Battery cell and battery pack

Abstract

The invention relates to the technical field of battery cells, and discloses a battery cell and a battery pack, and the battery cell comprises a packaging film, a pole group and a tab. The width and the length of the external tab are limited according to the formula that (N2 * Q2 * R-0. 0267 * W * H * delta T / 106) * t / Cp / m is greater than 0 DEG C and less than or equal to 10 DEG C, so that the minimum value of the product of the length and the width of the external tab is obtained, the surface area of the external tab is ensured, the heat dissipation of the external tab is ensured, the heat production of the external tab in unit time is reduced, and the service life of the external tab is prolonged. The heat generation amount of the external tab in unit time is obtained by subtracting the heat dissipation amount from the heat generation amount, so that the temperature rise of the external tab is less than or equal to 10 DEG C, the temperature rise of the external tab is prevented from being too high, the risk of thermal runaway of the battery cell can be reduced, and the service life, the charging speed and the charging performance of the battery cell can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery cells, and in particular to a battery cell and a battery pack. Background Art

[0002] For high-power soft-pack batteries, the size design requirements for the tabs are high. The existing tab size design is unreasonable, the tabs generate a lot of heat, the tab temperature rises significantly, and the risk of thermal runaway of the battery cell increases. At the same time, excessive tab temperature rise will affect the battery cell's life, charging speed, and charging performance. Summary of the Invention

[0003] In view of this, the present invention provides a battery cell and a battery pack to solve the problem of large temperature rise of the tab of the battery cell in the prior art.

[0004] In a first aspect, the present invention provides a battery cell, comprising:

[0005] A packaging film having a receiving groove thereon;

[0006] An electrode group is disposed in the accommodating groove, and the packaging film wraps the electrode group;

[0007] The pole ear has one end connected to the pole group and the other end extending out of the packaging film. The pole ear located outside the packaging film is the external pole ear. The width of the external pole ear is W, the length of the external pole ear is H, the required continuous charge and discharge rate is N, the resistance of the pole ear is R, the charge and discharge time is t, and the specific heat capacity of the battery cell is C. p , the capacity of the battery cell is Q, N>0, the mass of the battery cell is m, the ideal temperature difference between the external tab and the air is ΔT, the unit of W and H is mm, the unit of N is C, the unit of R is Ω, the unit of t is h, the unit of Cp is J / (Kg·℃), the unit of Q is Ah, the unit of m is Kg, the unit of ΔT is k, ΔT≤283k, 0℃<(N 2 *Q 2 *R-0.0267*W*H*ΔT / 10 6 )*t / Cp / m≤10℃.

[0008] Beneficial effect: The battery cell of this structure can be 2 *Q 2 *R-0.0267*W*H*ΔT / 10 6 )*t / Cp / m≤10℃ The width and length of the external tab are limited to obtain (N 2 *Q 2 *R-10m C p / t)*10 6 / 0.0267 / ΔT≤W*H≤N 2 *Q 2*R*10 6 / 0.0267 / ΔT, to obtain the lower and upper limits of the product of the length and width of the external tab, so as to ensure the surface area of the external tab. The heat dissipation of the external tab is positively correlated with its surface area. By limiting the minimum value of the surface area of the external tab, the heat dissipation of the external tab is ensured. N 2 *Q 2 *R is the heat generated by the external tab, 0.0267*W*H*ΔT / 10 6 The heat dissipation of the external tab is improved. When the heat dissipation effect of the external tab is improved, the heat generation per unit time is reduced under the condition of constant heat generation. 2 *Q 2 *R minus heat dissipation 0.0267*W*H*ΔT / 10 6 To obtain the heat generation per unit time of the external tab, multiply the heat generation per unit time by the charge and discharge time, and then divide it by the specific heat capacity C of the battery cell. p The temperature rise of the external tab is calculated based on the mass of the battery cell, ensuring that the theoretical temperature rise of the external tab is less than or equal to 10°C. This prevents excessive temperature rise, helps reduce the risk of thermal runaway, and improves the battery cell's lifespan, charging speed, and performance. By limiting the upper limit of the product of the external tab length and width, we can prevent the tab from being too large and causing material waste.

[0009] In an optional embodiment, the external electrode tab includes an external positive electrode tab and an external negative electrode tab, the widths of the external positive electrode tab and the external negative electrode tab are W1 and W2 respectively, the thicknesses of the external positive electrode tab and the external negative electrode tab are T1 and T2 respectively, the units of W1, W2, T1 and T2 are mm, the width and thickness of the external positive electrode tab satisfy 3≤N*Q / (W1*T1)≤8, and the width and thickness of the external negative electrode tab satisfy 6≤N*Q / (W2*T2)≤14.

[0010] Beneficial effects: The current carrying capacity of the external tab is related to its longitudinal cross-sectional area. If the longitudinal cross-sectional area of the external tab is too small, the current carrying capacity of the external tab is weak and cannot meet the current carrying capacity required during the use of the battery cell, resulting in a significant increase in the heat generated by the battery cell, affecting the safety performance of the battery cell. If the longitudinal cross-sectional size of the external tab is too large, the current carrying capacity of the external tab increases, but the excessively large longitudinal cross-sectional design of the external tab will lead to an increase in the space occupied by the external tab, resulting in an increase in the space occupied by the overall structure of the battery cell, affecting the volume energy density of the battery cell; at the same time, the excessive size of the external tab will also lead to an increase in the material used for the external tab and redundant structural design, resulting in an increase in the production cost of the battery cell. The present invention ensures that the width and thickness of the external positive electrode tab satisfy 3≤N*Q / (W1*T1)≤8, that is, N*Q / 8≤W1*T1≤N*Q / 3, thereby limiting the lower limit and upper limit of the longitudinal cross-sectional area of the external positive electrode tab, avoiding the longitudinal cross-sectional area of the external positive electrode tab being too small or too large, thereby obtaining the width and thickness of the external positive electrode tab of appropriate size, while ensuring the overcurrent capacity of the external positive electrode tab, preventing the longitudinal cross-sectional area of the external positive electrode tab from being too large, saving the material used for the external positive electrode tab, and reducing the production cost of the battery cell; at the same time, the space occupied by the external positive electrode tab can be reduced, thereby reducing the space occupied by the battery cell, which is conducive to improving the volume energy density of the battery cell.

[0011] At the same time, by 6≤N*Q / (W2*T2)≤14, the lower limit and upper limit of the longitudinal cross-sectional area of the external negative electrode tab are limited to avoid the longitudinal cross-sectional area of the external negative electrode tab being too small or too large, thereby obtaining the width and thickness of the external negative electrode tab of appropriate size, while ensuring the overcurrent capacity of the external negative electrode tab and preventing the longitudinal cross-sectional area of the external negative electrode tab from being too large, saving the material of the external negative electrode tab and reducing the production cost of the battery cell; at the same time, it can reduce the space occupied by the external negative electrode tab and the battery cell, which is beneficial to improving the volume energy density of the battery cell.

[0012] In an optional embodiment, 0.1 mm ≤ T1 ≤ 0.5 mm.

[0013] Beneficial effect: This setting can control the thickness of the external positive electrode tab within an appropriate range, ensuring the flow capacity of the external positive electrode tab, while also ensuring the sealing effect of the packaging film of the battery cell at the external positive electrode tab.

[0014] In an optional embodiment, 0.1 mm ≤ T2 ≤ 0.5 mm.

[0015] Beneficial effect: This setting can control the thickness of the external negative electrode tab within an appropriate range, ensure the flow capacity of the external negative electrode tab, and also ensure the sealing effect of the packaging film at the external negative electrode tab.

[0016] In an optional embodiment, Q≤200AH.

[0017] In an optional embodiment, the cross-section of the battery cell is rectangular, the external tabs include an external positive tab and an external negative tab, and the external positive tab and the external negative tab are located on the same side of the battery cell.

[0018] Beneficial effects: The battery cell has tabs on the same side, which has a simple structure and low production cost. It can also reduce the space occupied by the external tabs and improve the volume energy density of the battery cell.

[0019] In an optional embodiment, the width of the battery cell is W3, the unit of W3 is mm, and W<0.45W3.

[0020] Beneficial effect: The width of the external positive electrode tab and the external negative electrode tab does not exceed half of the width of the battery cell. This arrangement can make the total width of the external positive electrode tab and the external negative electrode tab smaller than the width of the battery cell, and make the positive and negative tabs separated in the width direction of the battery cell, preventing the external tabs from exceeding the end faces of the two ends of the battery cell in the width direction, or the positive and negative tabs from contacting and short-circuiting.

[0021] In an optional embodiment, the cross-section of the battery cell is rectangular, and the external tabs include an external positive tab and an external negative tab, and the external positive tab and the external negative tab are arranged on two sides of the battery cell opposite to each other.

[0022] Benefits: Dual-sided tabs provide a shorter current transmission path, improving cell performance and charging speed. Furthermore, dual-sided tabs help balance current distribution within the cell, reducing internal resistance and heat generation.

[0023] In an optional embodiment, the width of the battery cell is W3, the unit of W3 is mm, and W<0.7W3.

[0024] Beneficial effect: This arrangement can avoid the width of the external tab being too wide, avoid the external tab being too wide and occupying more space, and can ensure the volume energy density of the battery cell.

[0025] In a second aspect, the present invention further provides a battery pack comprising any one of the above-mentioned battery cells. The battery pack comprises the battery cell and has the same technical effects as the battery cell, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 is a schematic diagram of a battery cell according to an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of another battery cell according to an embodiment of the present invention.

[0029] Description of reference numerals:

[0030] 1. Packaging film; 2. External positive electrode tab; 3. External negative electrode tab. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0032] For high-power soft-pack batteries, the size design requirements for the tabs are relatively high. The inventors have found that the size design of the external tabs of the battery cells in the related art is unreasonable, resulting in the inability of the external tabs to effectively dissipate heat. When the heat generated by the external tabs is constant, the temperature rise at the external tabs will be large, and the risk of thermal runaway of the battery cells will increase. At the same time, the excessive temperature rise of the external tabs will affect the life, charging speed and charging performance of the battery cells.

[0033] The following combination Figures 1 to 2 , describing embodiments of the present invention.

[0034] According to an embodiment of the present invention, on one hand, a battery cell is provided, comprising a packaging film 1, an electrode group, and a tab. The packaging film 1 is provided with a receiving groove; the electrode group is provided in the receiving groove, and the packaging film 1 wraps the electrode group; one end of the tab is connected to the electrode group, and the other end extends out of the packaging film 1. The tab located outside the packaging film 1 is the external tab, the width of the external tab is W, the length of the external tab is H, the required continuous charge and discharge rate is N, the resistance of the tab is R, the charge and discharge time is t, and the specific heat capacity of the battery cell is C. p, the capacity of the battery cell is Q, N>0, the mass of the battery cell is m, the ideal temperature difference between the external tab and the air is ΔT, the units of W and H are mm, the unit of N is C, the unit of R is Ω, the unit of t is h, C p The unit of is J / (Kg·℃), the unit of Q is Ah, the unit of m is Kg, the unit of ΔT is k, ΔT≤283k, 0℃<(N 2 *Q 2 *R-0.0267*W*H*ΔT / 10 6 )*t / Cp / m≤10℃, where 0.0267 is the thermal conductivity of air.

[0035] The battery cell of this structure is calculated by the formula 0℃<(N 2 *Q 2 *R-0.0267*W*H*ΔT / 10 6 )*t / Cp / m≤10℃ The width and length of the external tab are limited to obtain (N 2 *Q 2 *R-10mC p / t)*10 6 / 0.0267 / ΔT≤W*H≤N 2 *Q 2 *R*10 6 / 0.0267 / ΔT, to obtain the lower and upper limits of the product of the length and width of the external tab, so as to ensure the surface area of the external tab. The heat dissipation of the external tab is positively correlated with its surface area. By limiting the minimum value of the surface area of the external tab, the heat dissipation of the external tab is ensured. N 2 *Q 2 *R is the heat generated by the external tab, 0.0267*W*H*ΔT / 10 6 The heat dissipation of the external tab is improved. When the heat dissipation effect of the external tab is improved, the heat generation per unit time is reduced under the condition of constant heat generation. 2 *Q 2 *R minus heat dissipation 0.0267*W*H*ΔT / 10 6 To obtain the heat generation per unit time of the external tab, multiply the heat generation per unit time by the charge and discharge time, and then divide it by the specific heat capacity C of the battery cell. p The temperature rise of the external tab is calculated based on the mass of the battery cell, ensuring that the theoretical temperature rise of the external tab is less than or equal to 10°C. This prevents excessive temperature rise, helps reduce the risk of thermal runaway, and improves the battery cell's lifespan, charging speed, and performance. By limiting the upper limit of the product of the external tab length and width, we can prevent the tab from being too large and causing material waste.

[0036] Battery cells with different N, Q, R, W, and H values were designed. ΔT = 283k was set. The battery cells were charged and discharged for different times. The actual temperature rise of the external tabs was measured. The test results are shown in Table 1.

[0037] Table 1

[0038]

[0039] From Examples 1 to 4, it can be seen that when N, Q, R, W and H satisfy 0°C<(N 2 *Q 2 *R-0.0267*W*H*ΔT / 10 6 )*t / Cp / m≤10℃, the product of the length and width of the external tab is reasonable, which can ensure the heat dissipation area of the external tab, so that the actual temperature rise of the external tab is small, which can reduce the risk of thermal runaway of the battery cell, thereby improving the life, charging speed and charging performance of the battery cell. From the comparative example, it can be seen that when (N 2 *Q 2 *R-0.0267*W*H*ΔT / 10 6 When )*t / Cp / m>10℃, the actual temperature rise of the external tab is greater than 10℃, the product of the length and width of the external tab is set unreasonably, and the actual temperature rise of the external tab is large, which will increase the risk of thermal runaway in the battery cell.

[0040] In some embodiments, as Figure 1 and Figure 2As shown, the external tabs include an external positive tab 2 and an external negative tab 3. The widths of the external positive tab 2 and the external negative tab 3 are W1 and W2, respectively. The thicknesses of the external positive tab 2 and the external negative tab 3 are T1 and T2, respectively. The units of W1, W2, T1, and T2 are in mm. The width and thickness of the external positive tab 2 satisfy 3≤N*Q / (W1*T1)≤8, and the width and thickness of the external negative tab 3 satisfy 6≤N*Q / (W2*T2)≤14. The current carrying capacity of the external tab is related to its longitudinal cross-sectional area. If the longitudinal cross-sectional area of the external tab is too small, the current carrying capacity of the external tab is weak and cannot meet the current carrying capacity required during the use of the battery cell, resulting in a significant increase in the heat generated by the battery cell and affecting the safety performance of the battery cell. If the longitudinal cross-sectional dimension of the external tab is too large, the current flow capacity of the external tab increases, but the excessively large longitudinal cross-sectional design of the external tab will lead to an increase in the space occupied by the external tab, resulting in an increase in the space occupied by the overall structure of the battery cell, affecting the volume energy density of the battery cell; at the same time, an excessively large external tab size will also lead to an increase in the material used for the external tab and redundant structural design, resulting in an increase in the production cost of the battery cell. In order to solve these problems, the width and thickness of the external positive electrode tab 2 are made to satisfy 3≤N*Q / (W1*T1)≤8, that is, N*Q / 8≤W1*T1≤N*Q / 3, so as to limit the lower limit and upper limit of the longitudinal cross-sectional area of the external positive electrode tab 2, and avoid the longitudinal cross-sectional area of the external positive electrode tab 2 being too small or too large, so as to obtain the width and thickness of the external positive electrode tab 2 of appropriate size, while ensuring the overcurrent capacity of the external positive electrode tab 2, it can prevent the longitudinal cross-sectional area of the external positive electrode tab 2 from being too large, save the material of the external positive electrode tab 2, and reduce the production cost of the battery cell; at the same time, it can reduce the space occupied by the external positive electrode tab 2, thereby reducing the space occupied by the battery cell, which is conducive to improving the volume energy density of the battery cell.

[0041] Similarly, the width and thickness of the external negative electrode tab 3 satisfy 6≤N*Q / (W2*T2)≤14, that is, N*Q / 14≤W2*T2≤N*Q / 6, thereby limiting the lower and upper limits of the longitudinal cross-sectional area of the external negative electrode tab 3, and avoiding the longitudinal cross-sectional area of the external negative electrode tab 3 being too small or too large, so as to obtain the width and thickness of the external negative electrode tab 3 of appropriate size, while ensuring the overcurrent capacity of the external negative electrode tab 3 and preventing the longitudinal cross-sectional area of the external negative electrode tab 3 from being too large, saving the material of the external negative electrode tab 3, and reducing the production cost of the battery cell; at the same time, it can reduce the space occupied by the external negative electrode tab 3 and the battery cell, which is beneficial to improving the volume energy density of the battery cell.

[0042] Optionally, in some embodiments, the thickness of the external positive electrode tab 2 satisfies 0.1mm≤T1≤0.5mm. If the thickness of the external positive electrode tab 2 is too small, the current carrying capacity of the tab will be affected. The battery cell includes a pole group and a packaging film 1. The pole group is placed in a receiving groove on one side of the packaging film 1. The packaging film 1 is folded along its center line to wrap the pole group, or two pieces of packaging film 1 are docked and then wrapped around the pole group. One side of the external pole tab is located inside the packaging film 1 and one side extends out of the packaging film 1. The external pole tab is provided with a pole tab glue. During heat sealing, the pole tab glue and the inner layer of the packaging film 1 melt to bond the external pole tab to the packaging film 1 and form a seal at the external pole tab. If the thickness of the external pole tab is thicker, the distance between the upper and lower layers of the packaging film 1 at the external pole tab is larger. After heat sealing, the packaging film 1 on both sides of the external pole tab in the width direction is not firmly sealed, which easily affects the sealing performance of the battery cell. Therefore, in order to take into account both the flow capacity and the sealing effect, the thickness of the external positive electrode tab 2 is made to meet 0.1mm≤T1≤0.5mm, so as to control the thickness of the external positive electrode tab 2 within an appropriate range, ensure the flow capacity of the external positive electrode tab 2, and at the same time ensure the sealing effect of the packaging film 1 of the battery cell at the external positive electrode tab 2.

[0043] Similarly, in some embodiments, the thickness of the external negative electrode tab 3 satisfies 0.1 mm ≤ T2 ≤ 0.5 mm. This setting can control the thickness of the external negative electrode tab 3 within an appropriate range, ensure the flow capacity of the external negative electrode tab 3, and also ensure the sealing effect of the packaging film 1 at the external negative electrode tab 3.

[0044] Optionally, in some embodiments, the thickness of the external positive electrode tab 2 is the same as the thickness of the external negative electrode tab 3 .

[0045] In some embodiments, the capacity Q of the battery cell satisfies Q ≤ 200AH. A recess is punched into the packaging film 1. Excessive depth of the recess will affect the strength of the packaging film 1 in the vicinity of the recess, so the recess is generally not too deep. Because the depth of the recess is limited, the thickness of the electrode group within the packaging film 1 is also limited. Due to this limitation, the capacity of the battery cell is generally not too large, so the capacity Q of the battery cell is generally set to ≤ 200AH.

[0046] In some embodiments, as Figure 1 As shown, the cross-section of the battery cell is rectangular, and the external tabs include an external positive tab 2 and an external negative tab 3, which are located on the same side of the battery cell. Having the tabs on the same side of the battery cell simplifies the structure, reduces manufacturing costs, and reduces the space occupied by the external tabs, thereby increasing the volumetric energy density of the battery cell.

[0047] like Figure 1 and Figure 2As shown, the x-direction is referred to as the length direction of the battery cell, the y-direction is referred to as the width direction of the battery cell, and the z-direction is referred to as the thickness direction of the battery cell. Similarly, the x-direction is the length direction of the external tab, the y-direction is the width direction of the external tab, and the z-direction is the thickness direction of the external tab. In some embodiments, the width of the battery cell is W3, where W3 is expressed in mm and W<0.45W3. In this embodiment, the external positive tab 2 and the external negative tab 3 are located on one side of the width direction of the battery cell. The external positive tab 2 and the external negative tab 3 must be separated by a certain distance in the width direction of the battery cell to prevent contact short circuits. Therefore, in order to prevent the external pole tabs from exceeding the end faces at both ends in the width direction of the battery cell, and to prevent the external positive pole tab 2 and the external negative pole tab 3 from contacting and short-circuiting, the width W of the external pole tabs satisfies W<0.45W3, that is, the width of the external positive pole tab 2 and the external negative pole tab 3 does not exceed half of the width of the battery cell. This arrangement can make the total width of the external positive pole tab 2 and the external negative pole tab 3 less than the width of the battery cell, and make the positive and negative pole tabs separated in the width direction of the battery cell, preventing the external pole tabs from exceeding the end faces at both ends in the width direction of the battery cell, or preventing the positive and negative pole tabs from contacting and short-circuiting.

[0048] In some embodiments, the width of the external positive electrode tab 2 and the external negative electrode tab 3 are the same.

[0049] In other embodiments, Figure 2 As shown, the cross-section of the battery cell is rectangular, and the external tabs include an external positive tab 2 and an external negative tab 3, which are arranged on the two sides of the battery cell. The double-sided tabs can provide a shorter current transmission path, thereby improving the performance and charging speed of the battery cell. In addition, the double-sided tabs of the battery cell also help to balance the current distribution within the battery cell, reducing internal resistance and heat generation.

[0050] In this embodiment, the external tabs are arranged on the two wide sides of the battery cell, and the width of the battery cell is W3, W<0.7W3. This arrangement can avoid the width of the external tabs being too wide, avoid the external tabs being too wide and occupying more space, and can ensure the volume energy density of the battery cell.

[0051] In some embodiments, the battery cell includes a soft-pack battery cell, and the packaging film 1 includes an aluminum-plastic film.

[0052] In some embodiments, as Figure 1 As shown, a receiving groove is punched on one side of the fold line of the aluminum-plastic film, and the electrode group is arranged in the receiving groove.

[0053] In other embodiments, accommodating grooves are punched on both sides of the fold line of the aluminum-plastic film. This arrangement can increase the thickness of the electrode group that can be accommodated by the packaging film 1, which is beneficial to improving the capacity of the battery cell.

[0054] In some embodiments, the battery cell further includes an internal tab, the ends of which are electrically connected to the electrode group and the external tab. For example, the internal tab includes an internal positive tab and an internal negative tab, the ends of the internal positive tab being welded to the electrode group and the external positive tab 2, respectively, and the ends of the internal negative tab being welded to the electrode group and the external negative tab 3, respectively.

[0055] According to an embodiment of the present invention, on the other hand, a battery pack is provided, comprising the above-mentioned battery cell and a box body, wherein the battery cell is arranged in the box body.

[0056] The battery pack of this structure has an internal cell with the formula 0℃<(N 2 *Q 2 *R-0.0267*W*H*ΔT / 10 6 )*t / Cp / m≤10℃ The width and length of the external tab are limited to obtain (N 2 *Q 2 *R-10mC p / t)*10 6 / 0.0267 / ΔT≤W*H≤N 2 *Q 2 *R*10 6 / 0.0267 / ΔT to obtain the lower and upper limits of the product of the length and width of the external tab, thereby ensuring the surface area of the external tab. The heat dissipation of the external tab is positively correlated with its surface area. By limiting the minimum value of the surface area of the external tab, the heat dissipation of the external tab is guaranteed. After the heat dissipation effect of the external tab is improved, the heat generation per unit time is reduced, so that the theoretical temperature rise of the external tab is less than or equal to 10°C, thereby preventing the temperature rise of the external tab from being too high, which is beneficial to reducing the risk of thermal runaway of the battery cell and can improve the safety performance of the battery pack.

[0057] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that: include: A packaging film having a receiving groove thereon; An electrode group is disposed in the accommodating groove, and the packaging film wraps the electrode group; The pole ear has one end connected to the pole group and the other end extending out of the packaging film. The pole ear located outside the packaging film is the external pole ear. The width of the external pole ear is W, the length of the external pole ear is H, the required continuous charge and discharge rate is N, the resistance of the pole ear is R, the charge and discharge time is t, and the specific heat capacity of the battery cell is C. p , the capacity of the battery cell is Q, N>0, the mass of the battery cell is m, the ideal temperature difference between the external tab and the air is ΔT, the units of W and H are mm, the unit of N is C, the unit of R is Ω, the unit of t is h, C p The unit of is J / (Kg·℃), the unit of Q is Ah, the unit of m is Kg, the unit of ΔT is k, ΔT≤283k, 0℃<(N 2 *Q 2 *R-0.0267*W*H*ΔT / 10 6 )*t / Cp / m≤10℃.

2. The battery cell according to claim 1, characterized in that The external tab includes an external positive tab and an external negative tab. The widths of the external positive tab and the external negative tab are W1 and W2, respectively. The thicknesses of the external positive tab and the external negative tab are T1 and T2, respectively. The units of W1, W2, T1 and T2 are mm. The width and thickness of the external positive tab satisfy 3≤N*Q / (W1*T1)≤8, and the width and thickness of the external negative tab satisfy 6≤N*Q / (W2*T2)≤14.

3. The battery cell according to claim 2, characterized in that 0.1mm≤T1≤0.5mm.

4. The battery cell according to claim 2 or 3, characterized in that: 0.1mm≤T2≤0.5mm.

5. The battery cell according to any one of claims 1 to 3, characterized in that: Q≤200AH.

6. The battery cell according to any one of claims 1 to 3, characterized in that: The cross section of the battery cell is rectangular, and the external tabs include an external positive tab and an external negative tab, and the external positive tab and the external negative tab are located on the same side of the battery cell.

7. The battery cell according to claim 6, characterized in that The width of the battery cell is W3, the unit of W3 is mm, and W<0.45W3.

8. The battery cell according to any one of claims 1 to 3, characterized in that: The cross section of the battery cell is rectangular, and the external tabs include an external positive tab and an external negative tab. The external positive tab and the external negative tab are arranged on two sides of the battery cell opposite to each other.

9. The battery cell according to claim 8, characterized in that The width of the battery cell is W3, the unit of W3 is mm, and W<0.7W3.

10. A battery pack, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 9.

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