Electrode assembly, battery and electric equipment

Abstract

The invention provides an electrode assembly, a battery and electric equipment, and relates to the technical field of batteries. The electrode assembly includes a wound body. The winding body comprises a wound pole piece, and the pole piece comprises a pole piece body, a tab area and a transition area. The pole piece body is coated with an active substance, and the pole piece body is connected with the tab region through the transition region. And the tab region comprises a plurality of tabs which are arranged at intervals along the winding circumferential direction. The tab area comprises a first section and a second section, one end of the first section is connected with one end, far away from the pole piece body, of the transition area, the second section is connected with one end, far away from the transition area, of the first section, the first section is bent towards the direction far away from the winding center along the leveling direction of the tab area towards the pole piece body, and the second section is bent towards the direction of the winding center. In the leveling process of the tabs, the first section and the second section can be regularly leveled to the pole piece body according to the bending direction, so that the problem that metal chips are generated due to rubbing is effectively avoided, and the distribution rule of the tabs is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrode assembly, a battery and an electrical device. Background Art

[0002] The preparation process of the electrode assembly of the full-tab battery cell generally includes the winding of the pole piece and the flattening of the pole piece. In some related technologies, the flattening of the pole piece is carried out by mechanical flattening, which causes the pole piece to bend irregularly, resulting in a disorderly arrangement of the pole piece. In other related technologies, after the pole piece is wound, the pole piece is mechanically flattened. Although it can improve the regularity of the distribution of the pole piece, during the flattening process, metal shavings are easily generated due to collision and extrusion between the pole pieces, which may cause the risk of short circuit. Summary of the invention

[0003] The embodiments of the present application provide an electrode assembly, a battery and an electrical device for improving the problem that the tabs in the electrode assembly cannot simultaneously reduce the generation of metal chips and arrange the tabs regularly during the flattening process.

[0004] In a first aspect, an embodiment of the present application provides an electrode assembly, comprising a wound body, the wound body comprising a wound pole piece, the pole piece comprising a pole piece body, a pole lug region and a transition region, the pole piece body being coated with an active material, the pole lug region and the transition region being uncoated with an active material, the pole piece body being connected to the pole lug region via the transition region, and the pole lug region comprising a plurality of pole lugs arranged along a winding circumferential direction;

[0005] Among them, the pole ear area includes a first section and a second section, one end of the first section is connected to one end of the transition zone away from the pole piece body, and the second section is connected to the other end of the first section away from the transition zone. When the pole ear area is flattened to the winding body, one of the first section and the second section is bent in a direction away from the winding center, and the other is bent in a direction close to the winding center.

[0006] In some embodiments of the present application, the length of the first segment is d1, and the length of the second segment is d2;

[0007] Among them, d2>d1.

[0008] In some embodiments of the present application, the winding body includes an isolation film, which is wound between two adjacent pole pieces with different polarities, and along the axial direction of the winding body, the isolation film includes a first end point close to the first segment;

[0009] A first bending point is formed at the connection between the first section and the transition zone, a second bending point is formed at the connection between the second section and the first section, and along the axial direction of the winding body, the distance between the first bending point and the first end point is d3, and the distance between the second bending point and the first end point is Y1;

[0010] Wherein, Y1=d1×X±d3, X is a correction coefficient, and X is greater than 0 and less than 1.

[0011] In some embodiments of the present application, along the axial direction of the winding body, when the first bending point is located on the side of the first end point close to the pole piece body, Y1, d1, and d3 satisfy the following formula:

[0012] Y1=d1×X-d3;

[0013] Along the axial direction of the winding body, when the first bending point is located on the side of the first end point away from the pole piece body, Y1, d1, and d3 satisfy the following formula:

[0014] Y1=d1×X+d3.

[0015] In some embodiments of the present application, the pole piece includes a first pole piece and a second pole piece, the isolation film is provided between the first pole piece and the second pole piece, the first pole piece and the second pole piece have opposite polarities, the thickness of the first pole piece is b1, the thickness of the second pole piece is b2, the thickness of the isolation film is b3, and the total thickness of the adjacent first pole piece, the second pole piece and the two isolation films is t=b1+b2+2b3;

[0016] The number of windings e1 covered by the first section in the radial direction of the winding body satisfies:

[0017] e1≤d1÷t.

[0018] In some embodiments of the present application, the number of windings e2 covered by the second section in the radial direction of the winding body satisfies:

[0019] e2≤d2÷t.

[0020] In some embodiments of the present application, an angle formed by an extension line of the first segment and an extension line of the second segment is greater than 0° and less than 30°.

[0021] In some embodiments of the present application, the overlapping area between two adjacent pole lugs in the same winding coil accounts for S1 in the total area of ​​the two pole lugs, and along the radial direction of the winding body, the overlapping area between two adjacent pole lugs accounts for S2 in the total area of ​​the two pole lugs;

[0022] Among them, the range of S1 is 0<S1<30%;

[0023] S2=(d2+d1-d4-t / cosθ) / (d1+d2), and the range of S2 is 50%<S2<95%;

[0024] d4 is the length of the non-overlapping portion between two adjacent pole ears along the radial direction of the winding body, and θ is the angle formed by the extension line of the first section and the extension line of the second section.

[0025] In some embodiments of the present application, the plurality of pole tabs of the first pole piece are bent and stacked to form a first welding surface, and the first welding surface can be welded with a thickness range of greater than 0.04 mm and less than 1.2 mm;

[0026] The plurality of pole ears of the second pole piece are bent and stacked to form a second welding surface, and the second welding surface can be welded with a thickness range of greater than 0.03 mm and less than 0.6 mm.

[0027] In some embodiments of the present application, the pole piece arranged in a wound manner includes an inner circumference winding section without pole lugs, a winding section with pole lugs and an outer circumference winding section without pole lugs which are connected in sequence along the winding direction. The maximum radius of the inner circumference winding section without pole lugs is r, the radius of the center hole formed by the winding body is r0, and along the winding direction, the maximum pole lug height of the first pole lug of the winding section with pole lugs is h1<r-r0.

[0028] In some embodiments of the present application, the length of the inner circumference non-polar lug winding section in the winding direction satisfies: L2 ≥ L1-L0; the length of the outer circumference non-polar lug winding section in the winding direction satisfies: L5 ≥ L4-L3;

[0029] Wherein, L0 refers to the virtual arc length of the spiral trajectory of the inner circumference non-polar lug winding section, which is wound with the radius of the center hole as the maximum radius, simulating the spiral trajectory of the inner circumference non-polar lug winding section, L1 refers to the minimum winding path length from the winding radius of 0 to the minimum radius of the inner circumference non-polar lug winding section, L2 refers to the length of the inner circumference non-polar lug winding section in the winding direction, L3 refers to the total winding length of the winding body from the winding radius of 0 to the radius where the winding head end of the outer circumference non-polar lug winding section is located, L4 refers to the winding path length from the winding radius of 0 to the maximum winding radius, and L5 refers to the length of the outer circumference non-polar lug winding section in the winding direction;

[0030] The L0, L1, L3, and L4 all satisfy the following formula:

[0031] L=(a / 2)×{φ·√(1+φ 2 )+ln[φ+√(1+φ 2 )]};

[0032] Where a is the helix parameter and φ is the rotation angle.

[0033] In some embodiments of the present application, the stacking thickness of the first sections of the plurality of tabs in the axial direction of the winding body satisfies: D1≤d1÷t×H;

[0034] The stacking thickness of the second sections of the plurality of tabs in the axial direction of the winding body satisfies: D2≤d2÷t×H;

[0035] Wherein, D1 refers to the stacking thickness of the first sections of the plurality of pole tabs in the axial direction of the winding body, D2 refers to the stacking thickness of the second sections of the plurality of pole tabs in the axial direction of the winding body, and H refers to the thickness of the transition zone.

[0036] In some embodiments of the present application, a gap is formed between the stacking of the first section and the second section of the tab, and the height of the gap in the stacking direction satisfies: D3 = k1 × D1 + k2 × D2;

[0037] The total stacking thickness of the first sections and the second sections of the plurality of tabs after stacking satisfies: D4=D1+D2+D3;

[0038] Wherein, K1 and K2 are both coefficients, K1 satisfies: 0.2<K1<2, and K2 satisfies: 0.2<K2<2.

[0039] In some embodiments of the present application, along the axial direction of the winding body, the length of the pole piece body of the first pole piece is smaller than the length of the pole piece body of the second pole piece, and the shortest distance between the pole piece body of the second pole piece and the first section of the first pole piece is no more than 5 mm.

[0040] In a second aspect, an embodiment of the present application provides a battery, comprising a shell and an electrode assembly as described in the first aspect, wherein the electrode assembly is installed in the shell.

[0041] In a third aspect, an embodiment of the present application provides an electrical device, comprising the battery as described in the second aspect.

[0042] Beneficial effects of the embodiments of the present application:

[0043] The present application provides an electrode assembly, a battery and an electrical device, by dividing the pole ear into a first section and a second section, and pre-bending the first section and the second section in different directions, so that during the flattening process of the winding body, the first section and the second section can be regularly flattened onto the pole piece body in the bending direction, and the flattening process of the pole ear does not involve a mechanical flattening process, thereby effectively avoiding the problem of metal chips generated by flattening. Moreover, because the first section and the second section are bent in different directions, when the pole ear is flattened, the first section and the second section can be flattened in the bending direction, thereby improving the distribution regularity of multiple pole ears. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic structural diagram of an electrode assembly provided in an embodiment of the present application;

[0045] Figure 2 is a schematic diagram of the structure of adjacent pole pieces in an electrode assembly provided in an embodiment of the present application (a state when the pole tab is not bent);

[0046] Figure 3 It is a schematic diagram of the structure of adjacent pole pieces in an electrode assembly provided in an embodiment of the present application (a state in which the pole tab is bent);

[0047] Figure 4 It is a structural schematic diagram of a first bending point of adjacent pole pieces in an electrode assembly provided by an embodiment of the present application, which is located above a first end point;

[0048] Figure 5 It is a structural schematic diagram of a first bending point of adjacent pole pieces in an electrode assembly provided by an embodiment of the present application, which is located below a first end point;

[0049] Figure 6 It is a schematic structural diagram of an electrode assembly provided in an embodiment of the present application in which a plurality of pole pieces and an isolation membrane are arranged adjacent to each other.

[0050] Description of reference numerals:

[0051] 1. Winding body; 11. Pole piece; 111. Pole piece body; 112. Pole tab area; 1121. First section; 1122. Second section; 113. Transition zone; 114. First bending point; 115. Second bending point; 116. Inner winding section without pole tabs; 117. Outer winding section without pole tabs; 118. Winding section with pole tabs; 12. Isolation membrane; 121. First endpoint. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise stated, the directional words such as "upper" and "lower" used generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0053] See also Figure 1 , Figure 2 as well as Figure 3 , an embodiment of the present application provides an electrode assembly, including a winding body 1. The winding body 1 includes a pole piece 11 that is wound, and the pole piece 11 includes a pole piece body 111, a pole lug area 112, and a transition area 113. The pole piece body 111 is coated with an active material, and the pole piece body 111 is connected to the pole lug area 112 through the transition area 113. It should be noted that the pole piece body 111, the transition area 113, and the pole lug area 112 are actually part of the pole piece 11, and the three are integrally formed, except that the pole lug area 112 and the transition area 113 are not coated with active materials, the pole piece body 111 is coated with active materials, and the difference between the pole lug area 112 and the transition area 113 is mainly whether it is bent, the pole lug area 112 needs to be bent, and the transition area 113 does not need to be bent, so the pole piece 11 is divided into three parts. The pole lug area 112 also includes a plurality of pole lugs arranged at intervals along the winding circumference.

[0054] Among them, the pole ear area 112 includes a first section 1121 and a second section 1122, one end of the first section 1121 is connected to an end of the transition zone 113 away from the pole piece body 111, and the second section 1122 is connected to an end of the first section 1121 away from the transition zone 113. Along the flattening direction of the pole ear area 112 toward the pole piece body 111, the first section 1121 is bent in the direction away from the winding center, and the second section 1122 is bent in the direction toward the winding center.

[0055] It should be noted that the flattening direction refers to the direction in which the flattening machine flattens the tab during the flattening process.

[0056] The technical solution provided in the present application divides the pole ear into a first section 1121 and a second section 1122, and pre-bends the first section 1121 and the second section 1122 in different directions, so that during the flattening process of the winding body 1, the first section 1121 and the second section 1122 can be regularly flattened onto the pole piece body 111 in the bending direction, and the flattening process of the pole ear does not involve a mechanical flattening process, thereby effectively avoiding the problem of metal chips generated by flattening. In addition, because the first section 1121 and the second section 1122 are bent in different directions, the first section 1121 and the second section 1122 can be flattened in the bending direction when the pole ear is flattened, thereby improving the distribution regularity of multiple pole ears. In detail, firstly, an active material is coated on the pole piece 11, and the pole piece 11 is divided into a pole piece body 111 coated with the active material, a transition zone 113 and a pole ear zone 112 which are not coated with the active material, and then the pole ear is bent to form a first section 1121 and a second section 1122, wherein the first section 1121 is bent in a direction away from the winding center, and the second section 1122 is bent in a direction toward the winding center, thereby providing a bending direction for the pole ear to be subjected to flattening pressure, so that the pole ear can be flattened regularly along the bending direction.

[0057] In some embodiments, see Figure 2 and Figure 3 , the bend of the first section 1121 is distributed toward the outer circle of the winding body, and the bend of the second section 1122 is distributed toward the inner circle, thereby forming a double folding structure from the outside to the inside. This structure can effectively avoid the problem of inconsistent direction and disorderly distribution of the pole ears during mechanical flattening, and this structure does not need to be mechanically flattened, and only needs to be directly flattened to form a regular distribution of pole ears. Further, the length of the first section 1121 is d1, and the length of the second section 1122 is d2. Among them, d2>d1. Specifically, the length range of d1 is 0 to 10mm, and the length range of d2 is 0 to 20mm. The first section 1121 and the second section 1122 will both be pre-bent to a certain extent to ensure that the first section 1121 and the second section 1122 can be bent in a predetermined direction during the flattening process. The first section 1121 can play a certain supporting role, and the first section 1121 and the second section 1122 are stacked and bent on each other, which can effectively increase the thickness of the pole ear and facilitate subsequent welding.

[0058] Further, the winding body 1 includes an isolation film 12, which is wound between two adjacent pole pieces 11. Along the axial direction of the winding body 1, the isolation film 12 includes a first end point 121 close to the first section 1121. The connection between the first section 1121 and the transition zone forms a first bending point 114, and the connection between the second section 1122 and the first section 1121 forms a second bending point 115. Along the axial direction of the winding body 1, the distance between the first bending point 114 and the first end point 121 is d3, and the distance between the second bending point 115 and the first end point 121 is Y1.

[0059] Wherein, Y1=d1×X±d3, X is the correction coefficient, and X is greater than 0 and less than 1.

[0060] By setting the isolation film 12 between adjacent pole pieces 11, the risk of short circuit between adjacent pole pieces 11 can be effectively avoided, and the bent portion of the pole ear can also be supported and protected. By limiting the distance Y1 between the second bending point 115 and the first end point 121 and the distance between the first bending point 114 and the first end point 121 along the axial direction of the winding body 1, it can be ensured that the distribution of the pole ear after bending will not interfere with the isolation film 12.

[0061] For further information, see Figure 4 and Figure 5 , along the axial direction of the winding body 1, when the first bending point 114 is located below the first end point 121, Y1, d1, and d3 satisfy the following formula:

[0062] Y1=d1×X-d3.

[0063] Along the axial direction of the winding body 1, when the first bending point 114 is located above the first end point 121, Y1, d1, and d3 satisfy the following formula:

[0064] Y1=d1×X+d3.

[0065] By reasonably calculating the distance between the first end point 121 and the second bending point 115 of the isolation membrane 12 according to the position of the first bending point 114 in the axial direction, the influence of the tab bending on the isolation membrane 12 can be effectively avoided.

[0066] In some embodiments, the pole piece 11 includes a first pole piece and a second pole piece. The isolation film 12 is disposed between the first pole piece and the second pole piece, and the polarities of the first pole piece and the second pole piece are opposite. The thickness of the first pole piece is b1, the thickness of the second pole piece is b2, the thickness of the isolation film 12 is b3, and the total thickness of the adjacent first pole piece, the second pole piece and the two isolation films 12 is t=b1+b2+2b3. Among them, the number of windings covered by the second section 1122 along the radial direction of the winding body 1 satisfies: e2≤d2÷t.

[0067] Specifically, the first pole piece and the second pole piece are coated with active materials respectively for electrochemical reactions of the positive and negative electrodes. A layer of separator 12 is located between the first pole piece and the second pole piece, and another layer of separator 12 is located on the side of the first pole piece away from the second pole piece or on the side of the second pole piece away from the first pole piece. The first pole piece, the second pole piece and the two layers of separator 12 together constitute the basic unit of the winding core, and the winding body 1 is formed by spiraling a plurality of basic units of the winding core in sequence along the winding direction. The separator 12 is usually made of porous polypropylene (PP) or polyethylene (PE) material. The number of winding turns is controlled by the ratio of the length of the second section 1122 of the pole ear to the total thickness, and the distribution of the pole ear in the radial direction is more uniform, and the welding area is fully covered, thereby avoiding local overheating or stress concentration problems during welding. Under the premise of the same electrode assembly radius, an excessively thick t will reduce the stacking density of the pole ears in the radial direction, which may affect the welding strength, and there may also be a problem of burning of the separator 12. An excessively thin t is more difficult in the process. By controlling the reasonable value of t, the welding strength and the overall performance of the battery are balanced.

[0068] In some embodiments, see Figure 6 The number of windings covered by the first section 1121 along the radial direction of the winding body 1 satisfies: e1≤d1÷t, which is beneficial to improving the regularity of the first sections 1121 of the plurality of tabs after being bent and flattened.

[0069] In some embodiments, the extension line of the first section 1121 and the extension line of the second section 1122 form an angle, and the angle of the angle is greater than 0° and less than 30°. When the angle between the first section 1121 and the second section 1122 satisfies the requirement of being greater than 0° and less than 30°, it is beneficial to meet the regularity of the distribution of the pole ears during the winding process, and can provide reasonable stacking support and stability during welding. Specifically, when the angle is close to 0°, the first section 1121 and the second section 1122 tend to be parallel, resulting in the pole ears being stacked too densely and increasing local stress. When the angle is close to 30°, the first section 1121 and the second section 1122 show a clear separation trend, forming a larger distribution range, which is conducive to stacking uniformity, but too large an angle will lead to an increase in the gap in the stacking area, affecting the welding strength.

[0070] Furthermore, the overlapping area between two adjacent pole lugs in the same winding coil accounts for S1 in the total area of ​​the two pole lugs, and along the radial direction of the winding body 1, the overlapping area between two adjacent pole lugs accounts for S2 in the total area of ​​the two pole lugs.

[0071] Wherein, the range of S1 is 0<S1<30%; S2=(d2+d1-d4-t / cosθ) / (d1+d2), and the range of S2 is 50%<S2<95%. d4 is the length of the non-overlapping portion between two adjacent pole ears along the radial direction of the winding body 1.

[0072] There will be overlap between two adjacent tabs in the same winding, and the area of ​​the overlapping part is S1, which satisfies 0<S1<30%. There will also be overlap between two adjacent tabs in different windings, and the area of ​​the overlapping part is S2, which satisfies: 50%<S2<95%. The specific calculation formula of S2 is as follows:

[0073] S2=(d2+d1-d4-t / cosθ) / (d1+d2).

[0074] Among them, d1 and d2 are the lengths of the first section 1121 and the second section 1122 respectively; d4 is the length of the non-overlapping part between two adjacent pole ears along the radial direction of winding; t is the thickness of the basic unit of the winding core; θ is the angle formed by the extension line of the first section 1121 and the extension line of the second section 1122. In the same winding circle, the pole ears overlap partially due to the close distribution positions of adjacent pole ears. By controlling the overlapping area to 0%-30%, the problem of excessive stacking thickness caused by excessive overlap can be avoided while ensuring the compactness of the structure. The pole ears of adjacent winding circles overlap in the radial direction, and the overlapping area accounts for 50%-95%. This ratio setting is intended to improve the welding strength of the stack, while avoiding excessive gaps between adjacent pole ears, ensuring the uniformity and support of the overall stack.

[0075] By limiting the range of S1 and S2, the tightness of the tab stacking is ensured, while avoiding the problem of excessive local pressure caused by over-dense stacking or unstable welding caused by loose stacking. S1 controls the overlapping ratio of the tabs in the same winding circle. If the value is too large (such as >30%), the thickness of the stacking area will increase significantly, affecting the uniformity of the stacking, and there is a risk of poor end faces and tab folding, leading to uncontrollable process. S2 controls the overlapping ratio of the tabs between adjacent winding circles. If the value is too small (such as <50%), the welding strength of the stacking area will be insufficient and the internal resistance will increase. If the value is too large (such as >95%), the difficulty of the process will be increased and the electrode performance will be affected. The calculation formula of S2 clarifies the overlapping relationship between adjacent tabs, making the thickness and distribution of the welding area more uniform, and reducing the risk of failure due to thermal stress during welding.

[0076] In some embodiments, see Figure 1 The wound pole piece 11 includes an inner circumference winding section 116 without pole tabs, a winding section 118 with pole tabs and an outer circumference winding section 117 without pole tabs connected in sequence along the winding direction. The maximum radius of the inner circumference winding section 116 without pole tabs is r, and the radius of the center hole formed by the winding body 1 is r0. Along the winding direction, the maximum pole tab height of the first pole tab of the winding section 118 with pole tabs is h1<r-r0.

[0077] Furthermore, the length of the pole ear along the axial direction ranges from 1 to 6 mm. And along the winding direction, the lengths of multiple pole ears along the axial direction can be the same, or can be set to gradually increase. If it is set to gradually increase, along the winding direction, the length difference of adjacent pole ears in the axial direction ranges from 0.2 to 2 mm. As for the shape of the pole ear, it can be a rectangle, a trapezoid or other irregular shape, without limitation. And, after the winding body 1 is formed, the pole ear will also be wound with the winding of the pole piece body 111, and the curvature of the pole ear after winding is less than 30°, and the curvature difference between the two adjacent turns of the pole ear is less than 3°.

[0078] It should be noted that the inner circumference winding segment 116 without pole tabs refers to the portion of the winding body 1 close to the winding center along the winding direction and without pole tabs, the outer circumference winding segment 117 without pole tabs refers to the portion of the winding body 1 close to the winding edge along the winding direction and without pole tabs, and the winding segment 118 with pole tabs refers to the portion of the winding body located between the inner circumference winding segment 116 without pole tabs and the outer circumference winding segment 117 without pole tabs along the winding direction.

[0079] By setting the inner circumference non-polar lug winding section 116, it is beneficial to optimize the stability of the electrode assembly core. By setting the outer circumference non-polar lug winding section 117, it is beneficial to protect the outer ring of the electrode assembly and reduce stress concentration. After the flattening process, the second section 1122 will be flattened. According to the formula h1<r-r0, the minimum radius of the inner circumference non-polar lug winding section 116 can be determined. When the minimum radius is determined, the lower limit of the length of the inner circumference non-polar lug winding section 116 in the winding direction can be calculated according to the calculation formula related to the spiral line. The specific calculation method is as follows:

[0080] According to the spiral parameter calculation formula: a=t÷2π, where t is the thickness of the basic unit of the winding core. For the electrode assembly, t is equivalent to the thickness of the first pole piece, the second pole piece (generally the thickness of the first pole piece is 50-200um; the thickness of the second pole piece is 50-250um) and the thickness of the two layers of isolation film 12. The relationship between the radius r of the winding core and the rotation angle φ of the winding core of the corresponding radius satisfies: r=r0+a·φ. Wherein, r0 is the radius of the center hole. According to the Archimedean spiral theory, the following formulas can be used to calculate respectively: taking the radius of the center hole as the maximum radius, simulating the virtual arc length of the spiral trajectory of the inner circumference without pole ear winding section 116 for winding, the minimum arc length of the inner circumference without pole ear winding section 116, the winding length of the winding body 1 along the winding direction, and the total winding length of the winding body 1 from the winding radius of 0 to the radius of the winding head end of the outer circumference without pole ear winding section 117. The specific formula is:

[0081] L=(a / 2)×{φ·√(1+φ2)+ln[φ+√(1+φ2)]}.

[0082] Furthermore, the length of the inner circumference winding section 116 without a pole piece meets the following conditions in the winding direction: L2 ≥ L1 - L0. The length of the outer circumference winding section 117 without a pole piece meets the following conditions in the winding direction: L5 ≥ L4 - L3.

[0083] Among them, L0 refers to the virtual arc length of the spiral trajectory of the inner circumference non-polar lug winding segment 116 with the radius of the center hole as the maximum radius, L1 refers to the minimum winding path length from the winding radius of 0 to the minimum radius of the inner circumference non-polar lug winding segment 116, L2 refers to the length of the inner circumference non-polar lug winding segment 116 in the winding direction, L3 refers to the total winding length of the winding body 1 from the winding radius of 0 to the radius of the winding head end of the outer circumference non-polar lug winding segment 117, L4 refers to the winding path length from the winding radius of 0 to the maximum winding radius, and L5 refers to the length of the outer circumference non-polar lug winding segment 117 in the winding direction.

[0084] According to the above embodiments, it can be known that L0, L1, L3, and L4 all satisfy the following formula:

[0085] L = (a / 2) × {φ·√(1+φ2)+ln[φ+√(1+φ2)]}, where a is the helix parameter and φ is the rotation angle.

[0086] It should be noted that before using L4-L3 to calculate the length of the peripheral tab-free winding section 117 in the winding direction, L4 and L3 must be calculated. The calculation of L4 and L3 is different from the calculation of L0 and L1 mentioned above. Specifically, the maximum radius of the winding body 1 is r3. It can be seen from the polar coordinate formula that the total rotation angle φ1 of the winding body 1 satisfies: φ1=r3 / a, and the total rotation angle includes the winding angle of the virtual part of the center of the winding body 1. The number of peripheral die-cutting circles of the winding body 1 is e3, then the total rotation angle of the winding body 1 from the winding radius of 0 to the radius where the winding head end of the peripheral tab-free winding section 117 is located is φ2=r3 / a-2π·e3. On the basis of obtaining the rotation angle and helix parameters, the rotation angle and helix parameters are respectively substituted into the two formulas L=(a / 2)×{φ·√(1+φ2)+ln[φ+√(1+φ2)]} and L5≥L4-L3 to obtain the length of the peripheral tab-free winding section 117 in the winding direction.

[0087] In some embodiments, see Figure 6 , the stacking thickness of the first section 1121 of the plurality of tabs in the axial direction of the winding body 1 satisfies: D1≤d1÷t×H.

[0088] The stacking thickness of the second sections 1122 of the plurality of tabs in the axial direction of the wound body 1 satisfies: D2≤d2÷t×H.

[0089] Wherein, D1 refers to the stacking thickness of the first section 1121 of the plurality of pole tabs in the axial direction of the winding body 1 , D2 refers to the stacking thickness of the second section 1122 of the plurality of pole tabs in the axial direction of the winding body 1 , and H refers to the thickness of the transition zone 113 .

[0090] By limiting the stacking thickness of the first section 1121 in the axial direction of the winding body 1 and the stacking thickness of the second section 1122 in the axial direction of the winding body 1, the stacking uniformity of the pole ear in the axial direction is ensured, and the mechanical instability problem caused by excessive or insufficient stacking thickness is reduced.

[0091] Furthermore, a gap is formed between the stacking of the first section 1121 and the second section 1122 of the pole ear, and the height of the gap in the stacking direction satisfies: D3 = k1 × D1 + k2 × D2. The total stacking thickness after the first section 1121 and the second section 1122 of multiple pole ears are stacked satisfies: D4 = D1 + D2 + D3. Among them, K1 and K2 are coefficients, K1 satisfies: 0.2 < K1 < 2, and K2 satisfies: 0.2 < K2 < 2. This embodiment not only takes into account the stacking thickness of the first section 1121 and the second section 1122 themselves, but also takes into account the stacking gap formed between the first section 1121 and the second section 1122 due to structural reasons, so that the calculation of the total stacking thickness is more accurate, which is conducive to the control of the welding area and thickness in subsequent welding.

[0092] In some embodiments, the multiple tabs of the first pole piece are bent and stacked to form a first welding surface, and the first welding surface can be welded with a thickness range of greater than 0.04 mm and less than 1.2 mm. The multiple tabs of the second pole piece are bent and stacked to form a second welding surface, and the second welding surface can be welded with a thickness range of greater than 0.03 mm and less than 0.6 mm.

[0093] In some embodiments, along the axial direction of the winding body 1, the length of the pole piece body 111 of the first pole piece is less than the length of the pole piece body 111 of the second pole piece, and the distance between the pole piece body 111 of the second pole piece and the first section 1121 of the first pole piece is D5, and D5≤5mm. By limiting the distance between the pole piece body 111 of the second pole piece and the first section 1121 of the first pole piece to be no more than 5mm, it is helpful to improve the safety margin of the battery to cope with possible abnormal arrangement of the pole ears, such as the abnormal folding and sagging of the pole ears between the upper and lower pole ears in this area, and it can also cope with the expansion of the electrode assembly, leaving a margin for the expansion of the electrode assembly in the axial direction.

[0094] The embodiment of the present application further provides a battery, which may be a cylindrical battery. The battery includes a housing and an electrode assembly as described in any of the above embodiments, and the electrode assembly is installed in the housing. The battery has the structure and corresponding beneficial effects of the electrode assembly described in the above embodiments, which will not be described in detail here.

[0095] The embodiment of the present application further provides an electric device, which includes the battery described in the above embodiment. The electric device has the structure and corresponding beneficial effects of the battery described in the above embodiment, which will not be described in detail here.

[0096] The embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An electrode assembly, characterized in that: The invention comprises a winding body, wherein the winding body comprises a pole piece arranged in a winding manner, wherein the pole piece comprises a pole piece body, a pole lug region and a transition region, wherein the pole piece body is coated with an active material, and the pole lug region and the transition region are not coated with an active material, the pole piece body is connected to the pole lug region through the transition region, and the pole lug region comprises a plurality of pole lugs arranged along the winding circumference; Among them, the pole ear area includes a first section and a second section, one end of the first section is connected to one end of the transition zone away from the pole piece body, and the second section is connected to the other end of the first section away from the transition zone. When the pole ear area is flattened to the winding body, one of the first section and the second section is bent in a direction away from the winding center, and the other is bent in a direction close to the winding center.

2. The electrode assembly according to claim 1, characterized in that The length of the first segment is d1, and the length of the second segment is d2; Among them, d2>d1.

3. The electrode assembly according to claim 2, characterized in that The winding body includes an isolation film, which is wound between two adjacent pole pieces with different polarities, and along the axial direction of the winding body, the isolation film includes a first end point close to the first section; A first bending point is formed at the connection between the first section and the transition zone, a second bending point is formed at the connection between the second section and the first section, and along the axial direction of the winding body, the distance between the first bending point and the first end point is d3, and the distance between the second bending point and the first end point is Y1; Wherein, Y1=d1×X±d3, X is a correction coefficient, and X is greater than 0 and less than 1.

4. The electrode assembly according to claim 3, characterized in that Along the axial direction of the winding body, when the first bending point is located on the side of the first end point close to the pole piece body, Y1, d1, and d3 satisfy the following formula: Y1=d1×X-d3; Along the axial direction of the winding body, when the first bending point is located on the side of the first end point away from the pole piece body, Y1, d1, and d3 satisfy the following formula: Y1=d1×X+d3.

5. The electrode assembly according to any one of claims 2 to 4, characterized in that: The pole piece includes a first pole piece and a second pole piece, the isolation film is provided between the first pole piece and the second pole piece, the first pole piece and the second pole piece have opposite polarities, the thickness of the first pole piece is b1, the thickness of the second pole piece is b2, the thickness of the isolation film is b3, and the total thickness of the adjacent first pole piece, the second pole piece and the two isolation films is t=b1+b2+2b3; The number of windings e1 covered by the first section in the radial direction of the winding body satisfies: e1≤d1÷t.

6. The electrode assembly according to claim 5, characterized in that The number of windings e2 covered by the second section in the radial direction of the winding body satisfies: e2≤d2÷t.

7. The electrode assembly according to claim 5, characterized in that An angle formed by an extension line of the first segment and an extension line of the second segment is greater than 0° and less than 30°.

8. The electrode assembly according to claim 7, characterized in that The overlap area between two adjacent pole lugs in the same winding coil accounts for S1 in the total area of ​​the two pole lugs, and the overlap area between two adjacent pole lugs in the radial direction of the winding body accounts for S2 in the total area of ​​the two pole lugs; Among them, the range of S1 is 0<S1<30%; S2=(d2+d1-d4-t / cosθ) / (d1+d2), and the range of S2 is 50%<S2<95%; d4 is the length of the non-overlapping portion between two adjacent pole ears along the radial direction of the winding body, and θ is the angle formed by the extension line of the first section and the extension line of the second section.

9. The electrode assembly according to claim 5, characterized in that: The plurality of pole tabs of the first pole piece are bent and stacked to form a first welding surface, and the first welding surface can be welded with a thickness range of greater than 0.04 mm and less than 1.2 mm; The plurality of pole ears of the second pole piece are bent and stacked to form a second welding surface, and the second welding surface can be welded with a thickness range of greater than 0.03 mm and less than 0.6 mm.

10. The electrode assembly according to claim 1, characterized in that The pole piece arranged in a wound manner includes an inner circumference winding section without pole lugs, a winding section with pole lugs and an outer circumference winding section without pole lugs which are connected in sequence along the winding direction. The maximum radius of the inner circumference winding section without pole lugs is r, the radius of the center hole formed by the winding body is r0, and along the winding direction, the maximum pole lug height of the first pole lug of the winding section with pole lugs is h1<r-r0.

11. The electrode assembly according to claim 10, characterized in that The length of the inner circumference non-polar lug winding section in the winding direction satisfies: L2≥L1-L0; the length of the outer circumference non-polar lug winding section in the winding direction satisfies: L5≥L4-L3; Wherein, L0 refers to the virtual arc length of the spiral trajectory of the inner circumference non-polar lug winding section, which is wound with the radius of the center hole as the maximum radius, simulating the spiral trajectory of the inner circumference non-polar lug winding section, L1 refers to the minimum winding path length from the winding radius of 0 to the minimum radius of the inner circumference non-polar lug winding section, L2 refers to the length of the inner circumference non-polar lug winding section in the winding direction, L3 refers to the total winding length of the winding body from the winding radius of 0 to the radius where the winding head end of the outer circumference non-polar lug winding section is located, L4 refers to the winding path length from the winding radius of 0 to the maximum winding radius, and L5 refers to the length of the outer circumference non-polar lug winding section in the winding direction; The L0, L1, L3, and L4 all satisfy the following formula: L=(a / 2)×{φ·√(1+φ 2 )+ln[φ+√(1+φ 2 )]}; Where a is the helix parameter and φ is the rotation angle.

12. The electrode assembly according to claim 5, characterized in that The stacking thickness of the first sections of the plurality of tabs in the axial direction of the winding body satisfies: D1≤d1÷t×H; The stacking thickness of the second sections of the plurality of tabs in the axial direction of the winding body satisfies: D2≤d2÷t×H; Wherein, D1 refers to the stacking thickness of the first sections of the plurality of pole tabs in the axial direction of the winding body, D2 refers to the stacking thickness of the second sections of the plurality of pole tabs in the axial direction of the winding body, and H refers to the thickness of the transition zone.

13. The electrode assembly according to claim 12, characterized in that A gap is formed between the stacking of the first section and the second section of the electrode tab, and the height of the gap in the stacking direction satisfies: D3 = k1 × D1 + k2 × D2; The total stacking thickness of the first sections and the second sections of the plurality of tabs after stacking satisfies: D4=D1+D2+D3; Wherein, K1 and K2 are both coefficients, K1 satisfies: 0.2<K1<2, and K2 satisfies: 0.2<K2<2.

14. The electrode assembly according to claim 5, characterized in that Along the axial direction of the winding body, the length of the pole piece body of the first pole piece is smaller than the length of the pole piece body of the second pole piece, and the shortest distance between the pole piece body of the second pole piece and the first section of the first pole piece is no more than 5 mm.

15. A battery, characterized in that: The invention comprises a shell and an electrode assembly as claimed in any one of claims 1 to 14, wherein the electrode assembly is installed in the shell.

16. An electrical equipment, characterized in that: Comprising the battery of claim 15.

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