Secondary battery, battery pack, and electric device

Abstract

The utility model discloses a secondary battery, a battery pack and a power utilization device, the secondary battery comprises a shell, an electrode assembly and a top cover assembly, the shell is provided with a containing cavity, the electrode assembly is arranged in the containing cavity, the top cover assembly comprises a top cover piece and a lower insulating part, the top cover piece is connected with the shell and covers the containing cavity, and the top cover piece is provided with a first liquid injection hole; the lower insulating part is connected to the side, facing the electrode assembly, of the top cover piece, the lower insulating part comprises a body, a side plate and a baffle, the body is connected with the top cover piece, and the body is provided with a second liquid injection hole communicated with the first liquid injection hole; the side plate is connected to the side, away from the top cover piece, of the body, the baffle and the side plate are connected and spaced between the second liquid injection hole and the electrode assembly, the side plate is provided with a liquid outlet, and the liquid outlet is communicated with the second liquid injection hole; the overflowing area of the liquid outlet is S1, the outer surface area of the side plate is S2, and S1 / S2 is larger than or equal to 0.06 and smaller than or equal to 2. The diaphragm can be prevented from being folded, and the electrolyte injection efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a secondary battery, a battery pack and a power utilization device. BACKGROUND

[0002] In the production process of the secondary battery, electrolyte needs to be injected into the battery through an injection hole. During the injection of the electrolyte, the hydraulic pressure is large, so the impact on the electrode assembly in the battery is large, which is easy to cause the diaphragm of the electrode assembly to be folded, and further cause internal short circuit of the battery. CONTENT

[0003] The application provides a secondary battery, which aims to solve the problem that the diaphragm is easy to be folded during the injection of electrolyte, and further cause internal short circuit of the battery; another object of the application is to provide a battery pack; and still another object of the application is to provide a power utilization device.

[0004] TECHNICAL SCHEME The secondary battery provided by the application comprises:

[0005] a shell having a containing cavity;

[0006] an electrode assembly arranged in the containing cavity;

[0007] a top cover assembly comprising:

[0008] a top cover sheet connected with the shell and covering and sealing the containing cavity, the top cover sheet having a first injection hole;

[0009] a lower insulating piece connected to one side of the top cover sheet facing the electrode assembly; the lower insulating piece comprises:

[0010] a body connected with the top cover sheet, the body being provided with a second injection hole in communication with the first injection hole;

[0011] a side plate connected to one side of the body away from the top cover sheet;

[0012] a baffle connected to one side of the side plate away from the body, the baffle being spaced between the second injection hole and the electrode assembly, the side plate having a liquid outlet, the liquid outlet being in communication with the second injection hole;

[0013] wherein the flow area of the liquid outlet is S1 mm 2 , the outer surface area of the side plate is S2 mm 2 , and 0.06≤S1 / S2≤2 is met.

[0014] In some embodiments, the flow area of the liquid outlet and the outer surface area of the side plate meet 0.2≤S1 / S2≤0.4.

[0015] In some embodiments,

[0016] The flow area of the liquid outlet satisfies: 12≤S1≤100; and / or,

[0017] The outer surface area of the side plate satisfies: 50≤S2≤200.

[0018] In some embodiments,

[0019] The flow area of the liquid outlet satisfies: 20≤S1≤60; and / or,

[0020] The outer surface area of the side plate satisfies: 50≤S2≤150.

[0021] In some embodiments, the secondary battery has a first direction, the electrode assembly and the top cover assembly are arranged along the first direction, the electrode assembly includes a roll core and a tab, the tab is in electrically conductive connection with the roll core, the tab is arranged on a side of the roll core facing the top cover sheet; the baffle and the side plate enclose a cavity, the cavity is in communication with the liquid outlet and the second liquid injection hole respectively; along the first direction, the maximum size of the cavity is H1 mm, the distance between the side of the top cover sheet close to the lower insulating piece and the side of the roll core close to the lower insulating piece is H2 mm, and 0.14≤H1 / H2≤2.5 is satisfied.

[0022] In some embodiments,

[0023] The maximum size of the cavity satisfies: 1≤H1≤5; and / or,

[0024] The distance between the side of the top cover sheet close to the lower insulating piece and the side of the roll core close to the lower insulating piece satisfies: 2≤H2≤7.

[0025] In some embodiments, along the first direction, the maximum size of the baffle is H3 mm, and 0.5≤H3≤0.7 is satisfied.

[0026] In some embodiments, the maximum size of the cavity, the distance between the side of the top cover sheet close to the lower insulating piece and the side of the roll core close to the lower insulating piece, and the maximum size of the baffle further satisfy: H1+H3≤H2.

[0027] In some embodiments, the secondary battery has a second direction intersecting the first direction; the top cover assembly further comprises a pole post, a portion of the pole post protruding from a side of the body away from the top cover sheet; the lower insulating member further comprises an explosion-proof valve boss connected to the side of the body away from the top cover sheet; along the second direction, the side plate is disposed between the explosion-proof valve boss and the pole post, and the liquid outlet is disposed towards the pole post or the explosion-proof valve boss.

[0028] In some embodiments, the secondary battery has a third direction intersecting the first direction and the second direction respectively, the tab is conductively connected to the pole post, and along the third direction, the tab is disposed on a side of the side plate away from the cavity.

[0029] In some embodiments, the side plate has a plurality of liquid outlets, and the plurality of liquid outlets are spaced apart along a circumferential direction of the side plate; along the first direction, the liquid outlet penetrates through the side plate.

[0030] In some embodiments, the side plate has two liquid outlets, one of the two liquid outlets is disposed towards the pole post, and the other of the two liquid outlets is disposed towards the explosion-proof valve boss.

[0031] In some embodiments, the side of the baffle plate towards the second liquid injection hole is one of a planar surface, a circular arc surface protruding towards the second liquid injection hole, and a conical surface protruding towards the second liquid injection hole.

[0032] Correspondingly, the battery pack according to an embodiment of the present application comprises the secondary battery according to any one of the preceding embodiments.

[0033] Correspondingly, the power consumption device according to an embodiment of the present application comprises the secondary battery according to any one of the preceding embodiments or the battery pack according to the preceding embodiments.

[0034] Advantages: Compared with the prior art, the secondary battery according to an embodiment of the present application comprises a shell, an electrode assembly, and a top cover assembly, the shell has a receiving cavity, the electrode assembly is disposed in the receiving cavity, the top cover assembly comprises a top cover sheet and a lower insulating member, the top cover sheet is connected to the shell and covers and seals the receiving cavity, the top cover sheet has a first liquid injection hole; the lower insulating member is connected to a side of the top cover sheet facing the electrode assembly, the lower insulating member comprises a body, a side plate, and a baffle plate, the body is connected to the top cover sheet, the body is provided with a second liquid injection hole communicating with the first liquid injection hole; the side plate is connected to a side of the body away from the top cover sheet, the baffle plate is connected to a side of the side plate away from the body, the baffle plate is spaced apart between the second liquid injection hole and the electrode assembly, the side plate has a liquid outlet, and the liquid outlet communicates with the second liquid injection hole; wherein, the flow area of the liquid outlet is S1 mm 2 , and the outer surface area of the side plate is S2 mm 2, meet: 0.06≤S1 / S2≤2. The application sets the side plate connected with the baffle and the body, sets the liquid outlet on the side plate, sets the baffle opposite to the second liquid injection hole, realizes the baffle interval between the second liquid injection hole and the electrode assembly, and can block the electrolyte when electrolyte injection is carried out, so as to prevent the diaphragm from being folded caused by the direct impact of high-pressure electrolyte on the electrode assembly through the second liquid injection hole, and further improve the qualified rate of secondary battery production. In addition, the ratio of the flow area of the liquid outlet to the area of the outer surface of the side plate is 0.06≤S1 / S2≤2, which can ensure a faster injection rate, thereby improving the electrolyte injection efficiency, and thus improving the production efficiency of the secondary battery.

[0035] Compared with the prior art, the battery pack of the embodiment of the application comprises the secondary battery of any one of the preceding embodiments. It can be understood that the battery pack of the embodiment of the application comprises all the technical features and technical effects of the preceding secondary battery, which will not be described here.

[0036] Compared with the prior art, the power device of the embodiment of the application comprises the secondary battery of any one of the preceding embodiments, or the battery pack as described in the preceding embodiments. It can be understood that the power device of the embodiment of the application comprises all the technical features and technical effects of the preceding secondary battery or battery pack, which will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0038] Figure 1 is a schematic diagram of the overall structure of a secondary battery of the embodiment of the application;

[0039] Figure 2 is an exploded view of a secondary battery of the embodiment of the application;

[0040] Figure 3 is a sectional view of a secondary battery of the embodiment of the application along the first direction and the third direction;

[0041] Figure 4 is an enlarged view of part A in Figure 3

[0042] Figure 5 is a schematic diagram of the structure of a top cover assembly of a secondary battery of the embodiment of the application;

[0043] Figure 6 ​This is a cross-sectional view of a secondary battery according to an embodiment of this application along a first direction and a second direction;

[0044] Figure 7 yes Figure 6 Enlarged view of section B;

[0045] Figure 8 This is a cross-sectional view of a secondary battery along a second direction and a third direction, according to an embodiment of this application.

[0046] Reference numerals: 1. Housing; 11. Receiving cavity; 2. Electrode assembly; 21. Electrode tab; 22. Core; 3. Top cover assembly; 31. Top cover plate; 311. First liquid injection hole; 32. Lower insulating component; 321. Body; 3211. Second liquid injection hole; 322. Side plate; 3221. Liquid outlet; 323. Baffle; 324. Cavity; 325. Explosion-proof valve boss; 33. Electrode post; Z, First direction; X, Second direction; Y, Third direction. Detailed Implementation

[0047] 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.

[0048] 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 from 80° to 100° is considered perpendicular. Similarly, "parallel" means completely parallel or almost completely parallel, for example, the range of completely parallel angles from 10° is considered parallel.

[0049] It should be further noted that in the drawings of the present application, the arrow marked Z indicates the first direction Z, the arrow marked X indicates the second direction X, and the arrow marked Y indicates the third direction Y. The first direction Z, the second direction X and the third direction Y are introduced for the purpose of facilitating the description of the positional relationship of the structure of the secondary battery, and further facilitating the understanding of the structure. In the embodiments of the present application, the first direction Z is the height direction of the secondary battery, the second direction X is the length direction of the secondary battery, and the third direction Y is the width direction of the secondary battery; and the first direction Z, the second direction X and the third direction Z intersect with each other, and further, the first direction Z, the second direction X and the third direction Y are perpendicular to each other.

[0050] In the technical field of power batteries, in the production process of a secondary battery, electrolyte is usually injected into the interior of the secondary battery through a liquid injection hole provided in a top cover assembly of the secondary battery. The higher the injection efficiency of the electrolyte is, the higher the production efficiency of the battery is. However, in the current battery production process, in order to improve the liquid injection efficiency, the injection pressure of the electrolyte is usually large, which is easy to impact the diaphragm of the electrode assembly, causing the diaphragm to be folded, and the reduction of the injection pressure will result in the reduction of the injection efficiency of the electrolyte.

[0051] Therefore, the embodiments of the present application provide a secondary battery, a battery pack and an electric device, aiming at solving the above problems.

[0052] For a better understanding of the present application, please refer to Figures 1-5 The embodiments of the present application provide a secondary battery, which comprises 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, and the top cover assembly 3 comprises a top cover sheet 31 and a lower insulating piece 32. The top cover sheet 31 is connected with the shell 1 and covers and seals the receiving cavity 11, and the top cover sheet 31 has a first liquid injection hole 311. The lower insulating piece 32 is arranged between the top cover sheet 31 and the electrode assembly 2 and is connected with the top cover sheet 31. The lower insulating piece 32 comprises a body 321, a side plate 322 and a baffle 323. The body 321 is connected with the top cover sheet 31, and the body 321 is provided with a second liquid injection hole 3211 which is in communication with the first liquid injection hole 311. The side plate 322 is arranged on the side of the body 321 away from the top cover sheet 31 and is connected with the body 321. The baffle 323 is connected on the side of the side plate 322 away from the body 321, and the baffle 323 is spaced between the second liquid injection hole 3211 and the electrode assembly 2. The side plate 322 has a liquid outlet 3221 which is in communication with the second liquid injection hole 3211. The flow area of the liquid outlet 3221 is S1 mm 2 , the outer surface area of the side plate 322 is S2 mm 2 , and the following condition is met: 0.06≤S1 / S2≤2.

[0053] In the embodiment of the present application, the side plate 322 is connected with the baffle 323, and the liquid outlet 3221 is arranged on the side plate 322, the baffle 323 is arranged opposite to the second liquid injection hole 3211, the baffle 323 is arranged between the second liquid injection hole 3211 and the electrode assembly 2, and the electrolyte is blocked when the electrolyte is injected, so that the diaphragm is prevented from being folded due to the direct impact of the high-pressure electrolyte on the electrode assembly 2 through the second liquid injection hole 3211, and the qualified rate of the secondary battery production is improved. In addition, the ratio of the flow area of the liquid outlet 3221 to the area of the outer surface of the side plate 322 is 0.06≤S1 / S2≤2, which can ensure a faster injection rate, thereby improving the electrolyte injection efficiency, and thus improving the production efficiency of the secondary battery.

[0054] Specifically, in the embodiment of the present application, the body 321 and the top cover sheet 31 are stacked along the first direction Z, the second liquid injection hole 3211 is arranged on the body 321, part of the hole wall of the first liquid injection hole 311 on the top cover sheet 31 extends into the second liquid injection hole 3211, at this time, the electrolyte injection nozzle can be directly inserted into the first liquid injection hole 311, part of the hole wall of the first liquid injection hole 311 is arranged in the second liquid injection hole 3211, and thus the electrolyte can be injected into the second liquid injection hole 3211, the second liquid injection hole 3211 is in communication with the accommodating cavity 11 of the shell 1, at this time, the electrolyte can be smoothly injected into the accommodating cavity 11 through the second liquid injection hole 3211. The side plate 322 is arranged around the outer periphery of the second liquid injection hole 3211, and the baffle 323 is connected with the side plate 322, the baffle 323 is arranged opposite to the second liquid injection hole 3211, at this time, the baffle 323 can be arranged between the second liquid injection hole 3211 and the electrode assembly 2, and the electrolyte is effectively blocked from directly impacting the electrode assembly 2. The electrode assembly 2 is wound after the diaphragm, the positive electrode sheet, the diaphragm, and the negative electrode sheet are stacked, the diaphragm is relatively soft, and the diaphragm faces the second liquid injection hole 3211 along the side of the stack of the positive electrode sheet and the negative electrode sheet. Therefore, if there is no baffle 323, the high-pressure electrolyte directly impacts the electrode assembly 2, and can directly impact between the diaphragm and the positive electrode sheet and the negative electrode sheet, so that a gap is formed between the diaphragm and the positive electrode sheet or the negative electrode sheet. In the process of continuously injecting the electrolyte, the diaphragm is folded into the gap between the adjacent positive electrode sheet and negative electrode sheet, which may cause the diaphragm to be folded. At this time, there is a risk of partial overlap and short circuit of the positive electrode sheet and the negative electrode sheet on both sides of the folded diaphragm. The baffle 323 is arranged to block the electrolyte, effectively protect the diaphragm of the electrode assembly 2 from being folded, thereby effectively reducing the possibility of short circuit of the electrode assembly 2 and improving the safety of the secondary battery.

[0055] It can be understood that the application can withstand the high hydraulic impact of the electrolyte injection by setting the side plate 322 and the baffle 323, at this time the electrolyte can have a large injection speed. At the same time, in order to ensure that the electrolyte can be smoothly injected into the accommodating cavity 11, the reasonable control of the flow area of the liquid outlet 3221 can increase the rate of the electrolyte injected into the accommodating cavity 11, thereby improving the overall electrolyte injection efficiency. Specifically, since the side plate 322 is arranged around the second injection hole 3211, by controlling the ratio between the flow area of the liquid outlet 3221 and the remaining outer surface of the side plate 322, the injection rate of the secondary battery can be correspondingly controlled, and the injection efficiency of the electrolyte can be controlled. The application sets the flow area of the liquid outlet 3221 as S1 mm 2 , the outer surface area of the side plate 322 is S2 mm 2 , and satisfies: 0.06≤S1 / S2≤2, at this time the injection efficiency can be improved on the basis of preventing the diaphragm from folding.

[0056] It should be noted that in the embodiment of the application, the flow area of the liquid outlet 3221 is controlled to be S1 mm 2 , which is used to control the injection flow rate of the electrolyte. The greater the value of S1, the smaller the area of the side plate 322 that blocks the electrolyte, so the injection rate of the electrolyte will increase, and the injection efficiency of the secondary battery will also increase. The liquid outlet 3221 is arranged on the side plate 322, so when the circumferential dimension of the side plate 322 is unchanged and the dimension along the first direction Z is unchanged, the greater the flow area of the injection port, the smaller the remaining outer surface area of the side plate 322, at this time the ratio of S1 / S2 is also getting larger and larger, so in the embodiment of the application, the greater the ratio of S1 / S2, the faster the injection speed on the basis of preventing the diaphragm from folding, and the higher the injection efficiency. However, if the ratio of S1 / S2 is too large, for example, S1 / S2>2, at this time the connecting and supporting effect of the side plate 322 on the baffle 323 will also be poor, and in the case that the baffle 323 does not abut against the electrode assembly 2, there will be a risk of the side plate 322 breaking when the high-pressure electrolyte is injected, at this time the baffle 323 will lose the blocking of the electrolyte due to the flow of the electrolyte, causing the risk of the diaphragm folding of the electrode assembly 2; if the ratio of S1 / S2 is too small, for example, S1 / S2<0.06, at this time the flow of the electrolyte flowing out of the liquid outlet 3221 is too small due to the small flow area of the liquid outlet 3221 compared with the area of the outer surface of the side plate 322, which is not conducive to improving the injection efficiency of the electrolyte. Therefore, the application sets the flow area of the liquid outlet 3221 as S1 mm 2 , the outer surface area of the side plate 322 is S2 mm 2, and satisfies: 0.06≤S1 / S2≤2, the secondary battery can have a high liquid injection efficiency while avoiding the folding of the diaphragm. The value range of S1 / S2 can be any one of 0.06, 0.1, 0.13, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 or a range between any two values. When the overflow area of the liquid outlet 3221 and the outer surface area of the side plate 322 satisfy the range of 0.06≤S1 / S2≤2, the secondary battery can block the injected electrolyte through the baffle 323, avoiding the folding of the diaphragm; at the same time, the overflow area of the liquid outlet 3221 is within a reasonable range, which can ensure a faster liquid injection efficiency of the electrolyte, and ensure the structural strength of the side plate 322 and the stability of the fixed baffle 323.

[0057] Further, in some embodiments, the overflow area of the liquid outlet 3221 and the outer surface area of the side plate 322 satisfy: 0.2≤S1 / S2≤0.4.

[0058] In the embodiments of the present application, by controlling the ratio of the overflow area of the liquid outlet 3221 and the outer surface of the side plate 322 within the range of 0.2≤S1 / S2≤0.4, the overflow area (i.e. the opening area) of the liquid outlet 3221 can be more reasonably set, and the outer surface area of the side plate 322 can be further controlled to be more than twice the overflow area of the liquid outlet 3221, which can ensure a high liquid injection efficiency of the secondary battery, further ensure the structural strength of the side plate 322, and at the same time, the side plate 322 has a larger surface area, which can block and disturb the electrolyte from the side of the electrolyte injection direction, thereby realizing the directional flow of the electrolyte and better controlling the flow direction of the electrolyte.

[0059] Further, in some embodiments, the overflow area of the liquid outlet 3221 satisfies: 12≤S1≤100; and / or, the outer surface area of the side plate 322 satisfies: 50≤S2≤200.

[0060] In the embodiments of the present application, the value range of S1 can be any one of 12, 15, 18, 20, 25, 30, 30.6, 35, 40, 45, 48, 50, 55, 60, 65, 70, 75, 80, 85, 90, 100 or a range between any two values. The value range of S2 can be any one of 50, 55, 60, 65, 70, 77, 80, 90, 100, 110, 120, 124, 130, 140, 150, 160, 170, 180, 190, 200 or a range between any two values. At this time, not only can the secondary battery have a higher liquid injection efficiency, but also the strength and stability of the connection structure of the baffle 323 and the side plate 322 can be ensured. Moreover, as the value of S1 gradually increases, the corresponding liquid injection efficiency is higher; as the value of S2 gradually decreases, the corresponding liquid injection efficiency is higher.

[0061] Furthermore, in some embodiments, the overflow area of the liquid outlet 3221 satisfies: 20≤S1≤60; and / or, the outer surface area of the side plate 322 satisfies: 50≤S2≤150.

[0062] In the embodiments of the present application, based on the size of the secondary battery, the values of S1 and S2 are reasonably set, at this time, a better mutual balance of the liquid injection efficiency and the structural strength can be achieved. When the overflow area S1 of the liquid outlet 3221 satisfies: 20≤S1≤60; and / or, the outer surface area S2 of the side plate 322 satisfies: 50≤S2≤150, it is ensured that the overflow area of the liquid outlet 3221 is in a more preferred range, and the outer surface area of the side plate 322 is in a more preferred range, and also ensures that the ratio of S1 / S2 is in a more preferred range, that is, the high-pressure electrolyte can be blocked, the diaphragm can be prevented from being folded during liquid injection, and a higher liquid injection efficiency can be achieved.

[0063] It should be noted that, in the embodiments of the present application, the flow area of the liquid outlet 3221 is the total area of one or more liquid outlets 3221, and the flow area of the liquid outlet 3221 and the outer surface area of the side plate 322 can be measured and calculated by a conventional area measurement method if they are regular shapes (for example, square, circular, oval, annular, etc.). For the flow area of the liquid outlet 3221 and the outer surface area of the side plate 322 if they are irregular shapes, a film coating method can be used for measurement and calculation, that is, a film with uniform mass is attached to the part corresponding to the liquid outlet 3221 on the side plate 322, the film attached to the corresponding liquid outlet 3221 is removed, and the mass of the film is determined. The quotient of the mass of the removed film and the mass per unit area of the film determined in advance is determined as the area of the measured liquid outlet 3221. Correspondingly, a film with uniform mass is attached to the part corresponding to the outer surface of the side plate 322, the film is removed, and the mass of the film is determined. The quotient of the mass of the removed film and the mass per unit area of the film determined in advance is determined as the area of the measured outer surface of the side plate 322.

[0064] In some embodiments, the secondary battery has a first direction Z, the electrode assembly 2 and the top cover assembly 3 are arranged along the first direction Z, the electrode assembly 2 includes a winding core 22 and a tab 21, the tab 21 is in conductive connection with the winding core 22, and the tab 21 is arranged on the side of the winding core 22 facing the top cover sheet 31; the baffle 323 and the side plate 322 enclose a cavity 324, the cavity 324 is in communication with the second liquid injection hole 3211 and the liquid outlet 3221, respectively, along the first direction Z, the maximum dimension of the cavity 324 is H1 mm, the distance between the side of the top cover sheet 31 close to the lower insulating piece 32 and the side of the winding core 22 close to the lower insulating piece 32 is H2 mm, and the following condition is satisfied: 0.1≤H1 / H2≤2.5.

[0065] In the embodiment of the present application, the cavity 324 is used to accommodate the electrolyte injected from the injection hole, and buffers and redirects the electrolyte to prevent the electrolyte from impacting and damaging the internal structure of the battery, such as by changing the direction of the electrolyte, which can effectively prevent the folding of the separator. The gap between the side of the top cover sheet 31 close to the lower insulating member 32 and the side of the winding core 22 close to the lower insulating member 32 is used to accommodate the lower insulating member 32. Of course, in order to ensure the stability of the electrode assembly 2 in the accommodation cavity 11, the lower insulating member 32 is usually arranged to abut against the side of the top cover sheet 31 facing the lower insulating member 32 and the side of the winding core 22 facing the lower insulating member 32. In the embodiment of the present application, the maximum size of the cavity 324 along the first direction Z is H1 mm, and the distance between the side of the top cover sheet 31 close to the lower insulating member 32 and the side of the winding core 22 close to the lower insulating member 32 is H2 mm, which satisfies: 0.1≤H1 / H2≤2.5. At this time, the cavity 324 can have sufficient size to provide sufficient buffer space and direction-changing space for the electrolyte, thereby improving the injection efficiency.

[0066] It can be understood that the side plate 322 and the baffle plate 323 are connected to form the cavity 324, and the electrolyte enters the cavity 324 through the second injection hole 3211 first, and the cavity 324 is used to buffer the electrolyte. At this time, the side plate 322 and the baffle plate 323 cooperate to reduce the impact of the electrolyte on the electrode assembly 2 along the first direction Z by using the baffle plate 323, and the side plate 322 causes local blocking and disturbance to the electrolyte from the outer periphery of the cavity 324. At this time, the liquid outlet 3221 on the side plate 322 is in communication with the cavity 324 and the accommodation cavity 11 to realize the flow of the electrolyte out of the liquid outlet 3221 and into the accommodation cavity 11. The opening direction of the liquid outlet 3221 can be set according to the requirements, which can sufficiently reduce the impact of the electrolyte on the electrode assembly 2 and improve the safety and yield of the secondary battery production.

[0067] It should be noted that in the embodiments of the present application, the value range of H1 / H2 can be any one of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 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 or a range between any two values. When 0.1≤H1 / H2≤2.5, the baffle 323 can block the electrolyte to prevent the diaphragm from folding while having sufficient gap between the baffle 323 and the second liquid injection hole 3211, so that the electrolyte can flow to the liquid outlet 3221 after the electrolyte injected from the second liquid injection hole 3211 reaches the cavity 324 and finally impacts on the baffle 323, thereby achieving rapid and effective liquid injection and protecting the electrode assembly 2. The larger the value of H1 / H2, the better the effect of the cavity 324 on the flow rate and direction change of the electrolyte, which is more conducive to the faster injection of the electrolyte and improves the liquid injection efficiency of the electrolyte. When 1≤H1 / H2≤2.5, the baffle 323 abuts against one side of the core 22 towards the body 321, causing a certain bending deformation of the core 22, but the sealing assembly connection of the top cover sheet 31 and the shell 1 can still be achieved, and good liquid injection efficiency can be ensured. When H1 / H2<0.1, the size of the cavity 324 is relatively small compared with the distance between the top cover sheet 31 and the core 22, and the distance between the baffle 323 and the second liquid injection hole 3211 is also small, so that the resistance of the baffle 323 to the electrolyte is large when the electrolyte is injected, which affects the efficiency of the electrolyte injection. When H1 / H2>2.5, although the size of the cavity 324 is large, the baffle 323 continues to press the core 22, but the region of the core 22 that is not pressed may block the liquid outlet 3221, thereby affecting the liquid outlet rate of the electrolyte. Therefore, the embodiments of the present application preferably set the maximum size of the cavity 324 as H1 mm along the first direction Z, the distance between the side of the top cover sheet 31 close to the lower insulating member 32 and the side of the core 22 close to the lower insulating member 32 as H2 mm, and satisfy 0.1≤H1 / H2≤2.5.

[0068] It should be noted that when 1≤H1 / H2≤2.5, the baffle 323 and the side plate 322 can be partially inserted into the core 22, specifically, the baffle 323 can bend part of the diaphragm and the pole piece of the core 22, at this time, the liquid injection port can also be partially located between the diaphragms, and liquid injection can also be performed, and the baffle 323 and the side plate 322 are part of the lower insulating member 32, so the baffle 323 and the side plate 322 also have insulation and will not cause internal short circuit of the electrode assembly 2.

[0069] It should be noted that in the embodiments of the present application, the size of H1 and H2 can be measured by a ruler, a vernier caliper, a micrometer and the like length measurement tools.

[0070] In some preferred embodiments of the present application, the maximum size of the cavity 324 satisfies: 1≤H1≤5; and / or, the distance between the side of the top cover sheet 31 close to the lower insulating member 32 and the side of the roll core 22 close to the lower insulating member 32 satisfies: 2≤H2≤7.

[0071] In some embodiments, the maximum size of the baffle 323 along the first direction Z is H3 mm, satisfying: 0.5≤H3≤0.7.

[0072] In the embodiments of the present application, by setting the maximum size H3 of the baffle 323 along the first direction Z to satisfy 0.5≤H3≤0.7, the baffle 323 is avoided from occupying more size of the lower insulating member 32 along the first direction Z, so as to facilitate the cavity 324 to have a larger size along the first direction Z, thereby being able to ensure that the electrolyte has a higher liquid injection efficiency.

[0073] It should be noted that in the embodiments of the present application, the value range of the maximum size H3 of the baffle 323 along the first direction Z can be any one of 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7 or a range between any two values. When 0.5≤H3≤0.7, the baffle 323 can not only ensure a certain structural strength to avoid the baffle 323 from being broken by the impact of high-pressure electrolyte, but also reduce the size occupied along the first direction Z, thereby providing sufficient size space for the setting of the cavity 324, thereby facilitating to achieve a higher liquid injection efficiency. When H3<0.5, the thickness of the baffle 323 is relatively thin, and the corresponding structural strength is reduced; when H3>0.7, the baffle 323 will occupy the size along the first direction Z, which will cause the cavity 324 to be squeezed. Therefore, it is preferred that the maximum size H3 of the baffle 323 along the first direction Z satisfies 0.5≤H3≤0.7.

[0074] In some embodiments, the maximum size of the cavity 324 and the maximum size of the baffle 323 satisfy: 1.5≤H1+H3≤5.5.

[0075] In the embodiment of the present application, the maximum size of the cavity 324 and the maximum size of the baffle 323 satisfy 1.5≤H1+H3≤5.5, at this time, the size between the side of the baffle 323 far away from the cavity 324 and the side of the body 321 facing the electrode assembly 2 is within a reasonable range, avoiding the baffle 323 excessively extruding the winding core 22 due to excessively far away from the body 321.

[0076] It should be noted that in the embodiment of the present application, the value range of H1+H3 can be any one of 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, 3.2, 3.5, 3.8, 4, 4.5, 4.8, 5, 5.5 or a range between any two values. When 1.5≤H1+H3≤5.5, the side plate 322 and the baffle 323 are within a reasonable range, which can ensure that the electrolyte has a faster liquid injection efficiency, and can avoid that the baffle 323 excessively extrudes the winding core 22 or the diaphragm shields the liquid outlet 3221.

[0077] In some embodiments, the maximum size of the cavity 324, the distance between the top cover sheet 31 and the winding core 22, and the maximum size of the baffle 323 satisfy H1+H3≤H2.

[0078] In the embodiment of the present application, at this time, the value of H1+H3 is less than or equal to the distance between the side of the top cover sheet 31 facing the lower insulating piece 32 and the side of the winding core 22 facing the lower insulating piece 32, at this time, the baffle 323 is located between the body 321 and the winding core 22, and the maximum range is in abutment with the winding core 22, at this time, it can avoid that the side plate 322 and the baffle 323 affect the structure of the winding core 22, and also avoid that the diaphragm of the winding core 22 shields the liquid outlet 3221, thereby ensuring that the battery has a faster liquid injection efficiency.

[0079] In some embodiments, the secondary battery has a second direction X intersecting the first direction Z; the top cover assembly 3 further comprises a pole 33, part of the pole 33 protruding from the side of the body 321 away from the top cover sheet 31; the lower insulating piece 32 further comprises an explosion-proof valve boss 325 connected to the side of the body 321 away from the top cover sheet 31; along the second direction X, the side plate 322 is arranged between the explosion-proof valve boss 325 and the pole 33, and the liquid outlet 3221 is arranged towards the pole 33 or the explosion-proof valve boss 325.

[0080] In the embodiment of the present application, the tab 21 is generally arranged on both sides of the side plate 322 along the third direction Y, at this time, the liquid outlet 3221 is arranged towards the pole 33 or the explosion-proof valve boss 325, at this time, the electrolyte flows out from the liquid outlet 3221 towards the pole 33 or the explosion-proof valve boss 325, and there is a gap between the pole 33 and the liquid outlet 3221, and there is a gap between the explosion-proof valve boss 325 and the liquid outlet 3221, which can realize the smooth flow of the electrolyte. And it can avoid that the electrolyte flowing out from the liquid outlet 3221 directly impacts the tab 21, avoid that the tab 21 is short-circuited by the liquid outlet 3221 and the top cover, and also can protect the stable welding connection relationship between the tab 21 and the adapter piece.

[0081] In some embodiments, the secondary battery has a third direction Y intersecting the first direction Z and the second direction X respectively, the tab 21 is conductively connected with the pole 33, and along the third direction Y, the tab 21 is arranged on the side of the side plate 322 away from the cavity 324.

[0082] In the embodiment of the present application, by arranging the tab 21 on the side of the side plate 322 away from the cavity 324, at this time, the side plate 322 can be used to block and disturb the electrolyte from the side, so that the electrolyte flows out towards the liquid outlet 3221, avoiding that the electrolyte directly impacts the tab 21, avoiding that the tab 21 enters the cavity 324 through the liquid outlet 3221, further avoiding that the tab 21 is short-circuited by the top cover, and also avoiding that the welding relationship between the tab 21 and the adapter piece is damaged.

[0083] In some embodiments, the side plate 322 has a plurality of liquid outlets 3221, and the plurality of liquid outlets 3221 are arranged at intervals along the circumference of the side plate 322.

[0084] In the embodiment of the present application, by arranging a plurality of mutually spaced liquid outlets 3221, a plurality of liquid outlets 3221 can be realized to simultaneously shunt the electrolyte from different directions, providing a plurality of outlets for the electrolyte, so as to further improve the efficiency of the electrolyte injection.

[0085] In some embodiments, the side plate 322 has two liquid outlets 3221, one of the two liquid outlets 3221 is arranged towards the pole 33, and the other of the two liquid outlets 3221 is arranged towards the explosion-proof valve boss 325.

[0086] In the embodiments of the present application, only two can be provided, one of which is arranged towards the pole post 33 and spaced apart from the pole post 33, and the other is arranged towards the explosion-proof valve boss 325 and spaced apart from the explosion-proof valve, at this time the electrolyte flows out from the two liquid outlets 3221 respectively, on the basis of preventing the diaphragm from being folded, on the one hand, the secondary battery has a faster liquid injection efficiency, and on the other hand, by limiting the direction of the liquid outlet 3221, at this time the liquid outlet 3221 is not opposite to the pole lug 21, and the pole lug 21 can be effectively isolated from the pole lug 21 by the side plate 322, so as to prevent the pole lug 21 from falling into the second liquid injection hole 3211 through the liquid outlet 3221 to cause a short circuit with the top cover sheet 31.

[0087] In some embodiments, the liquid outlet 3221 penetrates the side plate 322 along the first direction Z.

[0088] In the embodiments of the present application, the liquid outlet 3221 penetrates the side plate 322 along the first direction Z, at this time the liquid outlet 3221 can be ensured to have a larger size along the first direction Z as much as possible, to ensure that the electrolyte flows out from the liquid outlet 3221 faster, and to improve the liquid injection efficiency, while avoiding the electrolyte being stored at the part where the side plate 322 is connected with the baffle plate 323.

[0089] In some embodiments, the side surface of the baffle plate 323 towards the second liquid injection hole 3211 is one of a plane, a circular arc surface protruding towards the second liquid injection hole 3211, and a circular conical surface protruding towards the second liquid injection hole 3211.

[0090] In the embodiments of the present application, the side surface of the baffle plate 323 towards the second liquid injection hole 3211 can be a plane, and the baffle plate 323 is further a flat plate structure, at this time the baffle plate 323 can be ensured to occupy as little space as possible between the roll core 22 and the top cover sheet 31, to provide sufficient size for the cavity 324 to buffer the electrolyte. At the same time, the flat plate structure can avoid the electrolyte being stored in the cavity 324.

[0091] In the embodiments of the present application, the side surface of the baffle plate 323 towards the second liquid injection hole 3211 can be a circular arc surface protruding towards the second liquid injection hole 3211, at this time the electrolyte can flow obliquely along the circular arc surface in a direction away from the second liquid injection hole 3211, which can directly redirect the electrolyte, is more conducive to the electrolyte flowing out from the liquid outlet 3221 quickly, and can avoid the electrolyte being stored in the cavity 324.

[0092] In the embodiments of the present application, the side surface of the baffle plate 323 towards the second liquid injection hole 3211 can be a circular conical surface protruding towards the second liquid injection hole 3211, at this time the apex of the circular conical surface is opposite to the second liquid injection hole 3211, at this time the circular conical surface can further reduce the obstruction to the electrolyte, so that the electrolyte is directly redirected along the circular conical surface, to improve the liquid injection efficiency of the liquid outlet 3221, and to avoid the electrolyte being stored on the baffle plate 323 and in the cavity 324.

[0093] Correspondingly, the application also provides a battery pack comprising the secondary battery according to any one of the preceding embodiments.

[0094] It can be understood that the battery pack according to the embodiments of the application comprises all the technical features and technical effects of the secondary battery described above, which will not be repeated here.

[0095] The application also provides a power consumption device comprising the secondary battery according to any one of the preceding embodiments or the battery pack according to the preceding embodiments.

[0096] It can be understood that the power consumption device according to the embodiments of the application comprises all the technical features and technical effects of the secondary battery or the battery pack described above, which will not be repeated here.

[0097] Of course, the power consumption device according to the application can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy and an electric tool, etc. The vehicle can be a new energy vehicle, which can be a pure electric vehicle, a hybrid electric vehicle or a range-extended electric vehicle, etc. The spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy and an electric plane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc. The embodiments of the application do not specially limit the power consumption device described above.

[0098] The secondary battery according to the application will be described in detail below in combination with specific embodiments.

[0099] Embodiment 1

[0100] A secondary battery is provided, which comprises a secondary battery according to any one of the preceding embodiments. Figure 4 The maximum size of the cavity 324 surrounded by the side plate 322 and the baffle 323 is 3 mm, the maximum distance between the side of the top cover sheet 31 close to the lower insulating member 32 and the side of the winding core 22 close to the lower insulating member 32 is 5 mm, the maximum size of the baffle 323 is 0.6 mm, and the overall structure of the secondary battery is as shown in FIG. 2B. Figure 1 and Figure 2 The side plate 322 is provided with a liquid outlet 3221, and the flow area of the liquid outlet and the outer surface area of the side plate satisfy: 0.06≤S1 / S2≤2. The specific structural size parameters are shown in Table 1.

[0101] Embodiments 2-10

[0102] A secondary battery is provided, which has the same configuration as that of Example 1, except that the overcurrent area of the liquid outlet 3221 is 40 mm2, the outer surface area of the side plate 322 is 100 mm2, the maximum dimension of the baffle 323 is 0.5 mm, the maximum dimension of the cavity 324 satisfies 1≤H1≤5, the distance between the side of the top cover sheet 31 close to the lower insulating member 32 and the side of the winding core 22 close to the lower insulating member 32 satisfies 2≤H2≤7, and 0.14≤H1 / H2≤2.5 is satisfied.

[0103] Examples 11-14

[0104] A secondary battery is provided, which has the same configuration as that of Example 1, except that the overcurrent area of the liquid outlet 3221 is 40 mm 2 , the outer surface area of the side plate 322 is 100 mm 2 , the maximum dimension of the baffle 323 is 0.5 mm, the maximum dimension of the cavity 324 satisfies 1≤H1≤5, the distance between the side of the top cover sheet 31 close to the lower insulating member 32 and the side of the winding core 22 close to the lower insulating member 32 satisfies 2≤H2≤7, and 0.14≤H1 / H2≤2.5 is satisfied.

[0105] Examples 15-17

[0106] A secondary battery is provided, which has the same configuration as that of Example 1, except that the overcurrent area of the liquid outlet 3221 is 40 mm 2 , the outer surface area of the side plate 322 is 100 mm 2 , the distance between the side of the top cover sheet 31 close to the lower insulating member 32 and the side of the winding core 22 close to the lower insulating member 32 is 5 mm, the maximum dimension of the cavity 324 is different, and the maximum dimension of the baffle 323 is different.

[0107] Comparative Examples 1-3

[0108] A secondary battery is provided, which has the same configuration as that of Example 1, except that the overcurrent area of the liquid outlet 3221 and the outer surface area of the side plate 322 do not satisfy the range of 0.06≤S1 / S2≤2; the maximum dimension of the cavity 324 and the distance between the side of the top cover sheet 31 close to the lower insulating member 32 and the side of the winding core 22 close to the lower insulating member 32 do not satisfy 0.14≤H1 / H2≤2.5; and the maximum dimension of the baffle 323 is mostly outside the range of 0.5≤H3≤0.7.

[0109] The specific experimental test method is as follows:

[0110] Diaphragm folding: after the secondary battery is completed, it is disassembled, the electrode assembly 2 is opened during the disassembly process, and whether the diaphragm inside the electrode assembly appears folding phenomenon is observed.

[0111] Efficiency of electrolyte injection: a secondary battery adopting an embodiment of the present application is put into an injection machine; the injection machine first evacuates the inside of the secondary battery, so that the air pressure inside the secondary battery is below -90 Kpa, at this time the electrolyte has been stored in the injection cup, because the inside of the secondary battery is in a negative pressure state, the electrolyte flows into the inside of the secondary battery; then the injection machine carries out positive and negative pressure alternating circulation (positive pressure 180 Kpa (30-60 S) negative pressure -60 Kpa (3-15 S), 4-12 times of circulation) to the secondary battery, so that the electrolyte can be fully injected into the inside of the secondary battery, the time required for the overall injection process is t1 min, the same specification secondary battery without side plate 322 and baffle 323 is subjected to the same injection operation, and the time required for the overall injection process is recorded as t2 min, if t1 / t2≥98%, then the injection efficiency meets the demand.

[0112] Whether the baffle is qualified: the lower insulating part is usually integrally injection molded, if the maximum size of the baffle 323 is less than 0.5 mm, then during the production of the baffle 323, there will be appearance defects such as notches or shrinkage, at this time the baffle 323 is unqualified; if the maximum size of the baffle 323 is greater than or equal to 0.5 mm, at this time the baffle 323 is qualified. For the lower insulating part that can be normally produced, the size can be directly measured by using a size measuring tool (such as a vernier caliper, etc.). If the size of the baffle is too large, it will occupy the space between the top cover sheet and the electrode assembly, and then squeeze the space of the cavity, which is not conducive to improving the injection efficiency.

[0113] Table 1

[0114]

[0115]

[0116]

[0117] From Table 1, it can be seen that the secondary batteries of Examples 1-17 all satisfy the range of 0.06≤S1 / S2≤2, meeting the requirements of preventing the folding of the separator and the injection efficiency of the electrolyte. From the comparison between Examples 1-17 and Comparative Examples 1-3, it can be seen that when S1 is too small or S2 is too large, the injection efficiency of the electrolyte will be reduced, which is not conducive to the improvement of production efficiency. When S1 is too large or S2 is too small, the side plate may be broken, and at this time, the baffle may be displaced, and at this time, there is a risk of folding of the separator. From Examples 11-14, it can be seen that the secondary batteries further satisfy the range of 0.14≤H1 / H2≤2.5 under the condition of satisfying the range of 0.06≤S1 / S2≤2, and under this range, by ensuring the size of the cavity, the cavity has a good buffering effect, which can further improve the injection efficiency of the secondary battery on the basis of preventing the folding of the separator. From Examples 15-17, it can be seen that under the condition of satisfying the range of 0.06≤S1 / S2≤2 and 0.14≤H1 / H2≤2.5, it further satisfies 0.5≤H3≤0.7, at this time, it can ensure the normal assembly of the secondary battery, avoid extruding the electrode assembly, and has a good injection efficiency. Comparative Examples 1-3 do not satisfy the range of 0.06≤S1 / S2≤2, and also do not satisfy the range of 0.14≤H1 / H2≤2.5; among them, although the separator of Comparative Example 1 will not be folded, the injection efficiency is low; Comparative Example 2 will have the folding of the separator, and Comparative Example 1 has H3 that does not satisfy 0.5≤H3≤0.7, at this time, H3 is too large, which will occupy the space of the cavity, and the H3 of Comparative Example 3 is too small, which will cause the embarrassment of the inability to produce the lower insulating member, at this time, the injection efficiency and whether the separator is folded cannot be measured.

[0118] In the above examples, the description of each example has its own emphasis, and the parts not described in detail in a certain example can be referred to the related description of other examples.

[0119] The above describes in detail a secondary battery, a battery pack and an electric device provided by the embodiments of the present application, and the principles and implementation manners of the present application are described by using specific examples; the above example is only used to help understand the technical solutions and core ideas of the present application; those skilled in the art should understand that the technical solutions recorded in the above examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A secondary battery, characterized in that, include: The shell has a receiving cavity; Electrode assembly is disposed in the receiving cavity; Top cover assembly, including: A top cover plate is connected to the housing and seals the receiving cavity; the top cover plate has a first injection hole. A lower insulating member is connected to the side of the top cover plate facing the electrode assembly; the lower insulating member includes: The main body is connected to the top cover plate, and the main body is provided with a second injection hole that communicates with the first injection hole; Side panel, connected to the side of the body away from the top cover plate; A baffle is connected to the side of the side plate away from the main body. The baffle is spaced between the second injection hole and the electrode assembly. The side plate has an outlet that communicates with the second injection hole. The flow area of ​​the liquid outlet is S1 mm. 2 The outer surface area of ​​the side plate is S2 mm. 2 The condition is satisfied that: 0.06≤S1 / S2≤2.

2. The secondary battery according to claim 1, characterized in that, It also satisfies: 0.2≤S1 / S2≤0.

4.

3. The secondary battery according to claim 1, characterized in that, The flow area of ​​the outlet satisfies: 12 ≤ S1 ≤ 100; and / or, The outer surface area of ​​the side plate satisfies: 50≤S2≤200.

4. The secondary battery according to claim 1, characterized in that, The flow area of ​​the outlet meets the following conditions: 20 ≤ S1 ≤ 60; and / or, The outer surface area of ​​the side plate satisfies: 50≤S2≤150.

5. The secondary battery according to claim 1, characterized in that, The secondary battery has a first direction, and the electrode assembly and the top cover assembly are arranged along the first direction. The electrode assembly includes a core and a tab, and the tab is electrically connected to the core. The tab is disposed on the side of the core facing the top cover. The baffle and the side plate form a cavity, and the cavity is connected to the liquid outlet and the second liquid injection hole respectively. Along the first direction, the maximum size of the cavity is H1 mm, and the maximum distance between the side of the top cover near the lower insulator and the side of the core near the lower insulator is H2 mm, satisfying: 0.14≤H1 / H2≤2.

5.

6. The secondary battery according to claim 5, characterized in that, The maximum size of the cavity satisfies: 1 ≤ H1 ≤ 5; and / or, The maximum distance between the side of the top cover plate closest to the lower insulator and the side of the winding core closest to the lower insulator satisfies: 2≤H2≤7.

7. The secondary battery according to claim 6, characterized in that, Along the first direction, the maximum dimension of the baffle is H3 mm, satisfying: 0.5≤H3≤0.

7.

8. The secondary battery according to claim 7, characterized in that, The maximum size of the cavity, the maximum distance between the side of the top cover plate near the lower insulator and the side of the winding core near the lower insulator, and the maximum size of the baffle also satisfy: H1+H3≤H2.

9. The secondary battery according to claim 5, characterized in that, The secondary battery has a second direction that intersects with the first direction; The top cover assembly also includes a pole post, a portion of which protrudes from the body on the side away from the top cover sheet; The lower insulating component also includes an explosion-proof valve boss, which is connected to the side of the body away from the top cover plate; along the second direction, the side plate is disposed between the explosion-proof valve boss and the pole post, and the liquid outlet is disposed towards the pole post or the explosion-proof valve boss.

10. The secondary battery according to claim 9, characterized in that, The secondary battery has a third direction that intersects the first direction and the second direction respectively. The tab is electrically connected to the post. Along the third direction, the tab is disposed on the side of the side plate away from the cavity.

11. The secondary battery according to claim 9, characterized in that, The side plate has multiple liquid outlets, which are spaced apart circumferentially along the side plate; along the first direction, the liquid outlets penetrate the side plate.

12. The secondary battery according to claim 11, characterized in that, The side plate has two liquid outlets, one of which is disposed toward the pole post, and the other of which is disposed toward the explosion-proof valve boss.

13. The secondary battery according to claim 1, characterized in that, The side of the baffle facing the second injection hole is one of a plane, an arc surface protruding towards the second injection hole, or a conical surface protruding towards the second injection hole.

14. A battery pack, characterized in that, Includes the secondary battery as described in any one of claims 1-13.

15. An electrical appliance, characterized in that, This includes the secondary battery as described in any one of claims 1-13, or the battery pack as described in claim 14.

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