Individual cells and battery packs

Abstract

This application discloses a single-cell battery and battery pack, belonging to the field of battery technology, including a casing, electrode assembly, cover plate, and explosion-proof valve. The embodiments of this application obtain a reasonable explosion-proof valve area S by measuring the maximum dimensions L, T, and H of the casing in three directions, the thicknesses I, M, and J of the first, second, and third walls of the casing, and the maximum dimension a of the cover plate in the third direction. This eliminates the need to calculate the explosion-proof valve area S using complex parameters such as areal density, specific capacity, and active material mass, avoiding errors introduced by complex measurements and calculations, and simplifying the calculation method. By rationally designing the dimensions of the explosion-proof valve, it can be ensured that the explosion-proof valve can open normally to release gas in the event of thermal runaway of the single-cell battery, thereby improving the safety and reliability of the single-cell battery.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a single cell battery and a battery pack. Background Technology

[0002] With the increasing maturity of lithium-ion battery technology, lithium-ion batteries are widely used as power batteries in electric vehicles. Among these applications, the area design of the explosion-proof valve is particularly important. Improperly designed valve dimensions can lead to the battery failing to open the valve in time or experiencing poor venting, resulting in battery leakage or even fire and explosion. Currently, the design of explosion-proof valve dimensions typically requires calculations based on parameters such as the capacity, material system, and rated voltage of individual cells. This calculation process is overly complex, and various measurement and calculation steps can introduce errors. Summary of the Invention

[0003] Purpose of the invention: The embodiments of this application provide a single battery and a battery pack, which aim to solve the technical problem that the calculation process for the size design of explosion-proof valves is cumbersome and prone to errors.

[0004] Technical solution: This application provides a single-cell battery, including:

[0005] The shell has a receiving cavity;

[0006] The electrode assembly is located within the receiving cavity;

[0007] A cover plate seals the receiving cavity, and at least one of the housing and the cover plate has an explosion-proof hole;

[0008] Explosion-proof valve, cover and seal the explosion-proof hole;

[0009] The maximum dimension of the housing in the first direction is L mm, the maximum dimension of the housing in the second direction is T mm, and the maximum dimension of the housing in the third direction is H mm. The housing includes a first wall disposed opposite to the cover plate in the first direction, a second wall disposed opposite to the cover plate in the second direction, and a third wall disposed opposite to the cover plate in the third direction. The thickness of the first wall is I mm, the thickness of the second wall is M mm, and the thickness of the third wall is J mm. The maximum dimension of the cover plate in the third direction is a mm. The first direction, the second direction, and the third direction intersect each other.

[0010] Individual cells meet the following requirements:

[0011] ;or

[0012] ;

[0013] Where S is the area of ​​the explosion-proof valve, and V is the rated voltage. This is a correction factor.

[0014] In some embodiments, a single battery cell satisfies:

[0015] ;or

[0016] ;

[0017] Where C represents the rated capacity of a single battery cell.

[0018] In some embodiments, a single cell satisfies at least one of the following characteristics:

[0019] a) L > T;

[0020] b) H > T.

[0021] c) J > I;

[0022] d) I≥M.

[0023] In some embodiments, the explosion-proof valve includes a connecting portion and a weak portion. The connecting portion is connected to the weak portion around the weak portion and is connected to a cover plate. The weak portion is provided with grooves and is configured to be destroyed along the grooves when subjected to a preset pressure impact. The area enclosed by the grooves is S', and the number of explosion-proof valves is n, satisfying: S=n×S'.

[0024] In some embodiments, the dimension of the connecting portion in the third direction is d mm, the maximum dimension of the weak portion in the third direction is e mm, the residual thickness at the indentation on the weak portion is f mm, and the single cell satisfies at least one of the following characteristics:

[0025] e) 0.3 ≤ d ≤ 0.8;

[0026] f) 0.1 ≤ e <d;

[0027] g) 0.04 ≤ f <e。

[0028] In some embodiments, a single cell satisfies: 0.08 ≤ f < 0.2.

[0029] In some embodiments, the first wall includes a body and a stepped portion, the stepped portion being located on the side of the body facing the electrode assembly, and a cover plate abutting against the stepped portion in a third-order upward direction.

[0030] In some embodiments, the cover plate has a maximum dimension B mm in the first direction, satisfying: 0 ≤ L - B ≤ 0.3.

[0031] In some embodiments, the single cell is a lithium iron phosphate single cell or a ternary lithium single cell.

[0032] Accordingly, this application provides a battery pack including the aforementioned single battery cell.

[0033] Beneficial Effects: The single-cell battery of this application embodiment includes a casing, an electrode assembly, a cover plate, and an explosion-proof valve. The casing has a receiving cavity; the electrode assembly is disposed in the receiving cavity; the cover plate seals the receiving cavity, and at least one of the casing and the cover plate has an explosion-proof hole; the explosion-proof valve seals the explosion-proof hole; the maximum dimension of the casing in a first direction is L mm, the maximum dimension of the casing in a second direction is T mm, and the maximum dimension of the casing in a third direction is H mm. The casing includes a first wall disposed opposite to the cover plate in the first direction, a second wall disposed opposite to the cover plate in the second direction, and a third wall disposed opposite to the cover plate in the third direction. The thickness of the first wall is I mm, the thickness of the second wall is M mm, and the thickness of the third wall is J mm; the maximum dimension of the cover plate in the third direction is a mm; the first direction, the second direction, and the third direction intersect each other; the single-cell battery satisfies:

[0034] ;or

[0035] Where S is the area of ​​the explosion-proof valve, and V is the rated voltage. This is a correction factor. In this embodiment, the area S of the explosion-proof valve is obtained by measuring the maximum dimensions L, T, and H of the housing in three directions, the thicknesses I, M, and J of the first, second, and third walls of the housing, and the maximum dimension a of the cover plate in the third direction. This eliminates the need to calculate the area S of the explosion-proof valve using complex parameters such as areal density, specific capacity, and active material mass, avoiding errors introduced by complex measurements and calculations, and simplifying the calculation method. By rationally designing the dimensions of the explosion-proof valve, it can be ensured that the explosion-proof valve can open normally to release gas in the event of thermal runaway of a single battery cell, thereby improving the safety and reliability of the single battery cell.

[0036] The battery pack of this application embodiment includes the above-described single battery cell, and therefore the battery pack can have all the technical features and beneficial effects of the above-described single battery cell, which will not be repeated here. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of a single battery cell according to an embodiment of this application;

[0039] Figure 2 This is a schematic diagram of the structure of a single battery cell according to another embodiment of this application;

[0040] Figure 3This is an exploded view of a single battery cell according to an embodiment of this application;

[0041] Figure 4 This is a cross-sectional view of a single battery cell according to an embodiment of this application;

[0042] Figure 5 This is a front view of a single battery cell according to an embodiment of this application;

[0043] Figure 6 yes Figure 5 Enlarged view of part A;

[0044] Figure 7 yes Figure 5 Enlarged view of part B;

[0045] Figure 8 yes Figure 5 Enlarged view of part C;

[0046] Figure 9 yes Figure 5 Enlarged view of part D;

[0047] Figure 10 This is a side view of a single battery cell according to an embodiment of this application;

[0048] Figure 11 yes Figure 10 Enlarged view of part E;

[0049] Figure 12 yes Figure 10 Enlarged view of part F;

[0050] Figure 13 This is a cross-sectional view of a single cell according to another embodiment of this application;

[0051] Figure 14 yes Figure 13 Enlarged view of part G;

[0052] Figure 15 This is a top view of a single battery cell according to an embodiment of this application;

[0053] Figure 16 This is a schematic diagram of the structure of an explosion-proof valve according to an embodiment of this application;

[0054] Figure 17 This is a side view of a cover plate according to an embodiment of this application;

[0055] Figure 18 yes Figure 17 Enlarged view of section H.

[0056] Reference numerals: 1. Housing; 2. Electrode assembly; 3. Cover plate; 4. Explosion-proof valve; 5. Explosion-proof hole; 10. Receiving cavity; 11. First wall; 12. Second wall; 13. Third wall; 40. Connecting part; 41. Weak part; 110. Body; 111. Stepped part; 410. Score; X, First direction; Y, Second direction; Z, Third direction. Detailed Implementation

[0057] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0058] In the description of this application, it should be understood that the terms "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation on this application. 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 indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, and "at least one" can mean one, two, or more, unless otherwise explicitly specified. In the description of this application, "perpendicular" means completely perpendicular to 90° or almost completely perpendicular, for example, the range of included angles between 80° and 100° is considered perpendicular. Similarly, "parallel" means completely parallel or almost completely parallel, for example, the range of completely parallel angles between 10° is considered parallel.

[0059] The applicant notes that with the increasing maturity of lithium-ion battery technology, lithium-ion batteries are widely used as power batteries in the electric vehicle field. Among these applications, the area design of the explosion-proof valve is particularly important. Improperly designed explosion-proof valve dimensions can lead to the battery failing to open the valve in time or to poor venting, resulting in battery leakage or even fire and explosion. Currently, the design of explosion-proof valve dimensions typically requires calculations based on parameters such as the capacity, material system, and rated voltage of individual cells. This calculation process is overly cumbersome, and various measurement and calculation steps can introduce errors.

[0060] In view of this, the single-cell battery of this application embodiment includes a casing, an electrode assembly, a cover plate, and an explosion-proof valve. The casing has a receiving cavity; the electrode assembly is disposed in the receiving cavity; the cover plate seals the receiving cavity, and at least one of the casing and the cover plate has an explosion-proof hole; the explosion-proof valve seals the explosion-proof hole; the maximum dimension of the casing in a first direction is L mm, the maximum dimension of the casing in a second direction is T mm, and the maximum dimension of the casing in a third direction is H mm. The casing includes a first wall disposed opposite to each other in the first direction, a second wall disposed opposite to each other in the second direction, and a third wall disposed opposite to the cover plate in a third direction. The thickness of the first wall is I mm, the thickness of the second wall is M mm, and the thickness of the third wall is J mm; the maximum dimension of the cover plate in a third direction is a mm; the first direction, the second direction, and the third direction intersect each other; the single-cell battery satisfies:

[0061] ;or

[0062] Where S is the area of ​​the explosion-proof valve, and V is the rated voltage. This is a correction factor. In this embodiment, the area S of the explosion-proof valve is obtained by measuring the maximum dimensions L, T, and H of the housing in three directions, the thicknesses I, M, and J of the first, second, and third walls of the housing, and the maximum dimension a of the cover plate in the third direction. This eliminates the need to calculate the area S of the explosion-proof valve using complex parameters such as areal density, specific capacity, and active material mass, avoiding errors introduced by complex measurements and calculations, and simplifying the calculation method. By rationally designing the dimensions of the explosion-proof valve, it can be ensured that the explosion-proof valve can open normally to release gas in the event of thermal runaway of a single battery cell, thereby improving the safety and reliability of the single battery cell.

[0063] The single-cell battery and battery pack of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.

[0064] Figure 1 This is a schematic diagram of the structure of a single battery cell according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a single battery cell according to another embodiment of this application; Figure 3 This is an exploded view of a single battery cell according to an embodiment of this application; Figure 4 This is a cross-sectional view of a single battery cell according to an embodiment of this application; Figure 5 This is a front view of a single battery cell according to an embodiment of this application; Figure 6 yes Figure 5 Enlarged view of part A; Figure 7 yes Figure 5 Enlarged view of part B; Figure 8 yes Figure 5 Enlarged view of part C; Figure 9 yes Figure 5Enlarged view of part D; Figure 10 This is a side view of a single battery cell according to an embodiment of this application; Figure 11 yes Figure 10 Enlarged view of part E; Figure 12 yes Figure 10 Enlarged view of part F; Figure 13 This is a cross-sectional view of a single cell according to another embodiment of this application; Figure 14 yes Figure 13 Enlarged view of part G; Figure 15 This is a top view of a single battery cell according to an embodiment of this application; Figure 16 This is a schematic diagram of the structure of an explosion-proof valve according to an embodiment of this application; Figure 17 This is a side view of a cover plate according to an embodiment of this application; Figure 18 yes Figure 17 Enlarged view of the H section. (Reference) Figures 1 to 18 The single-cell battery of this application embodiment includes a casing, an electrode assembly, a cover plate, and an explosion-proof valve. The casing has a receiving cavity; the electrode assembly is disposed within the receiving cavity; the cover plate seals the receiving cavity, and at least one of the casing and the cover plate has an explosion-proof hole; the explosion-proof valve seals the explosion-proof hole. Exemplarily, in... Figure 1 In the illustrated embodiment, the cover plate has an explosion-proof hole, and the explosion-proof valve is connected to the cover plate and seals the explosion-proof hole; Figure 2 In the illustrated embodiment, the housing has an explosion-proof vent, and an explosion-proof valve is connected to the housing and seals the explosion-proof vent. The maximum dimension of the housing in the first direction is L mm, the maximum dimension of the housing in the second direction is T mm, and the maximum dimension of the housing in the third direction is H mm. The housing includes a first wall opposite to each other in the first direction, a second wall opposite to each other in the second direction, and a third wall opposite to the cover plate in the third direction. The thickness of the first wall is I mm, the thickness of the second wall is M mm, and the thickness of the third wall is J mm. The maximum dimension of the cover plate in the third direction is a mm. The first, second, and third directions intersect each other. Specifically, in Figure 1 In the illustrated embodiment, the first direction is the length direction of the casing, the second direction is the width direction of the casing, and the third direction is the height direction of the casing. The first, second, and third directions are perpendicular to each other. A single battery cell satisfies:

[0065] ;or

[0066] Where S is the area of ​​the explosion-proof valve, and V is the rated voltage. This is a correction factor.

[0067] This application embodiment obtains a reasonable explosion-proof valve area S by measuring the maximum dimensions L, T, and H of the casing in three directions, the thicknesses I, M, and J of the first, second, and third walls of the casing, and the maximum dimension a of the cover plate in the third direction. This eliminates the need to calculate the explosion-proof valve area S using complex parameters such as areal density, specific capacity, and active material mass, avoiding errors introduced by complex measurements and calculations, and simplifying the calculation method. By rationally designing the explosion-proof valve dimensions, it can be ensured that the explosion-proof valve can open normally to release gas in the event of thermal runaway of a single battery cell, thereby improving the safety and reliability of the single battery cell. Furthermore, the above formula can provide a reference for setting the dimensions of the casing and cover plate, making the overall structure of the battery cell more reasonable, and thus improving the production efficiency of the single battery cell.

[0068] In some embodiments, the single cell is a lithium iron phosphate single cell, and the explosion-proof valve area S of the lithium iron phosphate single cell can be obtained by the following formula:

[0069] ;

[0070] ;

[0071] Where S represents the area of ​​the explosion-proof valve of the lithium iron phosphate cell, and its unit is mm. 2 V represents the rated voltage of a single lithium iron phosphate cell, and its unit is V. C is the correction factor for a single lithium iron phosphate cell, and C is the rated capacity of a single lithium iron phosphate cell. max for The rated capacity of a single lithium iron phosphate cell when the maximum value is reached. For example, V could be 3.2V. It can be 0.6. C = Dimension of the positive electrode material area in the first direction * Dimension of the positive electrode material area in the third direction / 100 * Compacted density * Percentage of active material / 100 * 2 (double-sided coating) / 1000 * Specific capacity * Number of positive electrode layers / 1000; Where, the number of negative electrode layers = number of positive electrode layers + 1, and the number of separator layers = 2 * number of positive electrode layers + 1; The thickness of the separator, the thickness of the positive electrode aluminum foil, and the thickness of the negative electrode copper foil are known parameters. Generally, the separator is 10~12um, the aluminum foil is 10~15um, and the copper foil is... The foil thickness is 4~6µm; the thickness of the positive and negative electrodes can be derived from the compaction density; from the above, the number of positive electrode layers contained in the space of the casing in the second direction can be calculated; through the above derivation process, a formula for calculating the single cell capacity can be obtained directly from the structural component dimensions. Due to slight fluctuations in compaction density, areal density, specific capacity, copper and aluminum foil, separator thickness, etc., the calculation will have a combined fluctuation range of 0.9~1.1 times. Therefore, a correction factor is introduced into the formula. , The range is between 0.9 and 1.1.

[0072] In some embodiments, the maximum dimension H of the housing in the third direction is 112 mm, the maximum dimension L of the housing in the first direction is 148 mm, the maximum dimension T of the housing in the second direction is 52 mm, the thickness J of the third wall is 1.2 mm, the thickness I of the first wall is 0.8 mm, the thickness M of the second wall is 0.6 mm, and the maximum dimension a of the cover plate in the third direction is 7.5 mm. Substituting these dimensions into the formula, we get C = 96.07 - 117.42AH. If calculated using the traditional method, C = 98.57 - 116.83AH. It can be seen that the above-derived formula allows us to obtain a reasonable explosion-proof valve area S simply by measuring the maximum dimensions L, T, and H of the housing in the three directions, the thicknesses I, M, and J of the first, second, and third walls of the housing, and the maximum dimension a of the cover plate in the third direction. This eliminates the need to calculate the explosion-proof valve area S using complex parameters such as areal density, specific capacity, and active material mass, thus avoiding errors introduced by complex measurements and calculations and simplifying the calculation method.

[0073] Substituting Cmax = 117.42AH into... The result is S≥225.45mm2, which means that the area S of the explosion-proof valve should be designed based on the upper limit of the single cell capacity in order to fully guarantee the normal valve opening of the single cell during thermal runaway. The following will also verify the rationality of the explosion-proof valve area design by conducting thermal runaway tests on multiple samples. Specifically, each sample includes 5 single cells. The thermal runaway test refers to verifying the rationality of the explosion-proof valve area design by heating with a heating plate. The test results are shown in Table 1.

[0074] Table 1:

[0075]

[0076] Referring to Examples 1 to 3, when the area of ​​the explosion-proof valve is between 225.5 and 300, the verification result shows that all five individual batteries open the valve normally. It can be understood that when the area of ​​the explosion-proof valve reaches or approaches 225.45 (calculated based on the upper limit of the individual battery capacity), it ensures that the explosion-proof valve can open normally to release gas in the event of thermal runaway of the individual battery, thereby improving the safety and reliability of the individual battery. However, referring to Comparative Examples 1 to 5, when the area of ​​the explosion-proof valve is less than 225.45, the verification result shows that some individual batteries experience problems such as poor gas release, fire, or eruption. It can be understood that when the area of ​​the explosion-proof valve is less than 225.45 (calculated based on the upper limit of the individual battery capacity), the gas release area of ​​the explosion-proof valve is insufficient, which can lead to poor gas release, fire, or eruption in the individual batteries, seriously affecting the safety of the individual batteries.

[0077] In other embodiments, the single cell is a ternary lithium battery, and the explosion valve area S of the ternary lithium battery can be obtained by the following formula:

[0078]

[0079]

[0080] Where S represents the area of ​​the explosion-proof valve of the ternary lithium battery cell, and its unit is mm. 2 V is the rated voltage of a ternary lithium battery cell, and its unit is V. V is a correction factor for ternary lithium-ion battery cells, and C is the rated capacity of the ternary lithium-ion battery cell. For example, V can be 3.6V. Because the materials in the ternary system are more reactive, the gas production and production rate are greater compared to lithium iron phosphate. It can be 1.2.

[0081] C = (Dimension of the positive electrode material area in the first direction * Dimension of the positive electrode material area in the third direction) / 100 * Compacted density * Percentage of active material / 100 * 2 (double-sided coating) / 1000 * Specific capacity * Number of positive electrode layers / 1000; where, the number of negative electrode layers = number of positive electrode layers + 1, and the number of separator layers = 2 * number of positive electrode layers + 1; the thickness of the separator, the thickness of the positive electrode aluminum foil, and the thickness of the negative electrode copper foil are known parameters, generally the separator is 10~12um, the aluminum foil is 10~15um, and the copper foil is... The foil thickness is 4~6µm; the thickness of the positive and negative electrodes can be derived from the compaction density; from the above, the number of positive electrode layers contained in the space of the casing in the second direction can be calculated; through the above derivation process, a formula for calculating the single cell capacity can be obtained directly from the structural component dimensions. Due to slight fluctuations in compaction density, areal density, specific capacity, copper and aluminum foil, separator thickness, etc., the calculation will have a combined fluctuation range of 0.9~1.1 times. Therefore, a correction factor is introduced into the formula. , The range is between 0.9 and 1.1.

[0082] In some embodiments, the maximum dimension H of the housing in the third direction is 112 mm, the maximum dimension L of the housing in the first direction is 148 mm, the maximum dimension T of the housing in the second direction is 52 mm, the thickness J of the third wall is 1.2 mm, the thickness I of the first wall is 0.8 mm, the thickness M of the second wall is 0.6 mm, and the maximum dimension a of the cover plate in the third direction is 7.5 mm. Substituting these dimensions into the formula, we get C = 115.21 - 140.81AH. If calculated using traditional methods, C = 119.7 - 138.25AH. It can be seen that the above-derived formula allows us to obtain a reasonable explosion-proof valve area S simply by measuring the maximum dimensions L, T, and H of the housing in the three directions, the thicknesses I, M, and J of the first, second, and third walls of the housing, and the maximum dimension a of the cover plate in the third direction. This eliminates the need to calculate the explosion-proof valve area S using complex parameters such as areal density, specific capacity, and active material mass, thus avoiding errors introduced by complex measurements and calculations and simplifying the calculation method.

[0083] C max =140.81AH, substitute Yes, S≥608.3mm 2 In other words, the area of ​​the explosion-proof valve must be designed based on the upper limit of the capacity of a single battery cell to fully guarantee the normal valve opening of the single battery cell during thermal runaway. The following will also verify the rationality of the explosion-proof valve area design by conducting thermal runaway tests on multiple samples. Specifically, each sample includes 5 single batteries. The thermal runaway test refers to verifying the rationality of the explosion-proof valve area design by heating with a heating plate. The test results are shown in Table 2.

[0084] Table 2:

[0085]

[0086] Referring to Examples 4 to 6, when the area of ​​the explosion-proof valve is between 610 and 700, the verification result shows that all five individual batteries open the valve normally. It can be understood that when the area of ​​the explosion-proof valve reaches or approaches 608.3 (calculated based on the upper limit of the individual battery capacity), it ensures that the explosion-proof valve can open normally to release gas in the event of thermal runaway of the individual battery, thereby improving the safety and reliability of the individual battery. However, referring to Comparative Examples 5 to 10, when the area of ​​the explosion-proof valve is less than 608.3, the verification result shows that some individual batteries experience problems such as poor gas release, fire, or eruption. It can be understood that when the area of ​​the explosion-proof valve is less than 608.3 (calculated based on the upper limit of the individual battery capacity), the gas release area of ​​the explosion-proof valve is insufficient, which can lead to poor gas release, fire, or eruption in the individual batteries, seriously affecting the safety of the individual batteries.

[0087] exist Figure 5 and Figure 10In the illustrated embodiment, the maximum dimension L of the housing in the first direction and the maximum dimension T of the housing in the second direction satisfy: L > T. The first direction is the length direction of the housing, and the second direction is the width direction of the housing. The maximum dimension L of the housing in the first direction is greater than the maximum dimension T of the housing in the second direction, which helps to optimize the space utilization and layout inside the single cell and improve space utilization.

[0088] exist Figure 10 In the illustrated embodiment, the maximum dimension H of the housing in the third direction and the maximum dimension T of the housing in the second direction satisfy: H > T. The second direction is the width direction of the housing, and the third direction is the height direction of the housing. The maximum dimension H of the housing in the third direction is greater than the maximum dimension T of the housing in the second direction, thereby providing more space for internal components such as electrode assemblies, which is beneficial for improving energy density.

[0089] In some embodiments, the housing includes a first wall disposed opposite to each other in a first direction, a second wall disposed opposite to each other in a second direction, and a third wall disposed opposite to each other in a third direction. The thickness of the first wall is 1 mm, the thickness of the second wall is M mm, and the thickness of the third wall is J mm, satisfying that J > 1. The third wall is the opposite surface of the housing and is used to support the electrode assembly; therefore, the thickness J of the third wall is greater than the thickness 1 of the first wall, thereby providing a certain degree of support for the electrode assembly.

[0090] Specifically, in Figure 5 , Figure 7 and Figure 8 In the illustrated embodiment, the thicknesses of the first walls of the housing, which are disposed opposite each other in a first direction, are I1 and I2, respectively. Typically, the third wall has a uniform thickness, i.e., I1 = I2. Figures 10 to 12 In the embodiment shown, the thicknesses of the second walls of the housing disposed opposite each other in the second direction are M1 and M2, respectively. Typically, the second walls have equal wall thickness, i.e., M1=M2.

[0091] In some embodiments, the thickness I of the first wall and the thickness M of the second wall satisfy: I > M. The first wall includes a body and a stepped portion, the stepped portion being located on the side of the body facing the electrode assembly and connected to the body, and a cover plate abutting against the stepped portion in a third-order upward direction. The stepped portion is used to support the cover plate; therefore, the thickness I of the first wall is greater than the thickness M of the second wall, thereby providing a certain degree of support for the cover plate.

[0092] In some embodiments, the cover plate and the housing may be joined by laser welding.

[0093] In some embodiments, the explosion-proof valve includes a connecting portion and a weak portion. The connecting portion surrounds and connects to the weak portion. The connecting portion is connected to the cover plate. The weak portion is configured to be damaged when impacted by a preset pressure. The weak portion is provided with a notch, and the area enclosed by the notch is S'. The number of explosion-proof valves is n, satisfying: S = n × S'. By providing the notch, the weak portion can break more accurately at the notch when subjected to the preset pressure, ensuring that the explosion-proof valve can release the gas inside the single cell in time during thermal runaway, thereby effectively reducing the internal pressure and preventing the single cell from catching fire or exploding. The number of explosion-proof valves in this application is not limited.

[0094] In Figure 18 In the illustrated embodiment, the dimension of the connecting portion in the third direction is d mm, the maximum dimension of the weak portion in the third direction is e mm, and the remaining thickness at the notch of the weak portion is f mm. The single cell satisfies: 0.3 ≤ d ≤ 0.8. Exemplarily, the dimension d of the connecting portion in the third direction can be any value among 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or the range value between any two of them. It can be understood that the penetration depth during the welding of the connecting portion to the cover plate or the housing is generally 0.3 mm. If the thickness of the connecting portion is too thin, it is not easy to weld and the connection strength is insufficient, while if the connecting portion is too thick, there is no cost advantage and the design is redundant. By limiting the dimension d of the connecting portion in the third direction, this application can ensure the connection strength between the connecting portion and the cover plate or the housing and ensure a relatively small overall occupied dimension.

[0095] In Figure 18 In the illustrated embodiment, the dimension of the connecting portion in the third direction is d mm, the maximum dimension of the weak portion in the third direction is e mm, and the single cell satisfies: 0.1 ≤ e < d. It can be understood that when the maximum dimension of the weak portion in the third direction is smaller than the dimension of the connecting portion in the third direction, it can be ensured that the weak portion can break along the notch in time when subjected to the preset pressure; on the other hand, when the maximum dimension e of the weak portion in the third direction is greater than or equal to 0.1, it can avoid the deformation of the weak portion caused by insufficient strength of the weak portion during the welding of the connecting portion to the cover plate or the housing or due to the internal and external pressure difference during the manufacturing process of the single cell, thereby ensuring that the explosion-proof valve can work properly during thermal runaway.

[0096] In Figure 18In the illustrated embodiment, the maximum dimension of the weak part in the third direction is e mm, and the remaining thickness at the notch on the weak part is f mm. The single cell satisfies: 0.04 ≤ f < e. It can be understood that when the remaining thickness at the notch on the weak part is less than the maximum dimension of the weak part in the third direction, it can be ensured that the weak part can break more accurately along the notch when subjected to a preset pressure, ensuring that the explosion-proof valve can release the gas inside the single cell in a timely manner during thermal runaway, thereby effectively reducing the internal pressure and preventing the single cell from catching fire or exploding. On the other hand, when the remaining thickness f at the notch on the weak part is greater than or equal to 0.04, it can avoid the problem that the explosion-proof valve is prone to open in advance along the notch during welding of the connecting part to the cover plate or the housing or during the manufacturing process of the single cell due to insufficient strength at the notch.

[0097] Further, in Figure 18 the illustrated embodiment, the remaining thickness at the notch on the weak part is f mm, satisfying: 0.08 ≤ f < 0.2. Exemplarily, the remaining thickness f at the notch on the weak part can be any value among 0.08, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2 or the range value between any two of them. It can be understood that by reasonably limiting the remaining thickness f at the notch on the weak part, it can be ensured that the weak part can break more accurately along the notch when the single cell is subjected to a preset pressure during thermal runaway. Because of the reasonable design of the size of the remaining thickness f, it will not be difficult to break due to being too thick, resulting in the inability to release the internal gas in a timely manner and causing dangerous situations such as too high internal pressure leading to fire and explosion; nor will it have the problem of opening the valve in advance during non-thermal runaway normal situations, such as during welding of the connecting part to the cover plate or the housing or during the manufacturing process of the single cell due to being too thin.

[0098] In Figure 15 the illustrated embodiment, the maximum dimension of the housing in the first direction is L mm, and the cover plate has a maximum dimension B mm in the first direction, satisfying: 0 ≤ L - B ≤ 0.3. It can be understood that the maximum dimension B of the cover plate in the first direction is less than the maximum dimension L of the housing in the first direction, and the difference between the two is less than 0.3. If the difference between the two is too large, it may cause the cover plate to shake inside the housing, affecting the stability of the assembly; if the difference is too small, the cover plate cannot be smoothly installed into the housing. By reasonably limiting the maximum dimension B of the cover plate in the first direction and the maximum dimension L of the housing in the first direction, the assembly difficulty can be reduced and the stability and sealing performance after assembly can be ensured.

[0099] Correspondingly, an embodiment of the present application provides a battery pack, including the above-mentioned single cell.

[0100] In the above embodiments, the descriptions of each embodiment have their own focuses. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0101] The foregoing has provided a detailed description of a single battery cell and a battery pack provided in the embodiments of this application, and specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A single-cell battery, characterized in that, include: The housing (1) has a receiving cavity (10); Electrode assembly (2) is disposed within the receiving cavity (10); A cover plate (3) covers the receiving cavity (10), and at least one of the housing (1) and the cover plate (3) has an explosion-proof hole (5). Explosion-proof valve (4), and cover the explosion-proof hole (5); The maximum dimension of the housing (1) in the first direction (X) is L mm, the maximum dimension of the housing (1) in the second direction (Y) is T mm, and the maximum dimension of the housing (1) in the third direction (Z) is H mm. The housing (1) includes a first wall (11) disposed opposite to each other in the first direction (X), a second wall (12) disposed opposite to each other in the second direction (Y), and a third wall (13) disposed opposite to the cover plate (3) in the third direction (Z). The thickness of the first wall (11) is I mm, the thickness of the second wall (12) is M mm, and the thickness of the third wall (13) is J mm. The maximum dimension of the cover plate (3) in the third direction (Z) is a mm. The first direction (X), the second direction (Y), and the third direction (Z) intersect each other. The single cell satisfies: When the single cell is a lithium iron phosphate single cell... , =0.6, ; or When the single cell is a ternary lithium single cell... , =1.2, ; Where S is the area of ​​the explosion-proof valve (4), and V is the rated voltage. Where C is the first correction factor, and C is the rated capacity of the single battery cell. This is the second correction factor. The range is 0.9-1.1, C max for The rated capacity of the single cell when the maximum value is taken.

2. The single-cell battery according to claim 1, characterized in that, The single cell battery satisfies at least one of the following characteristics: a) L > T; b) H > T; c) J > I; d) I≥M.

3. The single-cell battery according to claim 1, characterized in that, The explosion-proof valve (4) includes a connecting part (40) and a weak part (41). The connecting part (40) is connected around the weak part (41). The connecting part (40) is connected to one of the cover plate (3) and the housing (1). The weak part (41) is provided with a notch (410). The weak part (41) is configured to be destroyed along the notch (410) when subjected to a preset pressure impact. The area enclosed by the notch (410) is S'. The number of explosion-proof valves (4) is n, satisfying: S=n×S'.

4. The single-cell battery according to claim 3, characterized in that, The dimension of the connecting portion (40) in the third direction (Z) is d mm, the maximum dimension of the weak portion (41) in the third direction (Z) is e mm, the residual thickness at the notch (410) on the weak portion (41) is f mm, and the single cell satisfies at least one of the following characteristics: e) 0.3 ≤ d ≤ 0.8; f) 0.1 ≤ e <d; g) 0.04 ≤ f <e。 5. The single-cell battery according to claim 4, characterized in that, The single cell satisfies: 0.08 ≤ f < 0.

2.

6. The single-cell battery according to claim 1, characterized in that, The first wall (11) includes a body (110) and a step portion (111), the step portion (111) being located on the side of the body (110) facing the electrode assembly (2) and connected to the body (110), and the cover plate (3) abutting against the step portion (111) in the third direction (Z).

7. The single-cell battery according to claim 6, characterized in that, The cover plate (3) has a maximum dimension B mm in the first direction (X) and satisfies: 0 ≤ L - B ≤ 0.

3.

8. A battery pack, characterized in that, Includes a single cell battery as described in any one of claims 1-7.

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