Winding battery cell and battery

Abstract

The utility model relates to the technical field of batteries, and discloses a winding battery cell and a battery. The winding battery cell is provided with a straight area and an arc area, and comprises a positive plate, a diaphragm and a negative plate; the positive plate comprises a current collector, a first active material layer and a second active material layer, the tail part of the second active material layer exceeds the tail part of the first active material layer in the winding direction of the winding cell, a first junction region is formed at the tail part of the first active material layer, and a second junction region is formed at the tail part of the second active material layer; the first active material layer at the first junction region is partially or completely removed, the second active material layer at the second junction region is partially or completely removed, and the first junction region and the second junction region are both located in a straight region. The first junction region and the second junction region are arranged in the straight region of the winding battery cell, and the expansion of the flush region is smaller than that of an arc region, so that the pole piece breakage condition in the battery cell circulation process is improved, and the battery cell circulation performance and the energy density are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of battery, specifically relates to winding electric core and battery. BACKGROUND

[0002] Lithium ion batteries are widely used in consumer electronics, new energy vehicles and energy storage power stations due to their high specific energy, low discharge and good cycle performance. With the deepening of "double carbon", lithium ion batteries have strong development momentum and gradually move towards fast charging, long life, high energy density and high safety.

[0003] The positive plate of the lithium ion battery usually uses aluminum foil as the current collector, the surface of the current collector is covered with active material, the positive plate has double-sided area, single-sided area and empty foil area, the two sides of the empty foil area are not coated with active material, one side of the single-sided area is covered with active material, and the two sides of the double-sided area are coated with active material. The junction of the single-sided area and the double-sided area and the junction of the empty foil area and the single-sided area are located in the arc region of the winding electric core.

[0004] During the rolling process, when the rolling pressure is the same, due to the thickness of the single-sided area being less than the thickness of the double-sided area and the thickness of the empty foil area being less than the thickness of the single-sided area, the rolling pressure at the single-sided area and the empty foil area is larger when the rolling changes from the double-sided area to the single-sided area or from the single-sided area to the empty foil area, so that there are small irregular active material residues distributed on the surface of the foil. In the cycle use process of the electric core, the expansion of the arc region is relatively large, which further leads to the fracture of the junction area of the single-sided area and the empty foil area, the junction area of the single-sided area and the double-sided area, which seriously affects the cycle performance and energy density of the electric core. UTILITY MODEL CONTENTS

[0005] Therefore, the utility model provides a winding electric core and a battery to solve the problem of fracture of the junction area of the single-sided area and the double-sided area and the junction area of the empty foil area and the single-sided area, which are located in the arc region of the winding electric core.

[0006] In a first aspect, this utility model provides a wound battery cell having a flat region and arcuate regions located at both ends of the flat region. The wound battery cell includes: a positive electrode sheet, a separator, and a negative electrode sheet, which are stacked and wound together. The positive electrode sheet includes a current collector, a first active material layer, and a second active material layer. Along the thickness direction of the current collector, the current collector has a first surface and a second surface disposed opposite to each other. The first active material layer is disposed on the first surface, and the second active material layer is disposed on the second surface. Along the winding direction of the wound battery cell, the tail of the second active material layer extends beyond the tail of the first active material layer. The tail of the first active material layer forms a first boundary region, and the tail of the second active material layer forms a second boundary region. The first active material layer at the first boundary region is partially or completely removed, and the second active material layer at the second boundary region is partially or completely removed. Both the first boundary region and the second boundary region are located in the flat region.

[0007] Beneficial effects: By setting the first and second boundary regions of the positive electrode in the straight area of ​​the wound cell, the expansion of the straight area is smaller than that of the arc area during the cyclic use of the wound cell. This can improve the breakage of the electrode at the boundary between the single-sided area and the empty foil area, as well as between the single-sided area and the double-sided area, during the cell cycle, thereby improving the cell cycle performance and energy density.

[0008] In one optional embodiment, the wound cell has a first center point in a first direction and a first plane passing through the first center point. The first plane is perpendicular to the first direction. Along the winding direction of the wound cell, the head of the first boundary region has a first boundary line, and the head of the second boundary region has a second boundary line. The first plane has a first side and a second side disposed opposite to each other along the first direction. The first boundary line is located on the first side of the first plane, the second side of the first plane, or within the first plane. The second boundary line is located on the first side of the first plane, the second side of the first plane, or within the first plane.

[0009] Beneficial effects: The first boundary line of the first boundary region and the second boundary line of the second boundary region are both set far away from the arc area, which reduces the deformation of the electrode sheet during charge and discharge cycles, further improves the electrode sheet breakage during cell cycling, and improves the overall electrochemical performance of the battery.

[0010] In one optional implementation, along the first direction, the distance L1 between the first boundary line and the first plane is 0-50mm, and the distance L2 between the second boundary line and the first plane is 0-50mm.

[0011] In one alternative implementation, a first protective element is provided at the first boundary area, and a second protective element is provided at the second boundary area.

[0012] Beneficial effects: The first and second protective components can enhance the mechanical strength of the junction area, protect the junction area, and prevent the junction area from breaking due to collisions during the use of the battery cell, thereby improving the overall performance of the battery cell.

[0013] In one alternative embodiment, the first protective member has a second center point in a first direction, the second center point being located on a first side of the first plane, a second side of the first plane, or within the first plane; the second protective member has a third center point in a first direction, the third center point being located on a first side of the first plane, a second side of the first plane, or within the first plane.

[0014] Beneficial effects: Protective components can increase local mechanical strength, ensure that the battery cell maintains structural stability during charge and discharge cycles, and reduce the possibility of deformation.

[0015] In one alternative implementation, along the first direction, the distance L3 between the second center point and the first plane is 0-70 mm, and the distance L4 between the third center point and the first plane is 0-70 mm.

[0016] In one optional embodiment, the width W1 of the first protective member along the first direction is 10mm-50mm, and the width W2 of the second protective member along the first direction is 10mm-50mm.

[0017] Beneficial effects: The protective components can completely cover the boundary area, avoiding and reducing the risk of accidental contact inside the battery cell, thereby improving overall safety.

[0018] In one optional embodiment, the current collector where the first boundary area is located is the first region, the portion of the first active material layer other than the first boundary area forms the main region, the current collector where the main region is located is the second region, and the current collector where the second boundary area is located is the third region; along the thickness direction of the current collector, the ratio of the thickness T1 of the first region to the thickness T2 of the second region is (0.2-1):1, and the ratio of the thickness T3 of the third region to the thickness T2 of the second region is (0.2-1):1.

[0019] Beneficial effects: During the rolling process of the positive electrode sheet, active material layers are provided on both the first and second surfaces of the current collector in the double-sided region, making the pressure on the current collector relatively balanced. When the rolling pressure changes from the double-sided region to the single-sided region or from the single-sided region to the blank region, it cannot be adjusted in time. If the rolling pressure does not change, the rolling pressure in the junction region will not be released. Thus, when the rolling pressure remains unchanged and the thickness of the positive electrode sheet decreases, the current collector in the single-sided region and the current collector in the blank region will bear greater pressure than the current collector in the double-sided region. This makes the thickness of the first region and the third region smaller than the thickness of the second region. After rolling, the active material at the tail of the first active material layer and the tail of the second active material layer is cleaned off, which improves the overpressure situation of the foil in the junction region, improves the electrode sheet breakage during cell cycling, and improves the cell cycling performance and energy density.

[0020] In one optional embodiment, the wound cell has a first direction, a second direction, and a third direction, which are perpendicular to each other; the length L5 of the first region along the first direction is 3mm-20mm, and the width W3 of the first region along the second direction is 40mm-160mm; and / or, the length L6 of the third region along the first direction is 3mm-20mm, and the width W4 of the third region along the second direction is 40mm-160mm; and / or, along the thickness direction of the current collector, the thickness T4 of the first active material layer is 20μm-180μm, and the thickness T5 of the second active material layer is 20μm-180μm; and / or, both the first and second active material layers include active materials, conductive agents, and binders, wherein the ratio of the total mass of the binder to the total mass of the first active material layer in the first active material layer is 0.1%-10%; and the ratio of the total mass of the binder to the total mass of the second active material layer in the second active material layer is 0.1%-10%.

[0021] Beneficial effects: When the width and length of the first and third regions are within a suitable range, the mechanical strength of these regions can be increased, reducing the risk of foil tearing or breakage due to stress concentration during winding. The first and second active material layers, with a thickness of 20µm-180µm, can increase the mass of active material per unit area, significantly improving the battery's energy density and electrochemical performance, thereby effectively extending its cycle life.

[0022] Secondly, this utility model also provides a battery, including: the above-mentioned wound battery cell. Attached Figure Description

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

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

[0025] Figure 2 for Figure 1 The diagram shows the structure of the unfolded positive electrode sheet.

[0026] Figure 3 for Figure 2 The top view of the current collector shown;

[0027] Figure 4 This is a schematic diagram of another type of wound battery cell according to an embodiment of the present invention;

[0028] Figure 5 for Figure 4 The diagram shows the structure of the first protective component.

[0029] Figure 6 for Figure 4 The diagram shows the structure of the second protective component.

[0030] Figure 7 for Figure 6 The image shows a top view of the wound battery cell.

[0031] Explanation of reference numerals in the attached figures:

[0032] 101. Flat area; 102. Circular area;

[0033] 2. Positive electrode sheet; 201. Current collector; 2011. First region; 2012. Second region; 2013. Third region; 202. First active material layer; 2021. First boundary region; 2022. Main region; 2023. First boundary line; 203. Second active material layer; 2031. Second boundary region; 2032. Second boundary line;

[0034] 3. Diaphragm;

[0035] 4. Negative electrode plate;

[0036] 5. First center point;

[0037] 6. First plane;

[0038] 701, First protective element; 7011, Second center point; 702, Second protective element; 7021, Third center point;

[0039] 8. Positive electrode ear;

[0040] 9. Negative electrode ear;

[0041] 10. The fourth center point;

[0042] 11. Second plane. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0044] The following is combined with Figures 1 to 7 The following describes embodiments of the present invention.

[0045] According to an embodiment of the present invention, in one aspect, a wound battery cell is provided. The wound battery cell has a flat region 101 and an arc region 102 located at both ends of the flat region 101. The wound battery cell includes a positive electrode 2, a separator 3 and a negative electrode 4, which are stacked and wound together.

[0046] The positive electrode 2 includes a current collector 201, a first active material layer 202, and a second active material layer 203. Along the thickness direction of the current collector 201, the current collector 201 has a first surface and a second surface disposed opposite to each other. The first active material layer 202 is disposed on the first surface, and the second active material layer 203 is disposed on the second surface.

[0047] Along the winding direction of the battery cell, the tail of the second active material layer 203 extends beyond the tail of the first active material layer 202. The tail of the first active material layer 202 forms a first boundary region 2021, and the tail of the second active material layer 203 forms a second boundary region 2031. The first active material layer 202 at the first boundary region 2021 is partially or completely removed, and the second active material layer 203 at the second boundary region 2031 is partially or completely removed. Both the first boundary region 2021 and the second boundary region 2031 are located in the flat region 101.

[0048] In the winding cell of this embodiment, the first boundary region 2021 and the second boundary region 2031 of the positive electrode 2 are set in the flat region 101 of the winding cell. During the cyclic use of the winding cell, the expansion of the flat region 101 is smaller than that of the arc region 102. This can improve the breakage of the electrode at the junction of the single-sided region and the empty foil region and the single-sided region and the double-sided region during the cell cycle, thereby improving the cell cycle performance and energy density.

[0049] It should be noted that, along the winding direction, the positive electrode sheet has a double-sided area, a single-sided area, and an empty foil area. The empty foil area refers to the area where neither the first surface nor the second surface of the current collector 201 of the positive electrode sheet 2 has an active material layer. The single-sided area refers to the area where only the first surface or the second surface of the current collector 201 of the positive electrode sheet 2 has an active material layer. The double-sided area refers to the area where both the first surface and the second surface of the current collector 201 of the positive electrode sheet 2 have an active material layer.

[0050] Furthermore, during the manufacturing of the positive electrode 2, after coating the first and second surfaces of the current collector 201 with active material, the tail ends of the first active material layer 202 and the tail ends of the second active material layer 203 are cleaned. After cleaning, the first active material layer 202 at the first boundary region 2021 is partially or completely removed, and the second active material layer 203 at the second boundary region 2031 is partially or completely removed.

[0051] Specifically, the tail ends of the first active material layer 202 and the tail ends of the second active material layer 203 are cleaned. This can be done before or after the positive electrode 2 is rolled, but cleaning after rolling is preferred. This allows the rolled portion to release stress through cleaning, reducing the risk of breakage. The cleaning method may include laser cleaning.

[0052] In one embodiment, the wound cell has a first center point 5 in a first direction and a first plane 6 passing through the first center point 5. The first plane 6 is perpendicular to the first direction. Along the winding direction of the wound cell, the head of the first boundary region 2021 has a first boundary line 2023, and the head of the second boundary region 2031 has a second boundary line 2032. The first plane 6 has a first side and a second side disposed opposite to each other along the first direction. The first boundary line 2023 is located on the first side, the second side, or within the first plane 6, and the second boundary line 2032 is located on the first side, the second side, or within the first plane 6. The first boundary line 2023 of the first boundary region 2021 and the second boundary line 2032 of the second boundary region 2031 are both disposed away from the arc region 102, reducing the deformation of the electrode sheet during charge-discharge cycles, further improving the electrode sheet breakage during cell cycling, and improving the overall electrochemical performance of the battery.

[0053] Further, along the first direction, the distance L1 between the first boundary line 2023 and the first plane 6 is 0-50mm, and the distance L2 between the second boundary line and the first plane 6 is 0-50mm. For example, L1 is 0, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 20mm, 30mm, 40mm, 50mm, or within any two of the above values, and L2 is 0, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 20mm, 30mm, 40mm, 50mm, or within any two of the above values.

[0054] Preferably, L1 is 0-40mm and L2 is 0-40mm.

[0055] Specifically, the first boundary line and the second boundary line can be located on the same side of the first plane 6 or on different sides of the first plane 6. For example, the first boundary line is located on the first side of the first plane 6 and the second boundary line is located on the second side of the first plane 6, or the first boundary line is located on the second side of the first plane 6 and the second boundary line is located on the first side of the first plane 6.

[0056] It is understood that in some embodiments, the first boundary line and the second boundary line may be located within the first plane 6, in which case L1 and L2 are both 0.

[0057] In one embodiment, a first protective element 701 is provided at the first boundary region 2021, and a second protective element 702 is provided at the second boundary region 2031. The first protective element 701 and the second protective element 702 can enhance the mechanical strength of the boundary region, protect the boundary region, and prevent the boundary region from breaking due to collision during the use of the battery cell, thereby improving the overall performance of the battery cell.

[0058] Specifically, both the first protective component 701 and the second protective component 702 are made of adhesive tape. Adhesive tape is usually easy to cut into the required size and shape, and can be quickly pasted into place with simple tools or automated equipment, thereby improving production efficiency.

[0059] Furthermore, the first protective member 701 has a second center point 7011 in the first direction, which is located on the first side, the second side, or within the first plane 6; the second protective member 702 has a third center point 7021 in the first direction, which is located on the first side, the second side, or within the first plane 6. These protective members increase local mechanical strength, ensuring the cell maintains structural stability during charge-discharge cycles and reducing the possibility of deformation.

[0060] Specifically, along the first direction, the distance L3 between the second center point 7011 and the first plane 6 is 0-70mm, and the distance L4 between the third center point 7021 and the first plane 6 is 0-70mm. For example, L3 can be 0, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, or any two of the above values; L4 can be 0, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, or any two of the above values.

[0061] Preferably, L3 is 0-50mm and L4 is 0-50mm.

[0062] Furthermore, the width W1 of the first protective component 701 along the first direction is 10mm-50mm, and the width W2 of the second protective component 702 along the first direction is 10mm-50mm. The protective components can completely cover the boundary area, avoiding and reducing the risk of accidental contact inside the battery cell, thereby improving the overall safety.

[0063] For example, W1 is 10mm, 20mm, 30mm, 40mm, 50mm or within any two of the above values, and W2 is 10mm, 20mm, 30mm, 40mm, 50mm or within any two of the above values.

[0064] In one embodiment, the current collector 201 where the first boundary region 2021 is located is the first region 2011, the portion of the first active material layer 202 excluding the first boundary region forms the main region 2022, the current collector 201 where the main region 2022 is located is the second region 2012, and the current collector 201 where the second boundary region 2031 is located is the third region 2013; along the thickness direction of the current collector 201, the ratio of the thickness T1 of the first region 2011 to the thickness T2 of the second region 2012 is (0.2-1):1, and the ratio of the thickness T3 of the third region 2013 to the thickness T2 of the second region 2012 is (0.2-1):1.

[0065] During the rolling process of the positive electrode 2, active material layers are provided on both the first and second surfaces of the current collector 201 in the double-sided region, making the pressure on the current collector 201 relatively balanced. When the double-sided region changes to the single-sided region or the single-sided region changes to the blank region, the rolling pressure cannot be adjusted in time. When the rolling pressure is not changed, the rolling pressure in the junction region is not released. Thus, when the rolling pressure remains unchanged and the thickness of the positive electrode 2 becomes thinner, the current collector 201 in the single-sided region and the current collector 201 in the blank region will bear greater pressure than the current collector 201 in the double-sided region. This makes the thickness of the first region 2011 and the thickness of the third region 2013 smaller than the thickness of the second region 2012. After rolling, the active material at the tail of the first active material layer 202 and the tail of the second active material layer 203 is cleaned off, which improves the overpressure situation of the foil in the junction region, improves the electrode breakage situation during the cell cycle, and improves the cell cycle performance and energy density.

[0066] For example, T1 / T2 is 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1 or within any two of the above values, and T3 / T2 is 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1 or within any two of the above values.

[0067] In one embodiment, the wound cell has a first direction, a second direction, and a third direction, which are perpendicular to each other. The length L5 of the first region 2011 along the first direction is 3mm-20mm, and the width W3 of the first region 2011 along the second direction is 40mm-160mm. The length L6 of the third region 2013 along the first direction is 3mm-20mm, and the width W4 of the third region 2013 along the second direction is 40mm-160mm. The width and length of the first region 2011 and the third region 2013 are within a suitable range, which can increase the mechanical strength of the region and reduce the risk of foil tearing or breakage due to winding stress concentration.

[0068] For example, L5 is 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm or within any two of the above values, and L6 is 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm or within the above values. Within the range of any two values, W3 is 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm, 160mm or falls within the range of any two values ​​above, and W4 is 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm, 160mm or falls within the range of any two values ​​above.

[0069] In one embodiment, along the thickness direction of the current collector 201, the thickness T4 of the first active material layer 202 is 20 μm-180 μm, and the thickness T5 of the second active material layer 203 is 20 μm-180 μm. The first active material layer 202 and the second active material layer 203, with thicknesses of 20 μm-180 μm, can increase the mass of active material per unit area, significantly improving the energy density and electrochemical performance of the battery, thereby effectively extending its cycle life.

[0070] For example, T4 is 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm or within any two of the above values, and T5 is 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm or within any two of the above values.

[0071] In one embodiment, both the first active material layer 202 and the second active material layer 203 include an active material, a conductive agent, and an adhesive. In the first active material layer 202, the ratio of the total mass of the adhesive to the total mass of the first active material layer 202 is 0.1%-10%; in the second active material layer 203, the ratio of the total mass of the adhesive to the total mass of the second active material layer 203 is 0.1%-10%.

[0072] Furthermore, the active material includes at least one or a mixture of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and ternary materials; the binder includes at least one of polyvinylidene fluoride, sodium hydroxycellulose, lithium hydroxycellulose, styrene-butadiene rubber, polyacrylic acid, a monomer or copolymer of tetrafluoroethylene and hexafluoropropylene, polyvinyl alcohol, and other polymeric binders.

[0073] In one embodiment, such as Figure 1 As shown, along the second direction, a positive electrode tab 8 is provided on one side of the positive electrode 2, and a negative electrode tab 9 is provided on one side of the negative electrode tab 9. The wound cell has a fourth center point 10 in the third direction and a second plane 11 passing through the fourth center point 10. The second plane 11 is perpendicular to the third direction. In the winding direction, the positive electrode 2 and the negative electrode 4 form multiple layers from the inside to the outside. The positive electrode tab 8 is located in the middle layer of the positive electrode 2, and the negative electrode 4 is located in the middle layer of the negative electrode 4.

[0074] It is worth noting that the third direction refers to the thickness direction of the battery cell, the first direction refers to the width direction of the battery cell, and the second direction refers to the length direction of the battery cell.

[0075] It should be noted that after the positive electrode 2 and the negative electrode 4 are coated with the active material layer, the positive electrode 2 and the negative electrode 4 are rolled to the required thickness and compaction density.

[0076] According to an embodiment of the present invention, another aspect provides a battery comprising the aforementioned wound cell.

[0077] In one embodiment, the battery further includes a housing and a cover, the housing having an open receiving cavity in which the wound cell is disposed, and the cover covering the opening.

[0078] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A wound battery cell, characterized in that, The wound cell has a flat region (101) and arc regions (102) located at both ends of the flat region (101). The wound cell includes a positive electrode (2), a separator (3) and a negative electrode (4), wherein the positive electrode (2), the separator (3) and the negative electrode (4) are stacked and wound together. The positive electrode (2) includes a current collector (201), a first active material layer (202), and a second active material layer (203). Along the thickness direction of the current collector (201), the current collector (201) has a first surface and a second surface disposed opposite to each other. The first active material layer (202) is disposed on the first surface, and the second active material layer (203) is disposed on the second surface. Along the winding direction of the wound cell, the tail of the second active material layer (203) extends beyond the tail of the first active material layer (202). The tail of the first active material layer (202) forms a first boundary region (2021), and the tail of the second active material layer (203) forms a second boundary region (2031). The first active material layer (202) at the first boundary region (2021) is partially or completely removed, and the second active material layer (203) at the second boundary region (2031) is partially or completely removed. Both the first boundary region (2021) and the second boundary region (2031) are located in the flat region (101).

2. The wound battery cell according to claim 1, characterized in that, The wound cell has a first center point (5) in a first direction and a first plane (6) passing through the first center point (5). The first plane (6) is perpendicular to the first direction and along the winding direction of the wound cell. The head of the first junction area (2021) has a first boundary line (2023), and the head of the second junction area (2031) has a second boundary line (2032). The first plane (6) has a first side and a second side that are disposed opposite to each other along the first direction. The first boundary line (2023) is located on the first side of the first plane (6), the second side of the first plane (6), or within the first plane (6), and the second boundary line (2032) is located on the first side of the first plane (6), the second side of the first plane (6), or within the first plane (6).

3. The wound battery cell according to claim 2, characterized in that, Along the first direction, the distance L1 between the first boundary line (2023) and the first plane (6) is 0-50mm, and the distance L2 between the second boundary line (2032) and the first plane (6) is 0-50mm.

4. The wound battery cell according to claim 2, characterized in that, A first protective element (701) is provided at the first boundary area (2021), and a second protective element (702) is provided at the second boundary area (2031).

5. The wound battery cell according to claim 4, characterized in that, The first protective member (701) has a second center point (7011) in the first direction, the second center point (7011) being located on a first side of the first plane (6), a second side of the first plane (6), or within the first plane (6); The second protective member (702) has a third center point (7021) in the first direction, the third center point (7021) being located on a first side of the first plane (6), a second side of the first plane (6), or within the first plane (6).

6. The wound battery cell according to claim 5, characterized in that, Along the first direction, the distance L3 between the second center point (7011) and the first plane (6) is 0-70mm, and the distance L4 between the third center point (7021) and the first plane (6) is 0-70mm.

7. The wound battery cell according to claim 6, characterized in that, The width W1 of the first protective member (701) along the first direction is 10mm-50mm, and the width W2 of the second protective member (702) along the first direction is 10mm-50mm.

8. The wound battery cell according to any one of claims 1 to 7, characterized in that, The current collector (201) where the first boundary area (2021) is located is the first region (2011), the part of the first active material layer (202) excluding the first boundary area forms the main region (2022), the current collector (201) where the main region (2022) is located is the second region (2012), and the current collector (201) where the second boundary area (2031) is located is the third region (2013). Along the thickness direction of the current collector (201), the ratio of the thickness T1 of the first region (2011) to the thickness T2 of the second region (2012) is (0.2-1):1, and the ratio of the thickness T3 of the third region (2013) to the thickness T2 of the second region (2012) is (0.2-1):

1.

9. The wound battery cell according to claim 8, characterized in that, The wound cell has a first direction, a second direction, and a third direction, wherein the first direction, the second direction, and the third direction are perpendicular to each other. The length L5 of the first region (2011) along the first direction is 3mm-20mm, and the width W3 of the first region (2011) along the second direction is 40mm-160mm. And / or, the length L6 of the third region (2013) along the first direction is 3mm-20mm, and the width W4 of the third region (2013) along the second direction is 40mm-160mm; And / or, along the thickness direction of the current collector (201), the thickness T4 of the first active material layer (202) is 20μm-180μm, and the thickness T5 of the second active material layer (203) is 20μm-180μm; And / or, both the first active material layer (202) and the second active material layer (203) include active materials, conductive agents, and adhesives. In the first active material layer (202), the ratio of the total mass of the adhesive to the total mass of the first active material layer (202) is 0.1%-10%; in the second active material layer (203), the ratio of the total mass of the adhesive to the total mass of the second active material layer (203) is 0.1%-10%.

10. A battery, characterized in that, include: The wound battery cell according to any one of claims 1 to 9.

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