Secondary battery and electric device

Abstract

Disclosed in the present application are a secondary battery and an electric device. The secondary battery comprises a housing, a terminal post, an electrode assembly, an electrolyte, a first tab assembly and an insulating member. The terminal post is connected to the housing, part of the terminal post being located in a first space, and part of the terminal post extending out of the housing. The electrode assembly is accommodated in the first space. The first tab assembly is connected to the electrode assembly. The insulating member is arranged in the first space. The first tab assembly comprises a first portion, a bending portion and a second portion connected in sequence, wherein the first portion is connected to the electrode assembly, the second portion is connected to the terminal post, and the first portion and the second portion are respectively located on two opposite sides of the insulating member in a first direction. The insulating member is provided with a plurality of through holes, which penetrate the insulating member in the first direction. In the secondary battery provided in the present application, the insulating member is provided with a plurality of through holes through which the electrolyte passes, helping reduce the possibility of damage to the first tab assembly, and thereby prolonging the service life of the secondary battery.

Description

Secondary batteries and electrical equipment Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a secondary battery and electrical equipment. Background Technology

[0002] In the prior art, when a secondary battery is dropped or impacted, the electrolyte in the casing vibrates back and forth, impacting the insulating components in the casing and causing the insulating components to repeatedly pull on the tab assembly. This poses a risk that the tab assembly may break or become disconnected from the terminal, affecting the service life of the secondary battery. Summary of the Invention

[0003] In view of the above situation, it is necessary to provide a secondary battery that can reduce the possibility of damage to the electrode assembly.

[0004] A first aspect of this application provides a secondary battery, comprising a casing, terminals, an electrode assembly, an electrolyte, a first tab assembly, and an insulating member. The casing is made of a metallic material, and a first space is formed within the casing. Terminals are connected to the casing, with some terminals located in the first space and others extending out of the casing. The electrode assembly is housed within the first space. The first tab assembly is connected to the electrode assembly and is located on one side of the electrode assembly along a first direction. The insulating member is disposed in the first space. The first tab assembly includes a first portion, a bent portion, and a second portion connected sequentially. The first portion is connected to the electrode assembly, and the second portion is connected to the terminal. The first portion and the second portion are located on opposite sides of the insulating member along the first direction, and the orthographic projections of the first portion and the second portion overlap with the orthographic projection of the insulating member along the first direction. The bent portion is located on one side of the insulating member along a second direction, which is the thickness direction of the electrode assembly, and the first direction is perpendicular to the second direction. The insulating member has multiple through holes that penetrate the insulating member along the first direction.

[0005] In the secondary battery provided in this application, the insulating component has multiple through holes to allow the electrolyte to pass through. When the electrolyte oscillates back and forth inside the casing, some of the electrolyte can pass through the insulating component, thereby reducing the range of movement of the insulating component, reducing its pulling on the first tab assembly, and thus reducing the possibility of damage to the first tab assembly and improving the service life of the secondary battery.

[0006] In one or more embodiments of this application, the free electrolyte coefficient of the secondary battery is R, which is the ratio of the free electrolyte in the secondary battery to the internal space of the battery; the orthographic projection area of ​​the insulating component along the first direction is S, and the total orthographic projection area of ​​the plurality of through holes along the first direction is S1, 0.18 g / cm³. 3 <R≤0.36g / cm 330% ≤ S1 / S ≤ 60%; or 0.01 g / cm³ 3 ≤R≤0.18g / cm 3 15% ≤ S1 / S ≤ 50%. When 0.18 g / cm³ 3 <R≤0.36g / cm 3 When S1 / S ≥ 30%, the opening ratio of the insulating component is not too low, which facilitates the passage of electrolyte through the insulating component and reduces the impact of electrolyte on the insulating component. When S1 / S ≤ 60%, the opening ratio of the insulating component is not too high, which helps to reduce the impact of electrolyte on the first tab assembly, thereby reducing the possibility of damage to the first tab assembly. When 0.01 g / cm 3 ≤R≤0.18g / cm 3 When S1 / S is set to ≥15%, the opening ratio of the insulating component is not too low, which is conducive to the electrolyte passing through the insulating component and reduces the impact of the electrolyte on the insulating component. When S1 / S is set to ≤50%, the opening ratio of the insulating component is not too high, which is conducive to reducing the impact of the electrolyte on the first tab assembly and thus reducing the possibility of damage to the first tab assembly.

[0007] In one or more embodiments of this application, the maximum dimension of any through hole along the second direction is A1, where 0.05mm ≤ A1 ≤ 1mm. Setting A1 ≥ 0.05mm ensures that the through hole size is not too small, facilitating the passage of electrolyte through the insulating component and reducing the impact force of the electrolyte on the insulating component. Setting A1 ≤ 1mm ensures that the through hole size is not too large, improving the electrolyte diversion effect of the through hole and reducing the direct impact of the electrolyte on the first tab assembly, thereby reducing the possibility of damage to the first tab assembly.

[0008] In one or more embodiments of this application, the maximum dimension of any through-hole along a third direction is A2, where 0.05mm ≤ A2 ≤ 1mm, and the third direction is perpendicular to the first and second directions. Setting A2 ≥ 0.05mm ensures that the through-hole size is not too small, facilitating the passage of electrolyte through the insulating component and reducing the impact force of the electrolyte on the insulating component. Setting A2 ≤ 1mm ensures that the through-hole size is not too large, improving the electrolyte diversion effect of the through-hole and reducing the direct impact of the electrolyte on the first tab assembly, thereby reducing the possibility of damage to the first tab assembly.

[0009] In one or more embodiments of this application, the width of the insulating member along the second direction is W, and the distance between any two adjacent through holes along the second direction is D1, where 0.5A1≤D1≤0.25W. Setting D1≥0.5A1 ensures that the distance between two adjacent through holes is not too close, which is beneficial to improving the structural strength of the insulating member; setting D1≤0.25W ensures that the distance between two adjacent through holes is not too large, which is beneficial to improving the electrolyte diversion effect of the insulating member and reducing the impact of the electrolyte on the insulating member.

[0010] In one or more embodiments of this application, the width of the insulating member along the second direction is W, and the distance between any two adjacent through holes along the third direction is D2, where 0.5A2≤D2≤0.25W. Setting D2≥0.5A2 ensures that the distance between two adjacent through holes is not too close, which is beneficial to improving the structural strength of the insulating member; setting D2≤0.25W ensures that the distance between two adjacent through holes is not too large, which is beneficial to improving the electrolyte diversion effect of the insulating member and reducing the impact of the electrolyte on the insulating member.

[0011] In one or more embodiments of this application, the width of the insulating member along the second direction is W, and for the one of the plurality of through holes closest to the edge of the insulating member, the minimum distance from it to the edge of the insulating member is D3, A1≥A2, 0.5A1≤D3≤0.25W; or, A1<A2, 0.5A2≤D3≤0.25W. When A1≥A2, setting D3≥0.5A1 ensures the distance between the through-hole and the edge of the insulating component is not too small, which helps improve the structural strength of the insulating component. Setting D3≤0.25W ensures the distance between the through-hole and the edge of the insulating component is not too large, preventing the through-holes from concentrating excessively towards the center of the insulating component, which helps reduce the impact of the electrolyte on the insulating component. When A1<A2, setting D3≥0.5A2 ensures the distance between the through-hole and the edge of the insulating component is not too small, which helps improve the structural strength of the insulating component. Setting D3≤0.25W ensures the distance between the through-hole and the edge of the insulating component is not too large, preventing the through-holes from concentrating excessively towards the center of the insulating component, which helps reduce the impact of the electrolyte on the insulating component.

[0012] In one or more embodiments of this application, the insulating member includes a first spacer portion. Along a first direction, the orthographic projections of the first portion and the second portion are both located within the range of the first spacer portion, and the first spacer portion does not have through holes. Thus, the electrolyte does not pass through the insulating member from the first spacer portion, which helps to reduce the direct impact of the electrolyte on the first tab assembly, thereby reducing the possibility of damage to the first tab assembly.

[0013] In one or more embodiments of this application, the insulating member includes a first spacer portion. Along a first direction, the orthographic projections of a first portion and a second portion are located within the orthographic projection range of the first spacer portion. A portion of the through holes are designated as first through holes. The first through holes are disposed in the first spacer portion, and the diameter of the first through holes is A3, where 0.1mm ≤ A3 ≤ 1mm. Setting A3 ≥ 0.1mm ensures that the diameter of the second through hole is not too small, which facilitates the passage of electrolyte through the insulating member, thereby reducing the impact of the electrolyte on the insulating member and also helps to reduce the difficulty of the manufacturing process. Setting A3 ≤ 1mm ensures that the diameter of the first through hole is not too large, which helps to reduce the impact of the electrolyte on the first tab assembly, thereby reducing the possibility of damage to the first tab assembly.

[0014] In one or more embodiments of this application, along a third direction, the width of the first portion is W1, the width of the bent portion is W2, and the width of the first gap portion is W3, where W1 ≥ W2, W1 ≤ W3 ≤ W1 + 1 mm; or, W1 < W2, W2 ≤ W3 ≤ W2 + 1 mm; the third direction is perpendicular to the first and second directions. In this embodiment, by limiting the maximum width of the first gap portion along the third direction, the width of the first gap portion is prevented from being too wide, which facilitates the opening of through holes of different sizes in the portion of the insulating member that differs from the first gap portion, thereby increasing the opening ratio of the insulating member and reducing the impact of the electrolyte on the insulating member.

[0015] In one or more embodiments of this application, the electrode assembly includes a first electrode, a second electrode, and a separator. The first and second electrodes have opposite polarities. A first tab assembly connects to the first electrode. The first electrode, the separator, and the second electrode are sequentially stacked and wound to form a wound structure. The insulating member includes a second spacer portion. Along a first direction, the orthographic projection of the separator located on the outermost and second outermost layers of the electrode assembly lies within the range of the second spacer portion. A portion of the through holes are second through holes, which are disposed in the second spacer portion. The diameter of the second through holes is A4, where 0.1mm ≤ A4 ≤ 1mm. Setting A4 ≥ 0.1mm ensures that the diameter of the second through holes is not too small, which facilitates the passage of electrolyte through the insulating member and reduces the impact of electrolyte on the insulating member. Setting A4 ≤ 1mm ensures that the diameter of the second through holes is not too large, which helps reduce the impact force of electrolyte on the outermost and second outermost layers of the separator of the electrode assembly, thereby reducing the risk of separator folding.

[0016] In one or more embodiments of this application, the minimum distance between the second through hole and the edge of the insulating member, which is closest to the edge of the insulating member, is D4, where 0.5mm ≤ D4 ≤ 1.4mm. Setting D4 ≥ 0.5mm ensures that the minimum distance between the second through hole and the edge of the insulating member is not too close, which helps reduce the possibility of edge deformation of the insulating member during the processing of the second through hole; setting D4 ≤ 1.4mm ensures that the minimum distance between the second through hole and the edge of the insulating member is not too large, which helps to improve the opening rate of the insulating member.

[0017] In one or more embodiments of this application, a portion of the through holes are designated as third through holes. These third through holes are located outside the first and second spacers. The diameter of the third through hole is A5, and the width of the insulating member along the second direction is W, where 0.2mm ≤ A5 ≤ W / 3. Setting A5 ≥ 0.2mm ensures that the diameter of the third through hole is not too small, facilitating the passage of electrolyte through the insulating member and reducing the impact force of the electrolyte on the insulating member. Setting A5 ≤ W / 3 ensures that the diameter of the third through hole is not too large, reducing the surface area occupied by the third through hole on the insulating member, thus facilitating the layout of the first and second through holes.

[0018] In one or more embodiments of this application, the minimum distance between the first through hole and the edge of the third through hole, which is closest to the edge of the insulating component, is D5, where 0.5mm ≤ D5 ≤ 3mm. Setting D5 ≥ 0.5mm ensures that the distance between the first and third through holes and the edge of the insulating component is not too small, which is beneficial for improving the structural strength of the insulating component. Setting D5 ≤ 3mm ensures that the distance between the first and third through holes and the edge of the insulating component is not too large, which is beneficial for improving the electrolyte diversion effect of the insulating component, thereby reducing the impact of the electrolyte on the insulating component.

[0019] In one or more embodiments of this application, the distance between any two adjacent through holes along the second direction is D6, where 0.5mm ≤ D6 ≤ 3mm. Setting D6 ≥ 0.5mm ensures that the distance between two adjacent through holes along the second direction is not too small, which helps reduce the possibility of deformation of the insulating component during the hole-opening process. Setting D6 ≤ 3mm ensures that the distance between two adjacent through holes along the second direction is not too large, which helps improve the electrolyte diversion effect of the insulating component and reduce the impact of the electrolyte on the insulating component.

[0020] In one or more embodiments of this application, the distance between any two adjacent through holes along a third direction is D7, where 0.5mm ≤ D7 ≤ 3mm, and the third direction is perpendicular to the first and second directions. Setting D7 ≥ 0.5mm ensures that the distance between two adjacent through holes along the third direction is not too small, which helps reduce the possibility of deformation of the insulating component during the hole-opening process; setting D7 ≤ 3mm ensures that the distance between two adjacent through holes along the third direction is not too large, which helps improve the electrolyte diversion effect of the insulating component and reduce the impact of the electrolyte on the insulating component.

[0021] In one or more embodiments of this application, the insulating member has a first surface and a second surface disposed opposite to each other along a second direction. The first surface includes a first region, a second region, and a third region connected sequentially. Along the second direction, the distance from the first region to the second surface is greater than the distance from the third region to the second surface, such that the first region, the second region, and the third region together form a stepped shape. A bent portion is disposed opposite to the third region along the second direction, and the width of the bent portion along the third direction is less than or equal to the width of the third region along the third direction. Furthermore, the orthographic projection of the bent portion along the third direction overlaps with the orthographic projection of the second region along the third direction, and the third direction is perpendicular to the first and second directions. By forming a stepped structure, the insulating member accommodates at least a portion of the bent portion, thereby reducing the sum of the thicknesses of the insulating member and the bent portion after being stacked along the second direction, thus reducing their impact on the thickness of the secondary battery, which is beneficial for improving the energy density of the secondary battery.

[0022] In one or more embodiments of this application, the first electrode assembly includes a first electrode bundle and a first adapter. The first electrode bundle includes a plurality of first electrodes, which are stacked. The first electrode bundle connects to the electrode assembly and the first adapter, and the first adapter connects to the electrode post. A portion of the first adapter and the first electrode bundle together form a first part, a portion of the first adapter forms a bent portion, and a portion of the first adapter forms a second part.

[0023] A second aspect of the embodiments of this application provides an electrical device that includes a secondary battery as described in any of the foregoing embodiments. Attached Figure Description

[0024] Figure 1 is a schematic diagram of the structure of a secondary battery in one embodiment of this application.

[0025] Figure 2 is an exploded view of the secondary battery structure in one embodiment of this application.

[0026] Figure 3 is a schematic diagram of the cross-sectional structure at point III-III in Figure 1.

[0027] Figure 4 is a schematic diagram of the structure of the insulating element in one embodiment of this application.

[0028] Fig. 5 is a diagram showing the structure of an insulating member according to an embodiment of the present application.

[0029] Fig. 6 is a diagram showing the structure of an insulating member according to an embodiment of the present application.

[0030] Fig. 7 is a diagram showing the structure of an electric appliance according to an embodiment of the present application.

[0031] Main element symbol explanation secondary battery 100 case 10 electrode assembly 20 first tab 21 second tab 22 separator 23 positive tab 201 positive current collector 2011 positive active material layer 2012 negative tab 202 negative current collector 2021 negative active material layer 2022 pole 30 first tab assembly 40 first portion 41 bent portion 42 inflection point 421 second portion 43 first tab bundle 401 first tab 4011 first adapter 402 insulator 50 first spacer 501 second spacer 502 through hole 51 first through hole511 Second through hole 512 Third through hole 513 First surface 52 First region 521 Second region 522 Third region 523 Second surface 53 Electrical equipment 1000 First direction X Second direction Y Third direction Z

[0032] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0034] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have a component that is centrally located. When a component is considered to be "set" on another component, it can be directly set on the other component or may also have a component that is centrally located.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0036] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0037] In the description of the embodiments of this application, the term "perpendicular" is used to describe the ideal state between two components. In actual production or use, two components may exist in a state that is approximately perpendicular. The two components described as "perpendicular" may not be absolutely straight lines or planes, but may be approximately straight lines or planes. From a macroscopic perspective, if the overall extension direction is a straight line or plane, the component can be considered as a "straight line" or "plane".

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. Where there is no conflict, the various embodiments in this application can be combined with each other.

[0039] It should be noted that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative examples and should not constitute any limitation on this application.

[0040] This application provides a secondary battery comprising a casing, terminals, an electrode assembly, an electrolyte, a first tab assembly, and an insulating member. The casing is made of a metal material, and a first space is formed within the casing. Terminals are connected to the casing, with some terminals located in the first space and others extending out of the casing. The electrode assembly is housed within the first space. The first tab assembly is connected to the electrode assembly and is located on one side of the electrode assembly along a first direction. The insulating member is disposed in the first space. The first tab assembly includes a first portion, a bent portion, and a second portion connected sequentially. The first portion is connected to the electrode assembly, and the second portion is connected to the terminals. The first portion and the second portion are located on opposite sides of the insulating member along the first direction, and the orthographic projections of the first portion and the second portion overlap with the orthographic projection of the insulating member along the first direction. The bent portion is located on one side of the insulating member along a second direction, which is the thickness direction of the electrode assembly, and the first direction is perpendicular to the second direction. The insulating member has multiple through holes that penetrate the insulating member along the first direction.

[0041] In the secondary battery provided in this application, the insulating component has multiple through holes to allow the electrolyte to pass through. When the electrolyte oscillates back and forth inside the casing, some of the electrolyte can pass through the insulating component, thereby reducing the range of movement of the insulating component, reducing its pulling on the first tab assembly, and thus reducing the possibility of damage to the first tab assembly and improving the service life of the secondary battery.

[0042] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0043] As shown in Figures 1 and 2, a first embodiment of this application provides a secondary battery 100, which includes a housing 10, an electrode assembly 20, and terminals 30. A first space is formed inside the housing 10, and the electrode assembly 20 is housed in the first space. The electrode assembly 20 is used to store and release electrical energy. The terminals 30 are connected to the electrode assembly 20. Part of the terminals 30 are located in the first space, and part of the terminals 30 extend out of the housing 10 to connect the secondary battery 100 to an external circuit.

[0044] In some embodiments, the housing 10 is made of a metallic material, for example, the housing 10 is made of steel.

[0045] In some embodiments, as shown in FIG3, the electrode assembly 20 includes a first electrode 21, a second electrode 22, and an insulating film 23 stacked together. The insulating film 23 is located between the first electrode 21 and the second electrode 22 to insulate the first electrode 21 and the second electrode 22. The first electrode 21 and the second electrode 22 have opposite polarities; in other words, one of the first electrode 21 and the second electrode 22 is a positive electrode 201, and the other is a negative electrode 202.

[0046] In some embodiments, the positive electrode 201, the separator 23, and the negative electrode 202 are stacked and then wound to form a wound structure; in other embodiments, multiple positive electrode 201, multiple separators 23, and multiple negative electrode 202 are alternately stacked to form a stacked structure.

[0047] In some embodiments, as shown in FIG3, the positive electrode 201 includes a positive current collector 2011 and a positive active material layer 2012, wherein the positive active material layer 2012 is disposed on one or both sides of the positive current collector 2011 along its thickness direction.

[0048] In some embodiments, for the stacked electrode assembly 20, when the outermost electrode of the electrode assembly 20 is a positive electrode 201, the outermost positive electrode 201 is provided with a positive active material layer 2012 only on the surface of the positive current collector 2011 facing the interior of the electrode assembly 20. Here, "outermost layer" refers to the outermost layer considering only the relative positional relationship between the electrodes.

[0049] In some embodiments, the positive current collector 2011 is a metal layer. As an example, the positive current collector 2011 may be a metal layer including at least one of aluminum, nickel, tantalum, and titanium, such as aluminum foil.

[0050] In some embodiments, the positive electrode active material layer 2012 includes a positive electrode active material, which includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate, or lithium manganese oxide.

[0051] In some embodiments, as shown in FIG3, the negative electrode 202 includes a negative electrode current collector 2021 and a negative electrode active material layer 2022, wherein the negative electrode active material layer 2022 is disposed on one or both sides of the negative electrode current collector 2021 along its thickness direction.

[0052] In some embodiments, for the stacked electrode assembly 20, when the outermost electrode of the electrode assembly 20 is a negative electrode 202, the outermost negative electrode 202 is provided with a negative electrode active material layer 2022 only on the surface of the negative electrode current collector 2021 facing the interior of the electrode assembly 20. Here, "outermost layer" refers to the outermost layer considering only the relative positional relationship between the electrodes.

[0053] In some embodiments, the negative electrode current collector 2021 is a metal layer. As an example, the negative electrode current collector 2021 may be a metal layer including at least one of copper, nickel, tantalum, and titanium, such as copper foil.

[0054] In some embodiments, the negative electrode active material layer 2022 includes a negative electrode active material, which includes at least one of graphite, hard carbon, soft carbon, silicon, silicon-oxygen materials, and silicon-carbon materials.

[0055] In some embodiments, the material of the separator 23 is one of polyethylene film, polypropylene film, polyester film or polyimide film.

[0056] In some embodiments, the secondary battery 100 further includes an electrolyte (not shown), which is contained in a first space and is used for ion transport. The electrolyte can be liquid, solid, or gel.

[0057] In some embodiments, the electrolyte comprises an electrolyte salt. The electrolyte salt comprises at least one of an organic lithium salt or an inorganic lithium salt.

[0058] In some embodiments, the electrolyte salt includes, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium bis(fluoromethanesulfonyl)imide LiN(CF3SO2)2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO2F)2) (LiFSI), lithium hexafluorocesium oxide (LiCsF6), lithium perchlorate (LiClO4), or lithium trifluoromethanesulfonate (LiCF3SO3).

[0059] In some embodiments, as shown in FIG2, one pole post 30 is provided, a first pole piece 21 is connected to the pole post 30, and a second pole piece 22 is connected to the housing 10.

[0060] In some embodiments, the pole post 30 is provided with two poles, with the first pole piece 21 connected to the pole post 30 and the second pole piece 22 connected to the other pole post 30.

[0061] In some embodiments, as shown in FIG3, the secondary battery 100 further includes a first tab assembly 40 and an insulating member 50. The first tab assembly 40 is connected to the electrode assembly 20. Specifically, the first tab assembly 40 is connected to the first electrode 21, and the first tab assembly 40 is located on one side of the electrode assembly 20 along the first direction X. An insulating member 50 is disposed in the first space. The first electrode assembly 40 includes a first part 41, a bent part 42, and a second part 43 connected in sequence. The first part 41 is connected to the electrode assembly 20, and the second part 43 is connected to the electrode post 30. The first part 41 and the second part 43 are located on opposite sides of the insulating member 50 along the first direction X. Along the first direction X, the orthographic projections of the first part 41 and the second part 43 overlap with the orthographic projection of the insulating member 50. In other words, at least a portion of the insulating member 50 is sandwiched between the first part 41 and the second part 43. The bent part 42 is located on one side of the insulating member 50 along the second direction Y. The second direction Y is the thickness direction of the electrode assembly 20, and the first direction X is perpendicular to the second direction Y. The insulating member 50 has a plurality of through holes 51, which penetrate the insulating member 50 along the first direction X. The first tab assembly 40 is bent to form a U-shaped structure, thus distinguishing the first part 41, the second part 43, and the bent portion 42 based on their relative positions to the insulating member 50. The first part 41 and the second part 43 extend approximately in a straight line, and the bent portion 42 connects the first part 41 and the second part 43. The dividing point between the bent portion 42 and the first part 41 is the inflection point 421 located inside the U-shaped structure, and the dividing point between the bent portion 42 and the second part 43 is also the inflection point 421 located inside the U-shaped structure. It should be noted that the first part 41, the second part 43, and the bent portion 42 are merely artificial divisions made for the purpose of clearly describing the structure of the first tab assembly 40. In most cases, it is not necessary to pay attention to the dividing lines of the first part 41, the second part 43, and the bent portion 42; they can be understood as a whole as the first tab assembly 40.

[0062] In the prior art, when the secondary battery 100 is dropped or impacted, the electrolyte in the casing 10 oscillates back and forth along the first direction X, causing the insulating member 50 to repeatedly pull on the first tab assembly 40. This poses a risk that the first tab assembly 40 may break or detach from the terminal post 30, affecting the service life of the secondary battery 100. In the secondary battery 100 provided in this application, the insulating member 50 has multiple through holes 51 to allow the electrolyte to pass through. When the electrolyte oscillates back and forth inside the casing 10, some of the electrolyte can pass through the insulating member 50, thereby reducing the range of movement of the insulating member 50 and reducing its pulling on the first tab assembly 40. This reduces the possibility of damage to the first tab assembly 40 and improves the service life of the secondary battery 100.

[0063] It should be noted that the shape of the through hole 51 is not limited in the embodiments of this application. As an example, the shape of the through hole 51 can be circular, elliptical, rectangular, triangular, hexagonal, etc. In addition, when the diameter of the through hole 51 is mentioned in the following content of the specification, when a range of diameter values ​​is given, for non-circular through holes 51, the lower limit of the range is equivalent to the inscribed circle diameter of the non-circular through hole 51, and the upper limit of the range is equivalent to the circumscribed circle diameter of the non-circular through hole 51.

[0064] In some embodiments, the first tab assembly 40 includes a single tab connected to the first electrode plate 21, and the tab, when bent, bypasses the insulating member 50 and connects to the pole post 30.

[0065] In some embodiments, as shown in FIG3, the first electrode assembly 40 includes a first electrode bundle 401 and a first adapter 402. The first electrode bundle 401 includes a plurality of first electrodes 4011, which are stacked. The first electrode bundle 401 connects the electrode assembly 20 and the first adapter 402, and the first adapter 402 connects the electrode post 30. Part of the adapter and the first electrode bundle 401 together form a first portion 41, part of the first adapter 402 forms a bent portion 42, and part of the first adapter 402 forms a second portion 43. In other words, in this structure, the first electrode bundles 401 are all located on the side of the insulating member 50 facing the electrode assembly 20 along the first direction X.

[0066] In some embodiments, as shown in FIG4, the insulating member 50 is a plate-like structure to reduce its occupation of the first space.

[0067] In some embodiments, as shown in FIG4, the insulating member 50 has a first surface 52 and a second surface 53 disposed opposite to each other along the second direction Y. The first surface 52 includes a first region 521, a second region 522 and a third region 523 connected in sequence. Along the second direction Y, the distance from the first region 521 to the second surface 53 is greater than the distance from the third region 523 to the second surface 53, such that the first region 521, the second region 522 and the third region 523 together form a stepped shape. The bent portion 42 is disposed opposite to the third region 523 along the second direction Y. The width of the bent portion 42 along the third direction Z is less than or equal to the width of the third region 523 along the third direction Z; and the orthographic projection of the bent portion 42 along the third direction Z overlaps with the orthographic projection of the second region 522 along the third direction Z. The insulating member 50 accommodates at least a portion of the bent portion 42 by forming a stepped structure, thereby reducing the sum of the thicknesses of the insulating member 50 and the bent portion 42 after being stacked along the second direction Y, thereby reducing the influence of both on the thickness of the secondary battery 100, which is beneficial to improving the energy density of the secondary battery 100.

[0068] In some embodiments, the free electrolyte coefficient of the secondary battery 100 is R, which is the ratio of the free electrolyte in the secondary battery 100 to the internal space of the battery; the orthographic projection area of ​​the insulating member 50 along the first direction X is S, and the total orthographic projection area of ​​the plurality of through holes 51 along the first direction X is S1. 0.18 g / cm³ 3 <R≤0.36g / cm 3 30% ≤ S1 / S ≤ 60%; or 0.01 g / cm³ 3 ≤R≤0.18g / cm 3 15% ≤ S1 / S ≤ 50%. Hereinafter, the value of S1 / S will be simply referred to as the porosity of the insulating element 50. In this embodiment, the ratio of the area of ​​the through hole 51 to the area of ​​the insulating element 50 is determined according to the free electrolyte coefficient. That is, when the free electrolyte coefficient is higher, the lower limit of the porosity of the insulating element 50 is also higher, so that the electrolyte can pass through the insulating element 50, thereby helping to reduce the possibility of damage to the first tab assembly 40; and, setting the upper limit of the porosity of the insulating element 50 according to different free electrolyte coefficients helps to reduce the impact of the electrolyte on the first tab assembly 40, thereby reducing the risk of damage to the first tab assembly 40. Specifically, when 0.18 g / cm³... 3 <R≤0.36g / cm 3 When S1 / S is set to ≥ 30%, the opening ratio of the insulating component 50 is not too low, which facilitates the passage of electrolyte through the insulating component 50 and reduces the impact of electrolyte on the insulating component 50. When S1 / S is set to ≤ 60%, the opening ratio of the insulating component 50 is not too high, which helps to reduce the impact of electrolyte on the first tab assembly 40, thereby reducing the possibility of damage to the first tab assembly 40. When 0.01 g / cm 3 ≤R≤0.18g / cm 3 When S1 / S is set to ≥15%, the opening ratio of the insulating component 50 is not too low, which is conducive to the electrolyte passing through the insulating component 50 and reduces the impact of the electrolyte on the insulating component 50. When S1 / S is set to ≤50%, the opening ratio of the insulating component 50 is not too high, which is conducive to reducing the impact of the electrolyte on the first tab assembly 40 and thus reducing the possibility of damage to the first tab assembly 40.

[0069] The free electrolyte coefficient of the secondary battery 100 can be measured by the following method: Disassemble the secondary battery 100 into two parts: the casing 10 and the electrode assembly 20. After disassembly, quickly put the casing into a sealed bag and weigh it. Then, open the sealed bag and dry the casing at high temperature to evaporate the residual electrolyte on the casing. Weigh it again. The weight difference is the mass of the electrolyte. For the electrode assembly 20, centrifuge it to remove the free electrolyte. The sum of the mass of the residual electrolyte on the casing 10 and the mass of the centrifuged electrolyte is the total mass of the free electrolyte. Then, measure the volume of the first space of the secondary battery 100. The ratio of the total mass of the free electrolyte to the volume of the first space is the free electrolyte coefficient.

[0070] In some embodiments, as shown in FIG4, the maximum dimension of any through hole 51 along the second direction Y is A1, where 0.05mm≤A1≤1mm. Setting A1≥0.05mm ensures that the size of the through hole 51 is not too small, facilitating the passage of electrolyte through the insulating member 50 and reducing the impact force of the electrolyte on the insulating member 50. Setting A1≤1mm ensures that the size of the through hole 51 is not too large, improving the electrolyte diversion effect of the through hole 51 and reducing the direct impact of the electrolyte on the first tab assembly 40, thereby reducing the possibility of damage to the first tab assembly 40.

[0071] In some embodiments, as shown in FIG4, the maximum dimension of any through hole 51 along the third direction Z is A2, 0.05mm≤A2≤1mm, and the third direction Z is perpendicular to the first direction X and the second direction Y. Setting A2≥0.05mm ensures that the size of the through hole 51 is not too small, which facilitates the passage of electrolyte through the insulating member 50 and helps to reduce the impact force of electrolyte on the insulating member 50; setting A2≤1mm ensures that the size of the through hole 51 is not too large, which helps to improve the diversion effect of the through hole 51 on electrolyte, reduce the direct impact of electrolyte on the first tab assembly 40, and thus reduce the possibility of damage to the first tab assembly 40.

[0072] In some embodiments, as shown in FIG4, the width of the insulating member 50 along the second direction Y is W, and the distance between any two adjacent through holes 51 along the second direction Y is D1, where 0.5A1≤D1≤0.25W. Setting D1≥0.5A1 ensures that the distance between two adjacent through holes 51 is not too close, which is beneficial to improving the structural strength of the insulating member 50 under deformation; setting D1≤0.25W ensures that the distance between two adjacent through holes 51 is not too large, which is beneficial to improving the electrolyte diversion effect of the insulating member 50 and reducing the impact of the electrolyte on the insulating member 50.

[0073] In some embodiments, as shown in FIG4, the width of the insulating member 50 along the second direction Y is W, and the distance between any two adjacent through holes 51 along the third direction Z is D2, where 0.5A2≤D2≤0.25W. Setting D2≥0.5A2 ensures that the distance between two adjacent through holes 51 is not too close, which is beneficial to the structural strength of the insulating member 50; setting D2≤0.25W ensures that the distance between two adjacent through holes 51 is not too large, which is beneficial to improving the electrolyte diversion effect of the insulating member 50 and reducing the impact of the electrolyte on the insulating member 50.

[0074] In some embodiments, as shown in FIG4, the width of the insulating member 50 along the second direction Y is W. For the one of the plurality of through holes 51 that is closest to the edge of the insulating member 50, the minimum distance from it to the edge of the insulating member 50 is D3, A1≥A2, 0.5A1≤D3≤0.25W; or, A1<A2, 0.5A2≤D3≤0.25W. When A1≥A2, setting D3≥0.5A1 ensures that the distance between the through hole 51 and the edge of the insulating component 50 is not too small, which is beneficial to improving the structural strength of the insulating component 50. Setting D3≤0.25W ensures that the distance between the through hole 51 and the edge of the insulating component 50 is not too large, and the through hole 51 is not excessively concentrated in the middle of the insulating component 50, which is beneficial to reducing the impact of the electrolyte on the insulating component 50. When A1<A2, setting D3≥0.5A2 ensures that the distance between the through hole 51 and the edge of the insulating component 50 is not too small, which is beneficial to improving the structural strength of the insulating component 50. Setting D3≤0.25W ensures that the distance between the through hole 51 and the edge of the insulating component 50 is not too large, and the through hole 51 is not excessively concentrated in the middle of the insulating component 50, which is beneficial to reducing the impact of the electrolyte on the insulating component 50.

[0075] In some embodiments, as shown in FIG5, the insulating member 50 includes a first spacer portion 501. Along the first direction X, the orthographic projection of the first portion 41 and the orthographic projection of the second portion 43 are both located within the range of the first spacer portion 501. The first spacer portion 501 does not have a through hole 51. In this way, the electrolyte does not pass through the insulating member 50 from the first spacer portion 501, which helps to reduce the direct impact of the electrolyte on the first tab assembly 40, thereby reducing the possibility of damage to the first tab assembly 40.

[0076] In some embodiments, as shown in FIG6, the insulating member 50 includes a first spacer portion 501. Along the first direction X, the orthographic projections of the first portion 41 and the second portion 43 are located within the orthographic projection range of the first spacer portion 501. A portion of the through holes 51 are first through holes 511. The first through holes 511 are disposed in the first spacer portion 501, and the diameter of the first through holes 511 is A3, 0.1mm≤A3≤1mm. Setting A3≥0.1mm ensures that the diameter of the second through hole 512 is not too small, which is beneficial for the electrolyte to pass through the insulating member 50, thereby reducing the impact of the electrolyte on the insulating member 50 and also reducing the difficulty of the process. Setting A3≤1mm ensures that the diameter of the first through hole 511 is not too large, which is beneficial for reducing the impact of the electrolyte on the first tab assembly 40, thereby reducing the possibility of damage to the first tab assembly 40.

[0077] Furthermore, as shown in Figure 5, along the third direction Z, the width of the first portion 41 is W1, the width of the bent portion 42 is W2, and the width of the first spacing portion 501 is W3, where W1 ≥ W2, W1 ≤ W3 ≤ W1 + 1 mm; or, W1 < W2, W2 ≤ W3 ≤ W2 + 1 mm. In this embodiment, by limiting the maximum width of the first spacing portion 501 along the third direction Z, the width of the first spacing portion 501 is prevented from being too wide. This facilitates the opening of through holes 51 of different sizes in the portion of the insulating member 50 that differs from the first spacing portion 501, thereby increasing the opening ratio of the insulating member 50 and reducing the impact of the electrolyte on the insulating member 50.

[0078] In some embodiments, as shown in Figures 3 and 5, the first electrode assembly 40 is connected to the first electrode 21, and the first electrode 21, the separator 23, and the second electrode 22 are sequentially stacked and wound to form a wound structure. The insulating member 50 includes a second spacer portion 502, and along the first direction X, the orthographic projection of the separator 23 located in the outermost and second outermost layers of the electrode assembly 20 lies within the range of the second spacer portion 502. A portion of the through holes 51 are second through holes 512, which are disposed in the second spacer portion 502, and the diameter of the second through holes 512 is A4, where 0.1mm ≤ A4 ≤ 1mm. Setting A4 ≥ 0.1 mm ensures the diameter of the second through-hole 512 is not too small, facilitating the passage of electrolyte through the insulating component 50 and reducing its impact. Electrolyte impact on the outermost and second-outermost insulating films 23 of the electrode assembly 20 could cause them to fold, potentially short-circuiting the first electrode 21 and the second electrode 22. Therefore, setting A4 ≤ 1 mm ensures the diameter of the second through-hole 512 is not too large, reducing the impact force of the electrolyte on the outermost and second-outermost insulating films 23 of the electrode assembly 20, thus lowering the risk of folding. When identifying the outermost and second-outermost insulating films 23 of the electrode assembly 20, observe the electrode assembly 20 along its winding axis. Starting from the end of the insulating film 23 located at the outermost layer of the electrode assembly 20, the portion that completes one revolution along the winding direction of the electrode assembly 20 is the outermost insulating film 23, and the portion that completes the second revolution is the second-outermost insulating film 23.

[0079] In some embodiments, as shown in FIG5, the minimum distance between the second through hole 512 and the edge of the insulating member 50, which is closest to the edge of the insulating member 50, is D4, where 0.5mm ≤ D4 ≤ 1.4mm. Setting D4 ≥ 0.5mm ensures that the minimum distance between the second through hole 512 and the edge of the insulating member 50 is not too close, which helps to reduce the possibility of edge deformation of the insulating member 50 during the processing of the second through hole 512; setting D4 ≤ 1.4mm ensures that the minimum distance between the second through hole 512 and the edge of the insulating member 50 is not too large, which helps to improve the opening ratio of the insulating member 50.

[0080] In some embodiments, as shown in FIG5, a portion of the through holes 51 are third through holes 513. The third through holes 513 are located outside the first spacer portion 501 and the second spacer portion 502. The diameter of the third through hole 513 is A5, and the width of the insulating member 50 along the second direction Y is W, where 0.2mm≤A5≤W / 3. Setting A5≥0.2mm ensures that the diameter of the third through hole 513 is not too small, which facilitates the passage of electrolyte through the insulating member 50 and reduces the impact force of the electrolyte on the insulating member 50. Setting A5≤W / 3 ensures that the diameter of the third through hole 513 is not too large, which helps to reduce the surface area occupied by the third through hole 513 on the insulating member 50, thus facilitating the layout of the first through hole 511 and the second through hole 512.

[0081] In some embodiments, as shown in FIG6, the minimum distance between the first through hole 511 and the third through hole 513, which is closest to the edge of the insulating member 50, and the edge of the third through hole 513, is D5, where 0.5mm≤D5≤3mm. Setting D5≥0.5mm ensures that the distance between the first through hole 511 and the third through hole 513 and the edge of the insulating member 50 is not too small, which is beneficial to improving the structural strength of the insulating member 50. Setting D5≤3mm ensures that the distance between the first through hole 511 and the third through hole 513 and the edge of the insulating member 50 is not too large, which is beneficial to improving the electrolyte diversion effect of the insulating member 50, thereby helping to reduce the impact of the electrolyte on the insulating member 50.

[0082] In some embodiments, as shown in FIG6, the distance between any two adjacent through holes 51 along the second direction Y is D6, where 0.5mm≤D6≤3mm. Setting D6≥0.5mm ensures that the distance between two adjacent through holes 51 along the second direction Y is not too small, which helps reduce the possibility of deformation of the insulating component 50 during the hole opening process. Setting D6≤3mm ensures that the distance between two adjacent through holes 51 along the second direction Y is not too large, which helps improve the electrolyte diversion effect of the insulating component 50, thereby helping to reduce the impact of the electrolyte on the insulating component 50.

[0083] In some embodiments, as shown in FIG6, the distance between any two adjacent through holes 51 along the third direction Z is D7, where 0.5mm≤D7≤3mm. Setting D7≥0.5mm ensures that the distance between two adjacent through holes 51 along the third direction Z is not too small, which helps to reduce the possibility of deformation of the insulating component 50 during the hole-making process; setting D7≤3mm ensures that the distance between two adjacent through holes 51 along the third direction Z is not too large, which helps to improve the opening rate of the insulating component 50.

[0084] As shown in FIG7, an embodiment of this application also provides an electrical device 1000, which includes a secondary battery 100 as described in any of the foregoing embodiments.

[0085] In some embodiments, the electrical device 1000 includes, but is not limited to, mobile phones, laptops, power tools, and electric toys.

[0086] To verify the effectiveness of the solutions in the embodiments of this application, the inventors of this application conducted the following experiments, which included a total of 74 experimental groups, two of which were comparative examples and the remaining 72 were implementation examples. Each experimental group included 20 secondary batteries 100. In the experiments, the through holes 51 opened on the insulating component 50 in each embodiment were all circular holes.

[0087] The preparation process of the secondary battery in Example 1 includes the following steps:

[0088] (1) Preparation of positive electrode 201: Active materials lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), CNTs (carbon nanotubes), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:0.5:0.5:1.5. N-methylpyrrolidone (NMP) was added as a solvent to prepare a positive electrode active material with a solid content of 75 wt%, and the mixture was stirred evenly for later use. A 10 μm thick aluminum foil was used as the positive electrode current collector 2011. The above active material was uniformly coated onto one side of the positive electrode current collector 2011 using a slot coater, and then dried at 90°C to obtain a positive electrode 201 with a single-sided coating of the positive electrode active material. At this time, the thickness of the positive electrode active material layer 2012 was 65 μm. The above coating steps were then repeated on the other side of the positive electrode current collector 2011. The coated positive electrode sheet 201 is then cold-pressed, resulting in a single-layer positive electrode active material layer 2012 with a thickness of 35 μm. The area of ​​the positive electrode current collector 2011 not covered by the positive electrode active material layer 2012 is the positive electrode empty foil area, which is then die-cut to obtain the positive electrode tab.

[0089] (2) Preparation of negative electrode 202: Artificial graphite, conductive carbon black (Super P), styrene-butadiene rubber (SBR), and CMC (sodium carboxymethyl cellulose) were mixed in a weight ratio of 97:0.5:1.3:1.2. Deionized water was added as a solvent to prepare a negative electrode active material with a weight percentage of 50 wt%, and the mixture was stirred evenly for later use. An 8 μm thick copper foil was used as the negative electrode current collector 2021. The above negative electrode active material was uniformly coated onto one side of the negative electrode current collector 2021 using a slot coater, and then dried at 110°C to obtain a negative electrode 202 with a single-sided coating of the negative electrode active material layer 2022. At this time, the thickness of the negative electrode active material layer 2022 was 80 μm. The above steps were then repeated on the other side of the negative electrode current collector 2021 to obtain a negative electrode 202 with coatings of the negative electrode active material layer 2022 on both sides. The coated negative electrode sheet 202 is then cold-pressed, resulting in a single-layer negative electrode active material layer 2022 with a thickness of 45 μm. The area of ​​the negative electrode current collector 2021 not covered by the negative electrode active material layer 2022 is the negative electrode empty foil area, which is then die-cut to obtain the negative electrode tab. It should be noted that multiple negative electrode sheets 202 are prepared in this step, with two negative electrode sheets 202 having the negative electrode active material layer 2022 coated only on one side of the negative electrode current collector 2021 to serve as the two outermost electrodes of the electrode assembly 20, and the copper foil thickness of such negative electrode sheets 202 is 20 μm.

[0090] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) is added to the basic organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0091] (4) Preparation of the isolation membrane 23: A 7 μm thick porous polyethylene polymer film was used as the isolation membrane 23;

[0092] (5) Preparation of electrode assembly 20: Multiple positive electrode sheets 201, multiple separators 23 and multiple negative electrode sheets 202 are stacked alternately along the first direction X; positive electrode tabs are gathered and welded along the first direction X to form a positive electrode tab bundle, and a positive electrode adapter is welded on the positive electrode tab bundle; negative electrode tabs are gathered and welded along the first direction X to form a negative electrode tab bundle, and a negative electrode adapter is welded on the negative electrode tab bundle; electrode tab protective paper is attached to the electrode tabs, and wrapping adhesive is attached to the side and bottom edge of the battery cell.

[0093] (6) Assembly of the secondary battery 100: The casing 10 is connected to the terminal post 30, the positive electrode adapter is connected to the terminal post 30, and the negative electrode adapter is connected to the casing 10. Take an insulating component, bend the positive electrode tab bundle and the positive electrode adapter, the negative electrode tab bundle and the negative electrode adapter, and partially bypass the insulating component 50. Place the electrode assembly 20 into the casing 10. After the casing is welded, baked, electrolyte is injected, left to stand, hot-pressed, and sealed, the secondary battery 100 is obtained. The insulating component 50 has through holes 51. Any two through holes 51 have the same diameter, ignoring manufacturing errors, and A1 = A2. The width W of the insulating component 50 along the second direction Y is 4mm, and the length along the third direction Z is 70mm.

[0094] The preparation process of the secondary battery 100 in Comparative Example 1 and Comparative Example 2 is basically the same as that in Example 1. The difference is that the insulating part 50 of the secondary battery 100 in Comparative Example 1 and Comparative Example 2 does not have through holes 51.

[0095] The preparation process of the secondary battery 100 in Examples 2 to 44 is basically the same as that in Example 1. The difference lies in that some parameters of the secondary battery 100 in Examples 2 to 44 are different from those in Example 1. The specific differences are listed in Table 1. It should be noted that the through holes of the insulating member 50 in Examples 1 to 44 do not distinguish between the first spacer portion 501 and the second spacer portion 502. In other words, all the through holes 51 have the same diameter, and the distance between any two adjacent through holes along the second direction Y is equal, the distance between any two adjacent through holes 51 along the third direction Z is equal, and D1 = D2.

[0096] The preparation process of the secondary battery 100 in Examples 45 to 72 is basically the same as that in Example 1. The difference is that the insulating part 50 of the secondary battery 100 in Examples 45 to 72 is divided into a first spacer 501, a second spacer 502 and other parts that are different from the first spacer 501 and the second spacer 502. The first spacer 501 has a first through hole 511, the second spacer 502 has a second through hole 512, and the other parts have a third through hole 513.

[0097] After the secondary batteries 100 in each experimental group were prepared, a drop test was conducted on each secondary battery in each experimental group. The drop test process included the following steps:

[0098] Secure the secondary battery to the drop test fixture with double-sided tape. Number the six sides of the fixture as 1, 2, 3, 4, 5, and 6 in sequence, and number the four corners of the fixture as C1, C2, C3, and C4 in sequence.

[0099] At 25℃, place the fixture on a test platform 1.5m high, and drop the secondary batteries in the order of numbers 1-6, then drop them in the order of numbers C1-C4, repeating the cycle 3 times to complete the drop test.

[0100] After the drop test, the internal resistance test is performed. The test process includes the following steps:

[0101] Connect the secondary battery 100 to an internal resistance voltage tester to measure its internal resistance. Compare the calculated resistance value with the set judgment resistor. The preset value for the judgment resistor in this test is 200mΩ. A resistance value below 200mΩ is considered a pass (OK). A resistance value greater than or equal to 200mΩ indicates a loose connection between the tab and the casing, and the test is considered a fail (NG). Calculate the internal resistance test failure rate as: (Number of NGs / Total number of secondary batteries 100 in each test group). Record the test results in a table.

[0102] After completing the above testing process, disassemble the secondary battery 100 and observe whether the insulation components of the secondary battery 100 are damaged. Count the number of secondary batteries 100 with damaged insulation components and calculate the insulation component damage rate = number of secondary batteries 100 with damaged insulation components / total number of secondary batteries 100 in each test group. Record the test results in the table.

[0103] In the following table, the unit of R is g / cm³. 3 The units for S1, S, and the area of ​​a single circular hole are mm. 2 The units for A1, D1, D3, A3, A4, A5, and D5 are mm.

[0104] Table 1 Note: In Table 1, " / " indicates that there is no such data.

[0105] As shown in Table 1, in Examples 1 to 21, the insulating component 50 of the secondary battery 100 has through holes 51. Compared with Comparative Examples 1 and 2, the secondary batteries 100 in Examples 1 to 21 have a higher pass rate in the internal resistance test. It is evident that by creating multiple through holes 51 on the insulating component 50 to allow electrolyte to pass through, the impact force on the insulating component 50 when the electrolyte oscillates back and forth within the casing 10 is reduced. This reduces the pulling force of the insulating component 50 on the first tab assembly 40 and diverts the electrolyte, which helps to reduce the possibility of damage to the first tab assembly 40.

[0106] In Examples 2 to 6, the secondary battery 100 satisfies 0.01 g / cm³. 3 ≤R≤0.18g / cm 315% ≤ S1 / S ≤ 50%. Compared to Examples 1 and 7, the secondary batteries 100 in Examples 2 to 6 have a higher pass rate in the internal resistance test. This shows that when 0.01 g / cm... 3 ≤R≤0.18g / cm 3 Setting S1 / S≥15% helps the electrolyte pass through the insulating component 50, thereby reducing the impact force of the electrolyte on the insulating component 50 and thus reducing the possibility of damage to the first tab assembly 40. Setting S1 / S≤50% helps reduce the direct impact of the electrolyte on the first tab assembly 50, thereby reducing the possibility of damage to the first tab assembly 40.

[0107] In Examples 9 to 12, the secondary battery 100 satisfies 0.18 g / cm³. 3 <R≤0.36g / cm 3 30% ≤ S1 / S ≤ 60%. Compared to Examples 8 and 13, the secondary batteries 100 in Examples 9 to 12 have a higher pass rate in the internal resistance test. This shows that when 0.18 g / cm... 3 <R≤0.36g / cm 3 Setting S1 / S≥30% helps the electrolyte pass through the insulating component 50, thereby reducing the impact force of the electrolyte on the insulating component 50 and thus reducing the possibility of damage to the first tab assembly 40. Setting S1 / S≤60% helps reduce the direct impact of the electrolyte on the first tab assembly 50, thereby reducing the possibility of damage to the first tab assembly 40.

[0108] In Examples 3, 14 to 17, the secondary battery 100 satisfies 0.01 g / cm³. 3 ≤R≤0.18g / cm 3 Under the condition that 15% ≤ S1 / S ≤ 50%, the secondary batteries 100 in Examples 3, 14 to 17 all passed the internal resistance test, and no insulation damage was observed; in Examples 18 to 21, the secondary battery 100 met the requirement of 0.18 g / cm³. 3 <R≤0.36g / cm 3 Under the condition that 30% ≤ S1 / S ≤ 60%, the secondary batteries 100 in Examples 19 to 22 all passed the internal resistance test and no insulation damage was found.

[0109] Table 2

[0110] In Examples 23 to 33, the secondary battery 100 satisfies 0.05mm≤A1≤1mm. Compared with Examples 22 and 34, the secondary battery 100 in Examples 23 to 33 has a higher pass rate in the internal resistance test. Since the electrolyte is viscous, if the size of the through hole 51 is too small, the electrolyte will have difficulty passing through. Setting A1≥0.05mm ensures that the size of the through hole 51 is not too small, which facilitates the electrolyte to pass through the insulating component and helps to reduce the impact force of the electrolyte on the insulating component. Setting A1≤1mm ensures that the size of the through hole 51 is not too large, which helps to reduce the direct impact of the electrolyte on the first tab assembly 40, thereby reducing the possibility of damage to the first tab assembly 40.

[0111] In Examples 29, 36 to 38, the secondary battery 100 satisfies 0.5A1≤D1≤0.25W. Compared to Example 35, the breakage rate of the insulating component 50 of the secondary battery 100 in Examples 29, 36 to 38 is lower. It can be seen that setting D1≥0.5A1 ensures that the distance between two adjacent through holes is not too close, which is beneficial to reducing the impact of the hole opening process and improving the structural strength of the insulating component. Compared to Example 39, the secondary battery 100 in Examples 29, 36 to 38 has a higher pass rate in the internal resistance test. The reason is that, due to the viscosity of the electrolyte, as the distance between the two through holes 51 increases, the shunting effect of the perforated insulating component 50 on the electrolyte decreases. It can be seen that setting D1≤0.25W ensures that the distance between two adjacent through holes is not too large, which is beneficial to improving the shunting effect of the insulating component 50 on the electrolyte and reducing the impact of the electrolyte on the insulating component 50.

[0112] In Examples 29 and 41 to 43, the secondary battery 100 satisfies 0.5A1≤D3≤0.25W. Compared to Example 40, the insulation breakage rate of the secondary battery 100 in Examples 29 and 41 to 43 is lower. It can be seen that setting D3 to be greater than or equal to half of the larger value of A1 and A2 prevents the distance between the through hole 51 and the edge of the insulation 50 from being too small, which is beneficial to reducing the structural strength of the insulation 50. Compared to Example 44, the secondary battery 100 in Examples 29 and 41 to 43 has a higher pass rate in the internal resistance test. It can be seen that setting D3≤0.25W prevents the through hole 51 from being excessively concentrated in the middle of the insulation 50, which is beneficial to improving the electrolyte diversion effect of the insulation 50, thereby reducing the impact of the electrolyte on the insulation 50.

[0113] Table 3

[0114] In Examples 46 to 50, the secondary battery 100 satisfies 0.1mm≤A3≤1mm. Compared with Examples 45 and 51, the secondary battery 100 in Examples 46 to 50 has a higher pass rate in the internal resistance test. It can be seen that setting A3≥0.1mm ensures that the diameter of the second through hole 512 is not too small, which is beneficial for the electrolyte to pass through the insulating component 50, thereby reducing the impact of the electrolyte on the insulating component 50. Setting A3≤1mm ensures that the diameter of the first through hole 511 is not too large, which is beneficial for reducing the impact of the electrolyte on the first tab assembly 40, thereby reducing the possibility of damage to the first tab assembly 40.

[0115] In Examples 48, 53 to 56, the secondary battery 100 satisfies 0.1mm≤A4≤1mm. Compared with Examples 52 and 57, the secondary battery 100 in Examples 48, 53 to 56 has a higher pass rate in the internal test. It can be seen that setting A4≥0.1mm ensures that the diameter of the second through hole 512 is not too small, which is beneficial for the electrolyte to pass through the insulating component 50, thereby reducing the impact of the electrolyte on the insulating component 50. Setting A4≤1mm ensures that the diameter of the second through hole 512 is not too large, which is beneficial for reducing the impact of the electrolyte on the outermost and second outermost separator membranes 23 of the electrode assembly 20, thereby reducing the risk of separator membrane 23 folding.

[0116] In Examples 48, 59 to 64, the secondary battery 100 satisfies 0.2mm≤A5≤W / 3. Compared with Example 58, the secondary battery 100 in Examples 48, 59 to 64 has a higher pass rate in the internal resistance test. It can be seen that setting A5≥0.2mm ensures that the diameter of the third through hole is not too small, which is beneficial for the electrolyte to pass through the insulating component 50 and reduce the impact force of the electrolyte on the insulating component 50. On this basis, setting A5≤W / 3 helps to reduce the occupation of the surface of the insulating component 50 by the third through hole 513, so as to facilitate the layout of the first through hole 511 and the second through hole 512.

[0117] In Examples 48, 67 to 71, the secondary battery 100 satisfies 0.5mm≤D5≤3mm. Compared with Example 66, the insulation breakage rate of the secondary battery 100 in Examples 48, 67 to 71 is lower. It can be seen that by setting D5≥0.5mm, the distance between the first through hole 511 and the third through hole 513 and the edge of the insulation 50 is not too small, which is beneficial to improving the structural strength of the insulation 50. Compared with Example 72, the internal resistance throughput of the secondary battery 100 in Examples 48, 67 to 71 is higher. It can be seen that by setting D5≤3mm, the distance between the first through hole 511 and the third through hole 513 and the edge of the insulation 50 is not too large, which is beneficial to improving the electrolyte diversion effect of the insulation 50, thereby helping to reduce the impact of the electrolyte on the insulation 50.

[0118] It is understandable that the differences in the effects of various proportions and embodiments can result in significant differences in absolute quantities during mass production.

[0119] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of this application.

Claims

1. A secondary battery, characterized in that, include: A housing, the housing being made of a metal material, and a first space being formed within the housing; A terminal post, which is connected to the housing, with a portion of the terminal post located in the first space and a portion of the terminal post extending out of the housing; Electrode components are housed in the first space; Electrolyte, contained in the first space; A first tab assembly is connected to the electrode assembly, and the first tab assembly is located on one side of the electrode assembly along a first direction; and An insulating element is disposed in the first space. The first electrode assembly includes a first part, a bent part, and a second part connected in sequence. The first part is connected to the electrode assembly, and the second part is connected to the electrode post. The first part and the second part are respectively located on opposite sides of the insulating element along the first direction, and the orthographic projections of the first part and the second part overlap with the orthographic projection of the insulating element along the first direction. The bent part is located on one side of the insulating element along the second direction, which is the thickness direction of the electrode assembly, and the first direction is perpendicular to the second direction. The insulating element has a plurality of through holes, which penetrate the insulating element along the first direction.

2. The secondary battery as described in claim 1, characterized in that, The free electrolyte coefficient of the secondary battery is R, which is the ratio of the free electrolyte in the secondary battery to the internal space of the battery; the projected area of ​​the insulating component along the first direction is S, and the total projected area of ​​the plurality of through holes along the first direction is S1, 0.18 g / cm³. 3 <R≤0.36g / cm 3 30% ≤ S1 / S ≤ 60%; or 0.01 g / cm³ 3 ≤R≤0.18g / cm 3 15% ≤ S1 / S ≤ 50%.

3. The secondary battery as described in claim 1 or 2, characterized in that, The maximum dimension of any of the through holes along the second direction is A1, 0.05mm ≤ A1 ≤ 1mm; and / or The maximum dimension of any of the through holes along a third direction is A2, 0.05mm≤A2≤1mm, and the third direction is perpendicular to the first direction and the second direction.

4. The secondary battery as described in claim 3, characterized in that, The width of the insulating element along the second direction is W, and the distance between any two adjacent through holes along the second direction is D1, where 0.5A1 ≤ D1 ≤ 0.25W; and / or The distance between any two adjacent through holes along the third direction is D2, where 0.5A2≤D2≤0.25W.

5. The secondary battery as described in claim 3, characterized in that, The width of the insulating member along the second direction is W. For the one of the plurality of through holes that is closest to the edge of the insulating member, the minimum distance from it to the edge of the insulating member is D3, where A1≥A2, 0.5A1≤D3≤0.25W; or A1<A2, 0.5A2≤D3≤0.25W.

6. The secondary battery as described in any one of claims 1-5, characterized in that, The insulating member includes a first spacer portion. Along the first direction, the orthographic projection of the first portion and the orthographic projection of the second portion are both located within the range of the first spacer portion, and the first spacer portion does not have the through hole.

7. The secondary battery as described in claim 1 or 2, characterized in that, The insulating component includes a first spacer portion. Along the first direction, the orthographic projections of the first portion and the second portion are located within the orthographic projection range of the first spacer portion. A portion of the through holes are designated as first through holes. The first through holes are disposed in the first spacer portion, and the diameter of the first through holes is A3, where 0.1mm ≤ A3 ≤ 1mm.

8. The secondary battery as described in claim 7, characterized in that, Along the third direction, the width of the first part is W1, the width of the bent part is W2, and the width of the first interval part is W3, where W1≥W2, W1≤W3≤W1+1mm; or W1<W2, W2≤W3≤W2+1mm; The third direction is perpendicular to the first direction and the second direction.

9. The secondary battery as described in claim 7 or 8, characterized in that, The electrode assembly includes a first electrode, a second electrode, and a separator. The first electrode and the second electrode have opposite polarities. The first electrode tab assembly is connected to the first electrode. The first electrode, the separator, and the second electrode are stacked and wound in sequence to form a wound structure. The insulating element includes a second spacer portion, and along the first direction, the orthogonal projection of the insulating film located in the outermost and second outermost layers of the electrode assembly lies within the range of the second spacer portion; A portion of the through holes are second through holes, which are located in the second spacer portion. The diameter of the second through hole is A4, and 0.1mm≤A4≤1mm.

10. The secondary battery as described in claim 9, characterized in that, In the second through hole, the minimum distance between the one closest to the edge of the insulating element and the edge of the insulating element is D4, where 0.5mm≤D4≤1.4mm.

11. The secondary battery as described in claim 9, characterized in that, A portion of the through holes are third through holes, which are located outside the first and second spacers. The diameter of the third through hole is A5, and the width of the insulating member along the second direction is W, where 0.2mm ≤ A5 ≤ W / 3.

12. The secondary battery as described in claim 11, characterized in that, Of the first through hole and the third through hole, the one closest to the edge of the insulating member has a minimum distance of D5, where 0.5mm≤D5≤3mm.

13. The secondary battery as described in claim 7, 9, or 10, characterized in that, The distance between any two adjacent through holes along the second direction is D6, where 0.5mm ≤ D6 ≤ 3mm; and / or The distance between any two adjacent through holes along a third direction is D7, where 0.5mm≤D7≤3mm, and the third direction is perpendicular to the first direction and the second direction.

14. The secondary battery as described in any one of claims 1-13, characterized in that, The insulating component has a first surface and a second surface disposed opposite to each other along the second direction, the first surface comprising a first region, a second region and a third region connected in sequence; Along the second direction, the distance from the first region to the second surface is greater than the distance from the third region to the second surface, such that the first region, the second region, and the third region together form a stepped shape; The bent portion and the third region are disposed opposite each other along the second direction. The width of the bent portion along the third direction is less than or equal to the width of the third region along the third direction. Furthermore, the orthographic projection of the bent portion along the third direction overlaps with the orthographic projection of the second region along the third direction. The third direction is perpendicular to both the first direction and the second direction.

15. The secondary battery as described in any one of claims 1-14, characterized in that, The first electrode assembly includes a first electrode bundle and a first adapter. The first electrode bundle includes a plurality of first electrodes, which are stacked. The first electrode bundle connects the electrode assembly and the first adapter, and the first adapter connects the electrode post. A portion of the first adapter and the first electrode bundle together form the first part, a portion of the first adapter forms the bent portion, and a portion of the first adapter forms the second part.

16. An electrical appliance, characterized in that, Includes the secondary battery as described in any one of claims 1 to 15.

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