Battery

Abstract

The invention relates to the technical field of batteries, and discloses a battery. The battery comprises a first stack core and a second stack core. The second laminated core and the first laminated core are laminated along the first direction, and the first laminated core and the second laminated core are different in size along the second direction, so that the shape of the battery is matched with a cabin, and the space utilization rate of the cabin and the energy density of the battery are improved; a second notch part corresponding to the first notch part in position is formed in the second pole piece, and the distance W1 from the joint of the first notch part and the first side edge to the second side edge is greater than the distance W2 from the third side edge to the second side edge, so that the third side edge exceeds the joint of the first notch part and the first side edge, and the battery is prevented from falling off in the falling process of the battery. And the second notch part of the second laminated core shares the stress borne by the first notch part of the first laminated core, so that the condition that the pole piece is broken at the corner due to the fact that the stress at the joint of the first notch part and the first side edge is too large is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to batteries. Background Art

[0002] Lithium-ion batteries, with their high energy density, excellent cycle performance, and compact size, are widely used in consumer electronics, new energy vehicles, and energy storage power stations. Compared to conventional wound lithium-ion batteries, laminated batteries offer advantages in energy density and rate performance. With the rapid development of portable electronic devices, specialized laminated batteries, such as L-shaped batteries, have gained widespread application. These specialized batteries can adapt to various cabin shapes, effectively improving cabin space utilization.

[0003] However, since the L-shaped battery consists of two partitions, the intersection of the two partitions forms a right-angle corner. When the battery falls during production and use, the stress on the right-angle corner is relatively large, and it is easy for the electrode in the battery to break at the corner, seriously affecting the performance of the battery. Summary of the Invention

[0004] In view of this, the present invention provides a battery to solve the problem that the battery pole piece is easily broken at the corner.

[0005] The present invention provides a battery, comprising: a first core stack comprising a plurality of first pole pieces stacked along a first direction; a second core stack, wherein the second core stack and the first core stack are stacked along the first direction, the second core stack comprising a plurality of second pole pieces stacked along the first direction, and the first core stack having a larger size than the second core stack along the second direction; the first pole piece comprising a first main body overlapping with the second core stack, and a second main body not overlapping with the second core stack; a first notch portion being provided between the first main body and the second main body on one side of the first pole piece along a third direction, the first main body having a first side connected to the first notch portion, and the second main body having a second side facing away from the first main body along the second direction; a second notch portion being provided at a corner of the second pole piece, the second notch portion being positioned corresponding to the first notch portion; the second pole piece having a third side adjacent to the second side along the second direction, wherein a distance from a junction of the first notch portion and the first side to the second side is W1, and a distance from the third side to the second side is W2, wherein W1>W2; and the first direction, the second direction, and the third direction are mutually perpendicular.

[0006] Beneficial Effects: By arranging the second core stack and the first core stack to be stacked along the first direction, and the first core stack and the second core stack to have different sizes along the second direction, the shape of the battery can be adapted to the cabin of the electrical equipment, thereby improving the space utilization of the cabin and the energy density of the battery. In addition, by constructing a first notch between the first body and the second body of the first electrode sheet, and constructing a second notch on the second electrode sheet corresponding to the position of the first notch, that is, a non-right-angle transition angle is formed on the side of the second core stack close to the second body. At the same time, by providing the first electrode sheet with a second side facing away from the second electrode sheet along the second direction, and the distance W1 from the connection between the first notch and the first side to the second side being greater than the distance W2 from the third side to the second side, the third side exceeds the connection between the first notch and the first side along the direction from the first body to the second body. Therefore, when the battery falls, the second notch of the second core stack shares the stress exerted on the first notch of the first core stack, preventing the stress at the connection between the first notch and the first side from being excessive and causing the electrode sheet to break at the corner, thereby improving the safety of the battery.

[0007] In an optional embodiment, on the contour line of the first notch, the point farthest from the extension line of the first side along the third direction is the first point, and the distance from the first point to the second side is W3, where W3≤W2.

[0008] Beneficial effect: By setting the distance W3 from the first point to the second side to be less than or equal to the distance W2 from the third side to the second side, the third side on the second electrode does not exceed the lowest point of the first notch of the first electrode along the direction from the first body to the second body, thereby avoiding the formation of sharp corners at the second notch of the second electrode, thereby avoiding powder falling off at the sharp corners or puncturing the diaphragm during die-cutting of the second electrode, thereby avoiding internal short circuit or micro-short circuit in the second stack, and ensuring that the battery has good self-discharge performance.

[0009] In an optional embodiment, along the third direction, the size of the second body is larger than that of the first body, and at the inner corner of the first pole piece, the second body has a fourth side connected to the first notch.

[0010] Beneficial effect: By setting the size of the second body along the third direction to be larger than that of the first body, the first pole piece can further fully utilize the space in the cabin and further increase the area of ​​the first pole piece, thereby improving the energy density of the battery.

[0011] In an optional embodiment, the contour line of the first notch portion includes: a first arc segment, a first hypotenuse and a second hypotenuse, the first hypotenuse and the second hypotenuse are each tangently connected to one end of the first arc segment, the first hypotenuse and the first side are connected by a first rounded corner, and the second hypotenuse and the fourth side are connected by a second rounded corner.

[0012] Beneficial effect: By setting the contour line of the first notch portion to adopt a circular arc plus hypotenuse structure, the contour line of the first notch portion is smoothly connected between the first side and the fourth side, avoiding the appearance of right angles or sharp angles in the first notch portion, thereby avoiding the phenomenon of stress concentration, and can avoid the first electrode sheet from being torn from the first notch portion when the battery falls, thereby improving the safety performance of the battery; and compared with the structural form of only setting a circular arc segment, the structural form of the circular arc segment plus the hypotenuse can reduce the area of ​​the region enclosed by the first notch portion, thereby reducing the energy loss of the first electrode sheet caused by setting the first notch portion, thereby increasing the energy density of the battery.

[0013] In an optional embodiment, the second pole piece further has a fifth side edge corresponding to the first side edge, and the second notch portion is formed between the fifth side edge and the third side edge;

[0014] The contour line of the second notch portion includes: a third rounded corner, a third oblique side, and a second arc segment, the third oblique side is arranged corresponding to the first oblique side, the third rounded corner is connected between the third oblique side and the fifth side, the second arc segment is connected between the third oblique side and the third side, and the second arc segment is arranged corresponding to a portion of the first arc segment;

[0015] And / or, the contour line of the second notch portion includes: a third rounded corner and a third hypotenuse, the third hypotenuse corresponds to at least a portion of the first hypotenuse, the third rounded corner is connected between the third hypotenuse and the fifth side, the end of the third hypotenuse away from the third rounded corner is smoothly connected to the third side, or the third hypotenuse is connected to the third side at an obtuse angle.

[0016] Beneficial effect: by arranging the third oblique side and the fifth side to be connected by the third fillet, and the third oblique side and the third side to be connected by the second arc segment, the contour line of the second notch portion and the fifth side and the third side are smoothly transitioned, thereby avoiding the phenomenon of stress concentration at the second notch portion, and by arranging the third oblique side to correspond to the first oblique side on the first pole piece, the second notch portion is better fitted with the first notch portion, preventing the second core stack from being misaligned with the second core stack, thereby avoiding contact or powder loss of pole pieces of different polarities in the first and second core stacks, resulting in a short circuit, and at the same time, by constructing a second arc segment on the second pole piece corresponding to part of the first arc segment, the area of ​​the overlapping region between the second notch portion and the first notch portion is increased, further increasing the ability of the second core stack to share the stress during the fall process, and further ensuring the safety of the battery;

[0017] By setting the contour line of the second notch portion to be a structural form of an arc segment plus a bevel, the third bevel and the fifth side are connected by a third rounded corner, so that the contour line of the second notch portion and the fifth side have a smooth transition. At the same time, the length of the third bevel is set not to exceed the length of the first bevel, and the third bevel and the third side have a smooth transition or form an obtuse angle, which can also ensure that the second notch portion fits better with the first notch portion, and avoid forming a sharp corner at the second notch portion, avoid powder falling off the pole piece during die-cutting, and prevent the sharp corner from puncturing the diaphragm, thereby ensuring the safety performance of the battery.

[0018] In an optional embodiment, the radius of the first rounded corner is R1, and the radius of the third rounded corner is R3, wherein R3 and R1 satisfy the relationship: 0.8≤R1 / R3≤1, and the units of R1 and R3 are both mm;

[0019] And / or, the length of the first hypotenuse is L1, and the length of the third hypotenuse is L2, wherein L2 and L1 satisfy the relationship: 0.8≤L2 / L1≤1, and the units of L1 and L2 are both mm;

[0020] And / or, the angle between the third hypotenuse and the third side is α, where α≥135°.

[0021] Beneficial effect: By limiting the ratio R1 / R3 between the radius R1 of the first fillet and the radius R3 of the third fillet to a value within the range of 0.8 to 1, it is possible to ensure that the first electrode piece can completely cover the second electrode piece, thereby avoiding interference between the second stacked core and the aluminum-plastic film during packaging, and also to avoid a depression on the aluminum-plastic film at a position corresponding to the third fillet.

[0022] By setting L / L to a value within the range of .5 to .7, it is possible to ensure that the first electrode sheet can completely cover the second electrode sheet, ensure the fit between the second notch and the first notch, and avoid interference between the second laminated core and the aluminum-plastic film during packaging. It is also possible to avoid a dent in the aluminum-plastic film at a position corresponding to the second notch, and prevent the electrode sheet from tearing when the battery is dropped.

[0023] By setting the third bevel and the third side to be connected at an obtuse angle, and the angle α being greater than or equal to °, the second electrode can be prevented from easily losing powder during die-cutting, and the angle can be prevented from being too sharp and puncturing the diaphragm, thereby further improving the safety of the battery.

[0024] In an optional embodiment, the battery further includes: a membrane shell, the membrane shell being formed by buckling a first diaphragm and a second diaphragm, the second diaphragm being provided with a first pit and a second pit, the depth of the first pit being greater than the depth of the second pit, a step structure being formed on the surface of the second diaphragm facing away from the first diaphragm, the first stacked core being arranged in the first pit and the second pit, and the first main body of the first stacked core being located in the first pit, the second main body being located in the second pit, and a first corner portion corresponding to the first notch portion, and a second corner portion corresponding to the second notch portion being constructed at an inner corner of the membrane shell.

[0025] Beneficial effect: By setting the punching holes of the membrane shell to match the shapes of the first and second core stacks after being stacked, it is convenient to place the first and second core stacks in the punching holes on the second membrane sheet, thereby facilitating the encapsulation of the first and second core stacks by the membrane shell, with a simple structure and high reliability.

[0026] In an optional embodiment, the first corner portion includes a first arcuate surface corresponding to the first rounded corner, the second corner portion includes a second arcuate surface corresponding to the third rounded corner, and the arc radius of the first arcuate surface is equal to the arc radius of the second arcuate surface;

[0027] And / or, the first punching pit includes a first side surface corresponding to the third side edge, and the second corner portion is transitionally connected to the first side surface via a third arcuate surface.

[0028] Beneficial effect: By setting the arc radius of the first arc surface on the membrane shell to be equal to the arc radius of the second arc surface, the size consistency of the parts on the first punching pit corresponding to the first rounded corner of the first stacked core and the third rounded corner of the second stacked core is ensured, and the first punching pit can be punched and formed in one go, thereby ensuring that the second diaphragm is integrally formed, which is convenient for processing and production;

[0029] By arranging a transition connection between the second corner portion and the first side surface through a third arc-shaped surface, a right angle is avoided between the second corner portion and the first side surface, stress concentration at the corner can be avoided, thereby preventing the film shell from breaking at the connection between the second corner portion and the first side surface of the aluminum-plastic film when the battery falls, thereby further improving the safety performance of the battery.

[0030] In an optional embodiment, the packaging film of the membrane shell includes an aluminum layer, and the thickness of the packaging film at the non-pitted position of the membrane shell is H;

[0031] The thickness of the packaging film on the bottom wall of the first pit and located at the first corner of the first pit is H4, and the thickness of the aluminum layer of the packaging film located at the first corner is H2; the thickness of the packaging film on the bottom wall of the second pit and located at the second corner of the second pit is H5, and the thickness of the aluminum layer of the packaging film located at the second corner is H3;

[0032] Among them, H5≥H4≥0.6H, H2≥20μm, H3≥20μm;

[0033] And / or, the packaging film of the membrane shell includes an aluminum layer, and at a non-pitted position of the membrane shell, the thickness of the aluminum layer is H1, and the thickness of the packaging film is H, wherein 0.2≤H1 / H≤0.7, 50μm≤H≤120μm.

[0034] Beneficial effect: By setting the relationship between H5, H4 and H to satisfy H5≥H4≥0.6H, the minimum wall thickness of the first pit and the minimum wall thickness of the second pit are both greater than or equal to 0.6 times the thickness of the packaging film before the pit is punched, which can ensure that the packaging film does not break after the pit is punched; at the same time, by setting the thickness of the aluminum layer at the minimum wall thickness of the first pit and the minimum wall thickness of the second pit to be greater than or equal to 20μm, the sealing of the membrane shell can be ensured, preventing water in the air from entering the interior of the battery;

[0035] By setting the thickness H of the packaging film to a value between 50μm and 120μm, and the ratio between the thickness H1 of the aluminum layer at the non-pitted position of the membrane shell and the thickness H of the packaging film to a value between 0.2 and 0.7, it can be ensured that the packaging film has sufficient mechanical strength and good barrier properties, and avoids the packaging film being too heavy, thereby ensuring the energy density of the battery and controlling the battery cost.

[0036] In an optional embodiment, the size of the second punched hole along the third direction is larger than the size of the first punched hole along the third direction, so as to form a convex portion and a concave portion at one end of the battery along the third direction;

[0037] The membrane shell further includes an edge sealing structure provided around the first dent and the second dent, the edge sealing structure including a first flange and a second flange, the first flange being located on a side of the raised portion facing the recessed portion along the second direction, and the second flange being located on a side of the second dent away from the first dent, and the dimensions of the first flange and the second flange along the first direction being both smaller than or equal to the dimension of the second dent along the first direction;

[0038] And / or, the battery further comprises:

[0039] A first pole ear, a second pole ear and a protective plate, wherein the first pole ear is arranged on the first side edge of the first pole piece or on the fifth side edge of the second pole piece; one end of the second pole ear extends into the inner side of the membrane shell and is connected to the first pole ear, the other end of the second pole ear is located on the outer side of the membrane shell, and the part of the second pole ear located on the outer side of the membrane shell is located in the recessed portion; the protective plate is welded to the second pole ear, and the protective plate is located in the recessed portion.

[0040] Beneficial effects: By providing a convex portion and a concave portion at one end of the battery along the third direction, the space in the cabin is further fully utilized, and the energy density of the battery is improved. In addition, by providing an edge sealing structure, the sealing of the membrane shell package can be ensured, and the interference of structures such as the protection plate provided in the concave portion with the second pit can be avoided. By providing the heights of the first flange and the second flange located on both sides of the first pit along the first direction to be less than or equal to the thickness of the second pit, the edge sealing structure can be avoided from interfering with the cabin when the battery is placed in the cabin.

[0041] By arranging the portion of the second pole tab located outside the membrane shell in the recessed portion, the placement of the second stacked core is facilitated, and the protection plate welded to the second pole tab is also located in the recessed portion, thereby fully utilizing the space and ensuring that the battery size does not exceed the specification value. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 This is a schematic structural diagram of a battery according to an embodiment of the present invention;

[0044] Figure 2 for Figure 1 The battery shown includes a partially enlarged schematic diagram of a corner portion;

[0045] Figure 3 for Figure 1 A schematic structural diagram of the battery from another perspective;

[0046] Figure 4 for Figure 1 a top view of the battery shown;

[0047] Figure 5 This is a schematic structural diagram of a first pole piece according to an embodiment of the present invention;

[0048] Figure 6 for Figure 5 A partial enlarged schematic diagram;

[0049] Figure 7 This is a schematic structural diagram of a second pole piece according to an embodiment of the present invention;

[0050] Figure 8 for Figure 7 A partial enlarged schematic diagram of B in the middle;

[0051] Figure 9 This is a schematic structural diagram of another second pole piece according to an embodiment of the present invention;

[0052] Figure 10 for Figure 9 A partial enlarged schematic diagram of center C;

[0053] Figure 11 This is a schematic structural diagram of a second pole piece and a first pole piece stacked together according to an embodiment of the present invention;

[0054] Figure 12 for Figure 11 A partial enlarged schematic diagram of D in the middle;

[0055] Figure 13 A schematic diagram of a structure in which second pole pieces with three different sizes along the X direction are stacked on a first pole piece;

[0056] Figure 14 for Figure 13 A partial enlarged schematic diagram of E in the middle;

[0057] Figure 15 Schematic diagram of the positional relationship between the first rounded corner and the third rounded corner according to an embodiment of the present invention;

[0058] Figure 16 This is a cross-sectional view of a second electrode tab and a protection plate after welding according to an embodiment of the present invention;

[0059] Figure 17 Schematic diagram of the battery structure when the second stacked core does not include the second corner portion.

[0060] Description of reference numerals:

[0061] 1. First pole piece; 101. First side; 102. Fourth side; 103. Second side; 104. Inner corner; 110. First body; 120. Second body; 130. First notch; 131. First arc segment; 1311. First point; 132. First hypotenuse; 133. Second hypotenuse; 134. First fillet; 135. Second fillet; 2. Second pole piece; 201. Fifth side; 202. Third side; 2021. First position; 2022. Second position; 2023. Third position; 210. Second notch; 211. Third arc segment Corner; 212, third oblique side; 213, second arc segment; 3, membrane shell; 301, inner corner; 310, first diaphragm; 320, second diaphragm; 321, first punch hole; 3211, first side; 3212, third arc surface; 322, second punch hole; 331, first corner portion; 332, second corner portion; 333, first arc surface; 334, second arc surface; 410, raised portion; 420, recessed portion; 430, edge sealing structure; 431, first flange; 432, second flange; 501, first pole ear; 502, second pole ear; 6, protective plate. DETAILED DESCRIPTION

[0062] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0063] With the deepening promotion of "dual carbon", lithium-ion batteries are gradually moving towards fast charging, high energy density and high safety. Compared with conventional wound lithium-ion batteries, laminated batteries have advantages in energy density and rate performance. With the rapid development of portable electronic devices, special-shaped laminated batteries have gradually been widely used, such as L-shaped batteries. Special-shaped batteries can adapt to cabins of different shapes, effectively improving the space utilization of the cabin. However, since the two partitions of the L-shaped battery intersect to form a right-angle corner, when the battery falls during production and use, the stress at the right-angle corner is relatively large, and it is easy for the electrode in the battery to break at the corner, seriously affecting the safety performance of the battery.

[0064] The following combination Figures 1 to 17 , describing embodiments of the present invention.

[0065] According to an embodiment of the present invention, on the one hand, a battery is provided, such as Figures 1 to 16As shown, the battery includes: a first core stack and a second core stack. The first core stack includes a plurality of first pole pieces 1 stacked along a first direction Z; the second core stack and the first core stack are stacked along the first direction Z, and the second core stack includes a plurality of second pole pieces 2 stacked along the first direction Z. Along the second direction X, the size of the first core stack is larger than that of the second core stack; the first pole piece 1 includes a first main body 110 overlapping with the second core stack, and a second main body 120 not overlapping with the second core stack. On one side of the first pole piece 1 along the third direction Y, a first notch 130 is provided between the first main body 110 and the second main body 120. The first main body 110 has a first side 1 connected to the first notch 130. 01, the second main body 120 has a second side 103 away from the first main body 110 along the second direction X; a second notch portion 210 is provided at the corner of the second pole piece 2, and the second notch portion 210 and the first notch portion 130 are positioned correspondingly, and the second pole piece 2 has a third side 202 close to the second side 103 along the second direction X, wherein the distance from the connection between the first notch portion 130 and the first side 101 to the second side 103 is W1, and the distance from the third side 202 to the second side 103 is W2, wherein W1>W2; the first direction Z, the second direction X and the third direction Y are perpendicular to each other.

[0066] Among them, the first direction Z refers to Figure 1 The direction of "Z" pointed by the middle arrow is also the thickness direction of the battery; the second direction X refers to Figure 1 The arrow in the middle points to the direction of "X"; the third direction Y refers to Figure 1 The arrow in the middle points to the direction of "Y".

[0067] It should be noted that, by providing the first notch 130 on one side of the first pole piece 1 along the third direction Y, and the first notch 130 is located between the first body 110 and the second body 120, that is, a portion of the first notch 130 is formed on the first body 110 and the other portion is formed on the second body 120, and the first body 110 overlaps with the second laminated core, and the second body 120 does not overlap with the second laminated core, then the extension line of the third side 202 on one side of the second laminated core along the second direction X passes through the first notch 130; the first side 101 on the first body 110 connected to the first notch 130 is connected along the third direction Y. The second notch 130 extends in the second direction X, and the connection between the first notch 130 and the first side 101 is located on the first body 110; the second side 103 on the second body 120 is away from the first body 110 along the second direction X, and the second side 103 is away from the second stacked core overlapping with the first body 110 along the second direction X; the common pole piece is rectangular, and the second notch 210 is set at the corner of the second pole piece 2, which means that one of the four right angles of the traditional rectangular pole piece is constructed as a missing angle, and the missing angle corresponds to the position of the first notch 130 on the first pole piece 1, thereby forming a second notch 210 on the second pole piece 2.

[0068] In the battery of this embodiment, the second core stack is stacked with the first core stack along the first direction Z, and the first core stack and the second core stack have different sizes along the second direction X, so that the shape of the battery can be adapted to the cabin of the electrical equipment, thereby improving the space utilization of the cabin and the energy density of the battery. In addition, a first notch 130 is constructed between the first body 110 and the second body 120 of the first pole piece 1, and a second notch 210 corresponding to the position of the first notch 130 is constructed on the second pole piece 2, that is, a non-right angle transition angle is formed on the side of the second core stack close to the second body 120, and at the same time, the first pole piece 1 is provided with a non-right angle transition angle away from the second pole piece along the second direction X. 2, and the distance W1 from the connection between the first notch 130 and the first side 101 to the second side 103 is greater than the distance W2 from the third side 202 to the second side 103. As a result, along the direction from the first body 110 to the second body 120, the third side 202 exceeds the connection between the first notch 130 and the first side 101. Therefore, when the battery falls, the second notch 210 of the second stack shares the stress exerted on the first notch 130 of the first stack, preventing the stress at the connection between the first notch 130 and the first side 101 from being excessive and causing the electrode sheet to break at the corner, thereby improving the safety of the battery.

[0069] It should be noted that further combining Figure 11 As shown, the connection between the first notch portion 130 and the first side 101 is Figure 11The point P1 indicated by the middle arrow, that is, along the direction from the first body 110 to the second body 120, the third side 202 on the second pole piece 2 exceeds the point P1 on the first pole piece 1; if the above structure is not set, such as Figure 17 As shown, the second core stack does not include the second notch portion 210, and the second pole piece 2 is a common rectangular pole piece. The third side 202 on the second pole piece 2 does not exceed the connection between the first notch portion 130 and the first side 101 (point P1), and the second core stack no longer shares the force at the first notch portion 130. Since the first core stack includes a first partition (corresponding to the first main body 110 of the first pole piece 1) overlapping with the second core stack and a second partition (corresponding to the second main body 120 of the first pole piece 1) not overlapping with the second core stack, the weight of the first partition and the second core stack after superposition is greater than the weight of the second partition. Therefore, when the battery falls, the first main body 110 in the first partition is subjected to greater stress, which makes the first core stack easily break from the corner (point P1), affecting the safety of the battery.

[0070] In some embodiments, the first electrode sheet 1 includes a first positive electrode sheet and a first negative electrode sheet, and the second positive electrode sheet and the second negative electrode sheet are alternately arranged; the second electrode sheet 2 includes a second positive electrode sheet and a second negative electrode sheet, and the second positive electrode sheet and the second negative electrode sheet are alternately arranged.

[0071] In some embodiments, the first stacked core further includes a first diaphragm, and a first diaphragm is provided between adjacent first positive electrode sheets and first negative electrode sheets; the second stacked core further includes a second diaphragm, and a second diaphragm is provided between adjacent second positive electrode sheets and second negative electrode sheets to separate the positive and negative electrode sheets.

[0072] In some embodiments, further combined Figure 12 As shown, on the contour line of the first notch 130, the point farthest from the extension line of the first side 101 along the third direction Y is the first point 1311, and the distance from the first point 1311 to the second side 103 is W3, where W3≤W2. It should be noted that the first point 1311 is the lowest point of the contour line of the first notch 130. If W3>W2, then the third side 202 is located at Figure 14 At the third position 2023, a sharp corner is formed at the second notch 210 on the second electrode 2. When the electrode is die-cut, the sharp corner is prone to powder loss or puncture of the diaphragm, causing a short circuit or micro-short circuit inside the second stack, and thus leading to a poor K value of the battery cell, that is, poor self-discharge performance of the battery.

[0073] Therefore, by setting the distance W3 from the first point 1311 to the second side 103 to be less than or equal to the distance W2 from the third side 202 to the second side 103, the third side 202 on the second pole piece 2 does not exceed the lowest point of the first notch 130 of the first pole piece 1 along the direction from the first main body 110 to the second main body 120, thereby avoiding the formation of sharp corners at the second notch 210 of the second pole piece 2, thereby avoiding powder falling off at the sharp corners or puncturing the diaphragm during die-cutting of the second pole piece 2, thereby avoiding internal short circuit or micro-short circuit in the second stacked core, and ensuring that the battery has good self-discharge performance.

[0074] In some embodiments, further combined Figure 5 As shown, along the third direction Y, the size of the second body 120 is larger than that of the first body 110. At the inner corner 104 of the first pole piece 1, the second body 120 has a fourth side 102 connected to the first notch 130. By setting the size of the second body 120 along the third direction Y to be larger than that of the first body 110, the first pole piece 1 further fully utilizes the space within the cabin and further increases the area of ​​the first pole piece 1, thereby improving the energy density of the battery. Among them, the fourth side 102 is connected to one end of the contour line of the first notch portion 130, and the fourth side 102 extends along the third direction Y, and the first side 101 is connected to the other end of the contour line of the first notch portion 130, and the first side 101 extends along the second direction X, that is, the first side 101 is perpendicular to the fourth side 102, and the inner corner 104 of the first pole piece 1 is the intersection of the extension line of the first side 101 and the extension line of the fourth side 102. Since the first notch portion 130 is provided at the intersection of the first side 101 and the fourth side 102, the first side 101 and the fourth side 102 are avoided from directly intersecting to form a right angle, thereby reducing the stress at the corner and avoiding the first pole piece 1 from breaking at the inner corner 104 during the falling process of the battery.

[0075] In some embodiments, further combined Figure 6As shown, the contour line of the first notch portion 130 includes: a first arc segment 131, a first oblique side 132 and a second oblique side 133. The first oblique side 132 and the second oblique side 133 are each tangently connected to one end of the first arc segment 131. The first oblique side 132 and the first side 101 are connected through a first rounded corner 134, and the second oblique side 133 and the fourth side 102 are connected through a second rounded corner 135. By setting the contour line of the first notch portion 130 to adopt a circular arc plus hypotenuse structure, the contour line of the first notch portion 130 is smoothly connected between the first side 101 and the fourth side 102, avoiding the first notch portion 130 from having a right angle or a sharp angle, thereby avoiding the phenomenon of stress concentration, and preventing the first electrode 1 from being torn from the first notch portion 130 when the battery falls, thereby improving the safety performance of the battery; and compared with the structural form of only setting a circular arc segment, the structural form of the circular arc segment plus the hypotenuse can reduce the area of ​​the area enclosed by the first notch portion 130, thereby reducing the energy loss of the first electrode 1 caused by setting the first notch portion 130, thereby increasing the energy density of the battery.

[0076] In some embodiments, further combined Figures 7 and 8 As shown, the second pole piece 2 also has a fifth side 201 corresponding to the first side 101, and a second notch 210 is formed between the fifth side 201 and the third side 202. The outline of the second notch 210 includes: a third fillet 211, a third oblique side 212, and a second arc segment 213. The third oblique side 212 is corresponding to the first oblique side 132. The third fillet 211 is connected between the third oblique side 212 and the fifth side 201. The second arc segment 213 is connected between the third oblique side 212 and the third side 202. The second arc segment 213 is corresponding to a portion of the first arc segment 131. It should be noted that the second notch 210 is the missing angle formed between the fifth side 201 and the third side 202. The length of the third oblique side 212 is equal to the length of the first oblique side 132. The third fillet 211 is corresponding to the first fillet 134 on the first pole piece 1.

[0077] Among them, by providing a connection between the third oblique side 212 and the fifth side 201 through the third fillet 211, and by providing a connection between the third oblique side 212 and the third side 202 through the second arc segment 213, the contour line of the second notch portion 210 and the fifth side 201 and the third side 202 are smoothly transitioned, thereby avoiding stress concentration at the second notch portion 210. In addition, by providing the third oblique side 212 corresponding to the first oblique side 132 on the first pole piece 1, the second notch portion 210 is better fitted with the first notch portion 130, preventing the second core stack from being misaligned, thereby avoiding contact or powder loss of pole pieces of different polarities in the first and second core stacks, resulting in a short circuit. At the same time, by constructing a second arc segment 213 on the second pole piece 2 corresponding to a portion of the first arc segment 131, the area of ​​the overlapping region between the second notch portion 210 and the first notch portion 130 is increased, further increasing the ability of the second core stack to distribute stress during a drop, thereby further ensuring the safety of the battery.

[0078] In addition, in other embodiments, further combined Figures 9 and 10 As shown, the outline of the second notch 210 includes a third rounded corner 211 and a third oblique side 212. The third oblique side 212 corresponds to at least a portion of the first oblique side 132. The third rounded corner 211 is connected between the third oblique side 212 and the fifth side 201. The end of the third oblique side 212 away from the third rounded corner 211 is smoothly connected to the third side 202, or the third oblique side 212 is connected to the third side 202 at an obtuse angle. The length of the third oblique side 212 can be equal to or less than the length of the first oblique side 132. By setting the contour line of the second notch portion 210 to be a structural form of an arc segment plus a bevel, the third bevel 212 and the fifth side 201 are connected by the third rounded corner 211, so that the contour line of the second notch portion 210 and the fifth side 201 have a smooth transition. At the same time, the length of the third bevel 212 is set not to exceed the length of the first bevel 132, and the third bevel 212 and the third side 202 have a smooth transition or form an obtuse angle, which can also ensure that the second notch portion 210 fits better with the first notch portion 130, and avoid forming a sharp corner at the second notch portion 210, avoid powdering of the pole piece during die-cutting, and prevent the sharp corner from puncturing the diaphragm, thereby ensuring the safety performance of the battery.

[0079] The end of the third oblique edge 212 away from the third rounded corner 211 being smoothly transitioned to the third side edge 202 means that the third oblique edge 212 is transitionally connected to the third side edge 202 through the rounded corner.

[0080] In some embodiments, further combined Figure 10As shown, the contour line of the second notch portion 210 is a structural form of an arc segment plus a bevel, and the angle between the third bevel 212 and the third side 202 is α, where α ≥ 135°. If α is less than 135°, the angle between the third bevel 212 and the third side 202 is too small, and the second pole piece 2 is prone to powder loss during die-cutting, and the angle is too sharp and may puncture the diaphragm. Therefore, by setting the third bevel 212 and the third side 202 to be connected at an obtuse angle, and the angle α is greater than or equal to 135°, it is possible to prevent the second pole piece 2 from easily losing powder during die-cutting, and to prevent the angle from being too sharp and puncturing the diaphragm, thereby further improving the safety of the battery.

[0081] Further integration Figures 13 and 14 As shown, three different sizes of second pole pieces 2 are stacked on the first pole piece 1. When the third side 202 of the second pole piece 2 is at the first position 2021, the outline of the second notch 210 is composed of the third fillet 211 and the third oblique side 212, and the length of the third oblique side 212 is less than or equal to the length of the first oblique side 132. At this time, the angle between the third oblique side 212 and the third side 202 is α1, which is an obtuse angle, which can ensure the safety of the second stacked core; when the third side 202 of the second pole piece 2 is at the second position 2022, the outline of the second notch 210 is composed of the third fillet 211 , the third oblique edge 212 and the second arc segment 213. Since the second position 2022 will not exceed the first point 1311, the lowest point of the outline of the first notch portion 130, α2 will not be an acute angle, which can also ensure the safety of the second stacked core; and when the third side 202 is located at the third position 2023, the third side 202 exceeds the first point 1311, the lowest point of the outline of the first notch portion 130, α3 is an acute angle, and a sharp angle is formed between the third side 202 and the second arc segment 213. The second pole piece 2 is prone to powder loss during die-cutting, and the sharp corner will puncture the diaphragm, which is very dangerous and does not meet the design requirements.

[0082] In some embodiments, the radius of the first rounded corner 134 is R1 (e.g. Figure 8 As shown), the radius of the third fillet 211 is R3 (as shown Figure 8 and Figure 10 As shown), R3 and R1 satisfy the relationship: 0.8≤R1 / R3≤1, and the units of R1 and R3 are both mm. Figure 15As shown, when the radius R1 of the first rounded corner 134 is less than or equal to the radius R3 of the third rounded corner 211, the third rounded corner 211 will not exceed the range of the first rounded corner 134. If R1 / R3 is greater than 1, the third rounded corner 211 on the second electrode piece 2 will exceed the range of the first rounded corner 134 on the first electrode piece 1, thereby causing the third rounded corner 211 to interfere with the aluminum-plastic film during packaging; if R1 / R3 is less than 0.8, the difference between the third rounded corner 211 and the first rounded corner 134 is too large, and after the battery is packaged, a depression will appear on the aluminum-plastic film at a position corresponding to the third rounded corner 211.

[0083] Therefore, by limiting the ratio R1 / R3 between the radius R1 of the first fillet 134 and the radius R3 of the third fillet 211 to a value within the range of 0.8 to 1, it can be ensured that the first pole piece 1 can completely cover the second pole piece 2, thereby avoiding interference between the second stacked core and the aluminum-plastic film during packaging, and it can also avoid the occurrence of a depression at the position corresponding to the third fillet 211 on the aluminum-plastic film.

[0084] In some embodiments, the radius R1 of the first rounded corner 134 is in the range of 1.2 mm ≤ R1 ≤ 5 mm. Optionally, R1 is 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm.

[0085] In some embodiments, the radius of the second fillet 135 on the outline of the first notch 130 is R2, where R2 and R1 satisfy the relationship: R1 ≤ R2. It should be noted that the second fillet 135 is a major component of the outline of the first notch 130. By setting the radius R2 of the second fillet 135 to be greater than or equal to the radius R1 of the first fillet, the first notch 130 can be ensured to be large enough to mitigate the stress generated during a battery drop, thereby further ensuring battery safety.

[0086] In some embodiments, the value range of R2 is: 1.2 mm ≤ R2 ≤ 8 mm. Optionally, R2 is 1.2 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm.

[0087] In some embodiments, the length of the first oblique side 132 is L1, and the length of the third oblique side 212 is L2, where L2 and L1 satisfy the relationship: 0.8≤L2 / L1≤1, with L1 and L2 both expressed in mm. If L2 / L1 is greater than 1, i.e., L2 is greater than L1, the third oblique side 212 on the second notch 210 will extend beyond the first oblique side 132 on the first notch 130, resulting in poor fit between the second notch 210 and the first notch 130. This can cause interference between the second laminated core and the aluminum-plastic film during battery packaging. If L2 / L1 is less than 0.8, the length of the third oblique side 212 is too small relative to the length of the first oblique side 132, resulting in a depression on the aluminum-plastic film corresponding to the second notch 210. Furthermore, the second notch 210 cannot effectively distribute the stress during a battery drop. Therefore, by setting L2 / L1 to a value within the range of 0.8 to 1, it can be ensured that the first electrode piece 1 can completely cover the second electrode piece 2, ensure the fit between the second notch portion 210 and the first notch portion 130, avoid interference between the second stacked core and the aluminum-plastic film during packaging, and avoid the formation of depressions at the position corresponding to the second notch portion 210 on the aluminum-plastic film, and avoid the electrode piece from tearing during the battery falling process.

[0088] In some embodiments, the length L1 of the first oblique side 132 is in the range of 1 mm ≤ L1 ≤ 10 mm. Optionally, L1 is 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm.

[0089] In some embodiments, further combined Figures 1 to 4 As shown, the battery also includes: a membrane shell 3, which is formed by buckling a first diaphragm 310 and a second diaphragm 320, and a first pit 321 and a second pit 322 are provided on the second diaphragm 320, the depth of the first pit 321 is greater than the depth of the second pit 322, and a step structure is formed on the surface of the second diaphragm 320 away from the first diaphragm 310, the first stacked core is arranged in the first pit 321 and the second pit 322, and the first body 110 of the first stacked core is located in the first pit 321, and the second body 120 is located in the second pit 322, and the inner corner 301 of the membrane shell 3 is constructed with a first corner portion 331 corresponding to the first notch portion 130, and a second corner portion 332 corresponding to the second notch portion 210. It should be noted that the first main body 110 of the first stacked core and the second stacked core are arranged in the first pit 321, and the second main body 120 of the first stacked core is arranged in the second pit 322; along the third direction Y, the size of the second pit 322 is larger than the size of the first pit 321; along the first direction Z, the first corner portion 331 and the second corner portion 332 are a continuous arc surface, the size of the first corner portion 331 is the thickness size of the second pit 322, and the size of the second corner portion 332 is the thickness size of the step.

[0090] Among them, by setting the pits of the membrane shell 3 and matching the shapes of the first and second cores after stacking, it is convenient to place the first and second cores in the pits on the second membrane 320, thereby facilitating the encapsulation of the first and second cores through the membrane shell 3, with a simple structure and high reliability.

[0091] In some embodiments, further combined Figure 2 As shown, the first corner portion 331 includes a first curved surface 333 corresponding to the first rounded corner 134, and the second corner portion 332 includes a second curved surface 334 corresponding to the third rounded corner 211. The arc radius of the first curved surface 333 is equal to the arc radius of the second curved surface 334. By setting the arc radius of the first curved surface 333 and the arc radius of the second curved surface 334 on the membrane shell 3 to be equal, the dimensions of the portions of the first punched hole 321 corresponding to the first rounded corner 134 of the first stacked core and the third rounded corner 211 of the second stacked core are guaranteed to be consistent, ensuring that the first punched hole 321 can be stamped and formed in one go, thereby ensuring that the second diaphragm 320 is integrally formed, facilitating processing and production.

[0092] In some embodiments, further combined Figure 2 As shown, the first punching hole 321 includes a first side surface 3211 corresponding to the third side edge 202, and the second corner portion 332 is transitionally connected to the first side surface 3211 via a third curved surface 3212. The first side surface 3211 is the side surface of the step structure formed on the second diaphragm 320. By providing a transitional connection between the second corner portion 332 and the first side surface 3211 via the third curved surface 3212, a right angle is avoided between the second corner portion 332 and the first side surface 3211. This can prevent stress concentration at the corner, thereby preventing the membrane shell 3 from rupturing at the connection between the second corner portion 332 and the first side surface 3211 of the aluminum-plastic film when the battery is dropped, further improving the safety performance of the battery.

[0093] In some embodiments, further combined Figure 1 As shown, the packaging film of the membrane shell 3 includes an aluminum layer, and the thickness of the packaging film at the non-pit position of the membrane shell 3 is H; the thickness of the packaging film on the bottom wall of the first pit 321 and located at the first corner position A1 of the first pit 321 is H4, and the thickness of the aluminum layer of the packaging film located at the first corner position A1 is H2; the thickness of the packaging film on the bottom wall of the second pit 322 and located at the second corner position A2 of the second pit 322 is H5, and the thickness of the aluminum layer of the packaging film located at the second corner position A2 is H3; wherein, H5≥H4≥0.6H, H2≥20μm, and H3≥20μm.

[0094] It should be noted that the packaging film refers to the original material for forming the first diaphragm 310 and the second diaphragm 320. The packaging film is preferably an aluminum-plastic film. The second diaphragm 320 is punched out of the aluminum-plastic film. The first pit 321 and the second pit 322 are punched out. The film thickness is reduced after punching, and the wall thickness at the corner of the bottom wall of the pit is the smallest, that is, the thickness H4 of the packaging film on the bottom wall of the first pit 321 and located at the first corner position A1 of the first pit 321 is the minimum wall thickness of the first pit 321, and the thickness H5 of the packaging film on the bottom wall of the second pit 322 and located at the second corner position A2 of the second pit 322 is the minimum wall thickness of the second pit 322; the aluminum-plastic film includes an aluminum layer and a non-aluminum layer, and the thickness of the aluminum layer and the non-aluminum layer passing through the pit position are both reduced; the thickness H of the packaging film at the non-pit position of the membrane shell 3 is the thickness at the position without pitting, and H4 and H5 are both the film thickness after pitting.

[0095] Among them, by setting the relationship between H5, H4 and H to satisfy H5≥H4≥0.6H, the minimum wall thickness of the first pit 321 and the minimum wall thickness of the second pit 322 are both greater than or equal to 0.6 times the thickness of the packaging film before the pit is punched, which can ensure that the packaging film does not break after the pit is punched; at the same time, by setting the aluminum layer thickness at the minimum wall thickness of the first pit 321 and the minimum wall thickness of the second pit 322 to be greater than or equal to 20μm, the sealing of the membrane shell 3 can be guaranteed to prevent water in the air from entering the interior of the battery.

[0096] In some embodiments, the packaging film of the membrane shell 3 includes an aluminum layer. At the non-pitted position of the membrane shell 3, the thickness of the aluminum layer is H1, and the thickness of the packaging film is H, wherein 0.2≤H1 / H≤0.7, and 50μm≤H≤120μm. It should be noted that the aluminum layer of the packaging film has the functions of isolating moisture in the air from entering the interior of the battery and ensuring the mechanical strength of the packaging film. If H1 / H is less than 0.2, the aluminum layer is too thin, the barrier properties of the packaging film are insufficient, the mechanical strength is insufficient, and the reliability is poor. If H1 / H is greater than 0.7, the aluminum layer is too thick, the cost and weight of the packaging film increase, and the energy density of the battery is reduced.

[0097] Therefore, by setting the thickness H of the packaging film to a value between 50μm and 120μm, and the ratio between the thickness H1 of the aluminum layer at the non-pitted position of the membrane shell 3 and the thickness H of the packaging film to a value between 0.2 and 0.7, it can be ensured that the packaging film has sufficient mechanical strength and good barrier properties, and avoids the packaging film being too heavy, thereby ensuring the energy density of the battery and controlling the battery cost.

[0098] In some embodiments, further combined Figure 3As shown, the size of the second pit 322 along the third direction Y is greater than the size of the first pit 321 along the third direction Y, so as to form a protrusion 410 and a recessed portion 420 at one end of the battery along the third direction Y; the membrane shell 3 also includes a sealing edge structure 430 arranged around the first pit 321 and the second pit 322, and the sealing edge structure 430 includes a first flange 431 and a second flange 432, the first flange 431 is located on the side of the protrusion 410 toward the recessed portion 420 along the second direction X, and the second flange 432 is located on the side of the second pit 322 away from the first pit 321, and the sizes of the first flange 431 and the second flange 432 along the first direction Z are both less than or equal to the size of the second pit 322 along the first direction Z. By arranging a protrusion 410 and a recessed portion 420 at one end of the battery along the third direction Y, the space in the cabin can be further fully utilized and the energy density of the battery can be improved. By arranging the edge sealing structure 430, the sealing of the membrane shell 3 package can be ensured, and the interference between the protection plate 6 and other structures arranged in the recessed portion 420 and the second pit 322 can be avoided. By arranging the heights of the first flange 431 and the second flange 432 located on both sides of the first pit 321 along the second direction X to be less than or equal to the thickness of the second pit 322, the edge sealing structure 430 can be avoided from interfering with the cabin when the battery is put into the cabin.

[0099] In some embodiments, the battery further includes: a first pole tab 501, a second pole tab 502, and a protective plate 6. The first pole tab 501 is disposed on the first side 101 of the first pole sheet 1 or the fifth side 201 of the second pole sheet 2. One end of the second pole tab 502 extends into the inner side of the membrane shell 3 and is connected to the first pole tab 501. The other end of the second pole tab 502 is located outside the membrane shell 3. The portion of the second pole tab 502 located outside the membrane shell 3 is located within the recess 420. The protective plate 6 is welded to the second pole tab 502, and the protective plate 6 is located within the recess 420. The first pole tab 501 is a metal foil extending from the pole sheet, i.e., an inner pole tab. The first pole tab on the positive pole sheet is the positive pole tab, and the first pole tab on the negative pole sheet is the negative pole tab. The second pole tab 502 is an outer pole tab welded to the inner pole tab and extends outside the membrane shell 3. By arranging the portion of the second pole tab 502 located outside the membrane shell 3 to be located in the recessed portion 420, the placement of the second stacked core is facilitated, and the protection plate 6 welded to the second pole tab 502 is also conveniently located in the recessed portion 420, thereby fully utilizing the space and ensuring that the battery size does not exceed the specification value.

[0100] In some embodiments, the protective plate 6 includes a plate body and multiple connecting parts. The plate body is placed on the edge sealing structure on the side of the first pit 321 facing the recessed part 420. After the protective plate 6 is welded to the second pole ear 502, along the third direction Y, the edge of the protective plate 6 on the side away from the first pit 321 does not exceed the outer edge of the protrusion 410 away from the first stacked core; along the first direction Z, the protective plate 6 does not exceed the surface of the second stacked core on the side away from the first stacked core, thereby avoiding interference with the cabin when the battery is put into the cabin.

[0101] The edge sealing structure of the first punching hole 321 facing the recessed portion 420 may be folded together with the second tab 502 or may not be folded.

[0102] Compared with the existing L-shaped battery, the battery of this embodiment can not only effectively improve the space utilization of the cabin, but also improve the energy density of the battery; the first notch portion 130 of the first stacked core is designed with an arc and a bevel, and a second notch portion 210 is provided on the second stacked core at the position corresponding to the first notch portion 130, which can prevent the battery from being torn from the inner corner when it falls; at the same time, the first rounded corner 134 on the first pole piece 1 is set to be less than or equal to the third rounded corner 211 on the second pole piece 2, so that the first pole piece 1 can completely cover the second pole piece 2, avoiding interference between the corner of the second pole piece 2 and the aluminum-plastic film during packaging.

[0103] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery, characterized in that: include: A first stacked core comprising a plurality of first pole pieces (1) stacked along a first direction (Z); a second core stack, wherein the second core stack and the first core stack are stacked along the first direction (Z), the second core stack comprises a plurality of second pole pieces (2) stacked along the first direction (Z), and along the second direction (X), the size of the first core stack is larger than the size of the second core stack; The first pole piece (1) comprises a first main body (110) overlapping with the second stacked core, and a second main body (120) not overlapping with the second stacked core; a first notch (130) is provided between the first main body (110) and the second main body (120) on one side of the first pole piece (1) along a third direction (Y); the first main body (110) has a first side (101) connected to the first notch (130); and the second main body (120) has a second side (103) facing away from the first main body (110) along a second direction (X); A second notch portion (210) is provided at a corner of the second pole piece (2), and the second notch portion (210) corresponds to the first notch portion (130) in position. The second pole piece (2) has a third side (202) close to the second side (103) along a second direction (X), wherein: The distance from the connection between the first notch (130) and the first side (101) to the second side (103) is W1, and the distance from the third side (202) to the second side (103) is W2, wherein W1>W2; The first direction (Z), the second direction (X), and the third direction (Y) are perpendicular to each other.

2. The battery according to claim 1, characterized in that On the contour line of the first notch portion (130), the point farthest from the extension line of the first side (101) along the third direction (Y) is the first point (1311), and the distance from the first point (1311) to the second side (103) is W3, where W3≤W2.

3. The battery according to claim 1 or 2, characterized in that Along the third direction (Y), the size of the second body (120) is larger than the size of the first body (110), and at the inner corner (104) of the first pole piece (1), the second body (120) has a fourth side (102) connected to the first notch portion (130).

4. The battery according to claim 3, characterized in that The contour line of the first notch portion (130) includes: a first arc segment (131), a first oblique side (132) and a second oblique side (133); the first oblique side (132) and the second oblique side (133) are each tangently connected to one end of the first arc segment (131); the first oblique side (132) and the first side (101) are connected via a first rounded corner (134); and the second oblique side (133) and the fourth side (102) are connected via a second rounded corner (135).

5. The battery according to claim 4, characterized in that The second pole piece (2) further comprises a fifth side (201) arranged corresponding to the first side (101), and the second notch portion (210) is formed between the fifth side (201) and the third side (202); The contour line of the second notch portion (210) includes: a third fillet (211), a third oblique side (212) and a second arc segment (213); the third oblique side (212) and the first oblique side (132) are arranged correspondingly; the third fillet (211) is connected between the third oblique side (212) and the fifth side (201); the second arc segment (213) is connected between the third oblique side (212) and the third side (202); and the second arc segment (213) and a portion of the first arc segment (131) are arranged correspondingly; And / or, the contour line of the second notch portion (210) includes: a third fillet (211) and a third oblique side (212), the third oblique side (212) corresponds to at least a portion of the first oblique side (132), the third fillet (211) is connected between the third oblique side (212) and the fifth side (201), the end of the third oblique side (212) away from the third fillet (211) is smoothly connected to the third side (202), or the third oblique side (212) is connected to the third side (202) at an obtuse angle.

6. The battery according to claim 5, characterized in that The radius of the first rounded corner (134) is R1, and the radius of the third rounded corner (211) is R3, wherein R3 and R1 satisfy the relationship: 0.8≤R1 / R3≤1, and the units of R1 and R3 are both mm; And / or, the length of the first oblique side (132) is L1, and the length of the third oblique side (212) is L2, wherein L2 and L1 satisfy the relationship: 0.8≤L2 / L1≤1, and the units of L1 and L2 are both mm; And / or, the angle between the third oblique edge (212) and the third side edge (202) is α, wherein α≥135°.

7. The battery according to claim 5, characterized in that The battery further comprises: a membrane shell (3), the membrane shell (3) being formed by buckling a first membrane sheet (310) and a second membrane sheet (320), a first pit (321) and a second pit (322) being provided on the second membrane sheet (320), the depth of the first pit (321) being greater than the depth of the second pit (322), a step structure being formed on a surface of the second membrane sheet (320) facing away from the first membrane sheet (310), the first stacked core being provided in the first pit (321) and the second pit (322), the first main body (110) of the first stacked core being located in the first pit (321), the second main body (120) being located in the second pit (322), and a first corner portion (331) corresponding to the first notch portion (130), and a second corner portion (332) corresponding to the second notch portion (210) being constructed at an inner corner (301) of the membrane shell (3).

8. The battery according to claim 7, characterized in that The first corner portion (331) includes a first arcuate surface (333) corresponding to the first rounded corner (134), and the second corner portion (332) includes a second arcuate surface (334) corresponding to the third rounded corner (211), and the arc radius of the first arcuate surface (333) is equal to the arc radius of the second arcuate surface (334); And / or, the first punching hole (321) includes a first side surface (3211) corresponding to the third side edge (202), and the second corner portion (332) is transitionally connected to the first side surface (3211) via a third arcuate surface (3212).

9. The battery according to claim 8, characterized in that The packaging film of the membrane shell (3) comprises an aluminum layer, and the thickness of the packaging film at the non-pitted position of the membrane shell (3) is H; The thickness of the packaging film on the bottom wall of the first punching pit (321) and located at the first corner position (A1) of the first punching pit (321) is H4, and the thickness of the aluminum layer of the packaging film located at the first corner position (A1) is H2; The thickness of the packaging film on the bottom wall of the second punching pit (322) and located at the second corner position (A2) of the second punching pit (322) is H5, and the thickness of the aluminum layer of the packaging film located at the second corner position (A2) is H3; Among them, H5≥H4≥0.6H, H2≥20μm, H3≥20μm; And / or, the packaging film of the membrane shell (3) includes an aluminum layer, and at a non-pitted position of the membrane shell (3), the thickness of the aluminum layer is H1, and the thickness of the packaging film is H, wherein 0.2≤H1 / H≤0.7, 50μm≤H≤120μm.

10. The battery according to claim 8, characterized in that The size of the second punching hole (322) along the third direction (Y) is larger than the size of the first punching hole (321) along the third direction (Y), so as to form a protrusion (410) and a depression (420) at one end of the battery along the third direction (Y); The membrane shell (3) further includes a sealing edge structure (430) arranged around the first punching hole (321) and the second punching hole (322), the sealing edge structure (430) including a first flange (431) and a second flange (432), the first flange (431) being located on a side of the protrusion (410) facing the recessed portion (420) along the second direction (X), the second flange (432) being located on a side of the second punching hole (322) facing away from the first punching hole (321), and the dimensions of the first flange (431) and the second flange (432) along the first direction (Z) being less than or equal to the dimension of the second punching hole (322) along the first direction (Z); And / or, the battery further comprises: A first pole lug (501), a second pole lug (502) and a protective plate (6), wherein the first pole lug (501) is arranged on the first side (101) of the first pole piece (1) or on the fifth side (201) of the second pole piece (2); one end of the second pole lug (502) extends into the inner side of the membrane shell (3) and is connected to the first pole lug (501), and the other end of the second pole lug (502) is located on the outer side of the membrane shell (3), and the part of the second pole lug (502) located on the outer side of the membrane shell (3) is located in the recessed portion (420); the protective plate (6) is welded to the second pole lug (502), and the protective plate (6) is located in the recessed portion (420).

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