Design method of tab thickness, square battery, battery pack and electric equipment

Abstract

The invention relates to the technical field of batteries, and provides a tab thickness design method, a square battery, a battery pack and electric equipment. Wherein the square battery comprises a battery cell and a first switching piece, the battery cell is provided with at least one first tab, the first tab is electrically connected with the first switching piece, when the number of the first tabs is at least two, all the first tabs are arranged in a laminated mode in the thickness direction of the square battery, and the relation that d is larger than or equal to (rho1 * L1 * D) / (rho2 * L2 * N) is met, in the formula, d is the thickness of the first tab, rho1 is the resistivity of the first tab, L1 is the length of the first tab, D is the thickness of the switching piece, rho2 is the resistivity of the first switching piece, L2 is the length of the switching piece, and N is the number of the first tabs; wherein the units of d, D, L1 and L2 are millimeter, and the units of rho1 and rho2 are ohm meters. Therefore, the battery has the advantages of high energy density and long service life, and the reasonability of the thickness of the first tab is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a method for designing the thickness of a tab, a square battery, a battery pack and electrical equipment. Background Art

[0002] During the battery charging and discharging process, the current will flow through the tabs. According to Joule's law, heat will be generated at the tabs. This heat will be transferred to the battery cell through the foil, causing irreversible physical damage to the battery cell and seriously affecting the service life of the battery cell. Moreover, when the tabs are seriously heated, the diaphragm shrinks due to the heat, which can easily cause the positive and negative electrodes to contact, resulting in a short circuit and causing a safety accident. In the related art, the thickness of the tabs is usually selected within a numerical range, and the thickness of the tabs has not formed a design standard, resulting in unreasonable design of the thickness of the tabs. Summary of the invention

[0003] The purpose of the present invention is to provide a method for designing the thickness of a tab, a square battery, a battery pack and an electrical device, aiming to solve the technical problem of unreasonable tab thickness design in the related art.

[0004] In a first aspect, the present application provides a method for designing the thickness of a tab, which is applicable to designing the thickness of a tab of a square battery. The square battery includes a switching plate and at least one tab, and the tab is electrically connected to the switching plate. When at least two tabs are provided, all tabs are stacked along the thickness direction of the square battery. The design method includes:

[0005] Based on Joule's law: Q = I 2 ×R×t, and the resistance calculation formula: R=(ρ×L) / S, the heat generation calculation formula is obtained: Q=(I 2 ×ρ×L×t) / S, where ρ is the resistivity of the resistor, L is the length of the resistor, and S is the cross-sectional area of ​​the resistor;

[0006] Based on the contact width W between the tab and the adapter, the cross-sectional area S of the resistor is calculated, wherein the direction of the contact width W is perpendicular to the length direction of the adapter;

[0007] Let the ratio of Q1 to Q2 be less than or equal to 1, then the relationship is satisfied: d≥(ρ1×L1×D) / (ρ2×L2×N), where d is the thickness of the tab, ρ1 is the resistivity of the tab, L1 is the length of the tab, D is the thickness of the adapter, ρ2 is the resistivity of the first adapter, L2 is the length of the adapter, and N is the number of tabs;

[0008] Among them, Q1 is the calorific value of the tab, Q2 is the calorific value of the adapter, the units of Q1 and Q2 are kilojoules, the units of d, D, L1 and L2 are millimeters, and the units of ρ1 and ρ2 are ohm-meters.

[0009] The beneficial effect of a design method for the thickness of the pole lug provided by the present invention is that by constructing the relationship: d≥(ρ1×L1×D) / (ρ2×L2×N), the relationship between the thickness d of the pole lug and other parameters, such as the length L1 of the pole lug, is revealed, which has guiding significance for the design of the thickness of the pole lug. By making the thickness d of the pole lug satisfy the above relationship, the pole lug is as thin as possible while meeting the low calorific value requirement, thereby making the current collector as thin as possible, which is beneficial to improving the energy density of the battery cell. In other words, when the above relationship is satisfied, the battery can have the advantages of both high energy density and long service life, which greatly improves the rationality of the thickness of the pole lug.

[0010] Optionally, based on the current carrying capacity of the adapter, the thickness D of the adapter is calculated. The calculation formula of the thickness D of the adapter is: D = (A × C) / (B × L2), where,

[0011] A is the battery capacity in ampere-hours;

[0012] B is the current capacity of the adapter, in amperes per square millimeter;

[0013] C is the charge and discharge rate of the battery.

[0014] Optionally, the material of the tab is the same as the material of the adapter, satisfying the relationship: d≥(L1×D) / (L2×N).

[0015] In a second aspect, the present application provides a square battery, which includes a battery cell and a first adapter, the battery cell is provided with at least one first pole ear, the first pole ear is electrically connected to the first adapter, when there are at least two first pole ears, all the first pole ears are stacked along the thickness direction of the square battery, satisfying the relationship: d≥(ρ1×L1×D) / (ρ2×L2×N);

[0016] Wherein, d is the thickness of the first pole ear, ρ1 is the resistivity of the first pole ear, L1 is the length of the first pole ear, D is the thickness of the adapter, ρ2 is the resistivity of the first adapter, L2 is the length of the adapter, and N is the number of the first pole ears;

[0017] The units of d, D, L1 and L2 are millimeters, and the units of ρ1 and ρ2 are ohm-meters.

[0018] The square battery provided by the present invention has the beneficial effect that when the relationship d≥(ρ1×L1×D) / (ρ2×L2×N) is satisfied, the battery can have the advantages of high energy density and long service life, thereby greatly improving the rationality of the thickness of the first tab.

[0019] Optionally, the relationship is satisfied: D=(A×C) / (B×L2); wherein A is the battery capacity in ampere-hours, C is the charge and discharge rate, and B is the current capacity of the material of the first adapter in amperes per square millimeter.

[0020] Optionally, the material of the first electrode tab is the same as the material of the first adapter plate.

[0021] Optionally, the material of the first adapter plate is selected from one of aluminum, aluminum alloy, copper, copper alloy, nickel and copper-plated nickel.

[0022] Optionally, the first adapter is electrically connected to the two battery cells, and the first pole tabs of the two battery cells are respectively welded to two ends of the first adapter in the length direction.

[0023] In a third aspect, the present application provides a battery pack, comprising the above-mentioned square battery. Since the battery pack adopts the above-mentioned square battery, the safety performance is greatly improved.

[0024] In a fourth aspect, the present application provides an electrical device, comprising the above-mentioned square battery or the above-mentioned battery pack. Since the electrical device adopts the above-mentioned square battery or the above-mentioned battery pack, the safety performance is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 A schematic diagram of the structure of a square battery provided by an embodiment of the present invention;

[0027] Figure 2 Another structural schematic diagram of a square battery provided by an embodiment of the present invention;

[0028] Figure 3 A trend diagram of the thickness and heat generation of the copper adapter provided in an embodiment of the present invention;

[0029] Figure 4 A trend diagram of the thickness and heat generation of the aluminum adapter provided in an embodiment of the present invention;

[0030] Figure 5 A trend diagram of the number of copper tabs and heat generation provided in an embodiment of the present invention;

[0031] Figure 6 A trend diagram of the number of aluminum tabs and heat generation provided in an embodiment of the present invention;

[0032] Figure 7 A trend diagram of the thickness of the copper adapter plate, the thickness of the aluminum adapter plate, the number of copper tabs, and the number of aluminum tabs and heat generation provided in an embodiment of the present invention.

[0033] Among them, the reference numerals in the figure are:

[0034] 100. square battery; 10. battery cell; 20. first adapter;

[0035] 30. second adapter; 40. welding mark; 11. first tab;

[0036] 12. The second pole ear. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0038] Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, when the phrases "in one embodiment" or "in some embodiments" appear in various places throughout the specification, not all references are to the same embodiment. Furthermore, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner.

[0039] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0041] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] First, let's briefly explain the square battery. Generally, the square battery includes a shell and a battery cell accommodated in the shell. The shell is provided with a positive electrode column and a negative electrode column. The number of battery cells is not limited and can be two, four or more. For the convenience of description and understanding, the number of battery cells is now set to two. The battery cell is wound by a positive electrode sheet, a diaphragm and a negative electrode sheet, wherein the diaphragm has an insulating effect. A positive electrode ear is provided on the positive electrode sheet, and a negative electrode ear is provided on the negative electrode sheet. The positive electrode ears of the two battery cells are respectively electrically connected to the two ends of the positive electrode adapter sheet, and the side of the positive electrode adapter sheet facing away from the battery cell is electrically connected to the positive electrode column. The negative electrode ears of the two battery cells are respectively electrically connected to the two ends of the negative electrode adapter sheet, and the side of the negative electrode adapter sheet facing away from the battery cell is electrically connected to the negative electrode column.

[0043] Here, we will first explain how the current flows in the battery. The current starts from the positive electrode, flows through the positive ear, positive adapter, positive column, external conductor, negative column, negative adapter, negative ear, and finally flows to the negative electrode, thus forming a discharge circuit. The charging circuit is opposite to the discharge circuit, so I will not go into details here.

[0044] Please refer to Figure 1 to Figure 2 The present application provides a square battery 100 including a battery cell 10 and a first adapter 20. The battery cell 10 is provided with at least one first pole tab 11, and the first pole tab 11 is electrically connected to the first adapter 20. When at least two first pole tabs 11 are provided, all the first pole tabs 11 are stacked along the thickness direction of the square battery 100, satisfying the relationship: d≥(ρ1×L1×D) / (ρ2×L2×N);

[0045] Wherein, d is the thickness of the first pole tab 11, ρ1 is the resistivity of the first pole tab 11, L1 is the length of the first pole tab 11, D is the thickness of the adapter, ρ2 is the resistivity of the first adapter 20, L2 is the length of the adapter, and N is the number of the first pole tabs 11;

[0046] The units of d, D, L1 and L2 are millimeters, and the units of ρ1 and ρ2 are ohm-meters.

[0047] By making the thickness d of the first pole tab 11 satisfy the relationship: d≥(ρ1×L1×D) / (ρ2×L2×N), the first pole tab 11 can be made as thin as possible while meeting the requirement of low calorific value, thereby making the current collector as thin as possible, which is beneficial to improving the energy density of the battery cell 10. In other words, when the above relationship is satisfied, the battery can have the advantages of high energy density, long service life and high safety performance, which greatly improves the rationality of the thickness of the first pole tab 11.

[0048] Furthermore, the square battery 100 also satisfies the relationship: D = (A × C) / (B × L2), wherein A is the battery capacity in ampere-hours, C is the charge and discharge rate, and B is the current capacity of the material of the first adapter 20 in amperes per square millimeter. In the present application, the inventors found that the current capacity of the tab is not matched with the current capacity of the adapter, and did not find a calculation formula that can systematically link the two to calculate and design the thickness of the tab. Usually, the current capacity of the tab is weaker than that of the adapter, and the ability of the battery to carry current is closely related to the current capacity of the tab. If the battery is charged and discharged with a large current, the tab will generate a lot of heat, which may easily cause the tab to be desoldered from the adapter, thereby causing the battery to fail. Therefore, the inventors constructed a relationship based on the relationship between the tab and the current capacity so that the current capacity of the tab can match the current capacity of the adapter as much as possible. In this way, the battery can reduce the heat generated by the tab when charging and discharging at a high rate, thereby extending the battery life and improving the battery safety performance.

[0049] In some embodiments, the material of the first electrode tab 11 is the same as the material of the first adapter plate 20. This arrangement can improve the welding effect, thereby improving the current carrying capacity.

[0050] It is understandable that the material of the first adapter plate 20 is selected from one of aluminum, aluminum alloy, copper, copper alloy, nickel and copper-plated nickel. In this embodiment, the material of the first adapter plate 20 is aluminum.

[0051] In some embodiments, the first adapter 20 is electrically connected to the two battery cells 10, and the first tabs 11 of the two battery cells 10 are respectively welded to the two ends in the length direction of the first adapter 20. The square battery 100 adopts a combined core structure, which is conducive to improving the battery capacity.

[0052] In some embodiments, the square battery 100 also includes a second adapter plate 30, and the battery cell 10 is also provided with at least one second pole ear 12, and the second pole ear 12 is electrically connected to the second adapter plate 30. When there are at least two second pole ears 12, all the second pole ears 12 are stacked along the thickness direction of the square battery 100, wherein the polarity of the first pole ear 11 is opposite to the polarity of the second pole ear 12.

[0053] It can be understood that, in some embodiments, the first pole tab 11 can be a positive pole tab, then the first adapter 20 is a positive pole adapter, the second pole tab 12 is a negative pole tab, and the second adapter 30 is a negative pole adapter. Of course, in some other embodiments, the first pole tab 11 can also be a negative pole tab, then the first adapter 20 is a negative pole adapter, the second pole tab 12 is a positive pole tab, and the second adapter 30 is a positive pole adapter, which is not limited here.

[0054] The present application also provides a method for designing the thickness of a tab, which is applicable to designing the thickness of a tab of a square battery 100. The square battery 100 includes a switching plate and at least one tab, and the tab is electrically connected to the switching plate. When at least two tabs are provided, all tabs are stacked along the thickness direction of the square battery 100. The design method includes:

[0055] Based on Joule's law: Q = I 2 ×R×t, and the resistance calculation formula: R=(ρ×L) / S, the heat generation calculation formula is obtained: Q=(I 2 ×ρ×L×t), where ρ is the resistivity of the resistor, L is the length of the resistor, and S is the cross-sectional area of ​​the resistor.

[0056] The cross-sectional area S of the resistor is calculated based on the contact width W between the tab and the adapter, wherein the direction of the contact width W is perpendicular to the length direction of the adapter. Specifically, the tab and the adapter are welded together by ultrasonic wave to form a weld mark 40, which is rectangular, and the contact width W is the width of the weld mark 40 between the tab and the adapter.

[0057] Since the tab design is required, the heat generated by the tab must be less than the heat generated by the adapter, so the ratio of Q1 to Q2 is set to be less than or equal to 1, and the contact width W is substituted into the heat generation calculation formula, then the relationship is satisfied: d≥(ρ1×L1×D×C) / (ρ2×L2×N×C), that is, the relationship is satisfied: d≥(ρ1×L1×D) / (ρ2×L2×N), where d is the thickness of the tab, ρ1 is the resistivity of the tab, L1 is the length of the tab, D is the thickness of the adapter, ρ2 is the resistivity of the first adapter 20, L2 is the length of the adapter, and N is the number of tabs;

[0058] Among them, Q1 is the calorific value of the tab, Q2 is the calorific value of the adapter, the units of Q1 and Q2 are kilojoules, the units of d, D, L1 and L2 are millimeters, and the units of ρ1 and ρ2 are ohm-meters.

[0059] In this application, when calculating the cross-sectional area S of the resistor, the contact width W between the tab and the adapter is substituted, rather than the width of the tab or the width of the adapter. It is not used as a representation because in the industry, it is generally believed that the tab and the adapter are conducting current transfer through the weld mark 40. In the area where the tab does not act on the weld mark 40, it is usually regarded as a waste area and is not considered to participate in the transfer of current. Therefore, whether it is the cross-sectional area of ​​the tab or the cross-sectional area of ​​the adapter, the contact width W is used for calculation.

[0060] Furthermore, based on the current carrying capacity of the adapter, the thickness D of the adapter is calculated. The calculation formula for the thickness D of the adapter is: D = (A×C) / (B×L2), where A is the battery capacity in ampere-hours, B is the current carrying capacity of the adapter in amperes per square millimeter, and C is the charge and discharge rate of the battery.

[0061] By taking the current carrying capacity of the adapter as one of the design parameters of the tab thickness and comprehensively considering the relationship between the tab and the current carrying capacity, the design method can more reasonably calculate the required thickness of the tab.

[0062] Optionally, the material of the tab is the same as the material of the adapter, satisfying the relationship: d≥(L1×D) / (L2×N).

[0063] As an example, the following uses the fixed values ​​of various parameters for illustration.

[0064] The number of layers of the first pole ear 11 and the number of layers of the second pole ear 12 are both 50 layers, the width of the first pole ear 11 and the width of the second pole ear 12 are both 38mm, the contact width between the first pole ear 11 and the first adapter plate 20 is 32mm, and the contact width between the second pole ear 12 and the second adapter plate 30 is also 32mm. The length of the first pole ear 11 and the length of the second pole ear 12 are both 40mm, the length of the first adapter plate 20 and the length of the second adapter plate 30 are both 35mm, the first pole ear 11 is a positive pole ear, and its material is aluminum. The second pole ear 12 is a negative pole ear, and its material is copper. The first adapter plate 20 is a positive electrode adapter plate, and its material is aluminum. The second adapter plate 30 is a negative electrode adapter plate, and its material is copper. The current capacity of copper is 12A / mm 2 , the current carrying capacity of aluminum is 8A / mm 2 The requirement is to design a 100Ah battery that meets the maximum 1C charge and discharge requirements.

[0065] Based on the above parameters, D1 = (100Ah×1C) / (8A×35mm), that is, D1 is 0.36mm, so d1≥(0.36mm×40mm) / (50×35mm), that is, d1≥0.0082mm.

[0066] Similarly, the thickness of the second electrode tab 12 is greater than or equal to 0.0054 mm.

[0067] Since the foil material is in microns, the thickness of the first pole tab 11 is greater than or equal to 8.2 microns, and the thickness of the second pole tab 12 is greater than or equal to 5.4 microns. Since the thickness of the foil material is usually an integer, the thickness of the first pole tab 11 is designed to be 9 microns, and the thickness of the second pole tab 12 is designed to be 6 microns.

[0068] In summary, in order to meet the maximum 1C charge and discharge performance of a 100Ah battery, the first pole tab 11 needs to use a 9-micron thick foil, and the second pole tab 12 needs to use a 6-micron thick foil.

[0069] In this application, copper adapters of different specifications were selected for heating test. The thickness of the copper adapter was the only variable in the test. The experimental data are shown in Table 1:

[0070]

[0071] Table 1

[0072] Aluminum adapters of different specifications were selected for heating tests. The thickness of the aluminum adapter was the only variable in the test. The experimental data are shown in Table 2:

[0073]

[0074] Table 2

[0075] In order to verify the relationship between the calorific value of the copper tab and the thickness of the copper tab, different numbers of copper tabs were selected for testing. The number of copper tabs was controlled as the only variable in the test, as shown in Table 3:

[0076]

[0077]

[0078] Table 3

[0079] In order to verify the relationship between the calorific value of the aluminum tab and the thickness of the aluminum tab, different numbers of aluminum tabs were selected for testing. The number of aluminum tabs was controlled as the only variable in the test, as shown in Table 4:

[0080]

[0081] Table 4

[0082] According to the above test data, the heat generated by the adapter increases as the thickness of the adapter decreases; the heat generated by the tab decreases as the number of tabs increases.

[0083] To ensure the safety of the battery design, the heat generated by the tabs needs to be less than the heat generated by the adapter. Figure 7The intersection of the heat generated by the adapter and the heat generated by the tab is the threshold, which should be above the threshold during design.

[0084] Please refer to Figures 3 to 6 , Figure 3 , Figure 4 , Figure 5 and Figure 6 They are obtained from Table 1, Table 2, Table 3 and Table 4 respectively. Figure 3 and Figure 4 The vertical axis on the left side of the graph is the calorific value in kilojoules. The horizontal axis below the graph is the thickness of the adapter in mm. Figure 5 and Figure 6 The vertical axis on the left side of the chart is the calorific value in kilojoules, and the horizontal axis below the chart is the number of tabs. Figure 7 In the figure, the vertical axis on the left side of the chart is the calorific value in kilojoules. The horizontal axis below the chart is the thickness of the adapter in mm.

[0085] The present application also provides a battery pack, which includes the square battery 100 provided in the present application. Since the battery pack adopts the above-mentioned square battery 100, the safety performance is greatly improved.

[0086] The present application also provides an electrical device, including the square battery 100 provided in the present application or the battery pack provided in the present application. The electrical device greatly improves safety performance by using the square battery 100 or the battery pack.

[0087] The electrical equipment may include but is not limited to mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for designing the thickness of a tab, suitable for designing the thickness of a tab of a square battery (100), characterized in that: The square battery (100) comprises a switching plate and at least one pole lug, the pole lug being electrically connected to the switching plate, and when at least two pole lugs are provided, all the pole lugs are stacked and arranged along the thickness direction of the square battery (100), and the design method comprises: Based on Joule's law: Q = I 2 ×R×t, and the resistance calculation formula: R=(ρ×L) / S, the heat generation calculation formula is obtained: Q=(I 2 ×ρ×L×t) / S, where ρ is the resistivity of the resistor, L is the length of the resistor, and S is the cross-sectional area of ​​the resistor; Calculate the cross-sectional area S of the resistor based on the contact width W between the tab and the adapter, wherein the direction of the contact width W is perpendicular to the length direction of the adapter; Assuming that the ratio of Q1 to Q2 is less than or equal to 1, the relationship is satisfied: d≥(ρ1×L1×D) / (ρ2×L2×N), where d is the thickness of the tab, ρ1 is the resistivity of the tab, L1 is the length of the tab, D is the thickness of the adapter, ρ2 is the resistivity of the first adapter (20), L2 is the length of the adapter, and N is the number of tabs; Among them, Q1 is the calorific value of the electrode ear, Q2 is the calorific value of the adapter, the units of Q1 and Q2 are kilojoules, the units of d, D, L1 and L2 are millimeters, and the units of ρ1 and ρ2 are ohm-meters.

2. The method for designing the thickness of the tab according to claim 1, characterized in that: Based on the current carrying capacity of the adapter, the thickness D of the adapter is calculated. The calculation formula of the thickness D of the adapter is: D = (A × C) / (B × L2), where, A is the battery capacity in ampere-hours; B is the current capacity of the material of the adapter, in amperes per square millimeter; C is the charge and discharge rate of the battery.

3. The method for designing the thickness of the tab according to claim 1 or 2, characterized in that: The material of the tab is the same as that of the adapter, satisfying the relationship: d≥(L1×D) / (L2×N).

4. A square battery, characterized in that: The battery cell (10) comprises a battery cell (10) and a first adapter plate (20), wherein the battery cell (10) is provided with at least one first pole lug (11), the first pole lug (11) being electrically connected to the first adapter plate (20), and when at least two first pole lugs (11) are provided, all the first pole lugs (11) are stacked and arranged along the thickness direction of the square battery (100), satisfying the relationship: d≥(ρ1×L1×D) / (ρ2×L2×N); In the formula, d is the thickness of the first pole lug (11), ρ1 is the resistivity of the first pole lug (11), L1 is the length of the first pole lug (11), D is the thickness of the adapter sheet, ρ2 is the resistivity of the first adapter sheet (20), L2 is the length of the adapter sheet, and N is the number of the first pole lugs (11); The units of d, D, L1 and L2 are millimeters, and the units of ρ1 and ρ2 are ohm-meters.

5. The square battery according to claim 4, characterized in that: Satisfy the relationship: D = (A × C) / (B × L2); Wherein, A is the battery capacity, in ampere-hours, C is the charge and discharge rate, and B is the current capacity of the first adapter (20), in amperes per square millimeter.

6. The square battery according to claim 4, characterized in that: The material of the first pole tab (11) is the same as the material of the first adapter plate (20).

7. The square battery according to claim 4, characterized in that: The material of the first adapter plate (20) is selected from one of aluminum, aluminum alloy, copper, copper alloy, nickel and copper-plated nickel.

8. The square battery according to any one of claims 4 to 7, characterized in that: The first adapter plate (20) is electrically connected to the two battery cells (10), and the first pole lugs (11) of the two battery cells (10) are respectively welded to two ends of the first adapter plate (20) in the length direction.

9. A battery pack, characterized in that: A square battery (100) comprising any one of claims 4 to 8.

10. An electrical equipment, characterized in that: It comprises the square battery (100) according to any one of claims 4 to 8 or the battery pack according to claim 9.

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