Battery cell and battery pack

Abstract

The present application relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises a casing, an electrode assembly, a cover plate, and an explosion-proof valve. In the embodiments of the present application, the reasonable area S of the explosion-proof valve is obtained by measuring the maximum sizes L, T, and H of the casing in three directions, the thicknesses I, M, and J of a first wall, a second wall, and a third wall of the casing, and the maximum size a of the cover plate in a third direction; and the area S of the explosion-proof valve can be calculated without using complex parameters such as areal density, capacity per gram, and active substance mass, thereby avoiding errors caused by complex measurements and calculations, and simplifying the calculation method. By reasonably designing the size of the explosion-proof valve, it can be ensured that the explosion-proof valve can be opened normally for gas release when thermal runaway occurs to the battery cell, thereby improving the safety and reliability of the battery cell.

Description

Individual cells and battery packs

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. CN202510056144.7, filed on January 14, 2025, entitled "Single Battery and Battery Pack", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of battery technology, specifically relating to a single cell battery and a battery pack. Background Technology

[0004] 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.

[0005] Public content

[0006] In view of this, the purpose of this application is to provide a single battery cell and a battery pack, which aims to solve the technical problem that the calculation process for the size design of explosion-proof valves is cumbersome and prone to errors.

[0007] In a first aspect, this application provides a single-cell battery, comprising:

[0008] The shell has a receiving cavity;

[0009] The electrode assembly is located within the receiving cavity;

[0010] A cover plate seals the receiving cavity, and at least one of the housing and the cover plate has an explosion-proof hole;

[0011] Explosion-proof valve, cover and seal the explosion-proof hole;

[0012] 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.

[0013] Individual cells meet the following requirements:

[0014] ;or

[0015] ;

[0016] Where S is the area of ​​the explosion-proof valve, and V is the rated voltage. This is a correction factor.

[0017] In some embodiments, a single battery cell satisfies:

[0018] ;or

[0019] ;

[0020] Where C represents the rated capacity of a single battery cell.

[0021] In some embodiments, a single cell satisfies at least one of the following characteristics:

[0022] a) L > T;

[0023] b) H > T;

[0024] c) J > I;

[0025] d) I≥M.

[0026] 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'.

[0027] 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:

[0028] e) 0.3 ≤ d ≤ 0.8;

[0029] f) 0.1 ≤ e <d;

[0030] g) 0.04 ≤ f <e。

[0031] In some embodiments, a single cell satisfies: 0.08 ≤ f < 0.2.

[0032] 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.

[0033] In some embodiments, the cover plate has a maximum dimension B mm in the first direction, satisfying: 0 ≤ (LB) ≤ 0.3.

[0034] In some embodiments, the single cell is a lithium iron phosphate single cell or a ternary lithium single cell.

[0035] Accordingly, this application provides a battery pack including the aforementioned single battery cell.

[0036] 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:

[0037] ;or

[0038] 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.

[0039] 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

[0040] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0041] Figure 1 is a schematic diagram of the structure of a single battery according to an embodiment of this application;

[0042] Figure 2 is a structural schematic diagram of a single battery according to another embodiment of this application;

[0043] Figure 3 is an exploded view of a single battery cell according to an embodiment of this application;

[0044] Figure 4 is a cross-sectional view of a single battery cell according to an embodiment of this application;

[0045] Figure 5 is a front view of a single battery cell according to an embodiment of this application;

[0046] Figure 6 is an enlarged view of part A in Figure 5;

[0047] Figure 7 is an enlarged view of part B in Figure 5;

[0048] Figure 8 is an enlarged view of part C in Figure 5;

[0049] Figure 9 is an enlarged view of part D in Figure 5;

[0050] Figure 10 is a side view of a single battery cell according to an embodiment of this application;

[0051] Figure 11 is an enlarged view of part E in Figure 10;

[0052] Figure 12 is an enlarged view of part F in Figure 10;

[0053] Figure 13 is a cross-sectional view of a single cell according to another embodiment of this application;

[0054] Figure 14 is an enlarged view of part G in Figure 13;

[0055] Figure 15 is a top view of a single battery cell according to an embodiment of this application;

[0056] Figure 16 is a structural schematic diagram of an explosion-proof valve according to an embodiment of this application;

[0057] Figure 17 is a side view of a cover plate according to an embodiment of this application;

[0058] Figure 18 is an enlarged view of section H in Figure 17.

[0059] Figure label:

[0060] 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. Embodiments of the present invention

[0061] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0062] 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.

[0063] 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.

[0064] 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:

[0065] ;or

[0066] 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.

[0067] 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.

[0068] Referring to Figures 1 to 18, the single-cell battery of this application embodiment includes a housing 1, an electrode assembly 2, a cover plate 3, and an explosion-proof valve 4. The housing 1 has a receiving cavity 10; the electrode assembly 2 is disposed within the receiving cavity 10; the 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; the explosion-proof valve 4 covers the explosion-proof hole 5. Exemplarily, in the embodiment shown in Figure 1, the cover plate 3 has an explosion-proof hole 5, and the explosion-proof valve 4 is connected to the cover plate 3 and covers the explosion-proof hole 5; in the embodiment shown in Figure 2, the housing 1 has an explosion-proof hole 5, and the explosion-proof valve 4 is connected to the housing 1 and covers the explosion-proof hole 5. The maximum dimension of housing 1 in the first direction X is L mm, the maximum dimension of housing 1 in the second direction Y is T mm, and the maximum dimension of housing 1 in the third direction Z is H mm. Housing 1 includes a first wall 11 opposite to each other in the first direction X, a second wall 12 opposite to each other in the second direction Y, and a third wall 13 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. Specifically, in the embodiment shown in Figure 1, the first direction X is the length direction of housing 1, the second direction Y is the width direction of housing 1, and the third direction Z is the height direction of housing 1. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other. The single battery cell satisfies:

[0069] ;or

[0070] Where S is the area of ​​explosion-proof valve 4, and V is the rated voltage. This is a correction factor.

[0071] This embodiment of the application obtains a reasonable area S of the explosion-proof valve 4 by measuring the maximum dimensions L, T, and H of the housing 1 in three directions, the thicknesses I, M, and J of the first wall 11, second wall 12, and third wall 13 of the housing 1, and the maximum dimension a of the cover plate 3 in the third direction Z. This eliminates the need to calculate the area S of the explosion-proof valve 4 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 4, it can be ensured that the explosion-proof valve 4 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 housing 1 and the cover plate 3, making the overall structure of the battery cell more reasonable, thereby improving the production efficiency of the single battery cell.

[0072] In some embodiments, the single cell is a lithium iron phosphate single cell, and the area S of the explosion-proof valve 4 of the lithium iron phosphate single cell can be obtained by the following formula:

[0073] ;

[0074] ;

[0075] Where S represents the area of ​​the explosion-proof valve 4 of the lithium iron phosphate single 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 X × Dimension of the positive electrode material area in the third direction Z / 100 × Compacted density × Active material ratio / 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 1 in the second direction Y 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. Since there are slight fluctuations in compaction density, areal density, specific capacity, copper and aluminum foil, separator thickness, etc., the calculation will have a comprehensive 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.

[0076] In some embodiments, the maximum dimension H of the housing 1 in the third direction Z is 112 mm, the maximum dimension L of the housing 1 in the first direction X is 148 mm, the maximum dimension T of the housing 1 in the second direction Y is 52 mm, the thickness J of the third wall 13 is 1.2 mm, the thickness I of the first wall 11 is 0.8 mm, the thickness M of the second wall 12 is 0.6 mm, and the maximum dimension a of the cover plate 3 in the third direction Z is 7.5 mm. Substituting these dimensions into the formula, we get C = 96.07 - 117.42AH. If calculated using traditional methods... C = 98.57 - 116.83AH; it can be seen that the above derived formula can obtain the reasonable area S of the explosion-proof valve 4 by measuring the maximum dimensions L, T and H of the shell 1 in three directions, the thicknesses I, M and J of the first wall 11, the second wall 12 and the third wall 13 of the shell 1, and the maximum dimension a of the cover plate 3 in the third direction Z. It is not necessary to calculate the area S of the explosion-proof valve 4 through complex parameters such as areal density, specific capacity and active material mass, thus avoiding errors introduced by complex measurement and calculation and simplifying the calculation method.

[0077] C max =117.42AH, substitute Thus, S≥225.45mm 2 That is, the area S of the explosion-proof valve 4 should be designed according to 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 area design of the explosion-proof valve 4 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 area design of the explosion-proof valve 4 by heating with a heating plate. The test results are shown in Table 1.

[0078] Table 1:

[0079]

[0080] Referring to Examples 1 to 3, when the area of ​​the explosion-proof valve 4 is between 225.5 and 300, the verification result shows that all five individual batteries open normally. It can be understood that when the area of ​​the explosion-proof valve 4 reaches or approaches 225.45 (calculated based on the upper limit of the individual battery capacity), it ensures that the explosion-proof valve 4 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 4 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 4 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 4 is insufficient, which can lead to poor gas release, fire, or eruption in the individual batteries, seriously affecting the safety of the individual batteries.

[0081] 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:

[0082]

[0083]

[0084] Where S represents the area of ​​the explosion-proof valve 4 of the ternary lithium single 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.

[0085] C = (Dimension of the positive electrode material region in the first direction X) × (Dimension of the positive electrode material region in the third direction Z) / 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 = the number of positive electrode layers + 1, and the number of separator layers = 2 × the 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 1 in the second direction Y 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. Since there are slight fluctuations in compaction density, areal density, specific capacity, copper and aluminum foil, separator thickness, etc., the calculation will have a comprehensive 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.

[0086] In some embodiments, the maximum dimension H of the housing 1 in the third direction Z is 112 mm, the maximum dimension L of the housing 1 in the first direction X is 148 mm, the maximum dimension T of the housing 1 in the second direction Y is 52 mm, the thickness J of the third wall 13 is 1.2 mm, the thickness I of the first wall 11 is 0.8 mm, the thickness M of the second wall 12 is 0.6 mm, and the maximum dimension a of the cover plate 3 in the third direction Z is 7.5 mm. Substituting these dimensions into the formula, we have C = 115.21 - 140.81AH. If calculated using traditional methods... Calculation shows that C = 119.7 - 138.25AH. It can be seen that the above derived formula can be used to obtain the area S of the explosion-proof valve 4 by measuring the maximum dimensions L, T and H of the shell 1 in three directions, the thicknesses I, M and J of the first wall 11, the second wall 12 and the third wall 13 of the shell 1, and the maximum dimension a of the cover plate 3 in the third direction Z. It is not necessary to calculate the area S of the explosion-proof valve 4 through complex parameters such as areal density, specific capacity and active material mass, thus avoiding errors introduced by complex measurement and calculation and simplifying the calculation method.

[0087] C max =140.81AH, substitute Yes, S≥608.3mm 2 In other words, the area of ​​the explosion-proof valve 4 must 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 design of the explosion-proof valve 4 area 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 design of the explosion-proof valve 4 area by heating with a heating plate. The test results are shown in Table 2.

[0088] Table 2:

[0089]

[0090] Referring to Examples 4 to 6, when the area of ​​the explosion-proof valve 4 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 4 reaches or approaches 608.3 (calculated based on the upper limit of the individual battery capacity), it ensures that the explosion-proof valve 4 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 4 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 4 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 4 is insufficient, which can lead to poor gas release, fire, or eruption in the individual batteries, seriously affecting the safety of the individual batteries.

[0091] In the embodiments shown in Figures 5 and 10, the maximum dimension L of the housing 1 in the first direction X and the maximum dimension T of the housing 1 in the second direction Y satisfy: L > T. The first direction X is the length direction of the housing 1, and the second direction Y is the width direction of the housing 1. The maximum dimension L of the housing 1 in the first direction X is greater than the maximum dimension T of the housing 1 in the second direction Y, which helps to optimize the space utilization and layout inside the single cell and improve the space utilization rate.

[0092] In the embodiment shown in Figure 10, the maximum dimension H of the housing 1 in the third direction Z and the maximum dimension T of the housing 1 in the second direction Y satisfy: H > T. The second direction Y is the width direction of the housing 1, and the third direction Z is the height direction of the housing 1. The maximum dimension H of the housing 1 in the third direction Z is greater than the maximum dimension T of the housing 1 in the second direction Y, thereby providing more space for internal components such as the electrode assembly 2, which is beneficial to improving energy density.

[0093] In some embodiments, the housing 1 includes a first wall 11 disposed opposite to each other in a first direction X, a second wall 12 disposed opposite to each other in a second direction Y, and a third wall 13 disposed opposite to each other in a third direction Z of the cover plate 3. The thickness of the first wall 11 is 1 mm, the thickness of the second wall 12 is M mm, and the thickness of the third wall 13 is J mm, satisfying that J > 1. The third wall 13 is the opposite surface of the housing 1 and is used to support the electrode assembly 2. Therefore, the thickness J of the third wall 13 is greater than the thickness 1 of the first wall 11, thereby providing a certain degree of support for the electrode assembly 2.

[0094] Specifically, in the embodiments shown in Figures 5, 7, and 8, the thicknesses of the first walls 11 of the housing 1 disposed opposite each other in the first direction X are I1 and I2, respectively. Typically, the third wall 13 has a uniform wall thickness, i.e., I1 = I2. In the embodiments shown in Figures 10 to 12, the thicknesses of the second walls 12 of the housing 1 disposed opposite each other in the second direction Y are M1 and M2, respectively. Typically, the second walls 12 have a uniform wall thickness, i.e., M1 = M2.

[0095] In some embodiments, the thickness I of the first wall 11 and the thickness M of the second wall 12 satisfy: I > M. The first wall 11 includes a body 110 and a step portion 111. The step portion 111 is located on the side of the body 110 facing the electrode assembly 2 and is connected to the body 110. The cover plate 3 abuts against the step portion 111 in the third direction Z. The step portion 111 is used to support the cover plate 3. Therefore, the thickness I of the first wall 11 is greater than the thickness M of the second wall 12, thereby providing a certain degree of support for the cover plate 3.

[0096] In some embodiments, the cover plate 3 and the housing 1 may be connected by laser welding.

[0097] In some embodiments, the explosion-proof valve 4 includes a connecting portion 40 and a weak portion 41. The connecting portion 40 is connected around the weak portion 41. The connecting portion 40 is connected to the cover plate 3. The weak portion 41 is configured to be damaged when impacted by a preset pressure. The weak portion 41 is provided with a notch 410. The area enclosed by the notch 410 is S'. The number of explosion-proof valves 4 is n, satisfying: S = n × S'. By providing the notch 410, the weak portion 41 can break more accurately at the notch 410 when subjected to the preset pressure, ensuring that the explosion-proof valve 4 can timely release the gas inside the single cell 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 4 in this application is not limited.

[0098] In the embodiment shown in FIG. 18, 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, and the remaining thickness at the notch 410 of the weak portion 41 is f mm. The single cell satisfies: 0.3 ≤ d ≤ 0.8. Exemplarily, the dimension d of the connecting portion 40 in the third direction Z 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 welding of the connecting portion 40 to the cover plate 3 or the housing 1 is generally 0.3 mm. If the thickness of the connecting portion 40 is too thin, it is not easy to weld and the connection strength is insufficient. If the connecting portion 40 is too thick, there is no cost advantage and there is design redundancy. By limiting the dimension d of the connecting portion 40 in the third direction Z, the connection strength between the connecting portion 40 and the cover plate 3 or the housing 1 can be ensured, and the overall occupied dimension can be ensured to be small.

[0099] In the embodiment shown in FIG. 18, 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 single cell satisfies: 0.1 ≤ e < d. It can be understood that when the maximum dimension of the weak portion 41 in the third direction Z is smaller than the dimension of the connecting portion 40 in the third direction Z, it can be ensured that the weak portion 41 can break timely along the notch 410 when subjected to the preset pressure. On the other hand, when the maximum dimension e of the weak portion 41 in the third direction Z is greater than or equal to 0.1, it can avoid the deformation of the weak portion 41 caused by insufficient strength of the weak portion 41 during welding of the connecting portion 40 to the cover plate 3 or the housing 1, or due to the internal and external pressure difference during the manufacturing process of the single cell, thereby ensuring that the explosion-proof valve 4 can work normally during thermal runaway.

[0100] In the embodiment shown in FIG. 18, the maximum dimension of the weak part 41 in the third direction Z is e mm, and the remaining thickness at the notch 410 on the weak part 41 is f mm. The single cell satisfies: 0.04 ≤ f < e. It can be understood that when the remaining thickness at the notch 410 on the weak part 41 is less than the maximum dimension of the weak part 41 in the third direction Z, it can ensure that the weak part 41 can break more accurately along the notch 410 when subjected to a preset pressure, ensuring that the explosion-proof valve 4 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; on the other hand, when the remaining thickness f at the notch 410 on the weak part 41 is greater than or equal to 0.04, it can avoid the problem that the explosion-proof valve 4 is prone to open in advance along the notch 410 during the welding of the connecting part 40 to the cover plate 3 or the housing 1 or during the manufacturing process of the single cell due to insufficient strength at the notch 410.

[0101] Further, in the embodiment shown in FIG. 18, the remaining thickness at the notch 410 on the weak part 41 is f mm, satisfying: 0.08 ≤ f < 0.2. Exemplarily, the remaining thickness f at the notch 410 on the weak part 41 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 410 on the weak part 41, it can ensure that the weak part 41 can break more accurately along the notch 410 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 time and causing dangerous situations such as too high internal pressure leading to fire and explosion; nor will it open in advance during normal conditions other than thermal runaway, such as during the welding of the connecting part 40 to the cover plate 3 or the housing 1 or during the manufacturing process of the single cell due to being too thin.

[0102] In the embodiment shown in FIG. 15, the maximum dimension of the housing 1 in the first direction X is L mm, and the cover plate 3 has a maximum dimension B mm in the first direction X, satisfying: 0 ≤ (L - B) ≤ 0.3. It can be understood that the maximum dimension B of the cover plate 3 in the first direction X is less than the maximum dimension L of the housing 1 in the first direction X, 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 3 to shake inside the housing 1, affecting the stability of the assembly; if the difference is too small, the cover plate 3 cannot be smoothly installed into the housing 1. By reasonably limiting the maximum dimension B of the cover plate 3 in the first direction X and the maximum dimension L of the housing 1 in the first direction X, the assembly difficulty can be reduced and the stability and sealing performance after assembly can be ensured.

[0103] Accordingly, this application provides a battery pack including the aforementioned single battery cell. Therefore, the battery pack can have all the technical features and beneficial effects of the aforementioned single battery cell, which will not be repeated here.

[0104] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0105] The present application provides a detailed description of a single battery cell and a battery pack, and uses specific examples to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of the present 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. 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 the present application. Industrial applicability

[0106] The single-cell battery and battery pack 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.

Claims

1. A single-cell battery, characterized in that, include: The shell has a receiving cavity; The electrode assembly is disposed within the receiving cavity; A cover plate seals the receiving cavity, and at least one of the housing and the cover plate has an explosion-proof hole; Explosion-proof valve, cover the explosion-proof hole; 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. The single cell satisfies: ;or ； Where S is the area of ​​the explosion-proof valve, and V is the rated voltage. This is a correction factor.

2. The single-cell battery according to claim 1, characterized in that, The single cell satisfies: ;or ； Wherein, C is the rated capacity of the single battery cell.

3. 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.

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

5. The single-cell battery according to claim 4, characterized in that, 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 notch on the weak portion 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.

6. The single-cell battery according to claim 5, characterized in that, The single cell satisfies: 0.08 ≤ f < 0.

2.

7. The single-cell battery according to claim 1, characterized in that, 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 the cover plate abutting against the stepped portion in the third direction.

8. The single-cell battery according to claim 7, characterized in that, The cover plate has a maximum dimension B mm in the first direction, satisfying: 0 ≤ (LB) ≤ 0.

3.

9. The single-cell battery according to claim 1, characterized in that, The single battery cell is a lithium iron phosphate single battery cell or a ternary lithium single battery cell.

10. A battery pack, characterized in that, Includes the single-cell battery as described in any one of claims 1-9.

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