Battery

Abstract

The utility model provides a battery which comprises a shell and a square pole core accommodated in the shell, and the pole core comprises a laminated diaphragm and two pole pieces with opposite polarities; first notches, second notches, third notches and fourth notches are respectively arranged on the two kinds of pole pieces corresponding to four corners, the first notches are combined to form a first corner cut, the second notches are combined to form a second corner cut, the third notches are combined to form a third corner cut, and the fourth notches are combined to form a fourth corner cut; according to the utility model, a plurality of chamfers are formed at the corners of the pole piece, so that the pole piece is prevented from being bent at the four corners, and the internal short circuit condition of the battery is avoided; when the pole piece expands in the charge-discharge cycle process of the battery, the damage and internal corrosion at the corner of the shell cannot be caused, and the safety performance of the battery is improved; meanwhile, a plurality of chamfers are formed at the corners of the pole piece, so that the length and the width of the pole piece can be increased, and the energy density of the battery is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a battery technical field, specifically relates to a battery. BACKGROUND

[0002] In recent years, with the promotion of industrial upgrading, brand competition and intelligent technology, the electronic product develops faster and faster, and the continuous improvement of electronic equipment hardware and computing power will have higher and higher demand for the power supply used, such as AIPC integrated more computing resources and instant response to AI driven application, which requires high energy density, fast charging and discharging capacity, excellent thermal management ability and other requirements for the battery used. How to design a high energy density battery in a limited battery compartment size is the goal that each manufacturer is constantly pursuing.

[0003] Under the premise that the battery compartment size is fixed, the energy density of the battery is the highest when the three dimensions (thickness * width * length) of the battery size are utilized to the extreme.

[0004] As shown in Figures 1-3 When the shell film is formed, the four corner positions are the thinnest, when the distance between the pole piece in the pole core and the shell film is shortened (especially at the four corner positions of the shell film), the pole piece is easy to cause corner damage and internal corrosion when the pole piece expands during the battery charging and discharging cycle, causing reliability risk; and when the pole core is packaged into the shell, the pole piece at the four corner positions of the pole core is easy to bend, causing internal short circuit; therefore, the distance between the pole core and the shell film is generally designed to be larger in the industry, such as when the shell film is made of aluminum plastic film, the four corner positions of the shell film are prevented from internal corrosion or damage by sacrificing the battery energy density, which is difficult to further improve the battery energy density. Therefore, how to overcome the above technical problems and defects becomes a key problem to be solved. CONTENT OF THE UTILITY MODEL

[0005] In view of the problem of how to improve the battery energy density, the utility model provides a battery.

[0006] The technical scheme adopted by the utility model to solve the above technical problems is as follows:

[0007] The utility model provides a kind of battery, including shell and the square pole core being accommodated in the shell, the pole core includes the diaphragm of laminated arrangement and two kinds of square pole piece of opposite polarity;The pole core has four corner positions in the thickness direction perpendicular to it, the length of one kind of the pole piece is greater than or equal to the length of another kind of the pole piece;Two kinds of the pole piece of same length or at least length longer one kind of the pole piece is respectively set with first cutout, second cutout, third cutout and fourth cutout corresponding four corner positions, all first cutout combination forms first cut angle, all second cutout combination forms second cut angle, all third cutout combination forms third cut angle and all the fourth cutout combination forms fourth cut angle;The first cut angle, the second cut angle, the third cut angle and the fourth cut angle are distributed in the four corner positions of the square pole core.

[0008] Optionally, the first cutout, the second cutout, the third cutout and the fourth cutout are each independently selected from an arc shape, a triangular shape, a rectangular shape or an irregular shape.

[0009] Optionally, the first cutout, the second cutout, the third cutout, the fourth cutout are all right-angled triangles, and two right-angled sides of the right-angled triangle are respectively on the same straight line with adjacent sides of the pole piece.

[0010] Optionally, lengths of the two right-angled sides of the right-angled triangle are a and b respectively, the value range of a is 0.2mm-0.7mm, and the value range of b is 0.2mm-0.7mm.

[0011] Optionally, the value range of a2 is 0.4mm-0.6mm, and the value range of b2 is 0.4mm-0.6mm.

[0012] Optionally, the two kinds of pole pieces of opposite polarity are positive pole pieces and negative pole pieces respectively, and the positive pole pieces and the negative pole pieces are both provided with the pole piece cutout.

[0013] Optionally, the length of the negative pole piece is L1, and lengths of the two right-angled sides of the right-angled triangle on the negative pole piece are a1 and b1 respectively.

[0014] The length of the positive pole piece is L2, and lengths of the two right-angled sides of the right-angled triangle on the positive pole piece are a2 and b2 respectively.

[0015] The L1 and the L2 satisfy the relationship: 1mm≤L1-L2≤2.5mm.

[0016] The a1 and the a2 satisfy the relationship: 1.0a2≤a1≤1.2a2.

[0017] The b1 and the b2 satisfy a relationship: 1.0b2≤b1≤1.2b2.

[0018] Optionally, the L1 and the L2 satisfy a relationship: 1mm≤L1-L2≤1.5mm.

[0019] The a1 and the a2 satisfy a relationship: a1-a2=0.

[0020] The b1 and the b2 satisfy a relationship: b1-b2=0.

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

[0022] Optionally, the length of the negative electrode tab is greater than the length of the positive electrode tab, and in the pole core, the two ends of the negative electrode tab in the length direction protrude from the two ends of the positive electrode tab in the length direction.

[0023] The difference between the size of the shell inner cavity along the length direction of the negative electrode tab and the length of the negative electrode tab is in the range of 0.5mm-1.0mm.

[0024] According to the battery provided by the utility model, a plurality of cut angles are formed at the corner positions of the tabs, the plurality of tab cut angles are distributed at the four corner positions of the pole core, and the first cut angle, the second cut angle, the third cut angle and the fourth cut angle which are opposite to the corner positions of the shell are formed outside the four corner positions; thus, the bending phenomenon of the tabs at the four corner positions is avoided, and the internal short circuit condition of the battery is avoided; since a plurality of cut angles are formed at the corner positions of the tabs and the four corner positions of the shell are not in contact, when the tabs swell during the charging and discharging cycle of the battery, the corner positions of the shell will not be damaged and corroded, and the safety performance of the battery is improved; meanwhile, since a plurality of cut angles are formed at the corner positions of the tabs, the length and the width of the tabs of the application can be increased, and thus the energy density of the battery is improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical scheme of the embodiments of the utility model, the drawings which need to be used in the following description of the embodiments of the utility model will be briefly introduced, and obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained according to these drawings without the creative labor of the ordinary skilled in the art.

[0026] Figure 1 is a structural schematic view of an existing battery;

[0027] Figure 2 is Figure 1 a structural schematic view of a pole core in the application;

[0028] Figure 3 is Figure 2A cross-sectional view of the middle pole core at an angle position along a direction perpendicular to the thickness of the pole core;

[0029] Figure 4 A structure schematic view of the battery of the utility model;

[0030] Figure 5 Is through Figure 4 A structure schematic view of the middle pole core;

[0031] Figure 6 Is Figure 5 A cross-sectional view of the middle pole core at an angle position along a direction perpendicular to the thickness of the pole core;

[0032] Figure 7 A structure schematic view of the negative pole piece provided by an embodiment of the utility model;

[0033] Figure 8 A structure schematic view of the positive pole piece provided by an embodiment of the utility model;

[0034] Figure 9 A partial cross-sectional view of the middle pole core and the shell of the battery provided by an embodiment of the utility model;

[0035] The reference signs in the drawings of the specification are as follows:

[0036] 100-pole core; 101-first cut angle; 102-second cut angle; 103-third cut angle; 104-fourth cut angle; 105-first angle position 105; 106-second angle position; 107-third angle position; 108-fourth angle position; 1-pole piece; 11-first cutout; 12-second cutout; 13-third cutout; 14-fourth cutout; 1a-positive pole piece; 1b-negative pole piece; 200-shell. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical schemes and beneficial effects solved by the utility model more clearly understood, the utility model is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model, and are not used to limit the utility model.

[0038] In the description of the utility model, it is necessary to understand that the orientation or position relation 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 relation based on the drawings shown, 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, unless otherwise specified, the meaning of "a plurality of" is two or more than two.

[0039] 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 fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be 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.

[0040] As shown in the drawing, Figures 4-6 As shown in the drawing, in an embodiment, the utility model provides a battery, which comprises a shell 200 and a square pole core 1 accommodated in the shell 200, the pole core 1 comprises a diaphragm arranged in a plurality of laminations and two square pole pieces 1 of opposite polarity, the pole core 1 has four corner positions in the direction perpendicular to its thickness, the length of one pole piece 1 is greater than or equal to the length of the other pole piece 1, and the first cut 11, the second cut 12, the third cut 13 and the fourth cut 14 are arranged on the two pole pieces 1 of the same length or at least the longer one of the pole pieces 1 corresponding to the four corner positions respectively, all the first cuts 11 are combined to form the first cut corner 101, all the second cuts 12 are combined to form the second cut corner 102, all the third cuts 13 are combined to form the third cut corner 103 and all the fourth cuts 14 are combined to form the fourth cut corner 104, and the first cut corner 101, the second cut corner 102, the third cut corner 103 and the fourth cut corner 104 are distributed at the four corner positions of the square pole core 1.

[0041] Specifically, in order to simplify the subsequent description, the first cut corner 101, the second cut corner 102, the third cut corner 103 and the fourth cut corner 104 are collectively referred to as cut corners.

[0042] Specifically, in order to simplify the subsequent description, the first cut 11, the second cut 12, the third cut 13 and the fourth cut 14 are collectively referred to as cuts.

[0043] In the prior art, under the premise that the size of the battery compartment is fixed, the three dimensions (thickness * width * length) of the battery size are utilized to the extreme, and the energy density of the battery is the highest.

[0044] In the length direction of the battery, when the difference between the length of the pole piece 1 and the length of the shell punch is small, the distance between the pole piece 1 and the aluminum plastic film in the shell 200 is short, especially at the four corner positions of the shell 200. When the pole piece 1 expands during the battery charging and discharging cycle, it is easy to cause damage and internal corrosion at the corner positions of the shell 200, causing reliability risks. At the same time, when the pole core 1 is packaged into the shell, the pole piece 1 is easy to bend at the four corner positions, causing internal short circuit.

[0045] Specifically, the pole core 1 of the present application is a square pole core 1, and the part except the tab is square or rectangular in cross section perpendicular to the thickness direction. The pole core 1 has four corners in the four directions perpendicular to the thickness direction, which are the first corner 105, the second corner 106, the third corner 107 and the fourth corner 108. The pole piece 1 cutouts are distributed at the first corner 105, the second corner 106, the third corner 107 and the fourth corner 108 of the pole core 1, and the first cut corner 101 opposite the corner of the shell 200 is formed outside the first corner 105, the second cut corner 102 opposite the corner of the shell 200 is formed outside the second corner 106, the third cut corner 103 opposite the corner of the shell 200 is formed outside the third corner 107, and the fourth cut corner 104 opposite the corner of the shell 200 is formed outside the fourth corner 108. The first cut corner 101, the second cut corner 102, the third cut corner 103 and the fourth cut corner 104 are provided to avoid the bending of the pole piece 1 at the four corners of the pole core 1, and to avoid the internal short circuit of the battery. Due to the four cut corners, the pole piece 1 does not contact the four corners of the shell 200, so when the pole piece 1 expands during the battery charging and discharging cycle, it will not cause damage and internal corrosion at the corner positions of the shell 200, improving the safety performance of the battery. At the same time, since the pole piece 1 is provided with multiple cutouts for forming cut corners, the length and width of the pole piece 1 of the present application can be increased, thereby improving the energy density of the battery.

[0046] The battery provided by the embodiments of the present application can be a secondary battery or a primary battery, for example, a lithium ion battery, a sodium ion battery or a magnesium ion battery, etc. The embodiments of the present application do not limit this. The electrochemical device can be a flat body, a cuboid or other shapes, etc. The embodiments of the present application also do not limit this.

[0047] The embodiments of the present application provide a power consumption device using a battery as a power source. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric car, an electric vehicle, a ship, a spacecraft, etc.

[0048] AsFigures 4-5 As shown in the drawings, in an embodiment, the first cutout 11, the second cutout 12, the third cutout 13 and the fourth cutout 14 are each independently selected from an arc shape, a triangular shape, a rectangular shape or an irregular shape.

[0049] Specifically, the first cutout 11, the second cutout 12, the third cutout 13 and the fourth cutout 14 can be selected in different shapes according to actual needs.

[0050] As shown in the drawings, Figures 4-5 In an embodiment, the shapes of the first cutout 11, the second cutout 12, the third cutout 13 and the fourth cutout 14 are all right-angled triangles, and the two right-angled sides of the right-angled triangle are respectively in the same straight line with the adjacent sides of the pole piece 1.

[0051] The two right-angled sides of the right-angled triangle are respectively in the same straight line with the adjacent sides of the pole piece 1, so that the first cutout 11, the second cutout 12, the third cutout 13 and the fourth cutout 14 are respectively distributed at the first corner position 105, the second corner position 106, the third corner position 107 and the fourth corner position 108 of the pole core 1, and form a cut corner respectively opposite to the corner position of the shell 200 outside the four corner positions; avoid the bending phenomenon of the pole piece 1 at the four corner positions, and avoid the internal short circuit of the battery.

[0052] As shown in the drawings, Figures 4-5 In an embodiment, the lengths of the two right-angled sides of the right-angled triangle are a and b respectively, the value range of a is 0.2mm~0.7mm; the value range of b is 0.2mm~0.7mm.

[0053] Specifically, the value range of a in the first cutout 11, the second cutout 12, the third cutout 13 and the fourth cutout 14 is any point value or a range value composed of any two point values in 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm or 0.7mm.

[0054] Specifically, the value range of b in the first cutout 11, the second cutout 12, the third cutout 13 and the fourth cutout 14 is any point value or a range value composed of any two point values in 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm or 0.7mm.

[0055] When the value of 'a' in the first cut 11, second cut 12, third cut 13, and fourth cut 14 is in the range of 0.2mm to 0.7mm, and the value of 'b' in the first cut 11, second cut 12, third cut 13, and fourth cut 14 is in the range of 0.2mm to 0.7mm, when the electrode 1 is close to the inner side of the outer casing 200, not only can the energy density of the battery be improved, but also the bending phenomenon of the electrode 1 at the four corners can be avoided, thus preventing internal short circuits in the battery. Since multiple cuts are formed at the corners of the electrode 1, and they do not contact the four corners of the outer casing 200, the expansion of the electrode 1 during the battery charge and discharge cycle will not cause damage or internal corrosion at the corners of the outer casing 200, thus improving the battery safety performance.

[0056] When the value of 'a' in the first cut 11, second cut 12, third cut 13, and fourth cut 14 is less than 0.2 mm, and the value of 'b' in the first cut 11, second cut 12, third cut 13, and fourth cut 14 is less than 0.2 mm, it is easy to come into contact with the four corners of the outer casing 200. Therefore, when the electrode 1 expands during the battery charge and discharge cycle, it will cause damage and internal corrosion at the corners of the outer casing 200. When the value of 'a' in the first cut 11, second cut 12, third cut 13, and fourth cut 14 is greater than 0.7 mm, and the value of 'b' in the first cut 11, second cut 12, third cut 13, and fourth cut 14 is less than or greater than 0.7 mm, the battery energy density cannot be effectively improved.

[0057] In a preferred embodiment, electrode 1 is a square electrode with equal values ​​a and b, and the right triangle is an isosceles right triangle.

[0058] like Figures 4-6 As shown, in one embodiment, the value of a2 ranges from 0.4mm to 0.6mm; the value of b2 ranges from 0.4mm to 0.6mm.

[0059] like Figures 7-8 As shown, in one embodiment, the two electrodes 1 with opposite polarities are a positive electrode 1a and a negative electrode 1b, and both the positive electrode 1a and the negative electrode 1b are provided with electrode 1 cutouts.

[0060] Specifically, the number of the first cut 11, the second cut 12, the third cut 13 and the fourth cut 14 on the positive electrode 1a is the same as the number of the first cut 11, the second cut 12, the third cut 13 and the fourth cut 14 on the negative electrode 1b;

[0061] Preferably, the number of the first cut 11, the second cut 12, the third cut 13, and the fourth cut 14 on the positive electrode 1a is the same as the number of the positive electrode 1a, and the number of the first cut 11, the second cut 12, the third cut 13, and the fourth cut 14 on the negative electrode 1b is the same as the number of the negative electrode 1b. This not only improves the energy density of the battery, but also prevents the electrode 1 from bending at the four corners, thus avoiding internal short circuits in the battery. Since multiple cuts are formed at the corners of the electrode 1, they do not contact the four corners of the outer casing 200. Therefore, when the electrode 1 expands during the battery charge and discharge cycle, it will not cause damage or internal corrosion at the corners of the outer casing 200, thus improving the battery safety performance.

[0062] When the number of the first cut 11, the second cut 12, the third cut 13, and the fourth cut 14 on the positive electrode 1a is less than the number of positive electrode 1a, or the number of the first cut 11, the second cut 12, the third cut 13, and the fourth cut 14 on the negative electrode 1b is less than the number of negative electrode 1b, the electrode 1 without cuts is prone to contact with the four corners of the casing 200. Therefore, when the electrode 1 expands during the battery charge and discharge cycle, it will cause damage and internal corrosion at the corners of the casing 200.

[0063] like Figures 7-8 As shown, in one embodiment, the length of the negative electrode 1b is L1, and the lengths of the two legs of the right triangle on the negative electrode 1b are a1 and b1, respectively;

[0064] The length of the positive electrode 1a is L2, and the lengths of the two legs of the right triangle on the positive electrode 1a are a2 and b2, respectively;

[0065] L1 and L2 satisfy the following relationship: 1mm≤L1-L2≤2.5mm;

[0066] a1 and a2 satisfy the following relationship: 1.0a2≤a1≤1.2a2;

[0067] b1 and b2 satisfy the following relationship: 1.0b2≤b1≤1.2b2;

[0068] Specifically, the positive electrode 1a, the separator, and the negative electrode 1b are stacked to form the electrode core 1. The negative electrode 1b is located on the outermost side of the electrode core 1, and the length of the negative electrode 1b is greater than the length of the positive electrode 1a. When L1 and L2 satisfy the relationship: 1mm≤L1-L2≤2.5mm, lithium absorption can be avoided.

[0069] When a1 and a2 satisfy the relationship: 1.0a2≤a1≤1.2a2, the bending of electrode 1 at the four corners can be avoided, thus preventing internal short circuits in the battery.

[0070] When b1 and b2 satisfy the relationship: 1.0 < b1 / b2 < 1.2, the bending phenomenon of the pole piece 1 at the four corner positions can be avoided, and the internal short circuit condition of the battery can be avoided.

[0071] As shown in the drawings, Figures 7-8 In an embodiment, L1 and L2 satisfy the relationship: 1mm < L1-L2 < 1.5mm;

[0072] a1 and a2 satisfy the relationship: a1-a2=0;

[0073] b1 and b2 satisfy the relationship: b1-b2=0;

[0074] When L1 and L2 satisfy the relationship: 1mm < L1-L2 < 1.5mm, the battery energy density can be improved, and the lithium absorption phenomenon can be avoided;

[0075] When a1 and a2 satisfy the relationship: a1-a2=0; and b1 and b2 satisfy the relationship: b1-b2=0, the values of a and b are minimized under the premise that the pole piece 1 at the four corner positions will not be bent, which not only avoids the expansion of the pole piece 1 during the charging and discharging cycle of the battery, causing damage and internal corrosion at the corner positions of the shell 200, and improves the safety performance of the battery; but also improves the battery energy density.

[0076] As shown in the drawings, Figure 4 In an embodiment, the shell 200 is an aluminum plastic film.

[0077] Specifically, the battery cell of the present application is applied to a soft package battery, and the aluminum plastic film is wrapped around the battery cell.

[0078] As shown in the drawings, Figure 9 In an embodiment, the length of the negative pole piece 1b is greater than the length of the positive pole piece 1a, and in the pole core 1, the two ends of the negative pole piece 1b in the length direction protrude beyond the two ends of the positive pole piece 1a in the length direction.

[0079] The difference between the size of the inner cavity of the shell 200 in the length direction of the negative pole piece 1b and the length of the negative pole piece 1b is in the range of 0.5mm-1.0mm.

[0080] Specifically, the value of PA gap is in the range of 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1.0mm, or any two point values; in an embodiment, the value of PA gap is in the range of 0.6mm-0.8mm.

[0081] Further, the difference between the length of the negative pole piece 1b and the length of the shell 200 is at least 1.2mm, and at this time, b1 and PA gap satisfy the relationship: b1=1.2-PA gap;

[0082] b2 and PA gap satisfy the relationship: b2=1.2-PA gap, unit: mm;

[0083] When the value range of PA gap is 0.5mm-1.0mm, the bending phenomenon of the pole piece 1 at the four corner positions can be avoided, the internal short circuit of the battery can be avoided, the damage and internal corrosion of the shell 200 at the corner position caused by the expansion of the pole piece 1 in the battery charging and discharging cycle can be avoided, and the length and width of the negative pole piece 1b of the application can be increased to improve the energy density of the battery.

[0084] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application. 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 comprising a housing and a square-shaped core housed in the housing, the core comprising a separator and two square-shaped electrode sheets of opposite polarity arranged in a stack; the core having four corner positions in a direction perpendicular to its thickness, characterized in that: The length of one of the pole pieces is greater than the length of the other pole piece; the first, second, third and fourth cutouts are provided on each of the two pole pieces of the same length or at least the longer one of the pole pieces at four corner positions respectively, all the first cutouts combine to form a first cut corner, all the second cutouts combine to form a second cut corner, all the third cutouts combine to form a third cut corner and all the fourth cutouts combine to form a fourth cut corner; the first, second, third and fourth cut corners are distributed at the four corner positions of the square core.

2. The battery of claim 1, wherein: The first, second, third and fourth cutouts are each independently selected from an arc shape, a triangular shape or a rectangular shape.

3. The battery of claim 2, wherein: The first, second, third and fourth cutouts are each a right-angled triangle, and two right-angled sides of the right-angled triangle are respectively in line with adjacent sides of the pole piece.

4. The battery of claim 3, wherein: The lengths of the two right-angled sides of the right-angled triangle are a and b respectively, the value range of a is 0.2mm-0.7mm; the value range of b is 0.2mm-0.7mm.

5. The battery of claim 4, wherein: The value range of a is 0.4mm-0.6mm; the value range of b is 0.4mm-0.6mm.

6. The battery of claim 4, wherein: The two pole pieces with opposite polarities are positive pole pieces and negative pole pieces respectively, and the positive pole pieces and the negative pole pieces are each provided with the pole piece cutout.

7. The battery of claim 6, wherein: The length of the negative pole piece is L1, and the lengths of the two right-angled sides of the right-angled triangle on the negative pole piece are a1 and b1 respectively; The length of the positive pole piece is L2, and the lengths of the two right-angled sides of the right-angled triangle on the positive pole piece are a2 and b2 respectively; The L1 and the L2 satisfy the relationship: 1mm≤L1-L2≤2.5mm; The a1 and the a2 satisfy the relationship: 1.0a2≤a1≤1.2a2; The b1 and the b2 satisfy the relationship: 1.0b2≤b1≤1.2b2.

8. The battery of claim 7, wherein: The L1 and the L2 satisfy the relationship: 1mm≤L1-L2≤1.5mm; The a1 and the a2 satisfy the relationship: a1-a2=0; The b1 and the b2 satisfy the relationship: b1-b2=0.

9. The battery of any one of claims 1-8, wherein: The shell is an aluminum plastic film.

10. The battery of claim 9, wherein: The two pole pieces with opposite polarities are positive pole pieces and negative pole pieces respectively, the length of the negative pole piece is greater than the length of the positive pole piece, and in the core, the two ends of the negative pole piece in the length direction protrude beyond the two ends of the positive pole piece in the length direction; The difference between the size of the inner cavity of the shell along the length direction of the negative pole piece and the length of the negative pole piece is in the range of 0.5mm-1.0mm.

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