on the battery cell during cycle swelling due to the unsatisfactory flatness of the battery cell will eventually cause the battery cell to swell and deform, causing problems such as capacity decay and swelling failure. Therefore, it is urgent to improve the structure of the tab, the pole piece and the lithium ion battery, so that when the pole piece is processed into a battery cell, the flatness of the surface of the battery cell caused by the structure of the tab can be improved, thereby ensuring the service life of the lithium ion. SUMMARY

[0005] The present application provides a tab, a pole piece and a lithium ion battery to at least solve the technical problem of unsatisfactory flatness of the surface of the battery cell caused by the structure of the tab in the process of processing the existing pole piece into a lithium ion battery.

[0006] In order to achieve the above-mentioned purpose, the present application provides a tab, which comprises a first segment and a second segment connected with the first segment, and the top surface of the first segment has a recessed portion downward on both sides.

[0007] The first section has a recessed portion on both sides of the top surface, which is used to accommodate the insulating tape, thereby avoiding the insulating tape protruding above the top surface of the first section, causing the surface height variation difference of the pole piece to be large, resulting in uneven thickness of the pole piece.

[0008] In a possible implementation, the recessed portion extends through both ends of the first section in the length direction, and the width L1 of the recessed portion is 10mm-15mm.

[0009] The recessed portion has a spacing H1 between the bottom surface and the top surface of the first section, and the spacing H1 ranges from 15μm to 25μm; and / or,

[0010] The width of the first section is greater than the width of the second section.

[0011] In a possible implementation, the first section further has a step at the bottom of the recessed portion, the edge of the upper end of the step is in the form of a circular arc, and the radius R of the circular arc is 1 / 3 of the thickness of the first section; or

[0012] The radius R of the circular arc is 1 / 6 of the thickness of the first section.

[0013] The application further provides another pole piece, which comprises a current collector, an active material layer, and the above-mentioned tab, the active material layer is arranged on both surfaces of the current collector and / or one of the two surfaces of the current collector, at least one end of the current collector in the length direction is provided with an empty foil area without the active material layer, the tab is arranged on the empty foil area at one end of the current collector in the length direction, the tab comprises a first section and a second section connected with the first section, and both sides of the top surface of the first section are provided with a recessed portion downward.

[0014] In the pole piece provided by the application, both sides of the top surface of the first section are provided with a recessed portion downward, which is used to accommodate the insulating tape, thereby avoiding the insulating tape protruding above the top surface of the first section, causing the surface height variation difference of the pole piece to be large, resulting in uneven thickness of the pole piece. Therefore, after the pole piece is wound into a battery cell, the flatness of the surface of the battery cell caused by the structure of the tab is improved, the thickness distribution of the surface of the battery cell is uniform, the problems of uneven surface, depression and wave deformation of the battery cell caused by uneven stress of the pole piece during formation are improved, and the cycle swelling failure of the battery cell is improved.

[0015] In a possible implementation, the empty foil area is rectangular, and in the width direction of the first section, the side of the first section close to the active material layer is a limiting surface, and the distance between the end surface of the active material layer close to the limiting surface and the limiting surface is H2.

[0016] In a possible implementation, the first section extends in the width direction of the current collector, and the length of the first section is 40% to 105% of the width of the current collector.

[0017] Such a structure makes the thickness distribution of the pole piece tend to be uniform in the width direction of the current collector, and is beneficial to improving the flatness of the pole piece after the pole piece is processed into an electric cell.

[0018] In a possible implementation, the thickness of the second section is equal to the thickness of the first section, and the value of the thickness h of the first section ranges from 45 μm to 115 μm.

[0019] In a possible implementation, the pole piece further comprises an insulating adhesive tape, and the insulating adhesive tape covers at least the recess of the tab and at least part of the empty foil area of the pole piece.

[0020] The application further provides a lithium ion battery comprising an electric cell, wherein the electric cell comprises a negative pole piece, a positive pole piece, and a separator separating the negative pole piece and the positive pole piece, the negative pole piece and the positive pole piece are the pole piece described above, and the negative pole piece, the positive pole piece, and the separator are laminated and wound to form the electric cell, and the electric cell has a plurality of winding layers arranged outward in sequence.

[0021] The tab on the negative pole piece is located in the inner winding layer of the electric cell, or the tab on the negative pole piece is located in the outer winding layer of the electric cell.

[0022] The lithium ion battery provided by the application can fully utilize the thickness space of the electric cell itself to adjust the flatness of the electric cell itself by using the pole piece and the tab described above, without increasing the thickness of the electric cell itself and affecting the energy density of the electric cell, so that the flatness and the energy density are considered.

[0023] In a possible implementation, the first section of the tab has a limiting surface close to the side of the active material layer of the pole piece, and the distance between the end surface of the active material layer close to the limiting surface and the limiting surface is H2; the distance H2 is greater than twice the thickness h of the first section, and the difference between the distance H2 and twice the thickness h of the first section is δ1, and the value of δ1 ranges from 2 mm to 10 mm; and / or

[0024] The interval H2 is greater than pi / 2 times the thickness T of the battery cell, and the difference between the interval H2 and pi / 2 times the thickness T of the battery cell is delta2, the numerical range of delta2 is: 1mm<=delta2<=5mm or 1mm<=delta2<=4mm.

[0025] In a possible implementation, when the tab on the negative electrode sheet and / or the tab on the positive electrode sheet is located at the inner circle layer of the battery cell, the width D of the tab on the negative electrode sheet and / or the tab on the positive electrode sheet satisfies:

[0026] The inner width L2 of the battery cell - the interval H2 - 1mm >= D >= the inner width L2 of the battery cell - the interval H2 - 5mm;

[0027] The inner width L2 of the battery cell is the width of the innermost circle layer of the battery cell in the projection direction of the battery cell.

[0028] In a possible implementation, when the tab on the negative electrode sheet and / or the tab on the positive electrode sheet is located at the outer circle layer of the battery cell, the width D of the tab on the negative electrode sheet and / or the tab on the positive electrode sheet satisfies:

[0029] The outer width L3 of the battery cell - the thickness T of the battery cell - 1mm >= D >= the outer width L3 of the battery cell - the thickness T of the battery cell - 5mm;

[0030] The outer width L3 of the battery cell is the width of the outermost circle layer of the battery cell in the projection direction of the battery cell, and the thickness T of the battery cell is the height of the outermost circle layer of the battery cell in the side projection direction of the battery cell.

[0031] In a possible implementation, when the tab on the negative electrode sheet and / or the tab on the positive electrode sheet is located at the inner circle layer of the battery cell, the edge of the upper end of the step of the tab is in a circular arc shape, and the radius R of the circular arc shape is 1 / 6 times the thickness of the first segment; or

[0032] When the tab on the negative electrode sheet and / or the tab on the positive electrode sheet is located at the outer circle layer of the battery cell, the edge of the upper end of the step of the tab is in a circular arc shape, and the radius R of the circular arc shape is 1 / 3 times the thickness of the first segment.

[0033] The tabs, electrodes, and lithium-ion batteries provided by this invention, through improvements to the structure of the tabs and electrodes, can effectively improve the thickness distribution of the innermost layer of the cell, and improve problems such as uneven surface, dents, and wave deformation of the shipped cells caused by uneven stress on the electrodes during formation; uniform formation pressure can also effectively improve the problem of poor separator adhesion; improve the problem of poor adhesion between the electrodes and separator in the later stages of cycle charging and discharging, which causes lithium plating; improve the flatness of the cell; and at the same time, improve the situation of cycle expansion failure.

[0034] The improved electrode structure in this application can fully utilize the thickness space of the battery cell to adjust its flatness without increasing the cell thickness or affecting its energy density, achieving a balance between flatness and energy density. This effectively improves the problem of uneven internal stress on the electrode during cyclic expansion caused by cell flatness issues, which ultimately leads to cell bonding failure, cell expansion and deformation, capacity decay, and expansion failure, thus enhancing battery cycle life and safety performance.

[0035] In addition to the technical problems solved by the embodiments of the present invention, the technical features constituting the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions described above, other technical problems solved by the tab, electrode, and lithium-ion battery provided by the embodiments of the present invention, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific embodiments. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of an existing electrode.

[0038] Figure 2 for Figure 1 Top view;

[0039] Figure 3 This is another structural schematic diagram of an existing electrode.

[0040] Figure 4 for Figure 3 Top view;

[0041] Figure 5 A schematic diagram of the structure of a battery cell made from existing electrode sheets;

[0042] Figure 6 Structure schematic view of the pole piece provided for the embodiment one and the embodiment two of the present application;

[0043] Figure 7 Top view of Figure 6 ;

[0044] Figure 8 Structure schematic view of the pole piece provided for the embodiment two of the present application;

[0045] Figure 9 Top view of Figure 8 ;

[0046] Figure 10 Structure schematic view of the pole piece provided for the embodiment three of the present application;

[0047] Figure 11 Top view of Figure 10 ;

[0048] Figure 12 Structure schematic view of the pole piece provided for the embodiment three of the present application;

[0049] Figure 13 Top view of Figure 12 ;

[0050] Figure 14 Structure schematic view of the first section of the pole lug provided for the embodiment of the present application;

[0051] Figure 15 Structure schematic view of the electric core in the lithium ion battery provided for the embodiment one of the present application;

[0052] Figure 16 Structure schematic view of the electric core in the lithium ion battery provided for the embodiment two of the present application;

[0053] Figure 17 Structure schematic view of the electric core in the lithium ion battery provided for the embodiment three of the present application;

[0054] Figure 18 Position schematic view of the thickness data acquisition provided for the embodiment of the present application;

[0055] Figure 19 Right view of Figure 18 ;

[0056] Explanation of the reference signs:

[0057] 100 - pole piece;

[0058] 110 - current collector;

[0059] 120 - active material layer;

[0060] 130 - empty foil area;

[0061] 300 - tab;

[0062] 310 - first section;

[0063] 311 - limiting surface;

[0064] 312 - recess;

[0065] 313 - step;

[0066] 320 - second section;

[0067] 200 - insulating tape;

[0068] 400 - battery cell;

[0069] 420 - negative electrode sheet;

[0070] 430 - positive electrode sheet;

[0071] 500 - separator. DETAILED DESCRIPTION

[0072] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0073] Referring to Figure 1 and Figure 2 , in the existing electrode sheet 100, the tab 300 is welded on the electrode sheet 100. In order to avoid the burr produced by the edge of the active material layer 120 and the tab 300 during the production process of the electrode sheet 100 from piercing the separator 500 in the battery cell 400 to cause short circuit of the battery cell 400, it is necessary to paste a certain thickness of insulating tape 200 on the electrode sheet 100 to cover the burr and avoid safety problems. However, the factors such as welding the tab 300 on the electrode sheet 100 and pasting the insulating tape 200 will cause the thickness of the electrode sheet 100 to be uneven.

[0074] Referring to Figure 1 and Figure 2 , the insulating tape 200 is pasted on one side of the tab 300 welded on the electrode sheet 100. Referring to Figure 3 and Figure 4 , the insulating tape 200 is pasted on one side of the tab 300 welded on the electrode sheet 100, and the insulating tape 200 is also pasted on the back of the tab 300, so as to avoid the burr from conducting the negative electrode sheet 420 and the positive electrode sheet 430 to cause short circuit.

[0075] Reference Figure 5 As shown in the structural diagram of the battery cell 400 processed by the existing tab 100. In particular, after the existing tab 100 is processed into the battery cell 400 by winding, the thickness of the tab 100 which is already uneven is stacked at different parts of the battery cell 400, causing uneven thickness distribution on the plane of the battery cell 400, poor flatness of the battery cell 400, and especially the thickness of the innermost layer of the battery cell 400 is more uneven, which ultimately causes uneven stress on the tab 100 during formation, resulting in problems such as uneven surface, depression and wave deformation of the battery cell 400.

[0076] In view of the above background, the tab 300, the tab 100 and the lithium ion battery provided by the present application improve the structure of the tab 300 and the tab 100, and set a downward recessed recess 312 on both sides of the top surface of the first section 310 of the tab 300, the recess 312 is used to accommodate the insulating adhesive paper 200, thereby avoiding the insulating adhesive paper 200 protruding above the top surface of the first section 310 causing the thickness of the tab 100 to be uneven, thereby improving the flatness of the battery cell surface caused by the structure of the tab 100, and improving the thickness distribution of the tab 100 after being processed into the battery cell 400 by winding, thereby improving the problems such as uneven surface, depression and wave deformation of the battery cell 400 caused by uneven stress on the tab 100 during formation, and improving the cycle swelling failure of the battery cell 400.

[0077] Reference Figure 14 As shown, the present application provides a tab 300, the tab 300 includes a first section 310 and a second section 320 connected to the first section 310, and both sides of the top surface of the first section 310 have a downward recessed recess 312. The recess 312 is used to accommodate the insulating adhesive paper 200, thereby avoiding the insulating adhesive paper 200 protruding above the top surface of the first section 310 causing the thickness of the tab 100 to be uneven.

[0078] Reference Figure 14 As shown, in one possible implementation, both sides of the top surface of the first section 310 have a downward recessed recess 312, the recess 312 penetrates both ends of the length direction of the first section 310, the width L1 of the recess 312 is 10mm-15mm; the recess 312 has a spacing H1 between the bottom surface and the top surface of the first section 310, the value of the spacing H1 is in the range of 15μm-25μm. That is, the width direction of the tab 300 is 10mm-15mm thinner than the middle position of the tab; and / or, the width of the first section 310 is greater than the width of the second section 320. In this way, the flatness problem caused by the width direction of the first section 310 of the tab 300 can be improved.

[0079] In one possible implementation, the first section 310 has a step 313 on both sides of the first section 310 at the bottom of the recess 312, the edge of the upper end of the step 313 is in the form of a circular arc, and the radius R of the circular arc is 1 / 3 of the thickness of the first section 310, or the radius R of the circular arc is 1 / 6 of the thickness of the first section 310.

[0080] The edge of the upper end of the step 313 is in the form of a circular arc, which is conducive to the smooth bonding of the insulating adhesive paper 200 on the recess 312 to the empty foil area 130, and ensures the stable bonding effect of the insulating adhesive paper 200.

[0081] Reference Figure 6 and Figure 7 As shown in FIGS. 1 and 2, the application also provides a pole piece 100, which comprises a current collector 110, an active material layer 120, and a tab 300, the active material layer 120 is arranged on both surfaces of the current collector 110 and / or one of the two surfaces of the current collector 110, at least one end of the length direction of the current collector 110 is left with an empty foil area 130 without the active material layer 120, and the tab 300 is arranged on the empty foil area 130 at one end of the length direction of the current collector 110, the tab 300 comprises a first section 310 and a second section 320 connected with the first section 310, and both sides of the top surface of the first section 310 have a downward recess 312. It is easy to understand that the top surface of the first section 310 of the tab 300 is the surface of the first section 310 away from the empty foil area 130.

[0082] The first section 310 of the tab 300 can be connected with the current collector 110 by welding.

[0083] Reference Figure 8 and Figure 9 As shown in FIGS. 1 and 2, the first section 310 of the tab 300 extends along the width direction of the current collector 110, the first section 310 is connected with the empty foil area 130 of the current collector 110, and the second section 320 is exposed outside the current collector 110.

[0084] It is easy to understand that in other embodiments (not shown in the drawings), the empty foil area 130 can be arranged not only at one end of the length direction of the current collector 110, but also in the middle of the current collector 110.

[0085] It is easy to understand that the length direction of the first section 310 is the width direction of the current collector 110, and the width direction of the first section 310 is the length direction of the current collector 110.

[0086] The positive plate 100 provided in the embodiment is improved in structure of the tab 300, recesses 312 are arranged on both sides of the top surface of the first section 310 of the tab 300, and the recesses 312 are used to accommodate the insulating adhesive paper 200, so as to avoid that the insulating adhesive paper 200 is higher than the top surface of the first section 310 to cause a large difference in surface height of the positive plate 100, and the thickness of the positive plate 100 is uneven, so that the positive plate 100 provided in the embodiment is beneficial to improve the flatness of the surface of the battery cell caused by the structure of the positive plate 100, reduce the influence of the height difference between the first section 310 of the tab 300 and the current collector 110 on the flatness of the positive plate 100 itself, and is beneficial to improve the problem of poor surface flatness of the battery cell after the positive plate 100 is processed into the battery cell.

[0087] It is easy to understand that, as shown in Figure 10 and Figure 12 , in the positive plate 100 provided in the embodiment, the active material layer 120 can be arranged on both surfaces of part of the current collector 110, the active material layer 120 can be arranged on one surface of part of the current collector 110, and the active material layer 120 is not arranged on the other surface of the rest of the current collector 110. Figure 12 and Figure 13 , the empty foil area 130 formed by the current collector 110 without the active material layer 120 is located at at least one end of the current collector 110 in the length direction.

[0088] In a possible implementation manner, as shown in Figure 7 and Figure 11 , the empty foil area 130 is in a rectangular shape, in the width direction of the first section 310, one side of the first section 310 close to the active material layer 120 is a limiting surface 311, and the active material layer 120 has a spacing H2 between one end close to the limiting surface 311 and the limiting surface 311. Figure 7 and Figure 14 , the spacing H2 is greater than 2 times the thickness h of the first section 310, and the difference between the spacing H2 and 2 times the thickness h of the first section 310 is δ1, and the numerical range of δ1 is: 2mm≤δ1≤10mm.

[0089] By limiting the spacing H2 between one end of the active material layer 120 close to the limiting surface 311 and the limiting surface 311, on the one hand, the width of the battery cell 400 can be avoided from being affected when the positive plate 100 is bent, and the width of the battery cell 400 is avoided from being increased; on the other hand, by limiting the spacing H2 between one end of the active material layer 120 close to the limiting surface 311 and the limiting surface 311, the damage to the active material layer 120 can be reduced in the process of winding the positive plate 100 into the battery cell 400.

[0090] In a possible implementation, the tab 100 provided by the embodiment further comprises an insulating adhesive paper 200, which covers at least the recess 312 of the tab 300 and at least part of the empty foil area 130 of the tab 100.

[0091] In a possible implementation, the thickness of the insulating adhesive paper 200 is 15 μm to 25 μm.

[0092] The recess 312 is used to accommodate the insulating adhesive paper 200, and the bottom surface of the recess 312 and the top surface of the first section 310 have a spacing H1, so that after the insulating adhesive paper 200 is pasted on the first section 310, part of the insulating adhesive paper 200 covers the recess 312, and the insulating adhesive paper 200 fills the spacing H1 between the bottom surface of the recess 312 and the top surface of the first section 310 by its own thickness, so that the height difference between the insulating adhesive paper 200 and the top surface of the first section 310 is reduced, avoiding that the large height difference of the surface of the tab 100 leads to uneven thickness of the tab 100, and being beneficial to improve the flatness of the surface of the battery cell processed from the tab 100.

[0093] In a possible implementation, the first section 310 extends along the width direction of the current collector 110, and the length of the first section 310 is 40% to 105% of the width of the current collector 110. In a preferred implementation, the length of the first section 310 is 80% to 105% of the width of the current collector 110. Such a structure improves the thickness distribution of the tab 100 in the length direction, is beneficial to the uniform thickness distribution of the tab 100 after the tab 100 is processed into the battery cell 400 by winding, thereby improving the problems of uneven surface, depression and wave deformation of the battery cell 400 caused by uneven stress of the tab 100 during formation, and improving the cycle swelling failure of the battery cell 400.

[0094] In a possible implementation, the length of the first section 310 is 100% of the width of the current collector 110, i.e., the length of the first section 310 is equal to the width of the current collector 110.

[0095] In a possible implementation, the thickness of the second section 320 is equal to the thickness of the first section 310, and the thickness h of the first section 310 is in the range of 45 μm to 115 μm, so that after the first section 310 is arranged on the empty foil area 130, the first section 310 is prevented from protruding too much on the surface of the empty foil area 130 due to the too large thickness h of the first section 310, and the flatness of the surface of the battery cell processed from the tab 100 is affected.

[0096] The application further provides a lithium ion battery comprising the battery cell 400, which is described above. Figure 15As shown, the battery cell 400 includes a negative electrode tab 420, a positive electrode tab 430, and a separator 500 separating the negative electrode tab 420 and the positive electrode tab 430, the negative electrode tab 420 and the positive electrode tab 430 are the electrode tab 100 described above, and the negative electrode tab 420, the positive electrode tab 430, and the separator 500 are laminated and wound to form the battery cell 400. The battery cell 400 has a plurality of winding layers arranged outward in sequence along the radial direction of the battery cell 400, and the lug 300 on the negative electrode tab 420 is located in the innermost winding layer of the battery cell 400, or the lug 300 on the negative electrode tab 420 is located in the outermost winding layer of the battery cell 400.

[0097] The battery cell 400 provided by the application includes the electrode tab 100 described above, so that when the negative electrode tab 420 and the positive electrode tab 430 are wound to form the battery cell 400, the thickness distribution of the battery cell 400 is uniform, and the problems of uneven surface, depression, and wave deformation of the battery cell 400 caused by uneven stress on the electrode tab 100 during final formation are improved.

[0098] Since the first section 310 is welded on the empty foil area 130, burrs may be generated. In order to avoid the burrs piercing the separator 500 and causing short circuit of the battery cell, the insulating adhesive tape 200 is needed to cover the burrs, and the recess 312 is used to accommodate the insulating adhesive tape 200, so as to reduce the height difference on the surface of the electrode tab 100 after the insulating adhesive tape 200 is attached, thereby avoiding uneven surface of the electrode tab 100, and affecting the flatness of the surface of the battery cell after the electrode tab 100 is processed into the battery cell.

[0099] In a possible implementation manner, referring to Figure 13 As shown, the side of the first section 310 of the lug 300 close to the active material layer 120 of the electrode tab 100 is a limiting surface 311, and the end surface of the active material layer 120 close to the limiting surface 311 has a spacing H2 from the limiting surface 311; referring to Figure 7 and Figure 14 As shown, the spacing H2 is greater than 2 times the thickness h of the first section 310, and the difference between the spacing H2 and 2 times the thickness h of the first section 310 is δ1, and the numerical range of δ1 is: 2mm≤δ1≤10mm; and / or the spacing H2 is greater than π / 2 times the thickness T of the battery cell 400, and the difference between the spacing H2 and π / 2 times the thickness T of the battery cell 400 is δ2, and the numerical range of δ2 is: 1mm≤δ2≤5mm, or 1mm≤δ2≤4mm.

[0100] This structure, on the one hand, avoids the width of the electrode 100 being affected by bending during the fabrication of the battery cell 400, thus preventing an increase in the width of the battery cell 400; on the other hand, by limiting the distance H2 between one end face of the active material layer 120 near the limiting surface 311 and the limiting surface 311, there is sufficient distance between the limiting surface 311 of the tab 300 and the active material layer 120. During the process of winding the electrode 100 to form the battery cell 400, damage to the active material layer 120 can be reduced, and it is prevented that part of the active material layer 120 is located at a position where the bending curvature of the electrode 100 is extremely small, thus preventing the coated active material layer 120 from falling off.

[0101] In one possible implementation, when the tabs 300 on the negative electrode 420 and / or the tabs 300 on the positive electrode 430 are located in the inner ring of the cell 400, the width D of the tabs 300 on the negative electrode 420 and / or the tabs 300 on the positive electrode 430 satisfies:

[0102] The inner width L2 of cell 400 - the spacing H2 - 1mm ≥ D ≥ the inner width L2 of cell 400 - the spacing H2 - 5mm;

[0103] Wherein, the inner width L2 of the cell 400 is the width of the inner ring layer of the cell 400 in the orthogonal projection direction of the cell 400.

[0104] In one possible implementation, when the tabs 300 on the negative electrode 420 and / or the tabs 300 on the positive electrode 430 are located in the outer ring of the cell 400, the width D of the tabs 300 on the negative electrode 420 and / or the tabs 300 on the positive electrode 430 satisfies:

[0105] The outer width L3 of cell 400 - the thickness T-1mm of cell 400 ≥ D ≥ the outer width L3 of cell 400 - the thickness T-5mm of cell 400;

[0106] Wherein, the outer width L3 of the battery cell 400 is the width of the outer ring layer of the battery cell 400 in the orthogonal projection direction of the battery cell 400, and the thickness T of the battery cell 400 is the height of the outer ring layer of the battery cell 400 in the lateral projection direction of the battery cell 400.

[0107] In one possible implementation, when the tabs 300 on the negative electrode 420 and / or the tabs 300 on the positive electrode 430 are located in the inner ring of the cell 400, reference... Figure 14 As shown, the upper edge of the step 313 of the tab 300 on the negative electrode plate 420 and / or the tab 300 on the positive electrode plate 430 is arc-shaped, and the radius R of the arc is 1 / 6 times the thickness of the first segment 310.

[0108] In a possible implementation, when the tab 300 on the negative electrode sheet 420 and / or the tab 300 on the positive electrode sheet 430 are located at the outer ring layer of the battery cell 400, the edge of the upper end of the step 313 of the tab 300 on the negative electrode sheet 420 and / or the tab 300 on the positive electrode sheet 430 is in a circular arc shape, and the radius R of the circular arc shape is 1 / 3 of the thickness of the first section 310.

[0109] It is easily understood that the lithium ion battery provided in the embodiment further includes a packaging shell, and the battery cell 400 is accommodated in the packaging shell and filled with electrolyte in the packaging shell.

[0110] In the embodiment, the material of the current collector 110 in the negative electrode sheet 420 and the positive electrode sheet 430 can be set according to actual needs, and is not further limited herein. For example, the current collector 110 in the positive electrode sheet 430 can be an aluminum foil, and the current collector 110 in the negative electrode sheet 420 can be a copper foil.

[0111] In the embodiment, the type and proportion of the active material in the active material layer 120 in the negative electrode sheet 420 and the positive electrode sheet 430 can also be set according to actual needs, and is not further limited herein. For example, the active material in the active material layer 120 in the negative electrode sheet 420 can include graphite, hard carbon, silicon, silicon monoxide, and the like, and the active material in the active material layer 120 in the positive electrode sheet 430 can include lithium cobaltate, lithium iron phosphate, lithium manganate, and the like.

[0112] The separator 500 can include a base material and a coating layer, where the base material can be a polythene (PE) single-layer film, a polypropylene (PP) single-layer film, or a polypropylene-polythene-polypropylene three-layer composite film, and the coating layer can be at least one of porous silicon dioxide, aluminum trioxide, titanium dioxide, and zirconium dioxide.

[0113] Embodiment One

[0114] Reference Figure 15 As shown in FIG. 1, when the tab 300 on the negative electrode sheet 420 and the tab 300 on the positive electrode sheet 430 are both located at the inner ring layer of the battery cell 400:

[0115] In the width direction of the first section 310, the side of the first section 310 close to the active material layer 120 is a limiting surface 311, and the distance between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is a distance H2. The distance H2 is greater than 2 times the thickness h of the first section 310, and the difference between the distance H2 and 2 times the thickness h of the first section 310 is δ1, and the numerical range of δ1 is: 2mm≤δ1≤10mm.

[0116] The inner width L2 of the battery cell 400 is the width of the inner circle layer of the battery cell 400 in the direction of orthographic projection, and the width D of the tab 300 on the negative electrode sheet 420 and the width D of the tab 300 on the positive electrode sheet 430 both satisfy:

[0117] The inner width L2 of the battery cell 400 - the spacing H2 - 1 mm ≥ D ≥ the inner width L2 of the battery cell 400 - the spacing H2 - 5 mm ≥ 0.

[0118] In the tab 300 on the negative electrode sheet 420 and the tab 300 on the positive electrode sheet 430, the edge of the upper end of the step 313 of the tab 300 is in the form of a circular arc, and the radius R of the circular arc is 1 / 6 of the thickness of the first section 310.

[0119] Such a structure, on the one hand, can avoid the width affected by the bending of the electrode sheet 100 when the battery cell 400 is manufactured, and can avoid an increase in the width of the battery cell 400. On the other hand, by limiting the spacing H2 between the end face of the active material layer 120 close to the limiting face 311 and the limiting face 311, the limiting face 311 of the tab 300 has a sufficient distance from the active material layer 120, which can reduce damage to the active material layer 120 during the process of winding the electrode sheet 100 into the battery cell 400, and can avoid the situation that part of the active material layer 120 is located at a position where the bending radius of the electrode sheet 100 is minimal, and the coated active material layer 120 falls off.

[0120] The length of the tab 300 on the negative electrode sheet 420 and the length of the tab 300 on the positive electrode sheet 430 both satisfy: the length of the first section 310 is 40% to 105% of the width of the current collector 110.

[0121] The thickness of the second section 320 is equal to the thickness of the first section 310, and the thickness h of the first section 310 has a numerical range of 45 μm ≤ h ≤ 115 μm.

[0122] The length, width and position of the second section 320 on the first section 310 can be determined according to the use requirements.

[0123] Embodiment Two

[0124] Reference Figure 16 As shown in the figure, when the tab 300 on the negative electrode sheet 420 is located in the inner circle layer of the battery cell 400, and the tab 300 on the positive electrode sheet 430 is located in the outer circle layer of the battery cell 400:

[0125] For the tab 300 on the negative electrode sheet 420:

[0126] In the width direction of the first section 310, the side of the first section 310 close to the active material layer 120 is a limiting surface 311, and the distance between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is a distance H2. The distance H2 is greater than 2 times the thickness h of the first section 310, and the difference between the distance H2 and 2 times the thickness h of the first section 310 is δ1, and the numerical range of δ1 is: 2mm≤δ1≤10mm.

[0127] The inner width L2 of the battery cell 400 is the width of the inner ring layer of the battery cell 400 in the orthographic projection direction, and the width D of the tab 300 on the negative electrode sheet 420 satisfies:

[0128] The inner width L2 of the battery cell 400 minus the distance H2 minus 1mm is greater than or equal to D, and the inner width L2 of the battery cell 400 minus the distance H2 minus 5mm is greater than or equal to 0.

[0129] In the tab 300 on the negative electrode sheet 420: the edges of the upper end of the step 313 of the tab 300 are all in the form of a circular arc, and the radius R of the circular arc is 1 / 6 times the thickness of the first section 310.

[0130] The length of the tab 300 on the negative electrode sheet 420 and the length of the tab 300 on the positive electrode sheet 430 both satisfy: the length of the first section 310 is 40% to 105% of the width of the current collector 110.

[0131] For the tab 300 on the positive electrode sheet 430:

[0132] In the width direction of the first section 310, the side of the first section 310 close to the active material layer 120 is a limiting surface 311, and the distance between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is a distance H2. The distance H2 is greater than π / 2 times the thickness T of the battery cell 400, and the difference between the distance H2 and π / 2 times the thickness T of the battery cell 400 is δ2, and the numerical range of δ2 is: 1mm≤δ2≤5mm.

[0133] The outer width L3 of the battery cell 400 is the width of the outer ring layer of the battery cell 400 in the orthographic projection direction of the battery cell 400, the thickness T of the battery cell 400 is the height of the outer ring layer of the battery cell 400 in the side projection direction, and the width D of the tab 300 on the positive electrode sheet 430 satisfies:

[0134] The outer width L3 of the battery cell 400 minus the thickness T of the battery cell 400 minus 1mm is greater than or equal to D, and the outer width L3 of the battery cell 400 minus the thickness T of the battery cell 400 minus 5mm is greater than or equal to 0.

[0135] In the tab 300 on the positive electrode sheet 430: the edges of the upper end of the step 313 of the tab 300 are all in the form of a circular arc, and the radius R of the circular arc is 1 / 3 times the thickness of the first section 310.

[0136] Such structure can avoid the influence of the bending of the tab 100 on the width of the electrode sheet 100 when the electrode sheet 100 is made into the battery cell 400, and avoid the increase of the width of the battery cell 400. On the other hand, by limiting the distance H2 between the end face of the active material layer 120 close to the limiting face 311 and the limiting face 311, the limiting face 311 of the tab 300 has enough distance from the active material layer 120, which can reduce the damage to the active material layer 120 during the winding of the electrode sheet 100 into the battery cell 400, and avoid the partial active material layer 120 from being located at the position where the bending of the electrode sheet 100 is minimal, such as the bending position of the electrode sheet 100 in the innermost layer of the battery cell 400, and causing the active material layer 120 to fall off.

[0137] Embodiment Three

[0138] Referring to Figure 17 As shown in the figure, when the tab 300 on the positive electrode sheet 430 is located in the inner layer of the battery cell 400, and the tab 300 on the negative electrode sheet 420 is located in the outer layer of the battery cell 400:

[0139] For the tab 300 on the positive electrode sheet 430:

[0140] In the width direction of the first section 310, the side face of the first section 310 close to the active material layer 120 is the limiting face 311, and the distance between the end face of the active material layer 120 close to the limiting face 311 and the limiting face 311 is the distance H2. The distance H2 is greater than 2 times the thickness h of the first section 310, and the difference between the distance H2 and 2 times the thickness h of the first section 310 is δ1, and the numerical range of δ1 is: 2mm≤δ1≤10mm.

[0141] The inner width L2 of the battery cell 400 is the width of the inner layer of the battery cell 400 in the orthogonal projection direction, and the width D of the tab 300 on the positive electrode sheet 430 satisfies:

[0142] The inner width L2 of the battery cell 400 minus the distance H2 minus 1mm is greater than or equal to D, and D is greater than or equal to the inner width L2 of the battery cell 400 minus the distance H2 minus 5mm and greater than or equal to 0.

[0143] The length of the tab 300 on the negative electrode sheet 420 and the length of the tab 300 on the positive electrode sheet 430 both satisfy: the length of the first section 310 is 40% to 105% of the width of the current collector 110.

[0144] The thickness of the second section 320 is equal to the thickness of the first section 310, and the numerical range of the thickness h of the first section 310 is: 45μm≤h≤115μm.

[0145] The edge of the upper end of the step 313 of the tab 300 on the positive electrode sheet 430 is in the shape of a circular arc, and the radius R of the circular arc is 1 / 6 times the thickness of the first section 310.

[0146] For the tab 300 on the negative electrode sheet 420:

[0147] In the width direction of the first section 310, the side of the first section 310 close to the active material layer 120 is a limiting surface 311, and the distance between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is H2. The distance H2 is greater than π / 2 times the thickness T of the battery cell 400, and the difference between the distance H2 and π / 2 times the thickness T of the battery cell 400 is δ2, and the numerical range of δ2 is: 1mm≤δ2≤4mm.

[0148] The outer width L3 of the battery cell 400 is the width of the outer ring layer of the battery cell 400 in the orthographic projection direction, the thickness T of the battery cell 400 is the height of the battery cell 400 in the side projection direction of the battery cell 400, and the width D of the tab 300 on the negative electrode sheet 420 satisfies:

[0149] The outer width L3 of the battery cell 400 minus the thickness T of the battery cell 400 minus 1mm≥D≥The outer width L3 of the battery cell 400 minus the thickness T of the battery cell 400 minus 5mm≥0.

[0150] In the tab 300 on the negative electrode sheet 420: the edges of the upper end of the step 313 of the tab 300 are all in the form of a circular arc, and the radius R of the circular arc is 1 / 3 times the thickness of the first section 310.

[0151] Such a structure can avoid the influence of the bending of the tab 100 on the width when the battery cell 400 is made, and avoid the increase of the width of the battery cell 400. On the other hand, by limiting the distance H2 between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311, the limiting surface 311 of the tab 300 and the active material layer 120 have sufficient distance, which can reduce the damage to the active material layer 120 during the winding of the tab 100 into the battery cell 400, and avoid that part of the active material layer 120 is located at the position where the bending radius of the tab 100 is the smallest, for example, the bending position of the tab 100 located at the innermost ring of the battery cell 400, causing the active material layer 120 to fall off.

[0152] The lithium ion battery provided by the embodiment of the present application makes full use of the thickness space of the battery cell itself to adjust the flatness of the battery cell, without increasing the thickness of the battery cell itself, without affecting the energy density of the battery cell, and achieves the purpose of considering both the flatness and the energy density.

[0153] The lithium ion battery provided by the embodiment of the present application can effectively improve the thickness distribution of the innermost layer of the battery cell 400 by improving the structure of the tab 300, and solve the problems of uneven surface, depression and wave deformation of the tab 100 caused by uneven stress during formation.

[0154] The lithium ion battery provided by the embodiment of the present application can effectively improve the problem of poor adhesion of the separator 500, improve the problem of lithium precipitation at the interface caused by poor adhesion between the pole piece 100 and the separator 500 in the later stage of the charge-discharge cycle, and improve the flatness of the battery cell 400.

[0155] The lithium ion battery provided by the present application can effectively improve the problem that the uneven internal stress of the pole piece 100 in the cycle expansion process of the battery cell 400 caused by the flatness problem of the battery cell 400, finally leads to the failure of the adhesion surface of the battery cell 400, the expansion deformation of the battery cell 400, and the problems of capacity attenuation and expansion failure, and improves the cycle life and safety performance of the lithium ion battery.

[0156] The pole piece 100 provided by the present application is suitable for all battery cell models. Hereinafter, the battery cell 400 of the lithium ion battery is taken as an example for description, for example, the lithium ion battery with the model number "366283" is taken as an example for description.

[0157] Example 1

[0158] Example 1 is an example of embodiment 1.

[0159] Reference Figure 15 As shown in the figure, the tab 300 on the negative electrode piece 420 and the tab 300 on the positive electrode piece 430 are both located in the inner circle layer of the battery cell 400, the outer width L3 of the battery cell 400 is 60 mm, the inner width L2 of the battery cell 400 is 57 mm, and the height of the battery cell 400 is 80 mm.

[0160] In the positive electrode piece 430: the width of the pole piece 100 is 75.5 mm, the length of the empty foil area 130 on the positive electrode piece 430 for installing the tab 300 is 55 mm, the thickness of the tab 300 is 80 μm, the width of the tab 300 is 50 mm, and the length of the first section 310 of the tab 300 is 75.5 mm. The spacing H1 between the bottom surface of the recess 312 and the top surface of the first section 310 is 15 μm, that is, the edge of the tab 300 in the width direction is 10 mm inward from the middle position of the tab, and the edges of the upper ends of the two steps 313 of the tab 300 need to be rounded with a circular arc, and the radius R of the circular arc is 1 / 6 of the thickness of the first section 310. When the tab 300 is welded, the spacing H2 between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is 4 mm, the thickness of the second section 320 is equal to the thickness of the first section 310, and the length, width and protruding end position of the second section 320 can be determined according to the use requirement.

[0161] In the negative electrode tab 420: the width of the tab 100 is 77.5 mm, the length of the empty foil area 130 on the negative electrode tab 420 where the tab 300 is installed is 56 mm, the thickness of the tab 300 is 80 μm, the width of the tab 300 is 50 mm, and the length of the first section 310 of the tab 300 is 75.5 mm. The distance H1 between the bottom surface of the recess 312 and the top surface of the first section 310 is 15 μm, i.e., the edge of the tab 300 at a position 10 mm inward from the width direction edge of the tab 300 is 15 μm thinner than the middle position of the tab 300, and the edges of the upper ends of the two steps 313 of the tab 300 need to be rounded with a circular arc, and the radius R of the circular arc is 1 / 6 of the thickness of the first section 310. When the tab 300 is welded, the distance H2 between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is 5 mm, the thickness of the second section 320 is equal to the thickness of the first section 310, and the length, width, and protruding end position of the second section 320 can be determined according to the use requirements.

[0162] Example Two

[0163] Example Two is an example of Embodiment Two:

[0164] Examination Figure 16 As shown in the figure, the tab 300 on the negative electrode tab 420 is located in the inner ring layer of the battery cell 400, and the tab 300 on the positive electrode tab 430 is located in the outer ring layer of the battery cell 400. The outer width L3 of the battery cell 400 is 60 mm, the inner width L2 of the battery cell 400 is 57 mm, and the height of the battery cell 400 is 80 mm.

[0165] In the positive electrode tab 430: the width of the tab 100 is 75.5 mm, the length of the empty foil area 130 on the positive electrode tab 430 where the tab 300 is installed is 85 mm, the tab 300 on the positive electrode tab 430 is arranged on the outer ring layer of the battery cell 400, the thickness of the tab 300 is 80 μm, the width of the tab 300 is 55 mm, the length of the first section 310 of the tab 300 is 75.5 mm, and the distance H1 between the bottom surface of the recess 312 and the top surface of the first section 310 is 15 μm, i.e., the edge of the tab 300 at a position 10 mm inward from the width direction edge of the tab 300 is 15 μm thinner than the middle position of the tab 300, and the edges of the upper ends of the two steps 313 of the tab 300 need to be rounded with a circular arc, and the radius R of the circular arc is 1 / 3 of the thickness of the first section 310. When the tab 300 is welded, the distance H2 between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is 5 mm, the thickness of the second section 320 is equal to the thickness of the first section 310, and the length, width, and protruding end position of the second section 320 can be determined according to the use requirements.

[0166] In the negative electrode tab 420: the width of the tab 100 is 77.5 mm, the length of the empty foil area 130 on the negative electrode tab 420 where the tab 300 is installed is 56 mm, the thickness of the tab 300 is 80 μm, the width of the tab 300 is 50 mm, and the length of the first section 310 of the tab 300 is 77.5 mm. The distance H1 between the bottom surface of the recess 312 and the top surface of the first section 310 is 15 μm, i.e., the edge of the tab 300 at a position 10 mm inward from the width direction edge of the tab 300 is 15 μm thinner than the middle position of the tab 300, and the edges of the upper ends of the two steps 313 of the tab 300 need to be rounded with a circular arc, and the radius R of the circular arc is 1 / 6 of the thickness of the first section 310. When the tab 300 is welded, the distance H2 between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is 5 mm, the thickness of the second section 320 is equal to the thickness of the first section 310, and the length, width, and protruding end position of the second section 320 can be determined according to the use requirement.

[0167] Example Three

[0168] Example Three is an example of Embodiment Three:

[0169] Examination Figure 17 As shown in the figure, the tab 300 on the positive electrode tab 430 is located in the inner circle layer of the battery cell 400, and the tab 300 on the negative electrode tab 420 is located in the outer circle layer of the battery cell 400. The outer width L3 of the battery cell 400 is 60 mm, the inner width L2 of the battery cell 400 is 57 mm, and the height of the battery cell 400 is 80 mm.

[0170] In the positive electrode tab 430: the width of the tab 100 is 75.5 mm, the length of the empty foil area 130 on the positive electrode tab 430 where the tab 300 is installed is 55 mm, the thickness of the tab 300 is 80 μm, the width of the tab 300 is 50 mm, the length of the first section 310 of the tab 300 is 75.5 mm, the distance H1 between the bottom surface of the recess 312 and the top surface of the first section 310 is 15 μm, i.e., the edge of the tab 300 at a position 10 mm inward from the width direction edge of the tab 300 is 15 μm thinner than the middle position of the tab 300, and the edges of the upper ends of the two steps 313 of the tab 300 need to be rounded with a circular arc, and the radius R of the circular arc is 1 / 6 of the thickness of the first section 310. When the tab 300 is welded, the distance H2 between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is 4 mm, the thickness of the second section 320 is equal to the thickness of the first section 310, and the length, width, and protruding end position of the second section 320 can be determined according to the use requirement.

[0171] In the negative electrode sheet 420: the width of the electrode sheet 100 is 77.5 mm, the length of the empty foil area 130 on which the tab 300 is mounted on the negative electrode sheet 420 is 63 mm, the tab 300 on the negative electrode sheet 420 is arranged on the outermost layer of the battery cell 400, the thickness of the tab 300 is 80 μm, the width of the tab 300 is 54 mm, and the length of the first section 310 of the tab 300 is 77.5 mm. The spacing H1 between the bottom surface of the recess 312 and the top surface of the first section 310 is 15 μm, that is, the edge of the tab 300 inwardly 10 mm from the middle position of the tab is 15 μm thinner than the middle position of the tab, and the edges of the upper ends of the two steps 313 of the tab 300 need to be rounded with a circular arc, and the radius R of the circular arc is 1 / 3 of the thickness of the first section 310. When the tab 300 is welded, the spacing H2 between the end surface of the active material layer 120 close to the limiting surface 311 and the limiting surface 311 is 5 mm, the thickness of the second section 320 is equal to the thickness of the first section 310, and the length, width and protruding end position of the second section 320 can be determined according to the use requirements.

[0172] Reference Figure 18 and Figure 19 As shown in the following table 1, the thickness data of the existing battery cell 400 and the battery cells 400 of examples 1, 2 and 3 are collected, and the cycle test data are shown in the following table 1:

[0173] Table 1

[0174]

[0175]

[0176] The thickness is tested by a 3D high-resolution microscope, and the measurement has a certain error due to operation problems, but the error can be controlled within an error range of 0.01 mm. At the same time, during the preparation of the battery, the design value and the actual measured value may have errors due to factors such as the thickness difference of the coated electrode sheet, but the error can be basically controlled within a range of 0.03 mm.

[0177] Through the analysis of the data in table 1, it is found that by improving the structure of the tab 300 and the electrode sheet 100, the thickness distribution of the innermost layer of the battery cell 400 can be effectively improved, the uneven stress of the electrode sheet 100 during formation can be improved, the problems of uneven surface, depression and wave deformation of the battery cell 400 can be solved, the uniform formation pressure can effectively improve the poor adhesion of the separator 500, the poor adhesion between the electrode sheet 100 and the separator 500 after the cycle can cause lithium precipitation, the flatness of the battery cell 400 can be improved, and the cycle swelling failure can be improved.

[0178] The lithium ion battery provided by the application can effectively improve the problem that the uniformity of the internal stress suffered by the pole piece 100 of the battery cell 400 is not uniform in the cycle expansion process due to the flatness problem of the battery cell 400 in the long cycle process, and finally leads to the problems of the bonding section failure of the battery cell 400, the expansion deformation of the battery cell 400, the capacity attenuation, and the expansion failure, and improves the cycle life and safety performance of the battery.

[0179] It should be noted that the numerical values and numerical ranges involved in the present application are approximate values, and there may be a certain range of errors due to the influence of the manufacturing process, which can be considered negligible by those skilled in the art.

[0180] In the description of the present application, it should be understood that the terms "center", "length", "width", "thickness", "top end", "bottom end", "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inner", "outer", "axial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the indicated position or element must have a particular orientation, a particular structure and operation, and therefore cannot be understood as a limitation on the present application.

[0181] In addition, the terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0182] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0183] In the present application, unless otherwise explicitly specified and limited, "on" or "under" of a first feature to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "over" of a first feature to a second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. "Under", "below" and "underneath" of a first feature to a second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0184] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrode sheet, characterized in that, The electrode includes a current collector (110) and a tab (300). The tab (300) includes a first segment (310) and a second segment (320) connected to the first segment (310). Both sides of the top surface of the first segment (310) have downward recessed recesses (312). The first segment (310) extends along the width direction of the current collector (110), the first segment (310) is connected to the empty foil area (130) of the current collector (110), and the second segment (320) is exposed outside the current collector (110); It also includes insulating tape (200), which covers at least the recess (312) and at least part of the empty foil area (130); the recess (312) extends through both ends of the first segment (310) in the length direction, and the insulating tape (200) does not protrude above the top surface of the first segment (310).

2. The electrode sheet according to claim 1, characterized in that, The width L1 of the recess (312) is 10mm to 15mm; there is a distance H1 between the bottom surface of the recess (312) and the top surface of the first segment (310), the distance H1 being in the range of 15μm to 25μm; and / or The width of the first segment (310) is greater than the width of the second segment (320).

3. The electrode sheet according to claim 2, characterized in that, The first segment (310) also has steps (313) on both sides located at the bottom of the recess (312), the upper edge of the step (313) being arc-shaped, and the radius R of the arc being 1 / 3 times the thickness of the first segment (310); or The radius R of the arc is 1 / 6 times the thickness of the first segment (310).

4. The electrode sheet according to any one of claims 1-3, characterized in that, Also includes: An active material layer (120) is disposed on both the front and back surfaces of the current collector (110) and / or on one of the two front and back surfaces of the current collector (110). At least one end of the current collector (110) in the length direction has an empty foil area (130) where the active material layer (120) is not disposed. An electrode tab (300) is disposed on the empty foil area (130) of the current collector (110). The electrode tab (300) includes a first segment (310) and a second segment (320) connected to the first segment (310). Both sides of the top surface of the first segment (310) have downwardly recessed recesses (312).

5. The electrode sheet according to claim 4, characterized in that, The first segment (310) extends along the width direction of the current collector (110), and the length of the first segment (310) is 40% to 105% of the width of the current collector (110).

6. A lithium-ion battery, comprising a cell (400), characterized in that, The battery cell (400) includes a negative electrode sheet (420), a positive electrode sheet (430), and a separator (500) separating the negative electrode sheet (420) and the positive electrode sheet (430). The negative electrode sheet (420) and the positive electrode sheet (430) are electrode sheets (100) as described in any one of claims 1-5. The negative electrode sheet (420), the positive electrode sheet (430), and the separator (500) are stacked and wound to form the battery cell (400). The battery cell (400) has a plurality of layers wound outward in sequence. The tabs (300) on the negative electrode sheet (420) are located in the inner ring of the battery cell (400), or the tabs (300) on the negative electrode sheet (420) are located in the outer ring of the battery cell (400).

7. The lithium-ion battery according to claim 6, characterized in that, The first segment (310) of the electrode (300) has a limiting surface (311) on one side near the active material layer (120) of the electrode (100), and there is a gap H2 between one end face of the active material layer (120) near the limiting surface (311) and the limiting surface (311). The spacing H2 is greater than twice the thickness h of the first segment (310), and the difference between the spacing H2 and twice the thickness h of the first segment (310) is δ1, wherein the value of δ1 is in the range of 2mm ≤ δ1 ≤ 10mm; and / or The spacing H2 is greater than π / 2 times the thickness T of the battery cell (400), and the difference between the spacing H2 and π / 2 times the thickness T of the battery cell (400) is δ2. The value range of δ2 is: 1mm≤δ2≤5mm or 1mm≤δ2≤4mm.

8. The lithium-ion battery according to claim 7, characterized in that, When the tabs (300) on the negative electrode plate (420) and / or the tabs (300) on the positive electrode plate (430) are located in the inner ring of the cell (400), the width D of the tabs (300) on the negative electrode plate (420) and / or the tabs (300) on the positive electrode plate (430) satisfies: The inner width L2 of the cell (400) - the spacing H2 - 1mm ≥ D ≥ the inner width L2 of the cell (400) - the spacing H2 - 5mm; Wherein, the inner width L2 of the battery cell (400) is the width of the innermost ring of the battery cell (400) in the direction of the positive projection of the battery cell (400).

9. The lithium-ion battery according to claim 8, characterized in that, When the tabs (300) on the negative electrode plate (420) and / or the tabs (300) on the positive electrode plate (430) are located in the outer ring layer of the battery cell (400), the width D of the tabs (300) on the negative electrode plate (420) and / or the tabs (300) on the positive electrode plate (430) satisfies: The outer width L3 of the battery cell (400) - the thickness T-1mm of the battery cell (400) ≥ D ≥ the outer width L3 of the battery cell (400) - the thickness T-5mm of the battery cell (400); Wherein, the outer width L3 of the battery cell (400) is the width of the outer ring layer of the battery cell (400) in the orthogonal projection direction of the battery cell (400), and the thickness T of the battery cell (400) is the height of the outer ring layer of the battery cell (400) in the lateral projection direction of the battery cell (400).

10. The lithium-ion battery according to claim 9, characterized in that, When the tabs (300) on the negative electrode plate (420) and / or the tabs (300) on the positive electrode plate (430) are located in the inner ring of the cell (400), the upper edge of the step (313) of the tab (300) is arc-shaped, and the radius R of the arc is 1 / 6 times the thickness of the first segment (310); or When the tab (300) on the negative electrode sheet (420) and / or the tab (300) on the positive electrode sheet (430) are located in the outer ring layer of the cell (400), the upper edge of the step (313) of the tab (300) is arc-shaped, and the radius R of the arc is 1 / 3 times the thickness of the first segment (310).

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