Electrode assembly, core package and battery

Abstract

The utility model discloses a battery and a battery system, and relates to the technical field of batteries. The battery comprises first pole pieces and second pole pieces, the polarity of the first pole pieces is different from that of the second pole pieces, and the first pole pieces and the second pole pieces are alternately arranged. The center line of the first pole piece in the length direction and the center line of the second pole piece in the length direction are both located on the center face of the electrode assembly in the length direction. A first tab is arranged on the first pole piece, a second tab is arranged on the second pole piece, and the first tab and the second tab are positioned on the same side of the electrode assembly. The first tab and the second tab are positioned on two sides of the central surface, and the distance from the first tab to the central surface is equal to the distance from the second tab to the central surface. Or, the first tab and the second tab are respectively symmetrical about the central plane.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrode assembly, a core pack, and a battery. Background Art

[0002] With the development of lithium-ion batteries, industry competition is becoming increasingly fierce, and cost reduction has become a key factor in the lithium-ion battery industry. To reduce battery manufacturing and system management costs, related technologies increase the battery capacity of a single cell by increasing electrode size. This technology not only reduces material costs, but also reduces production and system management costs, improving user benefits. However, as electrode size increases, the current density distribution in the cell becomes uneven, leading to severe polarization, which affects the battery's rate and cycle performance. Utility Model Content

[0003] The embodiments of the present application provide a battery and a battery system that can improve the current density distribution in batteries with different electrode sizes by setting the position of the tabs, as well as the width and number of the tabs, so that the current density distribution is more uniform, thereby improving the cycle and rate performance of the battery.

[0004] In a first aspect, the present application provides an electrode assembly, comprising a first electrode piece and a second electrode piece, wherein the polarity of the first electrode piece is different from the polarity of the second electrode piece, and the first electrode piece and the second electrode piece are arranged alternately. The center line of the first electrode piece in the longitudinal direction and the center line of the second electrode piece in the longitudinal direction are both located on the center plane of the electrode assembly in the longitudinal direction. A first electrode tab is provided on the first electrode piece, and a second electrode tab is provided on the second electrode piece, and the first electrode tab and the second electrode tab are located on the same side of the electrode assembly. The first electrode tab and the second electrode tab are located on both sides of the center plane, and the distance from the first electrode tab to the center plane is equal to the distance from the second electrode tab to the center plane. Alternatively, the first electrode tab and the second electrode tab are symmetrical about the center plane.

[0005] In a possible design of the first aspect, the first pole piece and the second pole piece are both rectangular, the length of the first pole piece is a, the width of the first pole piece is b, and the diagonal length of the first pole piece is c.

[0006] When c≤0.8L, a first pole tab is provided on the first pole piece, a second pole tab is provided on the second pole piece, and the distance from the first pole tab to the center plane is equal to the distance from the second pole tab to the center plane.

[0007] When 0.8L<c≤1.2L, the first pole piece is provided with a first pole tab, the second pole piece is provided with two second pole tabs, the first pole tab is symmetrical about the center plane, and the two second pole tabs are symmetrical about the center plane.

[0008] When c>1.2L, two first pole tabs are provided on the first pole piece, and two second pole tabs are provided on the second pole piece. The two first pole tabs are symmetrical about the center plane, and the two second pole tabs are symmetrical about the center plane.

[0009] Where c is the diagonal length of the first electrode, cˋ is the diagonal length of the second electrode, c≤cˋ, and L is the characteristic length, which is the maximum length of electron diffusion in the electrode in the electrode assembly.

[0010] In a possible design of the first aspect, the length of the first pole piece is a, the width of the first pole piece is b, and the diagonal length of the first pole piece is c; the length of the second pole piece is aˋ, the width of the second pole piece is bˋ, and the diagonal length of the second pole piece is cˋ, wherein a≤aˋ, b≤bˋ, and c≤cˋ.

[0011] The relationship between the size and characteristic length of the first pole piece, and the relationship between the size and characteristic length of the second pole piece satisfy the following relationship:

[0012] When c≤0.8L, the distance from the first pole tab to the side of the first pole piece is 0.1a-0.25a, ​​and the second pole tab is symmetrical to the first pole tab about the center plane.

[0013] When 0.8L<c≤1.2L, the first pole ear is located at the center of the first pole piece, and the distance from the second pole ear to the side of the second pole piece is 0.1aˋ-0.25aˋ.

[0014] When c>1.2L, the distance from the first pole ear to the center plane is 0.1a-0.25a, ​​and the distance from the second pole ear to the side of the second pole piece is 0.1aˋ-0.25aˋ.

[0015] In a possible design of the first aspect, the relationship between the size and characteristic length of the first pole piece, and the relationship between the size and characteristic length of the second pole piece satisfy the following relationship:

[0016] When c≤0.8L, the distance from the first pole tab to the side of the first pole piece is 0.19a, and the second pole tab is symmetrical to the first pole tab about the center plane.

[0017] When 0.8L<c≤1.2L, the first pole ear is located at the center of the first pole piece, and the distance from the second pole ear to the side of the second pole piece is 0.19aˋ.

[0018] When c>1.2L, the distance from the first pole ear to the center plane is 0.19a, and the distance from the second pole ear to the side of the second pole piece is 0.19aˋ.

[0019] In a possible design of the first aspect, the relationship between the size and characteristic length of the first pole piece, and the relationship between the size and characteristic length of the second pole piece satisfy the following relationship:

[0020] When c≤0.8L, the width of the first tab is equal to the width of the second tab. When 0.8L<c≤1.2L, the width of the first tab is twice the width of the second tab. When c>1.2L, the width of the first tab is equal to the width of the second tab.

[0021] In a possible design of the first aspect, the relationship between the size and characteristic length of the first pole piece, and the relationship between the size and characteristic length of the second pole piece satisfy the following relationship:

[0022] When c≤0.8L, the width of the first tab is 2m, the width of the second tab is 2m, and 0.809a-(0.36L 2 -b 2 ) 1 / 2 ≤m

[0023] When 0.8L<c≤1.2L, the width of the first tab is 2m, the width of the second tab is m, 0.5a-(0.36L 2 -b 2 ) 1 / 2 ≤m

[0024] When c>1.2L, the width of the first tab is 2m, the width of the second tab is 2m, and 0.309a-(0.36L 2 -b 2 ) 1 / 2 ≤m

[0025] In a second aspect, the present application provides a core package comprising an insulating film and an electrode assembly of the first aspect and any possible design thereof, wherein the insulating film is disposed between the first pole piece and the second pole piece.

[0026] In a third aspect, the present application provides a battery, comprising a shell, a cover plate, and an electrode assembly of the first aspect and any possible design thereof or a core pack of the second aspect, wherein the electrode assembly or the core pack is disposed in the shell, and the cover plate is covered on the shell.

[0027] In a possible design of the third aspect, the shell is in the shape of a cuboid.

[0028] It can be understood that the beneficial effects that can be achieved by the core pack of the second aspect and the battery of the third aspect provided above can refer to the beneficial effects of the first aspect and any possible design thereof, and will not be repeated here.

[0029] Beneficial effects of this application:​​​

[0030] The battery in this application can set the corresponding tab position, number of tabs and width of the tab according to the specific size of the battery to improve the current density distribution in batteries with different electrode sizes, making the current density distribution more uniform, thereby improving the battery's cycle and rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 A schematic diagram of the overall structure of a battery provided in an embodiment of the present application;

[0033] Figure 2 A schematic diagram of the overall structure of another battery provided in an embodiment of the present application;

[0034] Figure 3 Schematic diagram of the overall structure of another battery provided in the embodiment of the present application

[0035] Figure 4 for Figure 1 a front view of the battery shown;

[0036] Figure 5 for Figure 1 A schematic structural diagram of the first and second pole pieces in the battery shown;

[0037] Figure 6 for Figure 2 a front view of the battery shown;

[0038] Figure 7 for Figure 2 A schematic structural diagram of the first and second pole pieces in the battery shown;

[0039] Figure 8 for Figure 3 a front view of the battery shown;

[0040] Figure 9 for Figure 3 A schematic structural diagram of the first and second pole pieces in the battery shown;

[0041] Figure 10 A cycle comparison diagram of a battery provided in an embodiment of the present application;

[0042] Figure 11 A cycle comparison diagram of another battery provided in an embodiment of the present application;

[0043] Figure 12 This is a cycle comparison chart of another battery provided in an embodiment of the present application.

[0044] In the figure: 100 - battery; 110 - first pole piece; 120 - second pole piece; 130 - first pole tab; 140 - second pole tab. DETAILED DESCRIPTION

[0045] The technical solution in this application will be described below with reference to the accompanying drawings.

[0046] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0047] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0048] It should be understood that the terms used in the description of the various examples herein are for the purpose of describing the particular examples only and are not intended to be limiting. As used in the description of the various examples, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0049] In this application, "at least one" means one, two, or more, and "more than one" means more than two. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or plural.

[0050] It should also be understood that in this application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a sliding connection, a detachable connection, or an integral connection, etc.; it can be a direct connection or an indirect connection through an intermediate medium.

[0051] It will also be understood that the term “comprise” (also known as “includes,” “including,” “comprises,” and / or “comprising”) when used in this specification specifies the presence of stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0052] It should be understood that references throughout this specification to "one embodiment," "another embodiment," or "a possible design" mean that specific features, structures, or characteristics associated with an embodiment or implementation are included in at least one embodiment of this application. Therefore, the appearance of "in one embodiment of this application," "in another embodiment of this application," or "a possible design" throughout this specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0053] It should also be understood that the specific numerical values ​​mentioned in the embodiments of this application do not limit the specific dimensions of specific features or structures. The relevant numerical values ​​may be provided for ease of explanation or may be the theoretically optimal value of a certain feature. In practice, the relevant dimensions may be within a range of the value, for example, the range may be ±10% of the optimal theoretical value, or ±20% of the optimal theoretical value. In practice, the range that achieves the corresponding technical effect shall prevail.

[0054] With the development of lithium-ion batteries, industry competition is becoming increasingly fierce, and cost reduction has become a key factor in the lithium-ion battery industry. To reduce battery manufacturing and system management costs, related technologies increase the battery capacity of a single cell by increasing electrode size. This technology not only reduces material costs, but also reduces production and system management costs, improving user benefits. However, as electrode size increases, the current density distribution in the cell becomes uneven, leading to severe polarization, which affects the battery's rate and cycle performance.

[0055] In order to improve the current density distribution in batteries with different electrode sizes, make the current density distribution more uniform, and thus improve the cycle and rate performance of the battery, an embodiment of the present application provides a battery that improves the relevant performance of the battery by setting the position of the tabs, as well as setting parameters such as the width and number of the tabs.

[0056] In one embodiment of the present application, an electrode assembly is provided. The electrode assembly 100 includes a plurality of electrode pieces, which are stacked. The plurality of electrode pieces include at least a first electrode piece 110 and a second electrode piece 120. The polarity of the first electrode piece 110 is different from the polarity of the second electrode piece 120, and the first electrode pieces 110 and the second electrode pieces 120 are alternately arranged. A first electrode tab 130 is provided on the first electrode piece 110, and a second electrode tab 140 is provided on the second electrode piece 120. It should be noted that an insulating film is provided between the first electrode piece 110 and the second electrode piece 120. The plurality of electrode pieces can be arranged in the following arrangement: second electrode piece 120 - insulating film - first electrode piece 110 - insulating film - second electrode piece 120 - insulating film - ... - first electrode piece 110 - insulating film - second electrode piece 120.

[0057] The first electrode piece 110 and the second electrode piece 120 can be configured with different polarities. For example, the first electrode piece 110 can be a positive electrode piece, and the second electrode piece 120 can be a negative electrode piece. The first electrode tab 130 on the first electrode piece 110 can be called a positive electrode tab, and the second electrode tab 140 on the second electrode piece 120 can be called a negative electrode tab. Of course, the first electrode piece 110 can also be a negative electrode piece, and the second electrode piece 120 can be a positive electrode piece. Correspondingly, the first electrode tab 130 is a negative electrode tab, and the second electrode tab 140 is a positive electrode tab.

[0058] Generally speaking, the first electrode 110 and the second electrode 120 are generally configured as rectangular electrode pieces, and the sizes of the first electrode 110 and the second electrode 120 can be set as needed. For example, when the first electrode 110 is a positive electrode piece and the second electrode 120 is a negative electrode piece, the first electrode piece 110 and the second electrode piece 120 can be set to the same size, or the size of the second electrode piece 120 can be set to be slightly larger than the size of the first electrode piece 110. In actual applications, the size of the second electrode piece is generally larger than the size of the first electrode piece, that is, the size of the negative electrode piece is larger than the size of the positive electrode piece.

[0059] In the embodiments of the present application, for ease of description, the first and second pole pieces 110, 120 are both rectangular pole pieces. The length of the first pole piece 110 is a, the width of the first pole piece 110 is b, and the diagonal length of the first pole piece 110 is c. The length of the first pole piece 110 is greater than its width, and its width is greater than its thickness. The length of the second pole piece 120 is aˋ, the width of the second pole piece 120 is bˋ, and the diagonal length of the second pole piece 120 is cˋ. The length of the second pole piece 120 is greater than its width, and its width is greater than its thickness.

[0060] The first pole pieces 110 and the second pole pieces 120 are alternately arranged, and an insulating film is provided between the first pole pieces 110 and the second pole pieces 120. When the first pole pieces 110 and the second pole pieces 120 are arranged, the center line of the first pole piece 110 in the longitudinal direction and the center line of the second pole piece 120 in the longitudinal direction are both in the same plane. The plane where the center line of the first pole piece 110 in the longitudinal direction and the center line of the second pole piece 120 in the longitudinal direction lie is the center plane of the electrode assembly 100 in the longitudinal direction, and the center plane divides the first pole piece 110 and the second pole piece 120 into two equal parts in the longitudinal direction.

[0061] According to electrochemical theory, the diffusion of electrons in electrodes is not infinite. There is a certain diffusion length, namely the "characteristic length". The current density in the electrode gradually decreases with the increase of the diffusion distance. The "characteristic length" is the maximum length of electron diffusion in the electrode of the battery. According to the electrochemical knowledge "Selected Theories of Chemical Power Sources", the characteristic length L = (Z / (ρ + +ρ - )) 1 / 2 , where L is the characteristic length, Z is the electrochemical reaction equivalent differential resistance of the corresponding unit length battery, ρ + , ρ - are the resistance per unit length of the positive and negative current collectors, respectively. As can be seen from the above, once the materials within the battery are determined, the characteristic length of the battery can also be determined. In other words, the characteristic length can be considered a fixed parameter of the battery. In the embodiment of the present application, the characteristic length of the electrode assembly 100 is L.

[0062] When the electrode assembly 100 is designed using the same material, the characteristic lengths of electrode assemblies 100 of different sizes are equal. However, due to the different sizes of the electrode assemblies 100, the maximum distance that electrons can travel in the electrodes varies in electrode assemblies 100 of different sizes. In order to make the current density distribution in the electrode assembly 100 more uniform and achieve better battery cell cycle performance and rate performance, the position, number, and width of the tabs in the electrode assembly 100 need to be set according to the size of the electrode assembly 100 to achieve good performance requirements.

[0063] In the embodiments of the present application, the position, number, and width of the tabs in the electrode assembly 100 are designed based on the relationship between the maximum distance electrons travel in the electrode and the characteristic length. In this application, the tab positions are configured such that the distance between the first tab 130 and the center plane of the electrode assembly 100 is equal to the distance between the second tab 140 and the center plane of the electrode assembly 100. Alternatively, the first tab 130 and the second tab 140 are symmetrical about the center plane of the electrode assembly 100.

[0064] It should be noted that in the embodiments of the present application, the distance from the first electrode tab 130 to the center plane may refer to the straight-line distance between the center line of the first electrode tab 130 in the longitudinal direction and the center plane of the electrode assembly 100. The distance from the second electrode tab 140 to the center plane may refer to the straight-line distance between the center line of the second electrode tab 140 in the longitudinal direction and the center plane of the electrode assembly 100. The center plane in the embodiments of the present application refers to the center plane of the electrode assembly 100 in the longitudinal direction.

[0065] refer to Figure 1 、 Figure 2 and Figure 3 , Figure 1 This is a schematic diagram of the overall structure of a battery provided in an embodiment of the present application. Figure 2 This is a schematic diagram of the overall structure of another battery provided in an embodiment of the present application. Figure 3 This is a schematic diagram of the overall structure of another battery provided in an embodiment of the present application. Figure 1 、 Figure 2 and Figure 3 The dotted lines in the figure represent the center planes of the electrode assembly 100 in the longitudinal direction.

[0066] like Figure 1 As shown, a plurality of first electrode sheets 110 and a plurality of second electrode sheets 120 are alternately stacked together to form an electrode assembly 100. A first electrode tab 130 is provided on the first electrode sheet 110, and a second electrode tab 140 is provided on the second electrode sheet 120. The first electrode tab 130 and the second electrode tab 140 are both located on the same side of the electrode assembly 100, and the first electrode tab 130 and the second electrode tab 140 are respectively located on either side of the center plane of the electrode assembly 100 in the longitudinal direction. The distance from the first electrode tab 130 to the center plane is equal to the distance from the second electrode tab 140 to the center plane.

[0067] like Figure 2 As shown, a plurality of first pole pieces 110 and a plurality of second pole pieces 120 are alternately stacked together to form a same-end tab electrode assembly 100. A first pole piece 130 is provided on the first pole piece 110, and two second pole pieces 140 are provided on the second pole piece 120. The first pole piece 130 and the second pole piece 140 are both located on the same side of the electrode assembly 100, and the first pole piece 130 is provided at the center of the first pole piece 110, and the first pole piece 130 is symmetrical about the center plane. The two second pole pieces 140 on the second pole piece 120 are respectively located on both sides of the center plane of the electrode assembly 100 in the longitudinal direction, and the two second pole pieces 140 are symmetrically arranged about the center plane. It should be noted that, in the embodiment of the present application, the first pole piece 130 is provided at the center position of the first pole piece 110, which means that the center line of the first pole piece 130 in the longitudinal direction coincides with the center line of the first pole piece 110 in the longitudinal direction.

[0068] like Figure 3 As shown, a plurality of first pole pieces 110 and a plurality of second pole pieces 120 are alternately stacked together to form a same-end tab electrode assembly 100. Two first pole pieces 130 are provided on the first pole piece 110, and two second pole pieces 140 are provided on the second pole piece 120. The first pole piece 130 and the second pole piece 140 are both located on the same side of the electrode assembly 100, and the two first pole pieces 130 on the first pole piece 110 are respectively located on either side of the center plane of the electrode assembly 100 in the longitudinal direction, and the two first pole pieces 130 are symmetrical about the center plane; the two second pole pieces 140 on the second pole piece 120 are respectively located on either side of the center plane of the electrode assembly 100 in the longitudinal direction, and the two second pole pieces 140 are symmetrical about the center plane.

[0069] The following describes the relationship between the specific dimensions and characteristic length of the electrode piece in the electrode assembly 100, and sets the corresponding tab position, tab quantity, and tab width.

[0070] Since the first pole piece 110 is a rectangle, the length of the first pole piece 110 is a, the width of the first pole piece 110 is b, and the diagonal length of the first pole piece 110 is c, then c=(a 2 +b 2 ) 1 / 2 Since the second pole piece 120 is rectangular, the length of the second pole piece 120 is aˋ, the width of the second pole piece 120 is bˋ, and the diagonal length of the second pole piece 120 is cˋ, then cˋ=(aˋ 2 +bˋ 2 ) 1 / 2 .

[0071] In one embodiment of the present application, when the relationship between the size and characteristic length of the first electrode piece 110 and the relationship between the size and characteristic length of the second electrode piece 120 satisfy c≤0.8L, the electrode assembly 100 adopts the following method: Figure 1 The two-pole lug design shown.

[0072] refer to Figure 4 , Figure 4 for Figure 1 The front view of the battery is shown. Figure 4 As shown in FIG, when the relationship between the size and characteristic length of the first pole piece 110 and the relationship between the size and characteristic length of the second pole piece 120 satisfy c≤0.8L, the size of the first pole tab 130 can be set to be the same as the size of the second pole tab 140, that is, the width of the first pole tab 130 is equal to the width of the second pole tab 140. This arrangement can achieve that the first pole tab 130 and the second pole tab 140 are evenly distributed on both sides of the center plane. That is, in Figure 1 In the embodiment, the distance from the first tab 130 to the center plane is equal to the distance from the second tab 140 to the center plane. Figure 4In FIG, the first electrode tab 130 and the second electrode tab 140 are symmetrical about the center plane.

[0073] refer to Figure 5 , Figure 5 for Figure 1 The schematic diagram of the structure of the first pole piece and the second pole piece in the battery shown, Figure 5 The two dotted lines in FIG represent the center line of the first pole piece 110 in the length direction and the center line of the second pole piece 120 in the length direction, respectively. Figure 5 As shown, when the first pole tab 130 and the second pole tab 140 are located on both sides of the center plane, and the distance from the first pole tab 130 to the center plane is equal to the distance from the second pole tab 140 to the center plane. The distance from the center line of the first pole tab 130 to the side of the first pole piece 110 can be set to 0.1a-0.25a. Among them, the optimal setting position of the first pole tab 130 is: the distance from the center line of the first pole tab 130 in the longitudinal direction to the center line of the first pole piece 110 in the longitudinal direction conforms to the golden section ratio (the ratio of the distance from the center line of the first pole tab 130 to the center line of the first pole piece 110 to half the length of the first pole piece 110 is 0.618). Assuming that the distance from the center line of the first pole tab 130 in the longitudinal direction to the side of the first pole piece 110 is M, then M = (1-0.618)*a / 2 = 0.191a.

[0074] Since the second pole tab 140 and the first pole tab 130 are symmetrical about the center plane, the distance from the second pole tab 140 to the center plane is equal to the distance from the first pole tab 130 to the center plane. Since the distance from the center line of the first pole tab 130 in the longitudinal direction to the side edge of the first pole piece 110 is 0.191a, the distance from the center line of the first pole tab 130 in the longitudinal direction to the center plane is 0.5a - 0.191a = 0.309a. Therefore, the distance from the center line of the second pole tab 140 in the longitudinal direction to the center plane is also 0.309a.

[0075] It should be noted that, in the embodiment of the present application, the distance from the first pole tab 130 to the side of the first pole piece 110 refers to the distance from the center line of the first pole tab 130 in the longitudinal direction to the side of the first pole piece 110. The distance from the first pole tab 130 to the center plane refers to the distance from the center line of the first pole tab 130 in the longitudinal direction to the center plane. The distance from the second pole tab 140 to the side of the second pole piece 120 refers to the distance from the center line of the second pole tab 140 in the longitudinal direction to the side of the second pole piece 120. The distance from the second pole tab 140 to the center plane refers to the distance from the center line of the second pole tab 140 in the longitudinal direction to the center plane.

[0076] In the first electrode 110, the maximum distance that electrons diffuse from the first electrode tab 130 is l, and in the second electrode 120, the maximum distance that electrons diffuse from the second electrode tab 140 is also l'. Assuming that the widths of the first electrode tab 130 and the second electrode tab 140 are both 2m, the distance from the center line of the first electrode tab 130 in the longitudinal direction to the side of the first electrode 110 is M, and the distance from the center line of the second electrode tab 140 in the longitudinal direction to the side of the second electrode 120 is M', then l = ((aMm) 2 +b 2 ) 1 / 2 =((0.809am) 2 +b 2 ) 1 / 2 .

[0077] In order to prevent excessive polarization in the electrode assembly 100, generally speaking, it is necessary to set l≤0.6L, where L represents the characteristic length of the electrode assembly 100. When the dimension c of the electrode assembly 100 is ≤0.8L, that is, (a 2 +b 2 ) 1 / 2 ≤0.8L. By l≤0.6L, ((0.809am) 2 +b 2 ) 1 / 2 ≤0.6L, m≥0.809a-(0.36L 2 -b 2 ) 1 / 2 In addition, since the first electrode tab 130 is disposed on one side of the center line of the first electrode sheet 110 , the width 2m of the first electrode tab 130 is less than a / 2, and m is less than a / 4.

[0078] It can be concluded that when the relationship between the size of the first electrode piece 110 and the characteristic length satisfies c≤0.8L, the widths of the first electrode tab 130 and the second electrode tab 140 are both 2m, and 0.809a-(0.36L 2 -b 2 ) 1 / 2 ≤m

[0079] In one embodiment of the present application, when the relationship between the size and characteristic length of the first electrode piece 110 and the relationship between the size and characteristic length of the second electrode piece 120 satisfy 0.8L<c≤1.2L, the electrode assembly 100 adopts the following Figure 2 Three-pole lug design shown.

[0080] refer to Figure 6 , Figure 6 for Figure 2 The front view of the battery is shown. Figure 6 ​As shown, when the relationship between the size and characteristic length of the first pole piece 110, and the relationship between the size and characteristic length of the second pole piece 120 satisfy 0.8L<c≤1.2L, the width of the first pole tab 130 can be set to twice the width of the second pole tab 140. Since when 0.8L<c≤1.2L, one first pole tab 130 is provided on the first pole piece 110, and two second pole tabs 140 are provided on the second pole piece 120. This arrangement can achieve the total length of the first pole tab 130 and the total length of the second pole tab 140 to be equal, and can also achieve symmetry of the second pole tab 140 about the center plane.

[0081] refer to Figure 7 , Figure 7 for Figure 2 The schematic diagram of the structure of the first pole piece and the second pole piece in the battery shown, Figure 7 The two dotted lines in FIG represent the center line of the first pole piece 110 in the length direction and the center line of the second pole piece 120 in the length direction, respectively. Figure 7 As shown, when the first tab 130 is arranged symmetrically about the center plane, and the two second tabs 140 are located on both sides of the center plane, the two second tabs 140 are symmetrical about the center plane. The center line of the first tab 130 can be arranged to coincide with the center line of the first pole piece 110, so that the first tab 130 is arranged in the middle of the first pole piece 110.

[0082] The distance from the centerline of the second pole tab 140 to the side of the second pole piece 120 can be set to 0.1aˋ-0.25aˋ. The optimal location of the second pole tab 140 is such that the distance from the centerline of the second pole tab 140 in the longitudinal direction to the centerline of the second pole piece 120 in the longitudinal direction conforms to the golden ratio (the ratio of the distance from the centerline of the second pole tab 140 to the centerline of the second pole piece 120 to half the length of the second pole piece 120 is 0.618). Assuming the distance from the centerline of the second pole tab 140 in the longitudinal direction to the side of the second pole piece 120 is Mˋ, then Mˋ = (1-0.618)*aˋ / 2 = 0.191aˋ.

[0083] In the first electrode 110, the maximum distance that electrons diffuse out of the first electrode tab 130 is l. The width of the first electrode tab 130 is set to 2m; the width of the second electrode tab 140 is set to m, and the total width of the two second electrode tabs 140 is 2m. According to the size of the first electrode 110, l = ((0.5am) 2 +b 2 ) 1 / 2 .

[0084] In order to prevent excessive polarization in the electrode assembly 100, generally speaking, it is necessary to set l≤0.6L, where L represents the characteristic length of the electrode assembly 100. When the size of the electrode assembly 100 is 0.8L<c≤1.2L, that is, (a 2 +b 2 ) 1 / 2 ≤0.8L. By l≤0.6L, ((0.5am) 2 +b 2 ) 1 / 2 ≤0.6L, m≥0.5a-(0.36L 2 -b 2 ) 1 / 2 In addition, the width of the first electrode tab 130 is generally set to be less than half the length of the first electrode piece 110 , and the width of the first electrode tab 130 2m<a / 2, m<a / 4.

[0085] It can be concluded that when the relationship between the size of the first electrode 110 and the characteristic length satisfies 0.8L<c≤1.2L, the width of the first electrode 130 is 2m, the width of the second electrode 140 is m, and 0.5a-(0.36L 2 -b 2 ) 1 / 2 ≤m

[0086] In one embodiment of the present application, when the relationship between the size and characteristic length of the first electrode piece 110 and the relationship between the size and characteristic length of the second electrode piece 120 satisfy c>1.2L, the electrode assembly 100 adopts the following Figure 3 Four-pole lug design shown.

[0087] refer to Figure 8 , Figure 8 for Figure 3 The front view of the battery is shown. Figure 8 As shown, when the relationship between the size and characteristic length of the first pole piece 110, and the relationship between the size and characteristic length of the second pole piece 120 satisfy c>1.2L, the size of the first pole tab 130 can be set to be the same as the size of the second pole tab 140, that is, the width of the first pole tab 130 is equal to the width of the second pole tab 140. This arrangement can achieve a uniform distribution of the first pole tab 130 and the second pole tab 140 on both sides of the center plane. In other words, the two first pole tabs 130 are symmetrical about the center plane, and the two second pole tabs 140 are symmetrical about the center plane.

[0088] refer to Figure 9 , Figure 9 for Figure 3 The schematic diagram of the structure of the first pole piece and the second pole piece in the battery shown, Figure 9 ​The two dotted lines in FIG represent the center line of the first pole piece 110 in the length direction and the center line of the second pole piece 120 in the length direction, respectively. Figure 9 As shown, there are two first pole tabs 130 on the first pole piece 110 and two second pole tabs 140 on the second pole piece 120 , and the two first pole tabs 130 are symmetrical about the center plane, and the two second pole tabs 140 are symmetrical about the center plane.

[0089] The distance between the centerline of the first electrode tab 130 and the centerline of the first electrode sheet 110 (the center plane of the electrode assembly 100) can be set to 0.1a-0.25a. The optimal location of the first electrode tab 130 is such that the distance from the centerline of the first electrode tab 130 in the longitudinal direction to the side of the first electrode sheet 110 conforms to the golden ratio (the ratio of the distance from the centerline of the first electrode tab 130 to the side of the first electrode sheet 110 to half the length of the first electrode sheet 110 is 0.618). Assuming that the distance from the centerline of the first electrode tab 130 in the longitudinal direction to the centerline of the first electrode sheet 110 is M, then M = (1-0.618)*a / 2 = 0.191a.

[0090] The distance from the centerline of the second pole tab 140 to the side of the second pole piece 120 can be set to 0.1aˋ-0.25aˋ. The optimal location of the second pole tab 140 is such that the distance from the centerline of the second pole tab 140 in the longitudinal direction to the centerline of the second pole piece 120 in the longitudinal direction conforms to the golden ratio (the ratio of the distance from the centerline of the second pole tab 140 to the centerline of the second pole piece 120 to half the length of the second pole piece 120 is 0.618). Assuming the distance from the centerline of the second pole tab 140 in the longitudinal direction to the side of the second pole piece 120 is Mˋ, then Mˋ = (1-0.618)*aˋ / 2 = 0.191aˋ.

[0091] In the first electrode piece 110, the maximum distance electrons diffuse from the first electrode tab 130 is l, and in the second electrode piece 120, the maximum distance electrons diffuse from the second electrode tab 140 is also l'. Assuming that the widths of the first electrode tab 130 and the second electrode tab 140 are both 2m, the distance from the centerline of the first electrode tab 130 in the longitudinal direction to the centerline of the first electrode piece 110 is M, and the distance from the centerline of the second electrode tab 140 in the longitudinal direction to the side edge of the second electrode piece 120 is M', then l = ((0.5aMm)² + b²)1 / 2.

[0092] In order to prevent excessive polarization in the electrode assembly 100, it is generally necessary to set l≤0.6L, where L represents the characteristic length of the electrode assembly 100. When the dimension c of the electrode assembly 100 is greater than 1.2L, that is, (a2+b2)1 / 2>1.2L. Since l≤0.6L, ((0.5am)2+b2)1 / 2≤0.6L, m≥0.309a-(0.36L2-b2)1 / 2. In addition, since the first electrode tab 130 is arranged on one side of the center line of the first electrode sheet 110, the width of the first electrode tab 130 is 2m<a / 2, and m<a / 4.

[0093] It can be concluded that when the relationship between the size of the first electrode piece 110 and the characteristic length satisfies c>1.2L, the widths of the first electrode tab 130 and the second electrode tab 140 are both 2m, and 0.309a-(0.36L2-b2)1 / 2≤m

[0094] In one embodiment of the present application, a core package is further provided, which includes an insulating film and the electrode assembly described in any of the above embodiments, wherein the insulating film is arranged between the first pole piece and the second pole piece.

[0095] In one embodiment of the present application, a battery is further provided. The battery includes a shell, a cover plate, and the electrode assembly described in any one of the above embodiments.

[0096] The electrode assembly 100 is arranged in the shell, and the cover plate is covered on the shell. The cover plate is provided with a first pole and a second pole; the first pole is electrically connected to the first pole ear 130 on the electrode assembly 100, and the second pole is electrically connected to the second pole ear 140 on the electrode assembly 100.

[0097] In one embodiment of the present application, the shell may be in the shape of a cuboid, and the battery formed using the cuboid shell is a square-shell battery.

[0098] In one embodiment of the present application, the battery adopts a square aluminum shell battery, which adopts a system of lithium iron phosphate as the positive electrode and graphite as the negative electrode, aluminum foil as the positive electrode collector, copper foil as the negative electrode collector, and lithium hexafluorophosphate as the electrolyte. The characteristic length L of the battery system is calculated to be 475mm, the length a of the first electrode 110 of the battery is 320mm, and the width b is 186mm, then c=(a 2 +b 2 ) 1 / 2 =370mm<0.8L. According to the design of the embodiment of this application, it can be used Figure 1 and Figure 5 ​The bipolar tab battery design shown in the figure has a lengthwise distance M from the centerline of the first tab 130 to the side of the first pole piece 110 of 61 mm, and a width 2m of the first tab 130 of 89 to 160 mm. The wider the tab, the more uniform the current density distribution. The following battery cell tab designs are compared:

[0099] Cell 1: The first electrode is the positive electrode, and the second electrode is the negative electrode. The positive electrode has a length a of 320 mm and a width b of 186 mm. The length and width OH of the negative electrode relative to the positive electrode are both 3 mm. The distance M from the longitudinal centerline of the positive tab to the side of the positive tab is 61 mm, and the tab width is 100 mm. The negative tab is symmetrical with the positive tab about the longitudinal centerline of the battery and is the same size.

[0100] Cell 2: The first electrode is the positive electrode, and the second electrode is the negative electrode. The positive electrode has a length a of 320 mm and a width b of 186 mm. The length and width OH of the negative electrode relative to the positive electrode are both 3 mm. The distance M from the longitudinal centerline of the positive tab to the side of the positive tab is 40 mm, and the tab width is 60 mm. The negative tab is symmetrical with the positive tab about the longitudinal centerline of the battery and is the same size.

[0101] Compare the cycle and rate performance of cell 1 and cell 2, refer to Figure 10 and Table 1, Figure 10 A cycle comparison chart of a battery provided in an embodiment of the present application.

[0102] Serial number cycle Cycle capacity retention rate 2C rate performance Battery Cell 1 1000 90.2％ 96.6％ Battery Cell 2 1000 86.1％ 93.4％

[0103] Table 1

[0104] like Figure 10 As shown in Table 1, after the tab is optimized, the cycle and rate performance of cell 1 are better than those of conventional cells. At the same number of cycles, the cycle capacity retention rate of cell 1 is 90.2% and the 2C rate performance is 96.6%, which are higher than the cycle capacity retention rate of 86.1% and the 2C rate performance of 93.4% of conventional cell 2.

[0105] In one embodiment of the present application, the battery adopts a square aluminum shell battery, which adopts a system of lithium iron phosphate as the positive electrode and graphite as the negative electrode. The positive electrode collector is aluminum foil, the negative electrode collector is copper foil, and lithium hexafluorophosphate electrolyte is used. The characteristic length L of the battery system is calculated to be 475mm; the length a of the first electrode 110 of the battery is 480mm, and the width b is 186mm, then c=(a 2 +b 2 ) 1 / 2 =514.8mm, between 0.8L and 1.2L. According to the design of the embodiment of this application, it can be used Figure 2 and Figure 7The three-tab battery design shown in Figure 1 is symmetrical about the longitudinal centerline of the battery. The distance M' from the longitudinal centerline of the second tab 140 to the side of the second pole piece 120 is 91.6 mm. The tab width 2m ranges from 51 to 240 mm. The two second tabs are symmetrical about the longitudinal centerline of the second pole piece. The wider the tab, the more uniform the current density distribution. The following battery cell tab designs are compared:

[0106] Battery cell 3: The first electrode is the positive electrode, and the second electrode is the negative electrode. The length a of the positive electrode of the battery is 480mm, the width b is 186mm, and the length and width OH of the negative electrode to the positive electrode are both 3mm. Figure 2 and Figure 7 In the three-tab design shown, the positive tab is centered and symmetrical about the center plane of the battery in the longitudinal direction, and the negative tab is 91.6mm from the edge; the negative tab is 80mm wide and the positive tab is 160mm wide.

[0107] Cell 4: The first electrode is the positive electrode, and the second electrode is the negative electrode. The positive electrode has a length a of 720mm and a width b of 186mm. The length and width OH of the negative electrode relative to the positive electrode are both 3mm. A conventional bipolar tab design is used, with the positive tab located 91.6mm from the edge of the tab (M) and a tab width of 80mm. The positive and negative tabs are symmetrical about the center of the battery's longitudinal plane and are of equal size.

[0108] Compare the cycle and rate performance of battery cell 3 and battery cell 4, refer to Figure 11 and Table 2, Figure 11 A cycle comparison chart of another battery provided in an embodiment of the present application.

[0109] Serial number cycle Cycle capacity retention rate 2C rate performance Battery 3 800 93.6％ 96.9％ Battery Cell 4 800 86.1％ 94.4％

[0110] Table 2

[0111] like Figure 11 As shown in Table 2, Cell 3, after tab optimization, adopts a three-tab core package design, resulting in superior cycle and rate performance compared to conventional cells. At the same number of cycles, Cell 3's cycle capacity retention rate is 93.6% and its 2C rate performance is 96.9%, exceeding the 86.1% and 94.4% of the conventional Cell 4.

[0112] In one embodiment of the present application, the battery adopts a square aluminum shell battery, which adopts a system of lithium iron phosphate as the positive electrode and graphite as the negative electrode. The positive electrode collector is aluminum foil, the negative electrode collector is copper foil, and lithium hexafluorophosphate electrolyte is used. The characteristic length L of the battery system is calculated to be 475mm; the length a of the first electrode of the battery is 720mm, and the width b is 186mm, then c=(a 2 +b 2 ) 1 / 2=743.6mm>1.2L. According to the design of the embodiment of this application, it can be used Figure 3 and Figure 9 The four-tab battery design shown in the figure. The distance M from the longitudinal centerline of the first tab 130 to the longitudinal centerline of the first electrode sheet 110 is 137.5 mm. The tab width 2m ranges from 16 to 360 mm. The two positive tabs are symmetrical about the longitudinal centerline of the first electrode sheet. The negative tab and the positive tab are symmetrical about the quadrant of the first electrode sheet. The wider the tab, the more uniform the current density distribution. The following battery cell tab designs are compared:

[0113] Battery cell 5: The first electrode is the positive electrode, and the second electrode is the negative electrode. The length a of the positive electrode of the battery is 720mm, the width b is 186mm, and the length and width OH of the negative electrode to the positive electrode are both 3mm. Figure 3 and Figure 9 In the four-tab design shown, the distance M between the longitudinal centerline of the positive tab and the longitudinal centerline of the positive electrode sheet is 137.5 mm, and the positive tab width is 110 mm. The two positive tabs are symmetrical about the longitudinal centerline of the positive electrode sheet. The negative tabs are symmetrical with the positive tabs about the longitudinal quadrant of the positive electrode sheet and are the same size as the positive tabs.

[0114] Cell 6: The first electrode is the positive electrode, and the second electrode is the negative electrode. The positive electrode has a length a of 720mm and a width b of 186mm. The length and width OH of the negative electrode relative to the positive electrode are both 3mm. A conventional bipolar tab design is used, with the positive tab located 137.5mm from the edge of the positive tab (M) and a tab width of 100mm. The negative tab is symmetrical with the positive tab about the center plane of the battery's length and is of the same size.

[0115] Compare the cycle and rate performance of battery cell 5 and battery cell 6, refer to Figure 12 and Table 3, Figure 12 This is a cycle comparison chart of another battery provided in an embodiment of the present application.

[0116] Serial number cycle Cycle capacity retention rate 2C rate performance Battery Cell 5 580 97.8％ 95.3％ Battery Cell 6 580 87.4％ 91.4％

[0117] Table 3

[0118] like Figure 12 As shown in Table 3, Cell 5, after tab optimization and featuring a four-tab core package design, exhibits superior cycling and rate performance compared to conventional cells. At the same number of cycles, Cell 5's cycle capacity retention rate of 97.8% and 2C rate performance of 95.3% are higher than the 87.4% and 91.4% of conventional Cell 6.

[0119] The electrode assembly 100, core pack, and battery provided in the embodiment of the present application can set corresponding tab positions, tab numbers, and tab widths according to the specific size of the electrode assembly 100, thereby achieving a more uniform current density of the electrode assembly 100.

[0120] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

[0121] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0122] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the scope of protection of this application includes the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0123] This document uses specific examples to illustrate the working principles and implementation methods of the batteries and battery systems of this application. The description of the above embodiments is only used to help understand the specific settings and core ideas of this application. At the same time, for those skilled in the art, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on this application.

[0124] The above content is only a specific embodiment of this application, but the scope of protection of this application is not limited to this. Any changes or replacements within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An electrode assembly, characterized in that: include: a first pole piece and a second pole piece, wherein the polarity of the first pole piece is different from the polarity of the second pole piece, and the first pole piece and the second pole piece are alternately arranged; The center line of the first pole piece in the length direction and the center line of the second pole piece in the length direction are both located on the center plane of the electrode assembly in the length direction; The first pole piece is provided with a first pole tab, the second pole piece is provided with a second pole tab, and the first pole tab and the second pole tab are located on the same side of the electrode assembly; The first electrode tab and the second electrode tab are located on both sides of the center plane, and the distance from the first electrode tab to the center plane is equal to the distance from the second electrode tab to the center plane; Alternatively, the first electrode tab and the second electrode tab are respectively symmetrical about the central plane.

2. The electrode assembly according to claim 1, wherein The first pole piece and the second pole piece are both rectangular; The length of the first pole piece is a, the width of the first pole piece is b, and the diagonal length of the first pole piece is c; When c≤0.8L, the first pole piece is provided with a first pole tab, the second pole piece is provided with a second pole tab, and the distance from the first pole tab to the center plane is equal to the distance from the second pole tab to the center plane; When 0.8L<c≤1.2L, one first pole tab is provided on the first pole piece, and two second pole tabs are provided on the second pole piece, the first pole tab is symmetrical about the center plane, and the two second pole tabs are symmetrical about the center plane; When c>1.2L, the first pole piece is provided with two first pole tabs, the second pole piece is provided with two second pole tabs, the two first pole tabs are symmetrical about the central plane, and the two second pole tabs are symmetrical about the central plane; Wherein, c is the diagonal length of the first electrode piece, cˋ is the diagonal length of the second electrode piece, c≤cˋ, and L is the characteristic length, which is the maximum length of electron diffusion in the electrode in the electrode assembly.

3. The electrode assembly according to claim 2, characterized in that The length of the first pole piece is a, the width of the first pole piece is b, and the diagonal length of the first pole piece is c; the length of the second pole piece is aˋ, the width of the second pole piece is bˋ, and the diagonal length of the second pole piece is cˋ, wherein a≤aˋ, b≤bˋ, and c≤cˋ; The relationship between the size of the first pole piece and the characteristic length, and the relationship between the size of the second pole piece and the characteristic length satisfy the following relationship: When c≤0.8L, the distance between the first pole tab and the side edge of the first pole piece is 0.1a-0.25a, ​​and the second pole tab is symmetrical with the first pole tab about the center plane; When 0.8L<c≤1.2L, the first pole tab is located at the center of the first pole piece, and the distance from the second pole tab to the side of the second pole piece is 0.1aˋ-0.25aˋ; When c>1.2L, the distance from the first pole tab to the center plane is 0.1a-0.25a, ​​and the distance from the second pole tab to the side edge of the second pole piece is 0.1aˋ-0.25aˋ.

4. The electrode assembly according to claim 3, characterized in that The relationship between the size of the first pole piece and the characteristic length, and the relationship between the size of the second pole piece and the characteristic length satisfy the following relationship: When c≤0.8L, the distance between the first pole tab and the side edge of the first pole piece is 0.19a, and the second pole tab is symmetrical with the first pole tab about the center plane; When 0.8L<c≤1.2L, the first pole tab is located at the center of the first pole piece, and the distance from the second pole tab to the side of the second pole piece is 0.19aˋ; When c>1.2L, the distance from the first pole tab to the center plane is 0.19a, and the distance from the second pole tab to the side edge of the second pole piece is 0.19aˋ.

5. The electrode assembly according to any one of claims 2 to 4, characterized in that: The relationship between the size of the first pole piece and the characteristic length, and the relationship between the size of the second pole piece and the characteristic length satisfy the following relationship: When c≤0.8L, the width of the first electrode tab is equal to the width of the second electrode tab; When 0.8L<c≤1.2L, the width of the first electrode tab is twice the width of the second electrode tab; When c>1.2L, the width of the first electrode tab is equal to the width of the second electrode tab.

6. The electrode assembly according to claim 5, characterized in that The relationship between the size of the first pole piece and the characteristic length, and the relationship between the size of the second pole piece and the characteristic length satisfy the following relationship: When c≤0.8L, the width of the first tab is 2m, the width of the second tab is 2m, 0.809a-(0.36L 2 -b 2 ) 1 / 2 ≤m <a / 4; When 0.8L<c≤1.2L, the width of the first tab is 2m, the width of the second tab is m, 0.5a-(0.36L 2 -b 2 ) 1 / 2 ≤m <a / 4; When c>1.2L, the width of the first tab is 2m, the width of the second tab is 2m, 0.309a-(0.36L 2 -b 2 ) 1 / 2 ≤m <a / 4。 7. A core package, characterized in that: The electrode assembly comprises an insulating film and the electrode assembly according to any one of claims 1 to 6, wherein the insulating film is arranged between the first pole piece and the second pole piece.

8. A battery, characterized in that: The battery comprises a shell, a cover plate, and the electrode assembly according to any one of claims 1 to 6 or the core pack according to claim 7. The electrode assembly or the core pack is arranged in the shell, and the cover plate is covered on the shell.

9. The electrode according to claim 8, characterized in that The shell is in the shape of a cuboid.

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