Tab thickness design method, square battery, battery pack and electric device

Abstract

The application relates to the technical field of batteries, and provides a tab thickness design method, a square battery, a battery pack and an electric device. The square battery comprises a battery cell and a first adapter sheet, the battery cell is provided with at least one first tab, the first tab is electrically connected with the first adapter sheet, when the first tab is provided with at least two, all the first tabs are arranged in a laminated mode along the thickness direction of the square battery, and the following relationship is met: d >= (p1*L1*D) / (p2*L2*N); in the formula, d is the thickness of the first tab, p1 is the resistivity of the first tab, L1 is the length of the first tab, D is the thickness of the adapter sheet, p2 is the resistivity of the first adapter sheet, L2 is the length of the adapter sheet, and N is the number of the first tabs; wherein the units of d, D, L1 and L2 are millimeters, and the units of p1 and p2 are ohm millimeters. In this way, the battery can have the advantages of high energy density and long service life, and the rationality of the first tab thickness is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method for designing tab thickness, a square battery, a battery pack, and an electrical device. Background Technology

[0002] During battery charging and discharging, current flows through the tabs. According to Joule's law, heat is generated at the tabs, and this heat is transferred to the battery cell through the foil, causing irreversible physical damage and severely affecting the cell's lifespan. Furthermore, when the tabs overheat, the separator shrinks due to heat, which can easily cause the positive and negative electrodes to come into contact, leading to a short circuit and potentially a safety hazard. In related technologies, the thickness of the tabs is usually selected within a certain range, and the lack of a design standard results in unreasonable tab thickness designs. Summary of the Invention

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

[0004] In a first aspect, this application provides a method for designing the thickness of the tabs, applicable to designing the tab thickness of a square battery. The square battery includes an adapter plate and at least one tab, the tab being electrically connected to the adapter 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, to obtain the heat generation calculation formula: 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 electrode and the adapter plate, calculate the cross-sectional area S of the resistor, where the direction of the contact width W is perpendicular to the length direction of the adapter plate.

[0007] Let the ratio of Q1 to Q2 be less than or equal to 1, then the following 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 piece, ρ2 is the resistivity of the first adapter piece, L2 is the length of the adapter piece, and N is the number of tabs.

[0008] Where Q1 is the heat generated by the tab, Q2 is the heat generated by the adapter, Q1 and Q2 are in kilojoules, d, D, L1 and L2 are in millimeters, and ρ1 and ρ2 are in ohmmeters.

[0009] The beneficial effects of the tab thickness design method provided by this invention are as follows: By constructing the relationship d≥(ρ1×L1×D) / (ρ2×L2×N), the relationship between the tab thickness d and other parameters, such as the tab length L1, is revealed, providing guidance for tab thickness design. By ensuring that the tab thickness d satisfies the above relationship, the tab can be made as thin as possible while meeting the requirement of low heat generation, 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 satisfying the above relationship, the battery can achieve both high energy density and long service life, greatly improving the rationality of tab thickness.

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

[0011] A represents the battery capacity, measured in ampere-hours (Ahs).

[0012] B represents the current-carrying capacity of the adapter plate, measured in amperes per square millimeter.

[0013] C represents the charge / discharge rate of the battery.

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

[0015] Secondly, this application provides a square battery, which includes a cell and a first adapter piece. The cell is provided with at least one first tab, and the first tab is electrically connected to the first adapter piece. When at least two first tabs are provided, all the first tabs are stacked along the thickness direction of the square battery, satisfying the relationship: d≥(ρ1×L1×D) / (ρ2×L2×N).

[0016] In the formula, d is the thickness of the first tab, ρ1 is the resistivity of the first tab, L1 is the length of the first tab, D is the thickness of the adapter piece, ρ2 is the resistivity of the first adapter piece, L2 is the length of the adapter piece, and N is the number of first tabs.

[0017] In this context, d, D, L1, and L2 are in millimeters, and ρ1 and ρ2 are in ohmmeters.

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

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

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

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

[0022] Optionally, the first adapter plate is electrically connected to the two battery cells, and the first tabs of each of the two battery cells are respectively welded to both ends of the first adapter plate along its length.

[0023] Thirdly, this application provides a battery pack including the aforementioned square battery. Because this battery pack uses the aforementioned square battery, its safety performance is greatly improved.

[0024] Fourthly, this application provides an electrical device including the aforementioned square battery or battery pack. Because this electrical device uses the aforementioned square battery or battery pack, its safety performance is greatly improved. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a square battery provided in an embodiment of the present invention;

[0027] Figure 2 This is another structural schematic diagram of a square battery provided in an embodiment of the present invention;

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

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

[0030] Figure 5 A trend chart of the number of copper tabs and the amount of heat generated is provided for an embodiment of the present invention;

[0031] Figure 6 A trend chart of the number of aluminum tabs and the amount of heat generated is provided for an embodiment of the present invention;

[0032] Figure 7 The graph shows the trend of the thickness of the copper adapter sheet, the thickness of the aluminum adapter sheet, the number of copper tabs, and the number of aluminum tabs in relation to the heat generation, as provided in the embodiments of the present invention.

[0033] The following are the labeling elements in the figure:

[0034] 100. Square battery; 10. Battery cell; 20. First adapter plate;

[0035] 30. Second adapter piece; 40. Solder mark; 11. First electrode tab;

[0036] 12. Second pole ear. Detailed Implementation

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

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

[0039] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] First, a brief explanation of square batteries: Generally, a square battery consists of a casing and battery cells housed within the casing. The casing has positive and negative terminals. The number of battery cells is unlimited; it can be two, four, or more. For ease of description and understanding, we will define the number of cells as two. The battery cells are formed by winding a positive electrode plate, a separator, and a negative electrode plate. The separator serves as an insulator. The positive electrode plate has a positive tab, and the negative electrode plate has a negative tab. The positive tabs of the two battery cells are electrically connected to the two ends of a positive adapter plate, with the side of the positive adapter plate facing away from the battery cell electrically connected to the positive terminal. The negative tabs of the two battery cells are electrically connected to the two ends of a negative adapter plate, with the side of the negative adapter plate facing away from the battery cell electrically connected to the negative terminal.

[0043] Here, we will first explain how current flows in the battery. The current starts from the positive electrode and flows sequentially through the positive tab, positive adapter, positive terminal, external conductor, negative terminal, negative adapter, and negative tab, finally flowing to the negative electrode, thus forming a discharge circuit. The charging circuit flows in the opposite direction to the discharging circuit, and will not be described further here.

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

[0045] In the formula, d is the thickness of the first tab 11, ρ1 is the resistivity of the first tab 11, L1 is the length of the first tab 11, D is the thickness of the adapter piece, ρ2 is the resistivity of the first adapter piece 20, L2 is the length of the adapter piece, and N is the number of first tabs 11.

[0046] In this context, d, D, L1, and L2 are in millimeters, and ρ1 and ρ2 are in ohmmeters.

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

[0048] Furthermore, the square battery 100 also satisfies the following formula: D = (A × C) / (B × L²), where A is the battery capacity in ampere-hours, C is the charge / discharge rate, and B is the current-carrying capacity of the material of the first adapter plate 20 in amperes per square millimeter. In this application, the inventors discovered that the current-carrying capacity of the tab and the adapter plate are not matched, and no formula exists to systematically link the two for calculating and designing the tab thickness. Typically, the current-carrying capacity of the tab is weaker than that of the adapter plate, and the battery's current-carrying capacity is closely related to the tab's current-carrying capacity. If the battery is charged and discharged with a large current, the tab will generate a large amount of heat, easily causing the tab and adapter plate to detach, leading to battery failure. Therefore, the inventors constructed a formula based on the relationship between the tab and the current-carrying capacity to ensure that the current-carrying capacity of the tab matches the current-carrying capacity of the adapter plate as closely as possible. This allows the battery to reduce heat generation at the tabs during high-rate charging and discharging, thereby extending battery life and improving battery safety.

[0049] In some embodiments, the first tab 11 is made of the same material as the first adapter piece 20. This configuration improves the welding effect, thereby increasing the current carrying capacity.

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

[0051] In some embodiments, the first adapter plate 20 is electrically connected to two battery cells 10, and the first tabs 11 of each of the two battery cells 10 are respectively welded to both ends of the first adapter plate 20 along its length. This square battery 100 adopts a combined-cell structure, which is beneficial to improving battery capacity.

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

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

[0054] This application also provides a method for designing the tab thickness, applicable to designing the tab thickness of a square battery 100. The square battery 100 includes an adapter plate and at least one tab, the tab being electrically connected to the adapter 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, to obtain the heat generation calculation formula: Q=(I 2 The formula is: ×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 electrode and the adapter piece, where the direction of the contact width W is perpendicular to the length direction of the adapter piece. Specifically, the electrode and the adapter piece are ultrasonically welded together to form a weld mark 40, which is rectangular, and the contact width W is the width of the weld mark 40 between the electrode and the adapter piece.

[0057] Since the design of the tabs is required, the heat generation of the tabs must be less than that of the adapter pieces. Therefore, the ratio of Q1 to Q2 is set to less than or equal to 1. Substituting the contact width W into the heat generation calculation formula, the following relationship is satisfied: d≥(ρ1×L1×D×C) / (ρ2×L2×N×C), which is: d≥(ρ1×L1×D) / (ρ2×L2×N). In the formula, 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 piece, ρ2 is the resistivity of the first adapter piece 20, L2 is the length of the adapter piece, and N is the number of tabs.

[0058] Where Q1 is the heat generated by the tab, Q2 is the heat generated by the adapter, Q1 and Q2 are in kilojoules, d, D, L1 and L2 are in millimeters, and ρ1 and ρ2 are in ohmmeters.

[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 used, rather than the width of the tab or the adapter itself. This is because, in the industry, it is generally considered that current is transferred between the tab and the adapter via the solder joint 40. Areas where the tab does not act on the solder joint 40 are typically considered abandoned areas and not considered to participate in current transfer. Therefore, both the cross-sectional area of ​​the tab and the cross-sectional area of ​​the adapter are calculated using the contact width W.

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

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

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

[0063] As an example, the following examples illustrate the use of fixed values ​​for various parameters.

[0064] The first tab 11 and the second tab 12 both have 50 layers. The width of both the first tab 11 and the second tab 12 is 38mm. The contact width between the first tab 11 and the first adapter piece 20 is 32mm, and the contact width between the second tab 12 and the second adapter piece 30 is also 32mm. The length of both the first tab 11 and the second tab 12 is 40mm. The length of both the first adapter piece 20 and the second adapter piece 30 is 35mm. The first tab 11 is the positive tab and is made of aluminum. The second tab 12 is the negative tab and is made of copper. The first adapter piece 20 is the positive adapter piece and is made of aluminum. The second adapter piece 30 is the negative adapter piece and is made of copper. The copper has a current carrying capacity of 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 charge / discharge requirement of 1C.

[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 tab 12 is greater than or equal to 0.0054 mm.

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

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

[0069] In this application, copper adapter sheets of different specifications were selected for heating tests. The thickness of the copper adapter sheet was controlled as the only variable in the experiment. The experimental data are shown in Table 1.

[0070]

[0071] Table 1

[0072] Different specifications of aluminum adapter sheets were selected for heating tests. The thickness of the aluminum adapter sheet was controlled as the only variable in the experiment. The experimental data are shown in Table 2.

[0073]

[0074] Table 2

[0075] To verify the relationship between the heat generation of the copper electrode tab and its thickness, experiments were conducted with different numbers of copper electrodes. The number of copper electrodes was controlled as the only variable in the experiments, as shown in Table 3.

[0076]

[0077]

[0078] Table 3

[0079] To verify the relationship between the heat generation of the aluminum electrode tab and its thickness, experiments were conducted with different numbers of aluminum electrodes. The number of aluminum electrodes was controlled as the only variable in the experiments, as shown in Table 4.

[0080]

[0081] Table 4

[0082] Based on the above experimental data, it can be seen that the heat generation of the adapter plate increases as the thickness of the adapter plate decreases; the heat generation of the tab decreases as the number of tabs increases.

[0083] To ensure battery safety design, the heat generated by the tabs must be less than that generated by the adapter. Please refer to the following: Figure 7The threshold is the intersection of the heat generated by the adapter and the heat generated by the electrode tab, and it should be above the threshold in the design.

[0084] Please refer to Figures 3 to 6 , Figure 3 , Figure 4 , Figure 5 and Figure 6 The results were obtained from Tables 1, 2, 3, and 4, respectively. Figure 3 and Figure 4 In the chart, the vertical axis on the left represents the calorific value in kilojoules. The horizontal axis at the bottom represents the thickness of the adapter plate in millimeters. Figure 5 and Figure 6 In the chart, the vertical axis on the left represents calorific value in kilojoules, and the horizontal axis at the bottom represents the number of tabs. Figure 7 In the chart, the vertical axis on the left represents the calorific value in kilojoules. The horizontal axis at the bottom represents the thickness of the adapter plate in millimeters.

[0085] This application also provides a battery pack, which includes the square battery 100 provided in this application. Due to the use of the square battery 100, the safety performance of this battery pack is greatly improved.

[0086] This application also provides an electrical device, including the square battery 100 or the battery pack provided in this application. Because this electrical device uses the aforementioned square battery 100 or the aforementioned battery pack, its safety performance is greatly improved.

[0087] The electrical equipment can include, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can 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 within the protection scope of the present invention.

Claims

1. A method for designing tab thickness, applicable to designing tab thickness for square batteries (100), characterized in that, The square battery (100) includes an adapter plate and at least one tab, the tab being electrically connected to the adapter plate. When at least two tabs are provided, all the tabs are stacked along the thickness direction of the square battery (100). The design method includes: Based on Joule's law: And the formula for calculating resistance: The formula for calculating calorific value is obtained as follows: In the formula, ρ is the resistivity of the resistor, L is the length of the resistor, and S is the cross-sectional area of ​​the resistor. The cross-sectional area S of the resistor is calculated based on the contact width W between the electrode and the adapter piece, wherein the direction of the contact width W is perpendicular to the length direction of the adapter piece. If the ratio of Q1 to Q2 is less than or equal to 1, then the following relationship is satisfied: In the formula, d is the thickness of the electrode tab, ρ1 is the resistivity of the electrode tab, L1 is the length of the electrode tab, D is the thickness of the adapter piece, ρ2 is the resistivity of the adapter piece, L2 is the length of the adapter piece, and N is the number of electrodes tabs. Wherein, Q1 is the heat generated by the electrode tab, Q2 is the heat generated by the adapter piece, 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 ohmmeters. Based on the current-carrying capacity of the adapter piece, the thickness D of the adapter piece is calculated. The formula for calculating the thickness D of the adapter piece is: In the formula, A represents the battery capacity, measured in ampere-hours (Ahs). B represents the current-carrying capacity of the adapter material, measured in amperes per square millimeter. C represents the charge / discharge rate of the battery.

2. The method for designing the electrode thickness according to claim 1, characterized in that: The material of the electrode tab is the same as the material of the adapter piece, satisfying the following relationship: .

3. A square battery, characterized in that: The battery includes a cell (10) and a first adapter plate (20). The cell (10) is provided with at least one first tab (11). The first tab (11) is electrically connected to the first adapter plate (20). When there are at least two first tabs (11), all the first tabs (11) are stacked along the thickness direction of the square battery (100) to satisfy the following relationship: ; In the formula, d is the thickness of the first tab (11), ρ1 is the resistivity of the first tab (11), L1 is the length of the first tab (11), D is the thickness of the adapter piece, ρ2 is the resistivity of the first adapter piece (20), L2 is the length of the adapter piece, and N is the number of the first tabs (11). Where d, D, L1 and L2 are in millimeters, and ρ1 and ρ2 are in ohmmeters; Satisfying the relation: ; Where A is the battery capacity in ampere-hours, C is the charge / discharge rate, and B is the overcurrent capacity of the first adapter piece (20) in amperes per square millimeter.

4. The square battery according to claim 3, characterized in that: The material of the first electrode (11) is the same as that of the first adapter piece (20).

5. The square battery according to claim 3, characterized in that: The material of the first adapter piece (20) is selected from aluminum, aluminum alloy, copper, copper alloy, nickel and nickel-plated copper.

6. The square battery according to any one of claims 3 to 5, characterized in that: The first adapter plate (20) is electrically connected to the two battery cells (10), and the first tabs (11) of each of the two battery cells (10) are respectively welded to the two ends of the first adapter plate (20) along its length.

7. A battery pack, characterized in that: Includes the square battery (100) as described in any one of claims 3 to 6.

8. An electrical appliance, characterized in that: Includes the square battery (100) according to any one of claims 3 to 6 or the battery pack according to claim 7.

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