Battery

Abstract

The utility model provides a battery which comprises a shell and a square roll core accommodated in the shell, and the roll core comprises a positive plate, a diaphragm and a negative plate; four corners are arranged on the periphery, perpendicular to the thickness direction, of the roll core. The positive plate comprises a positive current collector and positive active material layers formed on the two sides of the positive current collector, and a plurality of etching regions are arranged on the two sides of the width direction of the positive plate; the plurality of etching areas are distributed at four corners of the roll core, and each etching area comprises a plurality of etching grooves which are arranged at intervals; according to the utility model, the position of the positive plate corresponding to the corner area of the roll core is etched to form the etching area, and each etching area comprises a plurality of etching grooves arranged at intervals, so that the lithium removal amount of the positive electrode in the corner area of the positive plate can be reduced, the lithium insertion amount of the negative electrode corresponding to the position is reduced, the expansion rate is reduced, and the reliability of the membrane shell is improved; and the high energy density of the battery can be ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field, concretely relates to a battery. BACKGROUND

[0002] When the soft package battery aluminum plastic film is punched, the thickness of the aluminum layer at the four corners of the roll core will change according to different punching depths, the deeper the punching, the smaller the thickness of the aluminum layer at the four corners. When the thickness of the aluminum layer at the four corners is less than a certain value, the battery is prone to corrosion, which causes the film shell to break, thereby causing the roll core to leak, and there is a safety risk. The current silicon negative electrode system on the market itself has greater cyclic expansion, and is more prone to film shell breakage at the four corners of the roll core. The current main solution is to increase the thickness of the aluminum layer of the aluminum plastic film to ensure that the thickness of the aluminum layer at the four corners after punching is not less than the lower limit. However, this method increases the overall thickness of the roll core and reduces the energy density of the battery. Therefore, how to overcome the above technical problems and defects has become a key problem to be solved. SUMMARY

[0003] In view of the problem that the battery corner position is prone to breakage, the utility model provides a battery.

[0004] The utility model adopts the following technical scheme to solve the above technical problems:

[0005] The utility model provides a battery, which comprises an outer shell and a square roll core accommodated in the outer shell, the roll core comprises a positive plate, a diaphragm and a negative plate, the roll core has four corners in the direction perpendicular to its thickness, the positive plate comprises a positive current collector and positive active material layers formed on both sides of the positive current collector, and a plurality of etching areas are arranged on both sides of the positive plate in the width direction, the plurality of etching areas are distributed at the four corners of the roll core, and the etching area comprises a plurality of etching grooves arranged at intervals.

[0006] Optionally, the etching area is arranged on the positive active material layer, the thickness of the positive active material layer is h1, the unit is mu m, the depth of the etching area is h2, the unit is mu m, and h1 and h2 satisfy the relationship formula: 0.2<=h2 / h1<=0.6.

[0007] Optionally, the value range of h1 is 20 mu m<=h1<=200 mu m.

[0008] Optionally, the length direction of the etching area is the length direction of the positive plate, the length of the etching area is L, the unit is mm, the value range of L is 2 mm<=L<=10 mm, and / or,

[0009] The width direction of the etching area is the width direction of the positive plate, the width of the etching area is W, the unit is mm, and the value range of W is 2 mm<=W<=10 mm.

[0010] Optionally, along the width direction of the positive plate, the length of the etching area gradually decreases from the edge region of the positive plate inward; and / or,

[0011] Along the length direction of the positive plate, the width of the etching area first increases and then decreases.

[0012] Optionally, the etching area is formed by a scribing etching method, and the etching groove is a strip-shaped etching groove.

[0013] A plurality of the strip-shaped etching grooves are arranged in parallel to the length direction of the positive plate; and / or,

[0014] A plurality of the strip-shaped etching grooves are arranged in parallel to the width direction of the positive plate.

[0015] Optionally, the distance between two adjacent strip-shaped etching grooves is G1, and the value of G1 is in the range of 0.1mm≤G1≤1.5mm.

[0016] Optionally, the groove width of the strip-shaped etching groove is D1, and the value of D1 is in the range of 0.05mm≤D1≤0.15mm.

[0017] Optionally, the etching area is formed by a punching etching method, and the etching groove is a plurality of point-shaped etching grooves.

[0018] Optionally, the distance between two adjacent point-shaped etching grooves is G2, and the value of G2 is in the range of 0.1mm≤G2≤1.5mm.

[0019] Optionally, the diameter of the point-shaped etching groove is D2, and the value of D2 is in the range of 0.05mm≤D2≤0.15mm.

[0020] Optionally, the shape of the etching area is arc-shaped, semi-circular, semi-elliptical, triangular, trapezoidal, rectangular or irregular.

[0021] Optionally, the shell is an aluminum plastic film.

[0022] According to the battery provided by the utility model, the etching area is formed by etching the position corresponding to the winding core corner region of the positive plate, each etching area includes a plurality of interval arranged etching grooves, the lithium extraction amount of the positive plate corner region can be reduced, the lithium intercalation amount of the negative electrode corresponding to the position is reduced, the expansion rate is reduced, the reliability of the film shell is improved, and the high energy density of the battery can be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the following will briefly introduce the drawings to be used in the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0024] Figure 1 is a structural schematic diagram of a first positive plate provided by an embodiment of the present application;

[0025] Figure 2 is a top view schematic diagram of the first positive plate provided by an embodiment of the present application;

[0026] Figure 3 is a structural schematic diagram of a second positive plate provided by an embodiment of the present application;

[0027] Figure 4 is a structural schematic diagram of a third positive plate provided by an embodiment of the present application;

[0028] Figure 5 is a structural schematic diagram of a fourth positive plate provided by an embodiment of the present application;

[0029] Figure 6 is a structural schematic diagram of a fifth positive plate provided by an embodiment of the present application;

[0030] Figure 7 is a structural schematic diagram of a positive plate provided by a comparative example 1;

[0031] Figure 8 is a structural schematic diagram of a positive plate provided by a comparative example 2;

[0032] Figure 9 is a structural schematic diagram of a winding core provided by an embodiment of the present application;

[0033] Figure 10 is a structural schematic diagram of a battery provided by an embodiment of the present application;

[0034] The reference signs in the drawings of the specification are as follows:

[0035] 100 - battery; 10 - winding core; 101 - corner; 1 - positive plate; 11 - positive current collector; 12 - positive active material layer; 13 - etching area; 131 - strip-shaped etching groove; 132 - dot-shaped etching groove; 20 - shell. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical schemes and beneficial effects solved by the utility model clearer and more apparent, the utility model will be further described in detail below in combination with the drawings and embodiments.

[0037] In the description of the utility model, it is to be understood that the orientation or position relationship indicated by the terms "longitudinal", "radial", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is the orientation or position relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model. In the description of the utility model, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0038] In the description of the utility model, it should be explained that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected, it can be mechanical connection, or electrical connection, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0039] As shown in Figures 1-6 and Figures 9-10 In an embodiment, the utility model provides a battery, which comprises a shell 20 and a square winding core 10 accommodated in the shell 20, the winding core 10 comprising a positive plate 1, a diaphragm and a negative plate, the winding core 10 having four corners 101 in the direction perpendicular to its thickness, the positive plate 1 comprising a positive current collector 11 and a positive active material layer 12 formed on both sides of the positive current collector 11, and a plurality of etching areas 13 being arranged on both sides of the positive plate 1 in the width direction, the plurality of etching areas 13 being distributed in the four corners 101 of the winding core 10, and the etching area 13 comprising a plurality of etching grooves arranged at intervals.

[0040] The area of the four corners 101 of the winding core 10 has the smallest thickness of the aluminum layer of the aluminum plastic film, when the winding core 10 expands greatly, the extrusion of the plate to the corner 101 can cause the aluminum plastic film to be damaged, thereby causing the corner crack of the winding core 10 and the air leakage, and the safety risk is improved.

[0041] Specifically, the winding core 10 of the present application is a square winding core 10, that is, a flat body winding core 10, the part other than the tab is square or rectangular in cross section perpendicular to the thickness direction, and four corners 101 are formed on the four sides of the winding core 10 perpendicular to the thickness direction;

[0042] The present application can reduce the positive electrode lithium extraction amount of the corner 101 region of the positive electrode sheet 1 by etching the position corresponding to the corner 101 region of the winding core 10 of the positive electrode sheet 1 to form an etching area 13, the negative electrode lithium intercalation amount corresponding to the position is reduced, the expansion rate is reduced, the film shell reliability is improved, and the high energy density of the battery 100 can be ensured.

[0043] Specifically, the width of the negative electrode sheet is greater than the width of the positive electrode sheet 1, which can avoid lithium precipitation.

[0044] As shown in Figure 2 In an embodiment, the etching area 13 is opened on the positive electrode active material layer 12; the thickness of the positive electrode active material layer 12 is h1, unit: μm, the depth of the etching area 13 is h2, unit: μm, h1 and h2 satisfy the relationship: 0.2≤h2 / h1≤0.6.

[0045] Specifically, the value range of h2 / h1 is any one value or a range value composed of any two point values in 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55 or 0.6; in a preferred embodiment, the value range of h2 / h1 is 0.3≤h2 / h1≤0.5.

[0046] When the value range of h2 / h1 is 0.2≤h2 / h1≤0.6, the positive electrode lithium extraction amount of the corner 101 region of the positive electrode sheet 1 can be reduced, the negative electrode lithium intercalation amount corresponding to the position is reduced, the expansion rate is reduced, the film shell reliability is improved, and the high energy density of the battery 100 can be ensured; when the value range of h2 / h1 is less than 0.2, the battery 100 energy density loss is smaller, but it will lead to the positive electrode lithium extraction amount of the corner 101 region of the positive electrode sheet 1 cannot be effectively reduced, the negative electrode lithium intercalation amount corresponding to the position will not be significantly reduced, the expansion rate of the battery 100 cannot be reduced, and the corner 101 of the winding core 10 is still prone to rupture; when the value range of h2 / h1 is greater than 0.6, the film shell reliability is improved, but the battery capacity is reduced, and the energy density of the battery 100 is reduced.

[0047] As shown in Figure 2 In an embodiment, the value range of h1 is 20μm≤h1≤200μm.

[0048] Specifically, the value of h1 is any one point value or any two point values ​​from 20μm, 40μm, 60μm, 80μm, 100μm, 120μm, 140μm, 160μm, 180μm or 200μm; in a preferred embodiment, the value of h1 is 60μm≤h1≤160μm.

[0049] Specifically, the value of h2 is any one point value or any two point values ​​from 4μm, 8μm, 12μm, 16μm, 20μm, 24μm, 28μm, 32μm, 36μm, 40μm, 44μm, 48μm, 52μm, 56μm, 60μm, 64μm, 68μm, 72μm, 76μm, 80μm, 84μm, 88μm, 92μm, 96μm, 100μm, 104μm, 108μm, 112μm, 116μm or 120μm; in a preferred embodiment, the value of h2 is 12μm≤h1≤96μm.

[0050] like Figures 1-6 As shown, in one embodiment, the length direction of the etching region 13 is along the length direction of the positive electrode 1, and the length of the etching region 13 is L, in mm, and the value of L ranges from 2 mm ≤ L ≤ 10 mm; and / or,

[0051] The width direction of the etching region 13 is along the width direction of the positive electrode 1. The width of the etching region 13 is W, in mm. The value range of W is 2 mm ≤ W ≤ 10 mm.

[0052] Specifically, the value of L is any one point value or any two point values ​​from 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm or 10mm; in a preferred embodiment, the value of L is 4mm≤L≤8mm.

[0053] When the value of L is in the range of 2mm≤L≤10mm, it can reduce the amount of lithium stripping from the positive electrode in the corner 101 area of ​​the positive electrode plate 1, corresponding to a decrease in the amount of lithium insertion into the negative electrode at that position, a decrease in the expansion rate, and an improvement in the reliability of the membrane shell, while also ensuring the high energy density of the battery 100. When the value of L is less than 2mm, the energy density loss of the battery 100 is smaller, but it will lead to an inability to effectively reduce the amount of lithium stripping from the positive electrode in the corner 101 area of ​​the positive electrode plate 1, and the amount of lithium insertion into the negative electrode at that position will not be significantly reduced. The expansion rate of the battery 100 cannot be reduced, and cracking is still likely to occur at the corner 101 of the core 10. When the value of L is greater than 10mm, the reliability of the membrane shell is improved, but the battery capacity and the energy density of the battery 100 will be reduced.

[0054] Specifically, the value of W is any one point value or any two point values ​​from 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm or 10mm; in a preferred embodiment, the value of W is 4mm≤W≤8mm.

[0055] When the value of W is in the range of 2mm≤W≤10mm, it can reduce the amount of lithium stripping from the positive electrode in the corner 101 area of ​​the positive electrode plate 1, corresponding to a decrease in the amount of lithium insertion into the negative electrode at that position, a decrease in the expansion rate, and an improvement in the reliability of the membrane shell, while also ensuring the high energy density of the battery 100. When the value of W is less than 2mm, the energy density loss of the battery 100 is smaller, but it will lead to an inability to effectively reduce the amount of lithium stripping from the positive electrode in the corner 101 area of ​​the positive electrode plate 1, and the amount of lithium insertion into the negative electrode at that position will not be significantly reduced. The expansion rate of the battery 100 cannot be reduced, and cracking is still likely to occur at the corner 101 of the core 10. When the value of W is greater than 10mm, the reliability of the membrane shell is improved, but the capacity will be reduced, and the energy density of the battery 100 will be reduced.

[0056] like Figures 1-5 As shown, in one embodiment, along the width direction of the positive electrode 1, the length of the etched region 13 gradually decreases inward from the edge region of the positive electrode 1, that is, the length of the etched region 13 is the largest at the edge region of the positive electrode 1 and the smallest in the edge region away from the positive electrode 1; and / or,

[0057] Along the length of the positive electrode 1, the width of the etched region 13 first increases and then decreases, that is, the width of the etched region 13 is the largest in the middle and gradually decreases from the middle to both sides.

[0058] Etching regions 13 are formed at the four corners of the core. The closer the region is to the corner of the core, the longer and wider the etching region 13 is. This reduces the amount of lithium stripping from the positive electrode at the corner 101 of the positive electrode sheet 1. Correspondingly, the amount of lithium intercalation in the negative electrode at this position is reduced, the expansion rate is reduced, the reliability of the membrane is improved, and the high energy density of the battery 100 is guaranteed.

[0059] like Figures 1-5 As shown, in one embodiment, the etched area 13 is formed by scribing etching, and the etched groove is a strip-shaped etched groove 13, that is, the etched area 13 includes multiple strip-shaped etched grooves 13;

[0060] Multiple strip-shaped etched grooves 13 are arranged parallel to the length direction of the positive electrode plate 1; and / or,

[0061] Multiple strip-shaped etched grooves 13 are arranged parallel to the width direction of the positive electrode sheet 1.

[0062] Specifically, multiple strip-shaped etching grooves 13 are formed at the corner 101 position of the positive electrode 1 corresponding to the core 10 by laser scribing method, and the multiple strip-shaped etching grooves 13 form the etching area 13;

[0063] In one embodiment, the lengths of the multiple strip-shaped etched grooves 13 are arranged in a rectangular shape parallel to the length direction of the positive electrode sheet 1;

[0064] In another embodiment, multiple strip-shaped etched grooves 13 are arranged parallel to the width direction of the positive electrode sheet 1;

[0065] The above etching methods can reduce the amount of lithium stripping in the positive electrode region at the corner 101 of the positive electrode 1, corresponding to a reduction in the amount of lithium intercalation in the negative electrode at that position, a reduction in the expansion rate, improved film and shell reliability, and ensured high energy density of battery 100.

[0066] like Figures 1-5 As shown, in one embodiment, the distance between two adjacent strip-shaped etched grooves 13 is G1, in mm, and the value range of G1 is 0.1 mm ≤ G1 ≤ 1.5 mm.

[0067] Specifically, the value of G1 is any one point value or any two point values ​​from 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm or 1.5mm; in a preferred embodiment, the value of G1 is 0.5mm≤G1≤1mm.

[0068] When the value of G1 is in the range of 0.1mm≤G1≤1.5mm, it can reduce the amount of lithium stripping from the positive electrode in the corner 101 area of ​​the positive electrode plate 1, corresponding to a decrease in the amount of lithium insertion into the negative electrode at that position, a decrease in the expansion rate, and an improvement in the reliability of the membrane shell, while also ensuring the high energy density of the battery 100. When the value of G1 is less than 0.1mm, the reliability of the membrane shell is improved, but the battery capacity and energy density of the battery 100 will be reduced. When the value of G1 is greater than 1.5mm, the energy density loss of the battery 100 is smaller, but it will lead to an inability to effectively reduce the amount of lithium stripping from the positive electrode in the corner 101 area of ​​the positive electrode plate 1, and the amount of lithium insertion into the negative electrode at that position will not be significantly reduced. The expansion rate of the battery 100 cannot be reduced, and cracking is still likely to occur at the corner 101 of the core 10.

[0069] like Figures 1-5 As shown, in one embodiment, the groove width of the strip-shaped etched groove 13 is D1, in mm, and the value range of D1 is 0.05mm≤D1≤0.15mm.

[0070] Specifically, the value of D1 is any one point value or any two point values ​​from 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm or 0.15mm; in a preferred embodiment, the value of D1 is 0.08mm≤D1≤0.12mm.

[0071] When the value of D1 is in the range of 0.05mm≤D1≤0.15mm, it can reduce the amount of lithium stripping from the positive electrode in the corner 101 area of ​​the positive electrode 1, corresponding to a decrease in the amount of lithium insertion into the negative electrode at that position, a decrease in the expansion rate, and an improvement in the reliability of the membrane shell, while also ensuring the high energy density of the battery 100. When the value of D1 is less than 0.05mm, the energy density loss of the battery 100 is smaller, but it will lead to difficulty in lithium insertion, and the effect is close to the state of no etching. The expansion rate of the battery 100 cannot be reduced, and cracking is still likely to occur at the corner 101 of the core 10. When the value of D1 is greater than 0.15mm, the reliability of the membrane shell is improved, and lithium insertion is easier, but the battery capacity will be reduced, and the energy density of the battery 100 will be reduced.

[0072] like Figure 6 As shown, in one embodiment, the etched area 13 is formed by a drilling etching method, and the etched grooves are dot-shaped etched grooves 132, that is, the etched area 13 includes a plurality of dot-shaped etched grooves 132.

[0073] Specifically, multiple dot-shaped etching grooves 132 are formed at the corner 101 position of the positive electrode 1 corresponding to the core 10 by laser drilling, and the multiple dot-shaped etching grooves 132 form the etching area 13;

[0074] By using the above etching method, the amount of lithium stripping in the positive electrode region at the corner 101 of the positive electrode sheet 1 can be reduced, the amount of lithium insertion in the negative electrode at this position is reduced, the expansion rate is reduced, the reliability of the membrane shell is improved, and the high energy density of the battery 100 can be guaranteed.

[0075] like Figure 6 As shown, in one embodiment, the distance between two adjacent dot-shaped etched grooves 132 is G2, in mm, and the value range of G2 is 0.1 mm ≤ G2 ≤ ​​1.5 mm.

[0076] Specifically, the value of G2 is any one point value or any two point values ​​from 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm or 1.5mm; in a preferred embodiment, the value of G2 is 0.5mm≤G2≤1mm.

[0077] When the value range of G2 is 0.1 mm≤G2≤1.5 mm, the positive electrode lithium extraction amount in the corner 101 region of the positive electrode sheet 1 can be reduced, the negative electrode lithium intercalation amount corresponding to the position is reduced, the expansion rate is reduced, the membrane shell reliability is improved, and the high energy density of the battery 100 can be ensured; when the value range of G2 is less than 0.1 mm, the membrane shell reliability is improved, but the battery capacity is reduced, and the energy density of the battery 100 is reduced; when the value range of G2 is greater than 1.5 mm, the energy density loss of the battery 100 is smaller, but it cannot effectively reduce the positive electrode lithium extraction amount in the corner 101 region of the positive electrode sheet 1, the negative electrode lithium intercalation amount corresponding to the position cannot be significantly reduced, the expansion rate of the battery 100 cannot be reduced, and the corner 101 of the winding core 10 is still prone to cracking.

[0078] As shown in the drawings, Figure 6 In an embodiment, the diameter of the point-like etching groove 132 is D2, and the unit is mm, and the value range of D2 is 0.05 mm≤D2≤0.15 mm.

[0079] Specifically, the value range of D2 is 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.10 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm or 0.15 mm. Any point value or a range value composed of any two point values; in a preferred embodiment, the value range of D2 is 0.08 mm≤D2≤0.12 mm.

[0080] When the value range of D2 is 0.05 mm≤D2≤0.15 mm, the positive electrode lithium extraction amount in the corner 101 region of the positive electrode sheet 1 can be reduced, the negative electrode lithium intercalation amount corresponding to the position is reduced, the expansion rate is reduced, the membrane shell reliability is improved, and the high energy density of the battery 100 can be ensured; when the value range of D2 is less than 0.05 mm, the energy density loss of the battery 100 is smaller, but it will lead to difficulty in intercalating lithium, the effect is close to no etching state, the expansion rate of the battery 100 cannot be reduced, and the corner 101 of the winding core 10 is still prone to cracking; when the value range of D2 is greater than 0.15 mm, the membrane shell reliability is improved, and the intercalation of lithium is easier, but the battery capacity is reduced, and the energy density of the battery 100 is reduced.

[0081] As shown in the drawings, Figures 1-6 In an embodiment, the shape of the etching area 13 includes one of an arc shape, a semicircular shape, a semi-elliptical shape, a triangular shape, a trapezoidal shape, a rectangular shape or an irregular shape.

[0082] Specifically, the etching area 13 can select different shapes according to actual needs; in a preferred embodiment, the etching area 13 is selected from a semi-elliptical shape, and the major axis of the semi-elliptical shape coincides with the side of the positive electrode sheet 1.

[0083] As shown in the drawings, Figures 1-2As shown, in an embodiment, the outer shell 20 is an aluminum plastic film.

[0084] Specifically, the winding core 10 of the present application is applied to the soft package battery 100, and the aluminum plastic film is used to wrap the winding core 10.

[0085] The beneficial effects of the present application are further illustrated below in conjunction with examples.

[0086] In order to make the inventive purpose, technical scheme and beneficial technical effects of the present application clearer, the present application is further described in detail below in conjunction with examples. However, it should be understood that the examples of the present application are only for the purpose of explaining the present application, and are not intended to limit the present application, and the examples of the present application are not limited to the examples given in the specification. The specific experimental conditions or operation conditions not mentioned in the examples are made according to the conventional conditions or the conditions recommended by the material suppliers.

[0087] In addition, it should be understood that the one or more method steps mentioned in the present application do not exclude that there can be other method steps before and after the combination steps or other method steps can be inserted between the explicitly mentioned steps, unless otherwise stated; it should also be understood that the combination connection relationship between the one or more devices / apparatuses mentioned in the present application does not exclude that there can be other devices / apparatuses before and after the combination devices / apparatuses or other devices / apparatuses can be inserted between the two explicitly mentioned devices / apparatuses, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the arrangement order of each method step or to limit the range of implementation of the present application, and the change or adjustment of the relative relationship, without substantial change of the technical content, is also regarded as the scope of implementation of the present application.

[0088] In the following examples, the reagents, materials and instruments used are commercially available or obtained by synthesis methods known in the art, unless otherwise specified.

[0089] Table 1 Design of the positive electrode sheet of Examples 1-13 and Comparative Examples 1-10;

[0090]

[0091] Note: The longitudinal direction is the direction parallel to the width direction of the positive electrode sheet; the transverse direction is the direction perpendicular to the width direction of the positive electrode sheet.

[0092] L is the length of the etching area; W is the width of the etching area; G is the distance between two adjacent strip-shaped etching grooves, or the distance between two adjacent point-shaped etching grooves; D is the groove width of the strip-shaped etching groove, or the diameter of the point-shaped etching groove; h1 is the thickness of the positive electrode active material layer, and h2 is the depth of the etching area.

[0093] Example 1

[0094] This example is used to illustrate the battery disclosed in the present application; including the following operating steps:

[0095] Manufacture of the positive electrode sheet:

[0096] Form a plurality of strip-shaped etching grooves at the corner position of the positive electrode sheet corresponding to the core by laser scribing method, the plurality of strip-shaped etching grooves form a semicircular etching area, and the plurality of strip-shaped etching grooves are parallel to the width direction of the positive electrode sheet;

[0097] The length of the etching area is 6 mm, and the width is 6 mm;

[0098] The distance between the adjacent two strip-shaped etching grooves is 0.5 mm, and the groove width of the strip-shaped etching groove is 0.08 mm;

[0099] The thickness of the positive electrode active material layer is 35 μm, and the depth of the etching area is 10.5 μm.

[0100] Preparation of the battery:

[0101] The negative electrode sheet, the separator and the positive electrode sheet are wound to form a core, the core is placed in an aluminum plastic film, an electrolyte is injected into the aluminum plastic film, and a secondary battery is formed by packaging.

[0102] Examples 2-13

[0103] Examples 2-13 are used to illustrate the battery disclosed in the present application, including most of the operating steps in Example 1, the difference is that:

[0104] Various parameters in the positive electrode sheet shown in Table 1 are used.

[0105] Comparative Examples 1-10

[0106] Comparative Examples 1-10 are used to illustrate the battery disclosed in the present application, including most of the operating steps in Example 1, the difference is that:

[0107] Various parameters in the positive electrode sheet shown in Table 1 are used.

[0108] Performance test

[0109] The batteries prepared in the above Examples 1-13 and Comparative Examples 1-10 are subjected to the following performance tests:

[0110] (1) Cycle performance test: the battery is charged at 3C constant current and constant voltage to 4.5V, 0.05C cut-off, discharged at 0.5C, and the time point of confirming the damage of the corner position is confirmed after 1000 cycles.

[0111] (2) Calculation of the energy density of the battery: energy density = battery capacity * nominal voltage / battery height / battery width / battery thickness.

[0112] The test results are shown in Table 2.

[0113] Table 2 Electrochemical performance of lithium battery

[0114]

[0115] As shown in Table 2 and Figures 1-8 , when no etching is performed on the positive electrode sheet, the energy density of the roll core is higher, but the four corner regions 101 of the roll core 10 are subjected to the thinnest aluminum layer of the aluminum plastic film, and when the roll core 10 expands greatly, the extrusion of the electrode sheet on the corner 101 can cause the aluminum plastic film to break, thereby reducing the reliability of the film shell and affecting the cycle life of the battery. When the laser cleaning method is used to etch the positive electrode sheet, the capacity of the roll core is reduced, and the energy density of the battery is reduced.

[0116] As shown in Table 2 and Figures 1-8 , when no etching is performed on the positive electrode sheet, the energy density of the roll core is higher, but the four corner regions 101 of the roll core 10 are subjected to the thinnest aluminum layer of the aluminum plastic film, and when the roll core 10 expands greatly, the extrusion of the electrode sheet on the corner 101 can cause the aluminum plastic film to break, thereby reducing the reliability of the film shell and affecting the cycle life of the battery. When the laser cleaning method is used to etch the positive electrode sheet, the capacity of the roll core is reduced, and the energy density of the battery is reduced.

[0117] As shown in Table 2 and Figures 1-8 , when no etching is performed on the positive electrode sheet, the energy density of the roll core is higher, but the four corner regions 101 of the roll core 10 are subjected to the thinnest aluminum layer of the aluminum plastic film, and when the roll core 10 expands greatly, the extrusion of the electrode sheet on the corner 101 can cause the aluminum plastic film to break, thereby reducing the reliability of the film shell and affecting the cycle life of the battery. When the laser cleaning method is used to etch the positive electrode sheet, the capacity of the roll core is reduced, and the energy density of the battery is reduced.

[0118] It can be seen from Comparative Example 1, Examples 8-9 and Comparative Examples 5-6 that when the value range of G is 0.1mm≤G≤1.5mm, the positive electrode lithium extraction amount of the positive electrode tab corner area can be reduced, the negative electrode lithium intercalation amount corresponding to the position is reduced, the expansion rate is reduced, the film shell reliability is improved, and the high energy density of the battery can be ensured; when the value range of G is less than 0.1mm, the film shell reliability is improved, but the capacity of the winding core is reduced, and the energy density of the battery is reduced; when the value range of G is greater than 1.5mm, the loss of the energy density of the battery is smaller, but the positive electrode lithium extraction amount of the positive electrode tab corner area cannot be effectively reduced, the negative electrode lithium intercalation amount corresponding to the position cannot be significantly reduced, the expansion rate of the battery cannot be reduced, and the winding core corner is still prone to cracking.

[0119] It can be seen from Comparative Example 1, Examples 10-11 and Comparative Examples 7-8 that when the value range of D is 0.05mm≤D≤0.15mm, the positive electrode lithium extraction amount of the positive electrode tab corner area can be reduced, the negative electrode lithium intercalation amount corresponding to the position is reduced, the expansion rate is reduced, the film shell reliability is improved, and the high energy density of the battery can be ensured; when the value range of D is less than 0.05mm, the loss of the energy density of the battery is smaller, but lithium intercalation is difficult, the effect is close to no etching state, the expansion rate of the battery cannot be reduced, and the winding core corner is still prone to cracking; when the value range of D is greater than 0.15mm, the film shell reliability is improved, lithium intercalation is easier, but the capacity of the battery is reduced, and the energy density of the battery is reduced.

[0120] The above only describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery, characterized by: The square core is accommodated in the shell, and the square core comprises a positive electrode sheet, a separator and a negative electrode sheet; the square core has four corners in the direction perpendicular to the thickness direction of the square core; characterized in that: the positive electrode sheet comprises a positive electrode current collector and positive electrode active material layers formed on both sides of the positive electrode current collector, and a plurality of etching areas are arranged on both sides of the positive electrode sheet in the width direction of the positive electrode sheet; the plurality of etching areas are distributed at the four corners of the square core; and the etching area comprises a plurality of etching grooves arranged at intervals.

2. The battery of claim 1, wherein: The etching area is opened in the positive electrode active material layer; the thickness of the positive electrode active material layer is h1, in units of μm, the depth of the etching area is h2, in units of μm, and h1 and h2 satisfy the relationship: 0.2≤h2 / h1≤0.

6.

3. The battery of claim 2, wherein: The value range of h1 is 20 μm≤h1≤200 μm.

4. The battery of claim 2, wherein: The length direction of the etching area is along the length direction of the positive electrode sheet, the length of the etching area is L, in units of mm, and the value range of L is 2 mm≤L≤10 mm; and / or, The width direction of the etching area is along the width direction of the positive electrode sheet, the width of the etching area is W, in units of mm, and the value range of W is 2 mm≤W≤10 mm.

5. The battery of claim 4, wherein: Along the width direction of the positive electrode sheet, the length of the etching area gradually decreases from the edge region of the positive electrode sheet inward; and / or, Along the length direction of the positive electrode sheet, the width of the etching area first increases and then decreases.

6. The battery of claim 4, wherein: The etching area is formed by a scribing etching method, and the etching groove is a strip-shaped etching groove; A plurality of strip-shaped etching grooves are arranged in parallel to the length direction of the positive electrode sheet; and / or, A plurality of strip-shaped etching grooves are arranged in parallel to the width direction of the positive electrode sheet.

7. The battery of claim 6, wherein: The distance between two adjacent strip-shaped etching grooves is G1, in units of mm, and the value range of G1 is 0.1 mm≤G1≤1.5 mm.

8. The battery of claim 6, wherein: The groove width of the strip-shaped etching groove is D1, in units of mm, and the value range of D1 is 0.05 mm≤D1≤0.15 mm.

9. The battery of claim 4, wherein: The etching area is formed by a punching etching method, and the etching groove is a dot-shaped etching groove.

10. The battery of claim 9, wherein: The distance between two adjacent dot-shaped etching grooves is G2, in units of mm, and the value range of G2 is 0.1 mm≤G2≤1.5 mm.

11. The battery of claim 9, wherein: The diameter of the dot-shaped etching groove is D2, in units of mm, and the value range of D2 is 0.05 mm≤D2≤0.15 mm.

12. The battery of any one of claims 1-11, wherein: The shape of the etching area is arc-shaped, semi-circular, semi-elliptical, triangular, trapezoidal or rectangular.

13. The battery of claim 1, wherein: The shell is an aluminum plastic film.

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