Battery

Abstract

The present application provides a battery, comprising a battery cell, and a package for packaging the battery cell. The battery cell is provided with a first tab, the first tab comprises a first tab portion extending out of the package, and the ratio of the cross-sectional area of the first tab portion parallel to the thickness direction of the first tab portion to the capacity of the battery cell is greater than or equal to 0.6 mm2 / Ah. The present application can achieve the performance of high power, long service life and the like of the battery.

Description

Battery

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on August 2, 2023, with application number 202322071731.2 and application name “Battery”, the entire contents of which are incorporated by reference into this application.

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on August 2, 2023, with application number 202310969768.9 and application name “Battery”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of electrochemical energy storage devices, and in particular to a battery. Background Art

[0004] Currently, increasingly stringent requirements are being placed on battery performance, such as power and lifespan. For example, low-voltage automotive systems (such as 12V and 48V) offer advantages such as low cost, reduced fuel consumption for gasoline vehicles, and improved safety for new energy vehicles. Batteries used in these systems (such as lithium-ion secondary batteries) are typically required to have excellent service lives (e.g., over eight years). However, as storage and usage time increases, battery performance and other performance characteristics degrade significantly, resulting in a shorter service life.

[0005] Application Contents

[0006] The present application provides a battery to at least solve the technical problems of the existing battery technology such as severe power performance degradation and short service life.

[0007] The present application provides a battery, comprising a battery cell and a package encapsulating the battery cell, wherein the battery cell is provided with a first tab, the first tab including a first tab portion extending from the package, the ratio of the cross-sectional area of ​​the first tab portion parallel to the thickness direction of the first tab portion to the capacity of the battery cell being greater than or equal to 0.6 mm 2 / Ah.

[0008] According to one embodiment of the present application, the battery cell is further provided with a second tab, the second tab including a second tab portion extending out of the package body, and the ratio of the cross-sectional area of ​​the second tab portion parallel to the thickness direction of the second tab portion to the capacity of the battery cell is greater than or equal to 0.6 mm 2 / Ah.

[0009] According to one embodiment of the present application, the first electrode tab is a positive electrode tab, and the ratio of the cross-sectional area of ​​the first electrode tab portion parallel to the thickness direction of the first electrode tab portion to the capacity of the battery cell is greater than or equal to 0.7 mm 2 / Ah.

[0010] According to one embodiment of the present application, the package body includes a accommodating area and a sealing area that encloses the accommodating area, and the battery cell is located in the accommodating area; the package body includes a first adhesive layer and a heat-sealing layer that are connected, and the package body has a first side and a second side, the heat-sealing layer on the first side of the sealing area is connected to the heat-sealing layer on the second side of the sealing area, the thickness of the first adhesive layer on the first side of the sealing area is T1, and the thickness of the first adhesive layer on the second side of the sealing area is T2. In the sealing area, the sum of the thicknesses of the heat-sealing layer on the first side and the heat-sealing layer on the second side is T3, and T3<T1+T2.

[0011] According to one embodiment of the present application, 10 μm≤(T1+T2)-T3≤60 μm; and / or, T1 is 18 μm to 66 μm; and / or, T2 is 18 μm to 66 μm; and / or, T3 is 20 μm to 90 μm.

[0012] According to one embodiment of the present application, the package body includes a first supporting layer, a third adhesive layer, a second supporting layer, a second adhesive layer, a metal layer, a first adhesive layer and a heat-sealing layer that are stacked; the package body includes a accommodating area and a sealing area that encloses the accommodating area, and the battery cell is located in the accommodating area; the package body has a first side and a second side, and the heat-sealing layer on the first side of the sealing area is connected to the heat-sealing layer on the second side of the sealing area.

[0013] According to one embodiment of the present application, the heat-sealing layer on the first side of the sealing area and the heat-sealing layer on the second side of the sealing area are composited into one; and / or, the first adhesive layer includes an acid-modified polypropylene layer; and / or, the heat-sealing layer includes a polypropylene layer; and / or, the first supporting layer includes a polyester layer; and / or, the second supporting layer includes a nylon layer; and / or, the metal layer includes an aluminum layer; and / or, the roughness of a side of the metal layer facing the second adhesive layer is greater than the roughness of a side of the metal layer facing the first adhesive layer.

[0014] According to one embodiment of the present application, the thickness of the sealing area is 210 μm to 260 μm; and / or the width of the sealing area is greater than or equal to 2 mm.

[0015] According to an embodiment of the present application, the thickness of the package body is greater than 90 μm.

[0016] According to one embodiment of the present application, the battery cell has a capacity of less than 30 Ah.

[0017] According to one embodiment of the present application, a ratio of the thickness of the battery cell to the capacity of the battery cell is less than 4 mm / Ah.

[0018] According to one embodiment of the present application, the volume of the battery cell is 240 cm 3 ~302cm 3 ; and / or, the length of the battery cell is 100mm to 250mm, and / or, the width of the battery cell is 80mm to 150mm, and / or, the thickness of the battery cell is 3mm to 15mm.

[0019] In the battery provided in this application, the ratio of the cross-sectional area of ​​the first pole ear extending out of the package to the cell capacity is greater than or equal to 0.6mm 2 / Ah, when the battery is working at high power under large current, it can reduce side reactions and heat generation. After using for a long time, it can still maintain the battery's high power performance and other performance, thereby improving the battery's service life. Specifically, it can be increased to more than 8 years. After using for more than 8 years, the battery's power performance attenuation rate is no more than 15%, achieving high power and long life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a schematic diagram of a battery structure according to an embodiment of the present application;

[0021] FIG2 is a schematic cross-sectional view of region Q1 in FIG1 ;

[0022] FIG3 is a schematic diagram of a cell structure of a battery according to an embodiment of the present application;

[0023] FIG4 is a cross-sectional schematic diagram of the connection structure between the first inner tab and the first tab portion of a battery according to an embodiment of the present application;

[0024] FIG5 is a schematic cross-sectional view of region Q2 in FIG1 ;

[0025] FIG6 is a schematic diagram of the stacked structure of the positive electrode sheet, separator, and negative electrode sheet of a battery according to an embodiment of the present application;

[0026] FIG7 is a schematic diagram of a battery structure when the package body is not heat-sealed according to an embodiment of the present application;

[0027] FIG8 is a schematic diagram of a battery structure after heat sealing of a package body according to an embodiment of the present application;

[0028] FIG9 is an electron microscope image of the structure of the package used in one embodiment of the present application.

[0029] Explanation of reference numerals: 11: top sealing edge; 12: side sealing edge; 101: heat sealing layer; 102: first adhesive layer; 103: metal layer; 104: second adhesive layer; 105: second supporting layer; 106: third adhesive layer; 107: first supporting layer; 108: connecting layer; 110: accommodation area; 10: sealing area; 20: non-sealing area; 111: first side portion; 1111: first main body area; 1112: first fusion area; 112: second side portion; 1121: second main body area; 1122: second fusion area; 2: battery cell; 21: first pole ear portion; 21 1: First internal portion; 212: First extension portion; 100: First inner pole tab; 2011: First sub-pole tab; 210: Connection portion between the first pole tab portion 21 and the first inner pole tab 100; 22: Second pole tab portion; 200: Second inner pole tab; 2021: Second sub-pole tab; 220: Connection portion between the second pole tab portion 22 and the second inner pole tab 200; 23: Protective layer; 201: First pole piece; 202: Second pole piece; 3: Diaphragm; 31: Third side portion; 32: Bend portion; 310: First region; 320: Second region; 30: Notch; T1, T2, T3: Thickness; T 10 : thickness of the sealing area; T0: thickness of the package body; w 10 : The width of the seal area; Q1, Q2: area. DETAILED DESCRIPTION

[0030] To enable those skilled in the art to better understand the solutions of the present application, the present application is further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present application. The examples cited are only used to explain the present application and do not limit the scope of the present application. Based on the embodiments of the present application, all other implementation methods obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of this application.

[0031] In the description of this application, unless otherwise clearly specified and limited, terms such as "provided on", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication connection (network connection); it can be a direct connection, an indirect connection through an intermediate medium, or the two elements can be internally connected. For ordinary technicians in this field, the specific meanings of the above-mentioned terms in this application can be understood according to the specific circumstances. In addition, terms such as "first", "second", and "third" are only used for descriptive purposes, such as distinguishing between components to more clearly illustrate / explain the technical solution, and cannot be understood as indicating or implying the number of technical features indicated or the order of substantial significance.

[0032] The present application provides a battery, as shown in Figures 1 to 8, which includes a battery cell 2 and a package encapsulating the battery cell 2. The battery cell 2 is provided with a first tab, and the first tab includes a first tab portion 21 extending out of the package. The ratio of the cross-sectional area of ​​the first tab portion 21 parallel to the thickness direction of the first tab portion (i.e., the cross-sectional area parallel to the thickness direction of the first tab portion) to the capacity of the battery cell 2 is greater than or equal to 0.6 mm. 2 / Ah.

[0033] In this way, when the battery is operating at high power under large current, side reactions and heat generation can be reduced. After a long period of use, the battery's high power performance and other properties can still be maintained, thereby improving the battery's service life, specifically to more than 8 years. After more than 8 years of use, the battery's power performance attenuation rate is no more than 15%.

[0034] In addition, the charge rate of the above battery can be greater than 10C, and the discharge rate can be greater than 20C.

[0035] Specifically, the first electrode tab may be a positive electrode tab or a negative electrode tab. In some preferred embodiments, the first electrode tab is a positive electrode tab, and the ratio of the cross-sectional area of ​​the first electrode tab portion 21 parallel to the thickness direction of the first electrode tab portion 21 to the capacity of the battery cell is greater than or equal to 0.7 mm. 2 / Ah, which helps to further reduce the attenuation rate of the battery's power performance.

[0036] In addition, as shown in Figures 1 and 3, the above-mentioned battery cell 2 is further provided with a second pole ear, and the polarity of the second pole ear is opposite to that of the first pole ear, that is, the first pole ear is a positive pole ear and the second pole ear is a negative pole ear, or the first pole ear is a negative pole ear and the second pole ear is a positive pole ear.

[0037] In some preferred embodiments, the second tab includes a second tab portion 22 extending out of the package body, and the ratio of the cross-sectional area of ​​the second tab portion 22 parallel to the thickness direction of the second tab portion 22 to the capacity of the battery cell is greater than or equal to 0.6 mm 2 / Ah, that is, the ratio of the cross-sectional area of ​​the positive and negative tabs of the battery to the capacity of the battery cell 2 is greater than or equal to 0.6mm 2 / Ah, which helps to further reduce the attenuation rate of battery power performance and increase battery life.

[0038] The thickness direction of the first pole ear portion 21 , the thickness direction of the second pole ear portion 22 , and the thickness direction of the battery or battery cell 2 (parallel to the third direction in FIG. 2 , FIG. 4 , FIG. 5 , FIG. 7 and FIG. 8 ) are parallel to each other.

[0039] In addition, as shown in Figures 1, 2 and 8, the package includes a accommodating area 110 and a sealing area 10 that seals the accommodating area 110, and the battery cell 2 is located in the accommodating area 110; the package includes a first adhesive layer 102 and a heat-sealing layer 101 that are connected to each other, and the package has a first side portion 111 and a second side portion 112. The heat-sealing layer 101 of the first side portion 111 of the sealing area 10 is connected to the heat-sealing layer 101 of the second side portion 112 of the sealing area 10. The thickness of the first adhesive layer 102 of the first side portion 111 of the sealing area 10 is T1, and the thickness of the first adhesive layer 102 of the second side portion 112 of the sealing area 10 is T 2. In the sealing area 10, the sum of the thicknesses of the heat-sealing layer 101 of the first side portion 111 and the heat-sealing layer 101 of the second side portion 112 is T3 (i.e., the sum of the thicknesses of the heat-sealing layer 101 of the first side portion 111 of the sealing area 10 and the heat-sealing layer 101 of the second side portion 112 of the sealing area 10 is T3), that is, the distance from the side of the heat-sealing layer 101 of the first side portion 111 of the sealing area 10 facing the first adhesive layer 102 of the first side portion 111 to the side of the heat-sealing layer 101 of the second side portion 112 of the sealing area 10 facing the first adhesive layer 102 of the second side portion 112 is T3, and T3<T1+T2.

[0040] In this way, the connecting portion (connecting layer 108) of the heat-sealing layer 101 at the first side portion 111 and the second side portion 112 of the sealing area 10 can have a relatively small cross-sectional area, and while the heat-sealing layer 101 is used to seal the accommodating area 110, it can reduce the entry of components such as water vapor into the accommodating area 110; at the same time, the first adhesive layer 102 located on the opposite sides of the connecting layer 108 has a relatively large cross-sectional area, and the first adhesive layer 102 located on the opposite sides thereof is combined with the connecting layer 108 to improve the packaging strength and structural stability of the sealing area 10, thereby maintaining the long-term excellent quality of the battery. The battery life is improved by improving power performance, cycle performance and safety, which can be extended to more than 8 years or even more than 12 years. After storage and use for more than 8 years, the battery packaging strength, capacity retention rate and power performance degradation are reduced. Through simulation, after 8 years of storage, its power performance degradation rate is no more than 15%. After 12 years of storage and use, its storage-induced capacity loss is no more than 10.5%, the cycle-induced capacity loss is no more than 6.4%, and the capacity retention rate is no less than 83.1%. The effect is significant.

[0041] Specifically, Figure 7 is a schematic diagram of the structure of the package when it is not heat-sealed, and Figure 8 is a schematic diagram of the battery structure after the package is heat-sealed. As shown in Figures 7 and 8, the first side portion 111 includes a first main area 1111 and a first fusion area 1112 that are connected. The first main area 1111 is the area of ​​the first side portion 111 corresponding to the accommodating area 110 (that is, the first main area 1111 is the part of the first side portion 111 corresponding to the accommodating area 110), and the first fusion area 1112 is the first side portion 111 of the sealing area 10 (that is, the first fusion area 1112 is the part of the first side portion 111 located in the sealing area 10). The second side portion 112 includes a second main area 1121 and a second fusion area 1122 that are connected. The second main area 1121 is the accommodating area 110. The corresponding second side portion 112 (that is, the second main body area 1121 is the part of the second side portion 112 corresponding to the accommodating area 110), the second fusion area 1122 is the second side portion 112 of the sealing area 10 (that is, the second fusion area 1122 is the part of the second side portion 112 located in the sealing area 10), the first main body area 1111 and the second main body area 1121 are respectively located on opposite sides of the battery cell 2, and the first fusion area 1112 is connected to the second fusion area 1122, specifically, the heat sealing layer 101 of the first fusion area 1112 and the heat sealing layer 101 of the second fusion area 1122 are connected (that is, the heat sealing layer 101 of the first side portion 111 of the sealing area 10 is connected to the heat sealing layer 101 of the second side portion 112 of the sealing area 10) to close the accommodating area 110.

[0042] Figure 2 is a cross-sectional schematic diagram of area Q1 in Figure 1 (i.e., the area where no tab extends). Referring to Figure 2, the heat-sealing layer 101 on the first side 111 of the sealing area 10 and the heat-sealing layer 101 on the second side 112 of the sealing area 10 can be bonded and generally can be compounded into one, that is, the two are fused into one layer (hereinafter referred to as the connecting layer 108).

[0043] Specifically, the heat-sealing layer 101 can be used to heat-seal the package to form a sealed edge. In practice, the first fusion region 1112 and the second fusion region 1122 can be heat-sealed at a high temperature. During the heat-sealing process, the heat-sealing layer 101 in the first fusion region 1112 and the heat-sealing layer 101 in the second fusion region 1122 melt and fuse together, forming a single layer (i.e., forming a single layer to form the connecting layer 108), thereby sealing the receiving region 110 and encapsulating the battery.

[0044] Among them, the thickness of the connecting layer 108 is T3. By controlling T3<T1+T2, the formed connecting layer 108 can have a relatively small thickness while achieving heat sealing to close the accommodating area 110, that is, a relatively small cross-sectional area (a cross-sectional area parallel to the thickness direction of the connecting layer 108), thereby reducing the penetration of components such as water vapor into the accommodating area 110. At the same time, combined with the first adhesive layer 102 located on opposite sides of the connecting layer 108 (that is, the first adhesive layer 102 on the first side 111 and the first adhesive layer 102 on the second side 112), the packaging strength and structural stability of the sealing area 10 can be improved, thereby improving the battery's service life and other performance.

[0045] The thickness direction of the connecting layer 108 , the thickness direction of the sealing area 10 , the direction from the first side 111 of the sealing area 10 to the second side 112 of the sealing area 10 , and the thickness direction of the battery or cell 2 are parallel to each other.

[0046] Specifically, as shown in FIG1 , the package includes a sealing edge, which may generally include a top sealing edge 11 located on one side of the battery cell 2 in a first direction, and side sealing edges 12 located on opposite sides of the battery cell 2 in a second direction. The sealing area 10 is an effective sealing area of ​​the sealing edge, that is, the sealing area 10 is the area where the heat-sealing layer 101 of the first side portion 111 and the heat-sealing layer 101 of the second side portion 112 are connected. The sealing area 10 substantially overlaps with the orthographic projection of the connecting layer 108 formed by the fusion of the heat-sealing layer 101 of the first side portion 111 and the heat-sealing layer 101 of the second side portion 112. The orthographic projection refers to the projection of the sealing area 10 and the connecting layer 108 along the third direction, that is, the orthographic projections of the two are perpendicular to the third direction, that is, the projections of the two on plane A substantially overlap, and plane A is perpendicular to the third direction.

[0047] The first direction, the second direction, and the third direction intersect with each other, and specifically may be perpendicular to each other, that is, the first direction is perpendicular to the second direction, the second direction is perpendicular to the third direction, and the first direction is perpendicular to the third direction. For example, as shown in Figures 2, 4, 5, 7, and 8, the third direction is the thickness direction of the battery or battery cell 2, and one of the first direction and the second direction is the length direction of the battery or battery cell 2, and the other is the width direction of the battery or battery cell 2, that is, the first direction is the length direction of the battery or battery cell 2, and the second direction is the width direction of the battery or battery cell 2, or the first direction is the width direction of the battery or battery cell 2, and the second direction is the length direction of the battery or battery cell 2.

[0048] Specifically, the thickness T of the sealing area 10 is 10The thickness of the sealing area 10 is equal to the distance from the side of the first side 111 of the sealing area 10 facing away from the second side 112 to the side of the second side 112 of the sealing area facing away from the first side 111 (the distance in the third direction).

[0049] Specifically, the thickness T of the sealing area of ​​the top sealing edge 11 is 10 The thickness T of the sealing area 10 of the side seal 12 may be 210 μm to 260 μm, for example, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm or any two thereof. 10 The thickness T of the sealing area 10 of the top sealing edge 11 may be 210 μm to 260 μm, for example, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm or any two thereof. 10 The thickness T of the sealing area 10 of the side sealing edge 12 10 Can be the same or different.

[0050] In addition, the width w of the sealing area 10 10 It can be greater than or equal to 2 mm, that is, the width w of the sealing area 10 of the top sealing edge 11 10 The width w of the sealing area 10 of the side seal 12 can be greater than or equal to 2 mm. 10 The width w of the seal area 10 of the top seal 11 can be greater than or equal to 2 mm. 10 The width w of the sealing area 10 of the side sealing edge 12 10 They can be the same or different (usually substantially the same).

[0051] Specifically, as shown in Figure 1, the width direction of the sealing area 10 of the top sealing edge 11 is basically parallel to the first direction, and the length direction is basically parallel to the second direction; the width direction of the sealing area 10 of the side sealing edge 12 is basically parallel to the second direction, and the length direction is basically parallel to the first direction.

[0052] As shown in Figures 1, 2, and 8, in addition to the sealing area 10, the sealing edge (i.e., the top sealing edge 11 and / or the side sealing edge 12) may also include a non-sealing area 20 where the first side portion 111 and the second side portion 112 are not connected. In other words, the first side portion 111 and the second side portion 112 of the non-sealing area 20 are independent of each other and are not connected, and their heat-sealing layers 101 are not fused together. The non-sealing area 20 is located on the side of the sealing area 10 that is away from the accommodating area 110.

[0053] In some embodiments, the range of (T1+T2)-T3 is 10μm to 60μm (i.e., 10μm≤(T1+T2)-T3≤60μm), and (T1+T2)-T3 is, for example, 10μm, 13μm, 15μm, 18μm, 20μm, 23μm, 25μm, 28μm, 30μm, 32μm, 35μm, 38μm, 40μm, 43μm, 45μm, 48μm, 50μm, 53μm, 55μm, 58μm, 60μm or a range between any two of them. This helps to further improve the packaging strength and structural stability of the sealing area 10 and increase the service life of the battery.

[0054] In some embodiments, T1 may be in the range of 18 μm to 66 μm, for example, 18 μm, 20 μm, 25 μm, 30 μm, 33 μm, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, 47 μm, 50 μm, 55 μm, 60 μm, 66 μm, or a range consisting of any two thereof.

[0055] In some embodiments, T2 may be in the range of 18 μm to 66 μm, for example, 18 μm, 20 μm, 25 μm, 30 μm, 33 μm, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, 47 μm, 50 μm, 55 μm, 60 μm, 66 μm, or a range consisting of any two thereof.

[0056] Specifically, T1 and T2 may be equal or unequal.

[0057] In some embodiments, T3 can be 20μm to 90μm, for example, 20μm, 25μm, 30μm, 35μm, 40μm, 43μm, 45μm, 48μm, 50μm, 53μm, 55μm, 58μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm or a range consisting of any two of them.

[0058] Specifically, the package body can be a multi-layer structure, which can also include a first support layer 107, a third adhesive layer 106, a second support layer 105, a second adhesive layer 104, and a metal layer 103. The first support layer 107, the third adhesive layer 106, the second support layer 105, the second adhesive layer 104, the metal layer 103, the first adhesive layer 102, and the heat sealing layer 101 are stacked in sequence. The use of such a multi-layer structure package body can further improve the packaging effect, prevent water vapor and other components from entering the accommodating area 110, and improve the battery's service life and other performance.

[0059] The heat sealing layer 101 is used to allow the package to encapsulate the battery cell 2, for example, by heat sealing process, to seal the accommodating area 110. In some embodiments, the heat sealing layer 101 may include a polypropylene layer (PP layer), that is, its material is polypropylene (PP).

[0060] Exemplarily, the thickness of the heat-sealing layer 101 may be 36 μm to 44 μm, for example, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, or a range consisting of any two thereof. It is understood that the thickness of the heat-sealing layer 101 (36 μm to 44 μm) herein refers to the thickness of the heat-sealing layer 101 in the area of ​​the package that is not involved in the heat sealing (i.e., the portion of the package that is not bonded to the first side portion 111 and the second side portion 112), such as the package portion corresponding to the accommodating area 110 (the first main body area 1111 and the second main body area 1121), and the non-sealing area 20, which are not involved in the heat sealing.

[0061] Furthermore, the first adhesive layer 102 may include an acid-modified polypropylene layer (APP layer), primarily made of acid-modified polypropylene (APP). APP is a material formed by acid-modifying polypropylene. The acid-modified APP introduces groups such as carboxyl groups, aldehyde groups, and hydroxyl groups into the APP, thereby enhancing the adhesive strength of the APP layer. The embodiments of the present application may utilize conventional acid-modified polypropylene materials in the art to form the APP layer, without particular limitation.

[0062] Specifically, the roughness of the side of the metal layer 103 facing the second adhesive layer 104 is greater than the roughness of the side of the metal layer 103 facing the first adhesive layer 102. The side of the metal layer 103 facing the second adhesive layer 104 is a rough surface (Mat surface), and the side of the metal layer 103 facing the first adhesive layer 102 is a smooth surface (Mirror surface). When the first adhesive layer 102 is an acid-modified polypropylene layer, the adhesion between the smooth surface of the metal layer 103 and the heat-sealing layer 101 can be improved, further improving the battery's service life and other performance.

[0063] Specifically, the metal layer 103 may include an aluminum layer, which may generally be a soft aluminum foil (ALM), for example, commercial 8021 aluminum foil, 8071 aluminum foil, etc. Exemplarily, the package body is an aluminum-plastic film.

[0064] Specifically, the thickness of the metal layer 103 may be 35 μm to 45 μm, for example, 35 μm, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, 45 μm, or a range consisting of any two thereof.

[0065] Furthermore, the second supporting layer 105 may include a nylon layer, i.e., its material is nylon (Oriented Nylon, ONy), but is not limited thereto. The thickness of the second supporting layer 105 may be 13 μm to 17 μm, for example, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, or any combination thereof.

[0066] In addition, the first support layer 107 may include a polyester layer, specifically a PET layer, i.e., its material is polyethylene terephthalate (PET), but is not limited thereto. The thickness of the first support layer 107 may be 10 μm to 14 μm, for example, 10 μm, 10.5 μm, 10.8 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.2 μm, 13.5 μm, 14 μm, or a range consisting of any two thereof.

[0067] In addition, the second adhesive layer 104 is used to bond the metal layer 103 and the second support layer 105, and the third adhesive layer 106 is used to bond the first support layer 107 and the second support layer 105. The third adhesive layer 106 and the second adhesive layer 104 can be conventional adhesive layers in the art, and their thickness can also be conventional thickness in the art.

[0068] For example, the ratio of the mass of the third adhesive layer 106 to the area of ​​the first supporting layer 107 or the second supporting layer 105 facing the third adhesive layer 106 may be (3.3-4.8) g / m 2 , for example 3.3g / m 2 3.5g / m 2 , 3.8g / m 2 , 4g / m 2 , 4.3g / m 2 4.5g / m 2 , 4.8g / m 2 or a range consisting of any two of them.

[0069] For example, the ratio of the mass of the second adhesive layer 104 to the area of ​​the second supporting layer 105 (or the metal layer 103) facing the second adhesive layer 104 may be (3.3-4.8) g / m 2 ), for example 3.3g / m 2 3.5g / m 2 , 3.8g / m 2 , 4g / m 2 , 4.3g / m 2 4.5g / m 2, 4.8g / m 2 or a range consisting of any two of them.

[0070] Furthermore, the thickness T0 of the package body can be greater than 90 μm, such as, but not limited to, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, or any combination thereof. This can better block water vapor penetration and further improve battery safety and service life.

[0071] It should be noted that, as shown in Figures 7 and 8, the thickness T0 of the package refers to the single-sided thickness of the area of ​​the package that is not involved in heat sealing in the battery structure, that is, the thickness T0 of the package is equal to the thickness of the first main body area 1111 or the thickness of the second main body area 1121.

[0072] Specifically, the volume of the battery cell 2 can be 240 cm 3 ~302cm 3 , for example 240cm 3 , 250cm 3 、 260cm 3 , 270cm 3 , 280cm 3 , 290cm 3 , 300cm 3 、302cm 3 or a range consisting of any two of them.

[0073] In some embodiments, the length of the battery cell 2 may be in the range of 100 mm to 250 mm, for example, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, or a range consisting of any two thereof.

[0074] In some embodiments, the width of the battery cell 2 may be 80 mm to 150 mm, for example, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, or a range consisting of any two thereof.

[0075] In some embodiments, the thickness of the battery cell 2 can be 3mm to 15mm, for example, 3mm, 5mm, 8mm, 10mm, 13mm, 15mm or a range consisting of any two of them, which is conducive to better heat dissipation effect of the battery cell 2 and further improves the safety and other performance of the battery.

[0076] In addition, the ratio of the thickness of the battery core 2 to the capacity of the battery core 2 can be less than 4 mm / Ah. In this way, the battery core 2 can have a better heat dissipation effect, further improving the safety and other performance of the battery.

[0077] For example, the ratio of the thickness of the battery cell 2 to the capacity of the battery cell 2 can be 0.7 mm / Ah, 0.9 mm / Ah, 1 mm / Ah, 1.3 mm / Ah, 1.5 mm / Ah, 1.2 mm / Ah, 2.3 mm / Ah, 2.5 mm / Ah, 2.8 mm / Ah, 3 mm / Ah, 3.3 mm / Ah, 3.5 mm / Ah, 3.8 mm / Ah or a range consisting of any two of them.

[0078] In addition, the battery cell 2 may have a capacity less than 30 Ah, for example, 2 Ah, 5 Ah, 8 Ah, 10 Ah, 13 Ah, 15 Ah, 18 Ah, 20 Ah, 23 Ah, 25 Ah, 28 Ah, 30 Ah or a range consisting of any two thereof.

[0079] Relatively speaking, the use of the above-mentioned small battery cell facilitates the battery cell 2 to absorb the electrolyte, thereby increasing the liquid retention capacity (the liquid retention capacity is equal to the ratio of the mass of the electrolyte injected into the accommodating area 110 to the capacity of the battery cell 2), that is, retaining more electrolyte and further optimizing the battery performance.

[0080] The embodiment of the present application can use conventional methods in the field to measure the battery cell capacity. For example, using conventional charging and discharging cabinets and other equipment, at room temperature, the battery is fully charged at a rate of 1C, and then the battery is discharged at a rate of 1C (i.e., 100% DOD (depth of discharge is 100%)) to measure the battery cell capacity.

[0081] Specifically, the battery cell 2 may be square, such as a rectangle or a square, but is not limited thereto and may also be other regular or irregular structures.

[0082] In addition, the battery cell 2 can be a wound battery cell or a laminated battery cell, and there is no particular limitation on this. Specifically, as shown in FIG6 , the battery cell 2 includes a first electrode 201, a second electrode 202, and a separator 3 located between the first electrode 201 and the second electrode 202. The polarity of the first electrode 201 and the second electrode 202 are opposite, that is, one of the first electrode 201 and the second electrode 202 is a positive electrode and the other is a negative electrode. For example, the first electrode 201 is a positive electrode and the second electrode 202 is a negative electrode.

[0083] In specific implementation, the first electrode piece 201, the diaphragm 3, and the second electrode piece 202 can be stacked in sequence and wound to form a wound structure to obtain a wound battery cell 2, or the first electrode piece 201, the diaphragm 3, and the second electrode piece 202 can be stacked in sequence to form a laminated battery cell 2.

[0084] As shown in FIG6 , the first electrode tab is connected to the first electrode piece 201 , and the second electrode tab is connected to the second electrode piece 202 .

[0085] As shown in Figures 1 and 3 to 5, the first pole ear portion 21 and the second pole ear portion 22 can specifically extend out of the package body from the edge seal (such as the top edge seal 11). At the edge seal, the first pole ear portion 21 and the second pole ear portion 22 are located between the first side portion 111 and the second side portion 112.

[0086] Specifically, the first pole ear portion 21 extends out of the package from the sealing area 10, and specifically can extend out of the package from the sealing area 10 of the top sealing edge 11. In the sealing area 10, the first pole ear portion 21 is located between the first side portion 111 and the second side portion 112; the second pole ear portion 22 extends out of the sealing area 10, and specifically can extend out of the package from the sealing area 10 of the top sealing edge 11. In the sealing area 10, the second pole ear portion 22 is located between the second side portion 111 and the second side portion 112.

[0087] Specifically, as shown in Figures 1 and 3 to 5, the first pole tab also includes a first inner pole tab 100, one end of the first inner pole tab 100 is connected to the battery cell 2, and the other end of the first inner pole tab 100 is connected to the first pole tab portion 21, and the second pole tab also includes a second inner pole tab 200, one end of the second inner pole tab 200 is connected to the battery cell 2, and the other end of the second inner pole tab 200 is connected to the second pole tab portion 22.

[0088] Specifically, Figure 5 is a cross-sectional schematic diagram of area Q2 in Figure 1 (i.e., the area where the pole ear extends). Referring to Figure 5, the first pole ear portion 21 includes a first built-in portion 211 and a first extension portion 212. The battery cell 2 (first pole piece 201), the first inner pole ear 100, the first built-in portion 211 and the first extension portion 212 are connected in sequence. The first built-in portion 211 is located in the sealing area 10. The first side portion 111 of the sealing area 10, the first built-in portion 211, and the second side portion 112 of the sealing area 10 are stacked in sequence. The first extension portion 212 is the part of the first pole ear portion 21 extending out of the package body, that is, the first extension portion 212 is located outside the package body, that is, the first extension portion 212 is located on the side of the sealing area 10 away from the accommodating area 110.

[0089] Specifically, the second pole ear portion 22 includes a second built-in portion and a second extended portion (not shown in the figure), the battery cell 2 (second pole piece 202), the second inner pole ear 200, the second built-in portion and the second extended portion are connected in sequence, the second built-in portion is located in the sealing area 10, the second side portion 111 of the sealing area 10, the second built-in portion, and the second side portion 112 of the sealing area 10 are stacked in sequence, and the second extended portion is the part of the second pole ear portion 22 extending out of the package body, that is, the second extended portion is located outside the package body, that is, the second extended portion is located on the side of the sealing area 10 away from the accommodating area 110.

[0090] 1 , 3 and 6 , the first inner tab 100 and the second inner tab 200 may be located on the same side of the battery cell 2 , for example, both located on the side of the battery cell 2 facing the top sealing edge 11 , so that the first tab portion 21 and the second tab portion 22 both extend out of the package from the top sealing edge 11 .

[0091] Specifically, the first inner pole ear 100 and the first pole ear portion 21 can be welded (specifically, welded to the first built-in portion 221 of the first pole ear portion 21) to electrically connect the two, that is, the first pole ear portion 21 can be a first adapter welded to the first inner pole ear 100, serving as a connector for connecting the battery and the electronic product using the battery, and specifically can be connected to the electronic product through the first extension portion 212 of the first pole ear portion 21.

[0092] Specifically, the second inner pole ear 200 and the second pole ear portion 22 can be welded (specifically, welded to the second built-in portion of the second pole ear portion 22) to electrically connect the two, that is, the second pole ear portion 22 is a second adapter welded to the second inner pole ear 200, serving as a connector for connecting the battery and the electronic product using the battery, and can specifically be connected to the electronic product through the second extension portion of the second pole ear portion 22.

[0093] In addition, the first inner tab 100 and the first tab portion 21 can extend in the same direction. Specifically, the first inner tab 100 and the first tab portion 21 can extend in the direction from the battery cell 2 to the sealing area 10. That is, the first inner tab 100, the first tab portion 21, and the first tab formed by the two are all straight structures and are substantially unbent. In a specific implementation, the first inner tab 100 and the first tab portion 21 can be straight-welded, that is, neither of them is bent, to form a straight first tab.

[0094] Among them, the length direction of the first pole ear, the length direction of the first inner pole ear 100, the length direction of the first pole ear part 21, the direction along the first built-in part 211 to the first extension part 212, the direction along the battery cell 2 to the sealing area 10, and the first direction are basically parallel to each other.

[0095] In addition, the second inner tab 200 and the second tab portion 22 can extend in the same direction. Specifically, the second inner tab 200 and the second tab portion 22 can extend in the direction from the battery cell 2 to the sealing area 10. That is, the second inner tab 200, the second tab portion 22, and the second tab formed by the two are all straight structures and are substantially unbent. In a specific implementation, the second inner tab 200 and the second tab portion 22 can be straight-welded, that is, neither of them is bent, to form a second tab with a straight structure.

[0096] Among them, the length direction of the second pole ear, the length direction of the second inner pole ear 200, the length direction of the second pole ear part 22, the direction along the second built-in part to the second extension part, the direction along the battery cell 2 to the sealing area 10, and the first direction are basically parallel to each other.

[0097] In addition, as shown in Figures 3 and 4, a protective adhesive layer 23 is provided on the surface of the connection portion 210 between the first pole lug portion 21 (first internal portion 211) and the first inner pole lug 100. At this connection portion 210, the protective adhesive layer 23 is provided on both the side of the first inner pole lug 100 facing away from the first pole lug portion 21 and the side of the first pole lug portion 21 facing away from the first inner pole lug 100. The connection portion 210 can specifically be the welding portion between the first pole lug portion 21 and the first inner pole lug 100, which generally forms a weld mark (such as a bump or other structure). By providing a protective adhesive layer 23 on its surface, the resulting weld mark structure such as the bump can be prevented from causing damage to battery components such as the package, further improving the safety and service life of the battery.

[0098] In addition, a protective adhesive layer 23 is also provided on the surface of the connection portion 220 between the second tab portion 22 (second internal portion) and the second inner tab 200. At this connection portion 220, the protective adhesive layer 23 is provided on both the side of the second inner tab 200 facing away from the second tab portion 22 and the side of the second tab portion 22 facing away from the second inner tab 200. This connection portion 220 can specifically be the weld between the second tab portion 22 and the second inner tab 200, typically forming weld marks (such as bumps). Providing a protective adhesive layer 23 on this surface can prevent these bumps and other weld marks from damaging battery components such as the package, further improving battery safety and service life.

[0099] The protective adhesive layer 23 may be made of conventional adhesive materials in the art, such as conventional tab adhesive.

[0100] Generally, as shown in Figure 6, the battery cell 2 can include multiple first pole pieces 201 and multiple second pole pieces 202, each first pole piece 201 is provided with a first sub-pole ear 2011, and the first sub-pole ears 2011 of these first pole pieces 201 are connected as a whole to form a first inner pole ear 100, and each second pole piece 202 is provided with a second sub-pole ear 2021, and the second sub-pole ears 2021 of these second pole pieces 202 are connected as a whole to form a second inner pole ear 200.

[0101] The diaphragm 3 is used to separate the first electrode piece 201 and the second electrode piece 202 to prevent the first electrode piece 201 and the second electrode piece 202 from contacting and short-circuiting.

[0102] In some embodiments, as shown in Figure 6, the diaphragm 3 includes at least two third side portions 31, and a bending portion 32 connecting each two adjacent third side portions 31, and each third side portion 31 is located between the first pole piece 201 and the second pole piece 202 to separate the first pole piece 201 and the second pole piece 202, thereby forming a battery cell 2 in a Z-shaped stacking manner.

[0103] Specifically, the diaphragm 3 can be folded to form the above-mentioned third side portion 31 and the bending portion 32. The third side portion 31 can be a straight portion (i.e., a flat structure), and the bending portion 32 is a curved structure. The third side portion 31 and the bending portion 32 of the diaphragm 3 are distributed along the third direction, and the first pole piece 201, the third side portion 31 of the diaphragm 3, and the second pole piece 202 are distributed along the third direction.

[0104] Specifically, as shown in Figure 6, the diaphragm 3 includes at least one repeating unit, which includes three third side portions 31 and two bending portions 32. In accordance with the distribution order along the third direction, the first third side portion 31, the first bending portion 32, and the second third side portion 31 are sequentially connected and enclosed into a first area 310, and the second third side portion 31, the second bending portion 32, and the third third side portion 31 are sequentially connected and enclosed into a second area 320; the first pole piece 201 is located in the first area 310 (generally not exceeding the opening of the first area 310), and the second pole piece 202 is located in the second area 320 (generally not exceeding the opening of the second area 320), so as to achieve the separation of the first pole piece 201 and the second pole piece 202 by the third side portion 31.

[0105] In which, when the diaphragm 3 includes multiple repeating units, the multiple repeating units are distributed along the third direction, and two adjacent repeating units share a third side 31, that is, according to the distribution order along the third direction, the third third side 31 of the previous repeating unit is the first third side 31 of the next repeating unit.

[0106] Exemplarily, as shown in Figure 6, the first sub-pole ear 2011 of the first pole piece 201 located in the first area 310 extends from the above-mentioned first bending portion 32, that is, the first sub-pole ear 2011 passes through the bending portion 32, and the bending portion 32 has a notch 30 for allowing the first sub-pole ear 2011 to pass through. The second sub-pole ear 2021 of the second pole piece 202 located in the second area 320 extends from the opening of the second area 320, so that the first sub-pole ear 2011 and the second sub-pole ear 2021 are located on the same side of the battery cell 2.

[0107] The material of the positive electrode ear can be aluminum (ie, the positive electrode ear is an aluminum electrode ear), and the material of the negative electrode ear can be copper-nickel-plated material (ie, the negative electrode ear is a copper-nickel-plated electrode ear), but is not limited thereto.

[0108] Furthermore, the battery may include a lithium-ion battery, but is not limited thereto.

[0109] Specifically, the above-mentioned positive electrode sheet includes a positive electrode collector and a positive electrode active layer provided on at least one surface of the positive electrode collector, the positive electrode active layer includes a positive electrode active material, a first conductive agent and a first binder, wherein the mass percentage of the positive electrode active material can be 90% to 98%, for example, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or a range consisting of any two thereof, the mass percentage of the first conductive agent can be 1% to 5%, for example, 1%, 2%, 3%, 4%, 5% or a range consisting of any two thereof, and the mass percentage of the first binder can be 1% to 5%, for example, 1%, 2%, 3%, 4%, 5% or a range consisting of any two thereof.

[0110] The positive electrode active layer may be provided on one surface of the positive electrode current collector, or on both the front and back surfaces of the positive electrode current collector (i.e., surfaces on opposite sides in the thickness direction of the positive electrode current collector). The positive electrode current collector may include aluminum foil, and the positive electrode active material may include one or more of lithium iron phosphate (LFP), lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium-rich manganese-based materials, and lithium nickel cobalt aluminum oxide.

[0111] In addition, the above-mentioned negative electrode sheet includes a negative electrode current collector and a negative electrode active layer provided on at least one surface of the negative electrode current collector, the negative electrode active layer includes a negative electrode active material, a second conductive agent and a second binder, wherein the mass percentage of the negative electrode active material can be 86% to 98%, for example, 86%, 88%, 90%, 93%, 95%, 98% or a range consisting of any two thereof, the mass percentage of the second conductive agent can be 1% to 7%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7% or a range consisting of any two thereof, and the mass percentage of the second binder can be 1% to 7%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7% or a range consisting of any two thereof.

[0112] The negative electrode active layer may be provided on one surface of the negative electrode current collector, or on both the front and back surfaces of the negative electrode current collector. The negative electrode current collector may include copper foil, and the negative electrode active material may include one or more of graphite, mesocarbon microbeads, soft carbon, hard carbon, silicon material, silicon-oxygen material, and silicon-carbon material. The graphite may specifically include artificial graphite and / or natural graphite.

[0113] In addition, the negative electrode active layer may further include a thickener, such as sodium carboxymethylcellulose.

[0114] Exemplarily, the first conductive agent and the second conductive agent may respectively include one or more of conductive carbon black, acetylene black, carbon nanotubes, conductive graphite, graphene, etc., and the first binder and the second binder may respectively include one or more of polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyethylene ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene and styrene-butadiene rubber (SBR).

[0115] In addition, the above-mentioned battery also includes an electrolyte, and the electrolyte may include an organic solvent and a lithium salt. The organic solvent includes, for example, one or more of ethylene carbonate, dimethyl carbonate, and 1,2-propylene glycol carbonate, and the lithium salt includes, for example, lithium hexafluorophosphate. The concentration of the lithium salt in the electrolyte is, for example, about 1 mol / L to 1.5 mol / L, for example, 1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L or a range consisting of any two thereof, but is not limited thereto.

[0116] The electrode sheets and batteries of the present application can be prepared by conventional methods in the field, for example, the positive electrode sheets and negative electrode sheets are prepared by a coating method, that is, the corresponding active materials, conductive agents, binders and other materials are mixed with solvents to form a slurry, and then the slurry is coated on the current collector, and the corresponding electrode sheets are prepared through processes such as drying and rolling. Then, the bare battery cell 2 can be formed in the above-mentioned Z-type stacking method, or wound to form a wound bare battery cell 2, and then the adapter is welded (the first adapter (first pole ear portion 21) is welded on the positive pole ear (first inner pole ear 100) of the positive electrode sheet, and the second adapter (second pole ear portion 22) is welded on the negative pole ear (second inner pole ear 200) of the negative electrode sheet) to rotate out the positive and negative pole ears, and the battery cell 2 is encapsulated in an encapsulation body, and the electrolyte is injected into the accommodating area 110, and then the battery is prepared through processes such as formation and aging.

[0117] The present application is further described below through specific embodiments.

[0118] Example 1

[0119] (1) Preparation of positive electrode

[0120] Mixing lithium iron phosphate, PVDF, and conductive carbon black, and uniformly dispersing them by high-speed stirring to prepare a first mixture; in the first mixture, the mass percentage of lithium iron phosphate is 95wt%, the mass percentage of PVDF is 2wt%, and the mass percentage of conductive carbon black is 3wt%;

[0121] The first mixture is mixed with N-methylpyrrolidone (NMP) to prepare a positive electrode slurry, wherein the solid content of the positive electrode slurry is 50 wt%;

[0122] The positive electrode slurry is evenly coated on both sides of the aluminum foil, dried, and compacted by a roller press to obtain a positive electrode sheet (the thickness of the positive electrode sheet is within 140 μm).

[0123] (2) Preparation of negative electrode sheet

[0124] artificial graphite, PVDF, aziridine (crosslinking agent), sodium carboxymethyl cellulose and conductive carbon black are mixed and uniformly dispersed by high-speed stirring to obtain a second mixture; in the second mixture, the weight percentage of artificial graphite is 95wt%, the weight percentage of sodium carboxymethyl cellulose is 1.5wt%, the weight percentage of conductive carbon black is 1.5wt%, and the weight percentage of PVDF is 2wt%;

[0125] mixing the second mixture with water to prepare a negative electrode slurry, wherein the solid content of the negative electrode slurry is 50 wt %;

[0126] The negative electrode slurry is evenly coated on both sides of the copper foil, dried, and compacted by a roller press to obtain a negative electrode sheet (the thickness of the negative electrode sheet is within 90 μm).

[0127] (3) Battery assembly

[0128] The battery structure is shown in Figures 1 to 9, and its preparation process is as follows:

[0129] The positive electrode sheet (first electrode sheet 201), the separator 3, and the negative electrode sheet (second electrode sheet 202) are stacked in a Z-shaped manner to form a bare battery cell 2 (or wound to form a bare battery cell 2);

[0130] The first sub-pole tabs (aluminum tabs) 2011 of the positive electrode sheets (multiple) in the battery cell 2 are welded together to form the first inner pole tab 100, and the second sub-pole tabs (copper-plated nickel tabs) 2021 of the negative electrode sheets (multiple) in the battery cell 2 are welded together to form the second inner pole tab 200; the first inner pole tab 100 is welded to the first pole tab portion 21 to form the first pole tab, and the second inner pole tab 200 is welded to the second pole tab portion 22 (with a width of about 20 mm and a thickness of about 0.2 mm) to form the second pole tab, thereby respectively rotating out the positive pole tab and the negative pole tab; wherein the width of the first pole tab portion (first adapter) 21 is about 20 mm, the thickness is about 0.2 mm, and the cross-sectional area parallel to the thickness direction of the first pole tab portion 21 is about 4 mm 2 (i.e. 20mm×0.2mm=4mm 2 )), the width of the second pole ear portion (second adapter) 22 is about 20mm, the thickness is about 0.2mm, and the cross-sectional area parallel to the thickness direction of the second pole ear portion 22 is about 4mm 2 (i.e. 20mm×0.2mm=4mm 2 ));

[0131] Clamp the bare cell 2 with a glass clamp. The force of the glass clamp is 100MPa / m. 2 , and then baked at 85°C in vacuum for 24 hours, and then encapsulated with an aluminum-plastic film with a thickness of 153 μm, and an electrolyte is injected into the accommodating area 110 for accommodating the battery core 2. The electrolyte consists of an organic solvent and lithium hexafluorophosphate. The organic solvent is a mixture of ethylene carbonate, dimethyl carbonate, and 1,2-propylene glycol carbonate in a volume ratio of 1:1:1. The concentration of lithium hexafluorophosphate in the electrolyte is 1.1 mol / L;

[0132] The length of the battery cell is about 130 mm, the width is about 110 mm, and the thickness is about 4.5 mm. The capacity of the battery cell is about 5 Ah, and the ratio of the cross-sectional area of ​​the first pole ear portion 21 parallel to the thickness direction of the first pole ear portion 21 to the capacity of the battery cell is about 0.8 mm. 2 / Ah, the ratio of the cross-sectional area of ​​the second pole ear portion 22 parallel to the thickness direction of the second pole ear portion 22 to the capacity of the battery cell is approximately 0.8mm 2 / Ah;

[0133] The aluminum-plastic film includes a PET layer with a thickness of about 12 μm, a third adhesive layer 106 (the ratio of the mass of the third adhesive layer 106 to the area of ​​the side of the PET layer (or nylon layer) facing the third adhesive layer 106 is about 3.3 g / m 2 ), a nylon layer having a thickness of about 15 μm, a second adhesive layer 104 (the ratio of the mass of the second adhesive layer 104 to the area of ​​the side of the nylon layer (or aluminum layer) facing the second adhesive layer 104 is about 3.3 g / m 2 ), a soft aluminum layer having a thickness of approximately 38.48 μm, an APP layer (PPa) having a thickness of approximately 40 μm, and a PP layer (heat sealing layer 101) having a thickness of approximately 40 μm, wherein the surface of the soft aluminum layer facing the second adhesive layer 104 (also the surface facing the nylon layer) is a rough surface, and the surface of the soft aluminum layer facing the APP layer (also the surface facing the PP layer) is a smooth surface;

[0134] Specifically, Figure 9 is a scanning electron microscope (SEM) image of the aluminum-plastic film used. It can be seen that the distance from the side of the PET layer facing away from the nylon layer to the side of the nylon layer facing away from the PET layer is approximately 35.4 μm (the distances measured in two different areas are 35.52 μm and 35.30 μm, respectively), the distance from the side of the APP layer facing the soft aluminum layer to the side of the PP layer facing away from the APP layer is approximately 80.96 μm, and the distance from the side of the PET layer facing away from the nylon layer to the side of the PP layer facing away from the APP layer (package thickness) is approximately 152.62 μm.

[0135] The packaging is performed by heat sealing to seal the accommodating area 110. The heat sealing layer 101 of the first side portion 111 of the sealing area 10 is combined with the heat sealing layer 101 of the second side portion 112 to form a whole (i.e., forming a connecting layer 108, as shown in FIG2 ); wherein the thickness T3 of the connecting layer 108 is approximately 50 μm, the thickness T1 of the APP layer (first adhesive layer 102) of the first side portion is approximately 40 μm, and the thickness T2 of the APP layer (first adhesive layer 102) of the second side portion is approximately 40 μm. The thickness of the sealing area 10 is approximately 235 μm. The width of the sealing area 10 (effective sealing area) of the top sealing edge 11 is 2 mm, and the width of the sealing area 10 of the side sealing edge 12 is 2 mm.

[0136] Then, after formation and aging treatments, a square soft-pack battery was produced. The battery has a length of 140 mm, a width of 145 mm, and a thickness of 14 mm.

[0137] The results of the high temperature and high humidity accelerated test show that the battery can meet a service life of more than 8 years, that is, after being used for more than 8 years, it can still maintain high power performance and other performance. Among them, the high temperature and high humidity accelerated test process is: at room temperature, the battery cell is charged to full power (100% SOC), and then placed in a high temperature (65°C) and high humidity (relative humidity 95%) box for accelerated testing. The battery cell packaging life at room temperature is calculated based on the high temperature storage time (equivalent factor AF = 40.83). For example: 71.6 days of storage at 60°C and 95% relative humidity (RH) is equivalent to 71.6×40.83÷365=8 years of storage at room temperature.

[0138] According to the above accelerated test process, the battery was stored at 60°C and 95% relative humidity (RH) for 71.6 days, then charged to 50% SOC at -30°C and discharged at 10C for 10s. The impedance DCR growth rate was calculated and the measured DCR growth rate was less than 5%, which is equivalent to the power performance attenuation rate of the battery within 15% after 8 years of storage.

[0139] Example 2

[0140] (1) Preparation of positive electrode

[0141] The lithium iron phosphate, PVDF, and conductive carbon black are mixed and dispersed uniformly by high-speed stirring to prepare a first mixture; in the first mixture, the mass percentage of lithium iron phosphate is 91wt%, the mass percentage of PVDF is 4wt%, and the mass percentage of conductive carbon black is 5wt%;

[0142] The first mixture is mixed with N-methylpyrrolidone (NMP) to prepare a positive electrode slurry, wherein the solid content of the positive electrode slurry is 50 wt%;

[0143] The positive electrode slurry is evenly coated on the front and back sides of the aluminum foil, dried, and compacted by a roller press to obtain a positive electrode sheet.

[0144] (2) Preparation of negative electrode sheet

[0145] artificial graphite, PVDF, aziridine (crosslinking agent), sodium carboxymethyl cellulose and conductive carbon black are mixed and uniformly dispersed by high-speed stirring to obtain a second mixture; in the second mixture, the weight percentage of artificial graphite is 95wt%, the weight percentage of sodium carboxymethyl cellulose is 1.5wt%, the weight percentage of conductive carbon black is 1.5wt%, and the weight percentage of PVDF is 2wt%;

[0146] mixing the second mixture with water to prepare a negative electrode slurry, wherein the solid content of the negative electrode slurry is 50 wt %;

[0147] The negative electrode slurry is evenly coated on the front and back sides of the copper foil, dried, and compacted by a roller press to obtain a negative electrode sheet.

[0148] (3) Battery assembly

[0149] The battery structure is shown in Figures 1 to 9, and its preparation process is as follows:

[0150] The positive electrode sheet, the separator 3, and the negative electrode sheet are stacked in a Z-shaped manner to form a bare battery cell 2 (or wound to form a bare battery cell 2);

[0151] The aluminum tabs (first sub-tabs 2011) of the positive electrode sheets (multiple) in the battery cell 2 are welded together to form a first inner tab 100, and the copper-plated nickel tabs (second sub-tabs 2021) of the negative electrode sheets (multiple) in the battery cell 2 are welded together to form a second inner tab 200; the first inner tab 100 is welded to the first tab portion 21 to form a first tab, and the second inner tab 200 is welded to the second tab portion 22 (with a width of approximately 20 mm and a thickness of approximately 0.2 mm) to form a second tab, thereby respectively rotating out the positive tab and the negative tab; wherein the width of the first tab portion (first adapter) 21 is approximately 20 mm, the thickness is approximately 0.2 mm, and the cross-sectional area parallel to the thickness direction of the first tab portion 21 is approximately 4 mm 2 (i.e. 20mm×0.2mm=4mm 2 )), the width of the second pole ear portion (second adapter) 22 is about 20mm, the thickness is about 0.2mm, and the cross-sectional area parallel to the thickness direction of the second pole ear portion 22 is about 4mm 2 (i.e. 20mm×0.2mm=4mm 2 ));

[0152] Clamp the bare cell 2 with a glass clamp. The force of the glass clamp is 100MPa / m. 2, and then baked at 85°C in vacuum for 24 hours, and then encapsulated with an aluminum-plastic film with a thickness of 153 μm, and an electrolyte is injected into the accommodating area 110 for accommodating the battery core 2. The electrolyte consists of an organic solvent and lithium hexafluorophosphate. The organic solvent is a mixture of ethylene carbonate, dimethyl carbonate, and 1,2-propylene glycol carbonate in a volume ratio of 1:1:1. The concentration of lithium hexafluorophosphate in the electrolyte is 1.1 mol / L;

[0153] The length of the battery cell is about 130 mm, the width is about 110 mm, and the thickness is about 4.5 mm. The capacity of the battery cell is about 5 Ah, and the ratio of the cross-sectional area of ​​the first pole ear portion 21 parallel to the thickness direction of the first pole ear portion 21 to the capacity of the battery cell is about 0.8 mm. 2 / Ah, the ratio of the cross-sectional area of ​​the second pole ear portion 22 parallel to the thickness direction of the second pole ear portion 22 to the capacity of the battery cell is approximately 0.8mm 2 / Ah;

[0154] The aluminum-plastic film includes a PET layer with a thickness of about 12 μm, a third adhesive layer 106 (the ratio of the mass of the third adhesive layer 106 to the area of ​​the side of the PET layer (or nylon layer) facing the third adhesive layer 106 is about 3.3 g / m 2 ), a nylon layer having a thickness of about 15 μm, a second adhesive layer 104 (the ratio of the mass of the second adhesive layer 104 to the area of ​​the side of the nylon layer (or aluminum layer) facing the second adhesive layer 104 is about 3.3 g / m 2 ), a soft aluminum layer having a thickness of approximately 38.48 μm, an APP layer (PPa) having a thickness of approximately 40 μm, and a PP layer (heat sealing layer 101) having a thickness of approximately 40 μm, wherein the surface of the soft aluminum layer facing the second adhesive layer 104 (also the surface facing the nylon layer) is a rough surface, and the surface of the soft aluminum layer facing the APP layer (also the surface facing the PP layer) is a smooth surface;

[0155] Specifically, Figure 9 is a scanning electron microscope (SEM) image of the aluminum-plastic film used. It can be seen that the distance from the side of the PET layer facing away from the nylon layer to the side of the nylon layer facing away from the PET layer is approximately 35.4 μm (the distances measured in two different areas are 35.52 μm and 35.30 μm, respectively), the distance from the side of the APP layer facing the soft aluminum layer to the side of the PP layer facing away from the APP layer is approximately 80.96 μm, and the distance from the side of the PET layer facing away from the nylon layer to the side of the PP layer facing away from the APP layer (package thickness) is approximately 152.62 μm.

[0156] The packaging is performed by heat sealing to seal the accommodating area 110. The heat sealing layer 101 of the first side portion 111 of the sealing area 10 is combined with the heat sealing layer 101 of the second side portion 112 to form a whole (i.e., forming a connecting layer 108, as shown in FIG2 ); wherein the thickness T3 of the connecting layer 108 is approximately 50 μm, the thickness T1 of the APP layer (first adhesive layer 102) of the first side portion is approximately 40 μm, and the thickness T2 of the APP layer (first adhesive layer 102) of the second side portion is approximately 40 μm. The thickness of the sealing area 10 is approximately 235 μm. The width of the sealing area 10 (effective sealing area) of the top sealing edge 11 is 2 mm, and the width of the sealing area 10 of the side sealing edge 12 is 2 mm.

[0157] Then, after formation and aging treatments, a square soft-pack battery was produced. The battery has a length of 140 mm, a width of 145 mm, and a thickness of 14 mm.

[0158] The results of the high-temperature and high-humidity accelerated test show that the battery can meet a service life of more than 12 years. Even after more than 8 years of use, it can still maintain a high capacity retention rate and other performance. The high-temperature and high-humidity accelerated test process is as follows: at room temperature, the battery cell is charged to full power (100% SOC), and then placed in a high-temperature (65°C) and high-humidity (relative humidity 95%) box for accelerated testing. The battery cell's package life at room temperature is calculated based on the high-temperature storage time (equivalent factor AF = 40.83). For example, 107.3 days of storage at 60°C and 95% relative humidity (RH) is equivalent to 107.3×40.83÷365=12 years of storage at room temperature.

[0159] Through the above simulation process, it was measured that after the battery was stored and used at room temperature for 12 years, the capacity loss caused by storage was 10.5%, the capacity loss caused by cycling was about 6.4%, and the total capacity retention rate was about 83.1%.

[0160] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery, characterized in that: The invention comprises a battery cell and a package encapsulating the battery cell, wherein the battery cell is provided with a first pole ear, the first pole ear comprises a first pole ear portion extending out of the package body, and the ratio of the cross-sectional area of ​​the first pole ear portion parallel to the thickness direction of the first pole ear portion to the capacity of the battery cell is greater than or equal to 0.6 mm 2 / Ah.

2. The battery according to claim 1, characterized in that The battery cell is further provided with a second pole ear, the second pole ear comprising a second pole ear portion extending out of the package body, and the ratio of the cross-sectional area of ​​the second pole ear portion parallel to the thickness direction of the second pole ear portion to the capacity of the battery cell is greater than or equal to 0.6 mm 2 / Ah.

3. The battery according to claim 1 or 2, characterized in that: The first pole ear is a positive pole ear, and the ratio of the cross-sectional area of ​​the first pole ear portion parallel to the thickness direction of the first pole ear portion to the capacity of the battery cell is greater than or equal to 0.7 mm 2 / Ah.

4. The battery according to claim 1, characterized in that The package body includes a containing area and a sealing area for sealing the containing area, and the battery cell is located in the containing area; the package body includes a first adhesive layer and a heat-sealing layer connected to each other, and the package body has a first side and a second side, the heat-sealing layer on the first side of the sealing area is connected to the heat-sealing layer on the second side of the sealing area, the thickness of the first adhesive layer on the first side of the sealing area is T1, the thickness of the first adhesive layer on the second side of the sealing area is T2, and in the sealing area, the sum of the thickness of the heat-sealing layer on the first side and the heat-sealing layer on the second side is T3, and T3<T1+T2.

5. The battery according to claim 4, characterized in that 10 μm ≤ (T1 + T2) - T3 ≤ 60 μm; and / or, The T1 is 18 μm to 66 μm; and / or, The T2 is 18 μm to 66 μm; and / or, The T3 is 20 μm to 90 μm.

6. The battery according to claim 1, characterized in that The package body includes a first supporting layer, a third adhesive layer, a second supporting layer, a second adhesive layer, a metal layer, a first adhesive layer and a heat-sealing layer which are stacked; the package body includes a receiving area and a sealing area which seals the receiving area, and the battery cell is located in the receiving area; the package body has a first side portion and a second side portion, and the heat-sealing layer on the first side portion of the sealing area is connected to the heat-sealing layer on the second side portion of the sealing area.

7. The battery according to claim 6, characterized in that The heat-sealing layer on the first side of the sealing area is composited with the heat-sealing layer on the second side of the sealing area; and / or, The first adhesive layer comprises an acid-modified polypropylene layer; and / or, The heat seal layer comprises a polypropylene layer; and / or, The first support layer comprises a polyester layer; and / or, The second supporting layer comprises a nylon layer; and / or, The metal layer comprises an aluminum layer; and / or, The roughness of a surface of the metal layer facing the second adhesive layer is greater than the roughness of a surface of the metal layer facing the first adhesive layer.

8. The battery according to claim 6, characterized in that The thickness of the sealing area is 210 μm to 260 μm; and / or, The width of the sealing area is greater than or equal to 2 mm.

9. The battery according to any one of claims 1 to 8, characterized in that: The thickness of the package body is greater than 90 μm.

10. The battery according to any one of claims 1 to 8, characterized in that: The battery cell has a capacity of less than 30 Ah.

11. The battery according to claim 1, characterized in that The ratio of the thickness of the battery cell to the capacity of the battery cell is less than 4 mm / Ah.

12. The battery according to claim 1 or 11, characterized in that: The volume of the battery cell is 240cm 3 ~302cm 3 ; And / or, the length of the battery cell is 100 mm to 250 mm, and / or, the width of the battery cell is 80 mm to 150 mm, and / or, the thickness of the battery cell is 3 mm to 15 mm.

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