Secondary batteries, battery packs and electrical devices

Abstract

The present application discloses a secondary battery, a battery pack and an electric device. The secondary battery has a first direction and a second direction intersecting each other, and includes a shell, an electrode assembly and a top cover assembly. The shell has a receiving cavity, the electrode assembly is arranged in the receiving cavity, the top cover assembly includes a top cover sheet and a lower insulating member, the top cover sheet is connected to the shell and covers the receiving cavity, the lower insulating member is located in the receiving cavity and connected to the top cover sheet; the top cover sheet is provided with a pressure relief member, the lower insulating member has a groove, and the positive projection of the pressure relief member on the lower insulating member along the first direction is located in the groove; the lower insulating member has a side wall, and the lower insulating member is provided with an exhaust channel; along the second direction, the exhaust channel runs through the side wall, and there is a gap between the side wall and the shell, and the exhaust channel is connected to the gap and the groove respectively; the size of the gap along the second direction is e mm, and the size of the exhaust channel along the first direction is a mm, which satisfies: 1≤e / a≤4. The present application achieves better exhaust pressure relief by arranging an exhaust channel on the side wall of the groove.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a secondary battery, a battery pack and an electrical device. Background Art

[0002] The secondary battery is provided with an explosion-proof valve on the top cover, which is used to open in time to release the internal pressure when the secondary battery is thermally runaway, so as to prevent the secondary battery from exploding. In order to ensure the insulation inside the secondary battery, an insulating member is provided between the winding core and the top cover sheet to ensure the insulation. However, during the use of the secondary battery, there is a problem that the insulating member is not vented smoothly, which affects the pressure relief of the explosion-proof valve. Summary of the invention

[0003] Purpose of the invention: An embodiment of the present application provides a secondary battery, aiming to solve the problem of poor exhaust of insulating parts during use of existing secondary batteries, which affects the pressure relief of explosion-proof valves; another purpose of an embodiment of the present application is to provide a battery pack, and another purpose of an embodiment of the present application is to provide an electrical device.

[0004] Technical solution: A secondary battery according to an embodiment of the present application has a first direction and a second direction intersecting each other, including:

[0005] A housing having a receiving cavity;

[0006] An electrode assembly, disposed in the accommodating cavity;

[0007] A top cover assembly, comprising a top cover sheet and a lower insulating member, wherein the top cover sheet is connected to the shell and covers the accommodating cavity, and the lower insulating member is located in the accommodating cavity and connected to the top cover sheet; the top cover sheet is provided with a pressure relief member, and the lower insulating member has a bottom wall and a side wall, the bottom wall is spaced apart from the pressure relief member along the first direction, the side wall is connected to the peripheral side of the bottom wall to form a groove, and the positive projection of the pressure relief member on the lower insulating member along the first direction is located in the groove; an exhaust channel is provided on the side wall and penetrates the side wall along the second direction; along the second direction, there is a gap between the side wall and the shell, and the exhaust channel is connected with the gap and the groove respectively; the size of the gap along the second direction is e mm, and the size of the exhaust channel along the first direction is a mm, satisfying: 1≤e / a≤4.

[0008] In some embodiments, along the first direction, the size of the side wall is b mm, satisfying: 0.5≤ba≤10.

[0009] In some embodiments, the lower insulator further satisfies at least one of the following features:

[0010] (a) 0.5≤a≤5;

[0011] (b) 1≤b≤15.

[0012] In some embodiments, the lower insulator further satisfies at least one of the following features:

[0013] (c) 1≤a≤3;

[0014] (d)2≤b≤11.

[0015] In some embodiments, there is a third direction intersecting with the first direction and the second direction respectively, and along the third direction, the size of the exhaust channel is c mm, satisfying: 0.5≤c≤10.

[0016] In some embodiments, along the second direction, the minimum dimension between the side wall and the pressure relief member is f mm, the minimum distance between the pressure relief member and the shell is d mm, and the following conditions are satisfied: 1≤df≤5.

[0017] In some embodiments, the side wall is provided with a plurality of the exhaust channels, and the total opening area of ​​the plurality of the exhaust channels is S1mm 2 The area of ​​the side wall excluding the plurality of exhaust passages along the second direction toward the housing is S2 mm 2 , satisfying: 0.5≤S1 / S2≤5.

[0018] In some embodiments, the bottom wall is provided with a plurality of through holes, and the plurality of through holes are connected to the groove, and the total area of ​​the plurality of through holes is S3mm 2 The area of ​​the pressure relief member facing the bottom wall is S4mm 2 , satisfying: 1≤S3 / S4≤3.

[0019] In some embodiments, the through hole and the pressure relief member further satisfy at least one of the following features:

[0020] (e) 50 ≤ S3 ≤ 6000;

[0021] (f)50≤S4≤2000.

[0022] In some embodiments, the through hole and the pressure relief member further satisfy at least one of the following features:

[0023] (g) 50 ≤ S3 ≤ 3000;

[0024] (h)50≤S4≤1500.

[0025] Accordingly, a battery pack described in an embodiment of the present application includes a secondary battery as described in any one of the aforementioned embodiments.

[0026] Accordingly, an electrical device described in an embodiment of the present application includes a secondary battery as described in any one of the aforementioned embodiments, or a battery pack as described in the aforementioned embodiments.

[0027] Beneficial effect: Compared with the prior art, a secondary battery in an embodiment of the present application has a first direction and a second direction intersecting each other, and includes a shell, an electrode assembly and a top cover assembly, the shell has a accommodating cavity, the electrode assembly is arranged in the accommodating cavity, the top cover assembly includes a top cover sheet and a lower insulating member, the top cover sheet is connected to the shell and covers the accommodating cavity, the lower insulating member is located in the accommodating cavity and connected to the top cover sheet; the top cover sheet is provided with a pressure relief member, and the positive projection of the pressure relief member on the lower insulating member along the first direction is located in the groove; the lower insulating member has a bottom wall and a side wall, the bottom wall is spaced from the pressure relief member along the first direction, the side wall is connected to the peripheral side of the bottom wall to form a groove, and the positive projection of the pressure relief member on the lower insulating member along the first direction is located in the groove; an exhaust channel is provided on the side wall and penetrates the side wall along the second direction; along the second direction, there is a gap between the side wall and the shell, and the exhaust channel is connected to the gap and the groove respectively; the size of the gap along the second direction is e mm, and the size of the exhaust channel along the first direction is a mm, satisfying: 1≤e / a≤4. The present application provides an exhaust channel on the side wall on the lower insulating member, the exhaust channel faces the shell, and the exhaust channel is connected to the accommodating chamber through the gap between the side wall and the shell. In this way, when the secondary battery is abnormally exhausted, the exhaust channel can be prevented from being blocked by the electrode assembly, and a flow path for the thermal runaway gas is provided, so that the thermal runaway gas can smoothly reach the pressure relief part, and the pressure relief part can be opened to smoothly release the pressure; when the range of 1≤e / a≤4 is met, the size of the gap and the exhaust channel is within a reasonable range, ensuring that a large amount of thermal runaway gas can be quickly discharged from the exhaust channel into the groove and act on the pressure relief part, so that the pressure relief part is opened and quickly releases pressure. In addition, within this range, the secondary battery can also be guaranteed to have a good cycle life.

[0028] Compared with the prior art, a battery pack according to an embodiment of the present application includes a secondary battery according to any one of the aforementioned embodiments. It is understandable that the battery pack according to the embodiment of the present application includes all the technical features and technical effects of the aforementioned secondary batteries, which will not be described in detail here.

[0029] Compared with the prior art, an electric device in an embodiment of the present application includes a secondary battery as in any one of the aforementioned embodiments, or a battery pack as in the aforementioned embodiments. It is understandable that the electric device in an embodiment of the present application includes all the technical features and technical effects of the aforementioned secondary battery, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 is a schematic diagram of the overall structure of a secondary battery in an embodiment of the present application;

[0032] Figure 2 is an exploded diagram of a secondary battery according to an embodiment of the present application;

[0033] Figure 3 is a side view of a secondary battery along a second direction according to an embodiment of the present application;

[0034] Figure 4 is a side view of a top cover assembly along a second direction according to an embodiment of the present application;

[0035] Figure 5 yes Figure 3 Sectional view of the AA section;

[0036] Figure 6 is a schematic structural diagram of a lower insulating member according to an embodiment of the present application;

[0037] Figure 7 is a side view of a lower insulating member along a second direction of an embodiment of the present application;

[0038] Figure 8 is a bottom view of a lower insulating member in which the through hole is circular in an embodiment of the present application along a first direction;

[0039] Fig. 9 is a bottom view of a lower insulating member with a square through hole in an embodiment of the present application along a first direction;

[0040] Fig.10 is a bottom view of a lower insulating member in which a through hole is diamond-shaped in an embodiment of the present application along a first direction;

[0041] Fig.11 is a schematic diagram of the flow direction of the thermal runaway gas when the exhaust passage of the embodiment of the present application does not penetrate the side wall toward the top cover sheet along the first direction;

[0042] Fig.12 It is a schematic diagram of the flow direction of thermal runaway gas when the exhaust channel of an embodiment of the present application penetrates the side wall along the first direction toward the side of the top cover sheet.

[0043] Figure numerals: 1, shell; 11, accommodating chamber; 2, electrode assembly; 3, top cover assembly; 31, top cover sheet; 311, pressure relief member; 32, lower insulating member; 321, groove; 3211, side wall; 3212, bottom wall; 322, exhaust channel; 323, through hole; 4, gap; Z, first direction; Y, second direction; X, third direction. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0045] In the description of the present application, it should be understood that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "multiple" means two or more, and at least one means one, two or more, unless otherwise clearly and specifically defined. In the description of this application, "vertical" means completely vertical at 90° or almost completely vertical, for example, an angle within the range of 80° to 100° is considered vertical. Similarly, "parallel" means completely parallel or almost completely parallel, for example, an angle within 10° of completely parallel is considered parallel.

[0046] It should also be noted that in the drawings of the present application, the arrow marked Z indicates the first direction Z, the arrow marked Y indicates the second direction Y, and the arrow marked X indicates the third direction X. The first direction Z, the second direction Y, and the third direction X are introduced to facilitate the description of the structural position relationship of the secondary battery, and thus facilitate the understanding of its structure. In the embodiment of the present application, the first direction Z is the height direction of the secondary battery, the second direction Y is the width direction of the secondary battery, and the third direction X is the length direction of the secondary battery; and the first direction Z, the second direction Y, and the third direction X intersect with each other, and further, the first direction Z, the second direction Y, and the third direction X are perpendicular to each other.

[0047] As the main power source for new energy vehicles, power batteries have become one of the key components of electric vehicles. Power batteries are usually composed of multiple secondary batteries, among which the top cover assembly of the secondary battery has a significant impact on the energy density, economy and safety of the secondary battery. The top cover assembly is provided with an explosion-proof valve, the purpose of which is to be able to open and release the internal pressure in time to prevent the secondary battery from exploding when the internal pressure increases sharply due to abnormal gas production inside the secondary battery. At the same time, in order to ensure the internal insulation of the secondary battery, an insulating member is set between the top cover sheet and the electrode assembly for insulation. However, the setting of the lower insulating member will hinder the transmission of gas to the explosion-proof valve when the secondary battery produces abnormal gas, which will prevent the explosion-proof valve from being able to release pressure in time and there is a risk of explosion.

[0048] In view of this, an embodiment of the present application provides a secondary battery to solve the above problems.

[0049] Please refer to Figure 1-Figure 7 A secondary battery provided in an embodiment of the present application has a first direction Z and a second direction Y intersecting each other, including a shell 1, an electrode assembly 2 and a top cover assembly 3, the shell 1 has a receiving cavity 11, the electrode assembly 2 is arranged in the receiving cavity 11, the top cover assembly 3 includes a top cover sheet 31 and a lower insulating member 32, the top cover sheet 31 is connected to the shell 1 and covers the receiving cavity 11, the lower insulating member 32 is located in the receiving cavity 11 and connected to the top cover sheet 31; the top cover sheet 31 is provided with a pressure relief member 311, the lower insulating member 32 has a bottom wall 3212 and a side wall 3211, and the bottom wall 3212 is along the first direction Z is spaced apart from the pressure relief member 311, the side wall 3211 is connected to the peripheral side of the bottom wall 3212 to enclose a groove 321, and the orthographic projection of the pressure relief member 311 on the lower insulating member 32 along the first direction Z is located in the groove 321; an exhaust channel 322 is provided on the side wall 3211 and penetrates the side wall 3211 along the second direction Y, and the exhaust channel 322 penetrates the side wall 3211 along the second direction Y; along the second direction Y, there is a gap 4 between the side wall 3211 and the shell 1, and the exhaust channel 322 is connected to the gap 4 and the groove 321 respectively; the size of the gap 4 along the second direction Y is e mm, and the size of the exhaust channel 322 along the first direction Z is a mm, satisfying: 1≤e / a≤4.

[0050] In the embodiment of the present application, the secondary battery is provided with an exhaust channel 322 on the side wall 3211 on the lower insulating member 32, the exhaust channel 322 faces the shell 1, and the exhaust channel 322 is connected with the accommodating chamber 11 through the gap 4 between the side wall 3211 and the shell 1. In this way, when the secondary battery is abnormally exhausted, the exhaust channel 322 can be prevented from being blocked by the electrode assembly 2 and a flow path for the thermal runaway gas can be provided, so that the thermal runaway gas can smoothly reach the pressure relief member 311, and the pressure relief member 311 can be opened to smoothly release the pressure. In addition, within this range, the secondary battery can also be guaranteed to have a good cycle life.

[0051] Please refer to Figure 2 , Figure 4 , Figure 5 , Figure 6 and Figure 7 ,in Figure 6 and Figure 7 It is shown that the lower insulating member 32 of the embodiment of the present application is provided with a groove 321, wherein the groove 321 is used to provide a gas-containing space and prevent the lower insulating member 32 from squeezing the pressure relief member 311, and also facilitate the thermal runaway gas to directly act on the pressure relief member 311 in the groove 321 so that the pressure relief member 311 is opened for pressure relief. An exhaust channel 322 is provided on the side wall 3211, which can provide a path for the thermal runaway gas to flow into the groove 321 when the electrode assembly 2 produces gas abnormally (i.e., produces thermal runaway gas). Among them, the opening of the groove 321 faces the pressure relief member 311, and at this time, the exhaust channel 322 located on the side wall 3211 will not be blocked by the electrode assembly 2. The exhaust channel 322 faces the shell 1 of the secondary battery, and there is a gap 4 between the side wall 3211 and the shell 1, so that the exhaust channel 322 will be connected to the gap 4, and the lower insulating member 32 is located in the accommodating chamber 11, therefore, the gap 4 is connected to the accommodating chamber 11, and the electrode assembly 2 is arranged in the accommodating chamber 11, so the thermal runaway gas generated by the abnormal gas production of the electrode assembly 2 will also accumulate in the accommodating chamber 11. At this time, when the internal pressure of the secondary battery continues to increase, the thermal runaway gas will enter the groove 321 from the accommodating chamber 11 through the gap 4 and the exhaust channel 322, and directly act on the pressure relief member 311. When the pressure reaches a certain value, the pressure relief member 311 can be opened and the thermal runaway gas can be discharged in time to relieve the pressure to avoid explosion of the secondary battery.

[0052] It should also be noted that the exhaust channel 322 of the embodiment of the present application not only penetrates the side wall 3211 along the second direction Y, but also penetrates the side wall 3211 along the first direction Z toward the side of the top cover sheet 31 to form a U-shaped exhaust groove. At this time, on the one hand, the process difficulty can be reduced, which is convenient for the molding and manufacturing of the lower insulating part 32, and at the same time, it can reduce the obstruction of the flow path of the thermal runaway gas, so that the thermal runaway gas can reach the groove 321 more quickly and act on the pressure relief part 311 to open the pressure relief part 311. Specifically, the thermal runaway gas generated by the abnormal gas production of the electrode assembly 2 flows from the accommodating cavity 11 to the gap 4. After reaching the top cover sheet 31, the airflow is blocked by the top cover sheet 31 and the shell 1 and turns to flow into the exhaust channel 322. Since the exhaust channel 322 passes through the side wall 3211 facing the top cover sheet 31, the airflow that is changed in direction by the top cover sheet 31 and the shell 1 loses part of the obstruction of the side wall 3211 and will directly turn to enter the exhaust channel 322, so that the airflow can reach the groove 321 more quickly for pressure relief, which can further increase the pressure relief rate and reduce the possibility of explosion of the secondary battery.

[0053] Specifically, Fig.11 As shown, when the exhaust channel 322 only penetrates the side wall 3211 along the second direction Y but does not penetrate the side of the side wall 3211 toward the top cover sheet 31 along the first direction Z, part of the thermal runaway gas will hit the top cover sheet 31 along the first direction Z and be blocked by the top cover sheet 31, and cooperate with the shell 1 to turn the airflow, but after turning, it will still be blocked by the side wall 3211, and further turn until it flows to the exhaust channel 322, passes through the exhaust channel 322 and enters the groove 321, and finally acts on the pressure relief member 311 to open the pressure relief member 311 for pressure relief. Figure 4 , Figure 6 , Figure 7 and Fig.12 When the exhaust channel 322 is a U-shaped exhaust groove, part of the thermal runaway gas impacts the top cover sheet 31 along the first direction Z and is blocked by the top cover sheet 31, and the airflow is diverted by the shell 1. At this time, the airflow flows directly to the exhaust channel 322 without the obstruction of the side wall 3211, and passes through the exhaust channel 322 and enters the groove 321, and finally acts on the pressure relief member 311 to open the pressure relief member 311 for pressure relief. In this way, the pressure relief can be carried out more quickly, the pressure relief rate can be increased, and the possibility of secondary battery explosion can be further reduced.

[0054] Furthermore, in the embodiment of the present application, the dimension a mm of the exhaust channel 322 along the first direction Z is used to limit the opening width of the exhaust channel 322, and the dimension e mm of the gap 4 along the second direction Y is used to limit the width of the gap 4. It should be further explained that the normal pressure relief of the pressure relief member 311 requires the air pressure inside the secondary battery to reach the preset opening air pressure value before the pressure relief is opened. Directly setting the exhaust channel 322 and the gap 4 to be connected can enable the thermal runaway gas to reach the groove 321 through the gap 4 and the exhaust channel 322 and act on the pressure relief member 311. If the opening width of the exhaust channel 322 is too small or the gap 4 is too narrow, the thermal runaway gas cannot quickly reach the pressure relief member 311 for pressure relief, and may still cause an explosion.

[0055] It should be noted that when the secondary battery is inverted for use, the lower insulating member 32 supports the electrode assembly 2. At this time, the bottom wall 3212 is used to abut against the electrode assembly 2. When the size of the exhaust channel 322 remains unchanged, if the gap 4 is larger, the corresponding e / a value is also larger. At this time, the supporting area of ​​the bottom wall 3212 for the electrode assembly 2 is smaller, which will affect the cycle life of the battery. Therefore, the embodiment of the present application sets e and a to satisfy 1≤e / a≤4, where the numerical range of e / a can be any one of 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.3, 2.5, 2.8, 3, 3.2, 3.5, 3.6, 3.7, 3.8, 3.9, 4 or the range between any two values. When the exhaust channel 322 and the gap 4 satisfy the range of 1≤e / a≤4, the size of the gap 4 and the exhaust channel 322 is within a reasonable range, ensuring that a large amount of thermal runaway gas can be quickly discharged from the exhaust channel 322 into the groove 321 and act on the pressure relief member 311, so that the pressure relief member 311 opens and quickly releases pressure. When e / a<1, the width of the gap 4 along the second direction Y is smaller than the width of the exhaust channel 322 along the first direction Z. The bottleneck of airflow is at the gap 4 position, and there will be a problem that the airflow rate is too slow to relieve pressure; when e / a>4, the size of the lower insulating member 32 in the second direction Y is too small. When the secondary battery is used upside down, there is a risk that the lower insulating member 32 does not have enough support area for the electrode assembly 2, thereby affecting the cycle life of the secondary battery.

[0056] Further, the dimension a mm of the exhaust channel 322 along the first direction Z further satisfies: 0.5≤a≤5, and the dimension e mm of the gap 4 along the second direction Y further satisfies: 0.5≤e≤10. The numerical range of a can be any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5, or a range between any two values. The numerical range of e can be any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, or a range between any two values.

[0057] like Figure 4 As shown, in some embodiments, along the first direction Z, the size of the side wall 3211 is b mm, satisfying: 0.5≤ba≤10.

[0058] It can be understood that the size of the side wall 3211 can be the size in the first direction Z at a position where the exhaust channel 322 is not provided on the side wall 3211 or the size in the first direction Z before the exhaust channel 322 is provided on the side wall 3211 .

[0059] It is understandable that in the embodiment of the present application, the range of ba can be any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10 or the range between any two values. When 0.5≤ba≤10 is satisfied, it can be ensured that when the size of the gap 4 between the side wall 3211 and the shell 1 is reasonable, it can be ensured that the thermal runaway gas can enter the groove 321 from the exhaust channel 322 and quickly open the pressure relief member 311. When ba<0.5, not only is the manufacturing difficulty great, the thickness of the lower plastic wall is too small, and the lower plastic is easily damaged under the vibration of the vehicle condition, and the corresponding side wall 3211 and the lower insulating member 32 have low overall support strength, and are prone to deformation risks, which affects the safety of the secondary battery when used in an inverted manner. When ba>10, at this time, either the exhaust effect of the exhaust channel 322 is sacrificed, or there is a corresponding risk of failure to release pressure smoothly; if the exhaust effect of the exhaust channel 322 is to be guaranteed, the corresponding size of the side wall 3211 along the first direction Z is relatively large, which will occupy too much space inside the secondary battery, resulting in a reduction in the volume of the electrode assembly 2, and a corresponding reduction in the capacity of the secondary battery.

[0060] It should be noted that, in the embodiment of the present application, there can be one or more exhaust channels 322. When there are multiple exhaust channels 322, the difference between the size of the side wall 3211 along the first direction Z and the size of each exhaust channel 322 along the first direction Z can be smaller or larger. If multiple exhaust channels 322 are arranged along the third direction X, each exhaust channel 322 can occupy a larger size range of the side wall 3211 in the first direction Z. At this time, the size of the exhaust channel 322 can be larger, which is more convenient for exhausting thermal runaway gases. If there is only one exhaust channel 322, it is more preferred that the difference between the size of the exhaust channel 322 in the first direction Z and the size of the side wall 3211 in the first direction Z is smaller, so that a better exhaust effect can be ensured. If there are multiple exhaust channels 322 arranged along the first direction Z, the difference between the size of each exhaust channel 322 in the first direction Z and the size of the side wall 3211 in the first direction Z can be larger. At this time, multiple exhaust channels 322 cooperate with each other to achieve a better exhaust effect.

[0061] In some embodiments, the dimension a mm of the exhaust channel 322 of the lower insulating member 32 along the first direction Z further satisfies 0.5≤a≤5. The value of a may be any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or a range between any two values. If the dimension a of the exhaust channel 322 along the first direction Z is too large, the overall processing difficulty of the lower insulating member 32 may be too large, and even the supporting strength of the lower insulating member 32 may be deteriorated, causing the lower insulating member 32 to be easily deformed, thereby affecting the safety performance of the secondary battery. If the dimension a of the exhaust channel 322 along the first direction Z is too small, the exhaust effect may be unsatisfactory, the pressure cannot be released smoothly, and even the secondary battery may explode.

[0062] In some embodiments, the dimension b mm of the side wall 3211 of the lower insulating member 32 along the first direction Z further satisfies: 1≤b≤15. The value of b can be any one of 1, 1.1, 1.2, 1.3, 1.5, 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or a range between any two values. If the dimension b mm of the side wall 3211 along the first direction Z is too small, the dimension of the exhaust channel 322 along the first direction Z is limited to be smaller. At this time, no matter how the exhaust channel 322 is arranged, a good exhaust effect cannot be achieved, resulting in failure to release pressure normally when the secondary battery is thermally runaway. The dimension b mm of the side wall 3211 along the first direction Z is too large. At this time, there can be a variety of layout schemes for the exhaust channel 322, all of which can achieve a good exhaust effect, but it will occupy more internal space of the secondary battery, resulting in a smaller overall volume of the electrode assembly 2, resulting in a smaller overall capacity of the secondary battery, affecting the volume energy density of the secondary battery.

[0063] like Figure 4 As shown, in some embodiments, there is a third direction X intersecting the first direction Z and the second direction Y respectively. Along the third direction X, the size of the exhaust channel 322 is c mm, satisfying: 0.5≤c≤10.

[0064] In the embodiment of the present application, the numerical range of the dimension c mm of the exhaust channel 322 along the third direction X can be any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, and 10, or the range between any two values. If the dimension c of the exhaust channel 322 along the third direction X is too small, that is, c<0.5, when there is only one exhaust channel 322, the pressure relief area of ​​the exhaust channel 322 is too small. When there are multiple exhaust channels 322, since the dimension of each exhaust channel 322 along the third direction X is too small, the problem that the total area of ​​the multiple exhaust channels 322 is still small is that the total area of ​​the multiple exhaust channels 322 is small. Therefore, if the dimension of the exhaust channel 322 along the third direction X is too small, it cannot play the role of exhaust and pressure relief, and there is a risk of explosion of the secondary battery. If the dimension c of the exhaust channel 322 along the third direction X is too large, that is, c>10, at this time, the part of the exhaust channel 322 surrounded by the side wall 3211 along the first direction Z is suspended, and the suspended dimension is too large, the mechanical strength is low, and the supporting strength is poor. Under the working condition of the inverted application of the secondary battery, the electrode assembly 2 squeezes the lower insulating member 32 under the action of gravity, and the lower insulating member 32 is prone to deformation, causing the exhaust channel 322 to deform or partially close, and the expected ventilation and pressure relief effect cannot be achieved. In severe cases, the lower insulating member 32 will be mechanically damaged and fail.

[0065] like Figure 5 As shown, in some embodiments, along the second direction Y, the minimum dimension between the side wall 3211 and the pressure relief member 311 is f mm, and the minimum distance between the pressure relief member 311 and the housing 1 is d mm, satisfying: 1≤df≤5.

[0066] In the embodiment of the present application, the side wall 3211 is used to enclose the groove 321, and the side wall 3211 is preferably located between the pressure relief member 311 and the shell 1. At this time, the positive projection of the pressure relief member 311 along the first direction Z on the lower insulating member 32 can be completely within the groove 321, so as to avoid blocking the pressure relief member 311, thereby achieving the thermal runaway gas to fully act on the pressure relief member 311, thereby facilitating the opening of the pressure relief member 311 for pressure relief when the internal pressure of the secondary battery reaches a certain value.

[0067] It should be noted that the minimum dimension f mm between the side wall 3211 and the pressure relief member 311 along the second direction Y and the minimum distance d mm between the pressure relief member 311 and the housing 1 along the second direction Y of the embodiment of the present application satisfy: 1≤df≤5, which can ensure that the pressure relief member 311 releases pressure smoothly, and is conducive to reserving a sufficient gap 4 width to allow the exhaust channel 322 to ventilate smoothly, and also ensure that the lower insulating member 32 has a sufficient support area when the secondary battery is used inverted, thereby ensuring the stable performance of the secondary battery. Among them, the numerical range of df can be any one of 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.2, 2.5, 2.8, 3, 3.5, 4, 4.5, 5 or the range between any two values. If df < 1, the corresponding gap 4 between the side wall 3211 and the shell 1 is small, so that the exhaust channel 322 cannot be ventilated smoothly. At the same time, the wall thickness of the side wall 3211 itself is small, and the overall support is poor. When the secondary battery is used upside down, the lower insulating member 32 is prone to deformation, and even mechanical damage and failure of the lower insulating member 32 may occur. There may also be problems that the battery cannot be produced normally due to assembly interference. If df > 5, the corresponding size of the lower insulating member 32 in the second direction Y is too small. When the secondary battery is used upside down, the lower insulating member 32 has insufficient support area for the electrode assembly 2. Under vehicle vibration, the lower plastic causes the diaphragm to collapse, and the pole piece will short-circuit, affecting the performance and safety of the secondary battery.

[0068] Further, the minimum dimension f mm between the side wall 3211 and the pressure relief member 311 along the second direction Y further satisfies: 1≤f≤45, and the minimum distance d mm between the pressure relief member 311 and the housing 1 along the second direction Y further satisfies: 2≤d≤50. The numerical range of f can be any one of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 35, 40, 45, or a range between any two values. The numerical range of d can be any one of 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 35, 40, 45, or a range between any two values.

[0069] It should also be noted that in the above embodiment, some commonly used dimension measurement methods can be selected to measure any one of the dimensions a, b, c, d, e, and f. For example, a ruler, a micrometer, a vernier caliper, or other measuring tools can be used to measure the corresponding dimensions. Alternatively, a projection method can be used to measure, using a projection measurement device (such as a digital microscope or an image measuring instrument) to obtain an image of the exhaust passage 322 and measure the corresponding dimensions.

[0070] In some embodiments, the side wall 3211 is provided with a plurality of exhaust channels 322, and the total opening area of ​​the plurality of exhaust channels 322 is S1 mm.2 The area of ​​the side wall 3211 along the second direction Y toward the housing 1 after removing the multiple exhaust channels 322 is S2mm 2 , satisfying: 0.5≤S1 / S2≤5.

[0071] In the embodiment of the present application, the notch area of ​​the groove 321 is preferably larger than the area of ​​the pressure relief member 311, so as to avoid affecting the smooth pressure relief of the pressure relief member 311. The larger the total opening area of ​​the exhaust channel 322, the better the corresponding ventilation effect, so that better and faster ventilation can be achieved, and then the pressure relief member 311 can be quickly relieved. However, the exhaust channel 322 is opened on the side wall 3211, so the total opening area of ​​the exhaust channel 322 needs to be constrained by the side wall 3211. Among them, when the total opening area S1 of multiple exhaust channels 322 and the remaining area S2 of the side wall 3211 after removing the exhaust channel 322 meet the range of 0.5≤S1 / S2≤5, the support of the lower insulating member 32 and the ventilation effect of the exhaust channel 322 can be guaranteed.

[0072] It should be noted that in the embodiments of the present application, the numerical range of S1 / S2 can be any value among 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, or the range between any two values. Among them, if the ratio of S1 / S2 is too small, the total opening area of ​​the exhaust channel 322 is too small, and the air permeability and pressure relief effect is relatively weak at this time; if the ratio of S1 / S2 is too large, the total opening area of ​​the corresponding exhaust channel 322 is larger, and the corresponding remaining area of ​​the side wall 3211 is smaller, and the corresponding side wall 3211 area for contacting with the top cover sheet 31 to play a supporting role is smaller, resulting in low mechanical strength of the lower insulating member 32. When the secondary battery is used in an inverted manner, the lower insulating member 32 may be deformed by the gravity of the electrode assembly 2, so that the total opening area of ​​the exhaust channel 322 on the side wall 3211 becomes smaller or partially closed, resulting in weak air permeability and pressure relief effect. In severe cases, the lower insulating member 32 may be mechanically damaged and fail.

[0073] Furthermore, the total opening area of ​​the plurality of exhaust passages 322 is S1 mm 2 Further satisfying: 50≤S1≤2000, the area of ​​the side wall 3211 excluding the plurality of exhaust passages 322 along the second direction Y toward the housing 1 is S2 mm 2Further satisfying: 50≤S2≤800. Wherein, the numerical range of S1 can be any one of 50, 60, 70, 80, 90, 100, 150, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 2000 or the range between any two values. The numerical range of S2 can be any one of 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 700, 800 or the range between any two values. Wherein, the larger S1 is, the better the corresponding exhaust effect is, and the smaller S2 is, the lower the mechanical strength of the corresponding lower insulating member 32 is.

[0074] In some embodiments, the bottom wall 3212 is provided with a plurality of through holes 323, and the plurality of through holes 323 are all connected to the groove 321, and the total area of ​​the plurality of through holes 323 is S3mm. 2 The area of ​​the pressure relief member 311 facing the bottom wall 3212 is S4 mm 2 , satisfying: 1≤S3 / S4≤3.

[0075] In the embodiment of the present application, not only is ventilation and pressure relief performed through the exhaust channel 322, but multiple through holes 323 may also be provided on the bottom wall 3212, and ventilation is performed through the through holes 323, thereby achieving a better ventilation effect of the lower insulating member 32. Even when the battery is used upside down, the electrode assembly 2 is pressed on the bottom wall 3212 under the action of gravity, which may cause blockage of some through holes 323, or some through holes 323 may be able to be smoothly ventilated, and combined with the exhaust channel 322, a better ventilation and pressure relief effect can be achieved.

[0076] It should be noted that, in the embodiment of the present application, the numerical range of S3 / S4 can be any one of 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3 or the range between any two values. Among them, if the ratio of S3 / S4 is too small, the total area of ​​the exhaust through hole 323 is smaller than the area of ​​the pressure relief member 311. At this time, the air permeability of the exhaust through hole 323 is low, especially when the secondary battery is used upside down, the exhaust through hole 323 may be completely blocked by the electrode assembly 2, resulting in no air permeability; if the ratio of S3 / S4 is too large, the corresponding area of ​​metal leakage is also increased accordingly, thereby increasing the risk of metal foreign matter overlapping the top cover sheet 31 and the electrode assembly 2, causing short circuit failure.

[0077] In some embodiments, the through hole 323 and the pressure relief member 311 further satisfy at least one of the following characteristics: 50≤S3≤6000; 50≤S4≤2000. The value of S3 may be any one of 50, 60, 70, 80, 100, 200, 300, 400, 500, 800, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000 or a range between any two values. The larger the value of S3, the better the air permeability of the corresponding plurality of exhaust through holes 323, which is more conducive to air permeability and pressure relief. However, when S3 is less than 50, the corresponding air permeability is low, which is not conducive to exhaust and pressure relief. When S3 is greater than 6000, more metal area will be exposed, and there is a risk that metal foreign matter can easily overlap the top cover sheet 31 and the electrode assembly 2 through the through hole 323, causing insulation failure. The value of S4 can be any one of 50, 60, 70, 80, 100, 200, 300, 400, 500, 800, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000 or a range between any two values. The larger the value of S4, the faster the thermal runaway gas can be discharged from the outside of the secondary battery when the pressure relief member 311 explodes, and the higher the pressure relief efficiency. However, if S4 is too large, the side wall 3211 will not have enough space to be set, which will cause the overall support of the lower insulating member 32 to deteriorate when the secondary battery is used upside down. When the electrode assembly 2 is squeezed by gravity, the lower insulating member 32 is easily deformed, and even the lower insulating member 32 is mechanically damaged, resulting in the risk of insulation failure; if S4 is too small, the pressure release will be too slow, and the safety performance of the secondary battery cannot be guaranteed. Furthermore, the through hole 323 and the pressure relief member 311 further meet at least one of the following characteristics: 50≤S3≤3000; 50≤S4≤1500.

[0078] Please refer to Figure 8-Figure 10 , wherein the through hole 323 can be a circular hole, an elliptical hole, a square hole, a diamond hole, etc., all of which can achieve smooth exhaust of the bottom wall 3212 of the groove 321.

[0079] Accordingly, the embodiment of the present application further provides a battery pack, including a secondary battery as in any one of the above embodiments. It is understandable that the battery pack of the embodiment of the present application includes all the technical features and technical effects of the above secondary batteries, which will not be repeated here.

[0080] Of course, the battery pack referred to in this application may be a battery module, or an integrated battery pack without a module.

[0081] Accordingly, the embodiment of the present application further provides an electric device, including a secondary battery as in any one of the aforementioned embodiments or a battery pack as in the aforementioned embodiments, the secondary battery or the battery pack is used to power the electric device. It is understandable that the electric device of the embodiment of the present application includes all the technical features and technical effects of the aforementioned secondary battery, which will not be repeated here.

[0082] Of course, the electrical devices referred to in this application may be application devices such as vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys and electric tools. Vehicles may be new energy vehicles, which may be pure electric vehicles, hybrid electric vehicles or extended-range vehicles, etc.; spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc.; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc. The embodiments of this application do not impose any special restrictions on the above-mentioned electrical devices.

[0083] The secondary battery of the present application is described in detail below with reference to specific embodiments.

[0084] Table 1-1

[0085]

[0086] Table 1-2

[0087]

[0088] Please refer to Table 1-1 and Table 1-2 above. It can be seen from the above embodiments and comparative examples that when the dimension a of the exhaust channel 322 along the first direction Z and the dimension e of the gap 4 along the second direction Y satisfy: 1≤e / a≤4, the secondary battery can be normally decompressed and exhausted during thermal runaway. Among them, when a is 0.5≤a≤5 and e is 0.5≤e≤10, the battery pressure relief and cycle life are normal, and there will be no assembly interference and mechanical damage. However, when a is 0.4, the cycle life is reduced. When a is 10, it will affect the pressure relief and even explode. When e is 0.2, the battery thermal runaway will delay the valve opening, and there will be a risk of explosion. When e is 20, the battery cycle life will be reduced. Therefore, the value range of a is preferably 0.5≤a≤5, and the value range of e is preferably 0.5≤e≤10. Under the condition of maintaining 1≤e / a≤4, if the minimum distance d between the pressure relief member 311 and the shell 1 along the second direction Y and the minimum dimension f between the side wall 3211 and the pressure relief member 311 along the second direction Y can satisfy 1≤df≤5, then the support area of ​​the lower insulating member 32 on the electrode assembly 2 when the secondary battery is used inverted can be further guaranteed, thereby maintaining the performance of the secondary battery, that is, ensuring the cycle life of the secondary battery when used inverted. Under the condition of maintaining 1≤e / a≤4, further making 0.5≤S1 / S2≤5, at this time, while ensuring the normal exhaust and pressure relief of the battery, it can ensure that the lower insulating member 32 will not be mechanically damaged by the gravity of the electrode assembly 2 when the battery is used inverted. Under the condition of maintaining 1≤e / a≤4, further making 1≤S3 / S4≤3, at this time, while ensuring the normal exhaust and pressure relief of the battery, it can prevent metal foreign matter from overlapping the top cover sheet 31 and the electrode assembly 2 through the exhaust through hole 323 to cause short circuit failure.

[0089] It should be noted that the normal pressure relief of the secondary battery shown in Table 1-1 and Table 1-2 above means that before the weld between the top cover sheet 31 and the shell is damaged, the pressure relief piece 311 (explosion-proof valve) is opened to achieve pressure relief. The reason why the pressure relief cannot be achieved in the comparison is that the area of ​​air conduction to the pressure relief piece 311 (explosion-proof valve) is insufficient, resulting in a slow speed of air flow to the pressure relief piece 311, so that the air pressure in the secondary battery has actually reached the opening pressure of the pressure relief piece 311 (explosion-proof valve), but has not yet been transmitted to the explosion-proof valve, and the weld between the top cover sheet 31 and the shell has been damaged (commonly known as explosion) due to excessive internal air pressure. For example, the valve opening pressure value of the secondary battery pressure relief part 311 is usually 0.9±0.2Mpa. The secondary battery opens the valve to release pressure within this internal pressure range. If the pressure relief part 311 (explosion-proof valve) is opened to release pressure, it is delayed pressure release. If the pressure relief part 311 (explosion-proof valve) is opened to release pressure, it is an explosion. The specific test method is: fix the large surface of the secondary battery with a clamp, process the vent hole on the secondary battery, use a digital display press to pressurize the vent hole until the pressure relief part 311 (explosion-proof valve) opens, and record the pressure value on the press. This is the pressure relief pressure value of the battery.

[0090] It should also be noted that whether the batteries in Tables 1-1 and 1-2 above cannot be produced normally due to assembly interference, wherein df is the distance between the side of the side wall 3211 close to the pressure relief member 311 and the shell 1, and this value includes the wall thickness of the side wall 3211. If df is too small, the lower insulating member 32 will interfere with the inner wall of the shell 1 during assembly into the shell and the assembly cannot be completed.

[0091] It should also be noted that when the secondary battery is used upside down, if the support area of ​​the lower insulating member 32 for the motor assembly is too small, the performance of the secondary battery will be reduced, and the battery cycle life will be reduced. For example, the normal cycle life is 2000 cycles. The specific test method for the cycle life is: at 25°C, the lithium-ion battery prepared in the embodiment and the comparative example is charged at a rate of 3C and discharged at a rate of 1C, and a full charge and discharge cycle test is performed until the capacity of the lithium-ion battery decays to 90% of the initial capacity, and the number of cycles is recorded.

[0092] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0093] The above is a detailed introduction to a secondary battery, a battery pack and an electrical device provided in the embodiments of the present application, and specific examples are used to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims

1. A secondary battery, characterized in that: Having an intersecting first direction and a second direction, comprising: A housing having a receiving cavity; An electrode assembly, disposed in the accommodating cavity; A top cover assembly comprises a top cover sheet and a lower insulating member, wherein the top cover sheet is connected to the shell and covers the accommodating cavity, and the lower insulating member is located in the accommodating cavity and connected to the top cover sheet; the top cover sheet is provided with a pressure relief member, and the lower insulating member has a bottom wall and a side wall, the bottom wall is spaced apart from the pressure relief member along the first direction, the side wall is connected to the peripheral side of the bottom wall to enclose a groove and form a boss, the side of the bottom wall facing the electrode assembly is a plane, and the positive projection of the pressure relief member on the lower insulating member along the first direction is located in the groove; an exhaust channel is provided on the side wall and passes through the side wall along the second direction; along the second direction, there is a gap between the side wall and the shell, and the exhaust channel is connected with the gap and the groove respectively; the exhaust channel passes through the side of the side wall facing the top cover sheet along the first direction; the size of the gap along the second direction is e mm, and the size of the exhaust channel along the first direction is a mm, satisfying: 1≤e / a≤4.

2. The secondary battery according to claim 1, characterized in that: Along the first direction, the size of the side wall is bmm, satisfying: 0.5≤ba≤10.

3. The secondary battery according to claim 2, characterized in that: The lower insulator further satisfies at least one of the following features: (a) 0.5≤a≤5; (b) 1≤b≤15.

4. The secondary battery according to claim 2, characterized in that: The lower insulator further satisfies at least one of the following features: (c) 1≤a≤3; (d)2≤b≤11.

5. The secondary battery according to claim 2, characterized in that: There is a third direction intersecting with the first direction and the second direction respectively. Along the third direction, the size of the exhaust channel is c mm, satisfying: 0.5≤c≤10.

6. The secondary battery according to claim 1, characterized in that: Along the second direction, the minimum dimension between the side wall and the pressure relief member is f mm, and the minimum distance between the pressure relief member and the shell is d mm, satisfying: 1≤df≤5.

7. The secondary battery according to claim 1, characterized in that: The side wall is provided with a plurality of exhaust channels, and the total opening area of ​​the plurality of exhaust channels is S1 mm 2 The area of ​​the side wall excluding the plurality of exhaust passages along the second direction toward the housing is S2 mm 2 , satisfying: 0.5≤S1 / S2≤5.

8. The secondary battery according to claim 1, characterized in that: The lower insulating member is provided with a plurality of through holes, the through holes passing through the bottom wall along the first direction and communicating with the groove, and the total area of ​​the plurality of through holes is S3 mm 2 The area of ​​the pressure relief member facing the bottom wall is S4 mm 2 , satisfying: 1≤S3 / S4≤3.

9. The secondary battery according to claim 8, characterized in that: The through hole and the pressure relief member further satisfy at least one of the following characteristics: (e) 50 ≤ S3 ≤ 6000; (f)50≤S4≤2000.

10. The secondary battery according to claim 8, characterized in that: The through hole and the pressure relief member further satisfy at least one of the following characteristics: (g) 50 ≤ S3 ≤ 3000; (h)50≤S4≤1500.

11. A battery pack, characterized in that: Comprising the secondary battery as claimed in any one of claims 1 to 10.

12. An electrical device, characterized in that: Comprising the secondary battery as described in any one of claims 1 to 10, or the battery pack as described in claim 11.

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