Electrochemical apparatus and electronic device

Abstract

The present application discloses an electrochemical apparatus and an electronic device. The electrochemical apparatus comprises an accommodating part and an electrode assembly accommodated in the accommodating part, and the electrochemical apparatus further comprises a metal strip, a sealing member and a functional layer. The metal strip comprises a first part, a second part and a third part, which are connected with each other, the first part being connected to the electrode assembly in the accommodating part, the accommodating part being provided with an extension hole, the second part being disposed in the extending hole, and the third part extending out of the accommodating part. The sealing member is disposed between the second part and the inner wall of the extension hole, the sealing member being adhered to the accommodating part. The functional layer is disposed on an outer surface of the second part and located between the second part and the sealing member, the functional layer being formed so as to melt when the temperature rises to a first threshold. When the electrochemical apparatus is in a short-circuit thermal runaway or thermal shock test process, the temperature rises to the first threshold, at which moment the functional layer melts so as to form a gas discharge channel placing the inside and the outside of the accommodating part in communication, so as to rapidly discharge gas and heat, and effectively reduce the risk of explosion of the electrochemical apparatus.

Description

Electrochemical devices and electronic devices

Technical field

[0001] The embodiments of the present application relate to the field of electrochemical technology, and in particular to an electrochemical device and an electronic device. [Background Technology]

[0002] As demand for electronic products grows, lithium-ion batteries are being required to fit into the diverse spaces of these products. For example, ultra-narrow lithium-ion batteries are required for slim products like smart glasses and headphones. In the prior art, batteries with a width or diameter of no more than 6 mm are generally referred to as ultra-narrow lithium-ion batteries.

[0003] Due to their small size, ultra-narrow batteries are difficult to set up with pressure relief structures. During use, ultra-narrow batteries may experience thermal runaway, resulting in increased pressure inside the housing, causing the battery housing to expand and even causing safety risks such as battery explosion.

[0004] [Summary of the invention]

[0005] The embodiments of the present application aim to provide a battery cell and an electrochemical device to reduce swelling and lower the risk of battery explosion.

[0006] In order to solve the technical problems, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, the present application proposes an electrochemical device comprising a housing and an electrode assembly housed within the housing. The electrochemical device also includes a metal strip, a seal, and a functional layer. The metal strip includes a first portion, a second portion, and a third portion, wherein the first portion is connected to the electrode assembly within the housing, the housing having an extension hole, the second portion being disposed within the extension hole, and the third portion extending outside the housing. The seal is disposed between the second portion and the inner wall of the extension hole and is bonded to the housing. The functional layer is disposed on the outer surface of the second portion and between the second portion and the seal, and the functional layer is configured to melt when the temperature rises to a first threshold.

[0008] In the above technical solution, by setting a functional layer between the second part and the seal, when the electrochemical device is in a short-circuit thermal runaway or thermal shock test, its temperature will rise to a first threshold value. At this time, the functional layer melts to form an exhaust channel connecting the inside and outside of the accommodation part, so that the gas and heat in the accommodation part can be quickly discharged to alleviate the expansion of the electrochemical device, which can effectively reduce the risk of explosion of the electrochemical device.

[0009] In some preferred embodiments, the electrochemical device further includes an insulating assembly. The insulating assembly is disposed on the outer surface of the third portion, which has a conductive region that is not covered by the insulating assembly. Providing the insulating assembly in the third portion outside the housing improves the strength and toughness of the metal strip, thereby reducing bending. The insulating assembly also separates the positive and negative metal strips of the electrochemical device, reducing the risk of short circuits caused by direct contact between the positive and negative metal strips. Furthermore, when multiple electrochemical devices are fabricated, the insulating assembly further isolates the metal strips of other electrochemical devices, further reducing the risk of short circuits.

[0010] In some preferred embodiments, the metal strip includes a first surface and a second surface arranged opposite to each other in a first direction. On the first surface, along the second direction, the ends of the third portion respectively have a first region and a second region, and the conductive region is located between the first region and the second region. The insulating component includes a first insulating layer and a second insulating layer, the first insulating layer is arranged in the first region, and the second insulating layer is arranged in the second region. The first part, the second part and the third part are arranged in sequence along the third direction, and the first direction, the second direction and the third direction are perpendicular to each other. Providing the insulating layer only in the first and second regions can, on the one hand, reduce the number of insulating layers and reduce costs; on the other hand, the first and second regions are the parts of the metal strip that are easily in contact with external conductive parts. Providing the insulating layer in the first and second regions can reduce the bending of the metal strip and reduce the risk of short circuit in the electrochemical device.

[0011] In some preferred embodiments, the first insulating layer, the second insulating layer, and the functional layer are integrally formed, thereby ensuring the strength and toughness of each insulating layer and thus the strength and toughness of the metal strip.

[0012] In some preferred embodiments, the electrochemical device further includes a third insulating layer, which is disposed on the second surface of the third portion, and can further improve the strength and toughness of the metal strip, thereby further reducing the short circuit risk of the electrochemical device.

[0013] In some preferred embodiments, the third portion further includes a first side surface and a second side surface disposed opposite each other in the second direction. The insulation assembly further includes a fourth insulation layer disposed on the first side surface; and / or the insulation assembly further includes a fifth insulation layer disposed on the second side surface. This further insulates the metal strip to reduce the risk of short circuits.

[0014] In some preferred embodiments, the material of the functional layer includes low-density polyethylene and / or polypropylene, and the density of the functional layer is ρ, 0.910 g / cm 3 ≤ρ≤0.925g / cm 3 .

[0015] In some preferred embodiments, the first threshold is T1, 110°C ≤ T1 ≤ 115°C.

[0016] In some preferred embodiments, the sealing member is made of at least one of polypropylene, o-phenylphenol, polyvinyl chloride, polyethylene terephthalate, polyamide resin, and phenolic resin, and has a melting point T2, where T2 is ≥ 120°C. When the temperature reaches a first threshold, the sealing member remains solid, isolating the housing from the metal strip. Furthermore, when the temperature decreases and the functional layer solidifies, the electrochemical device can be resealed by adding a melted functional layer to the exhaust passage. This arrangement facilitates the reuse of the electrochemical device and increases its service life.

[0017] In some preferred embodiments, the sealing member is bonded to the functional layer. When the temperature reaches a first threshold, the functional layer melts, while the high-melting-point sealing member is still solid. The sealing member still adheres to the partially melted functional layer, thereby reducing the spread of the melted functional layer to the surrounding area.

[0018] In some preferred embodiments, along the first direction, the thickness of the first insulating layer is H1, 30 μm≤H1≤40 μm, which improves the strength and toughness of the metal strip while reducing the risk of short circuit of the electrochemical device.

[0019] Optionally, along the first direction, the thickness of the second insulating layer is H2, 30 μm≤H2≤40 μm, so as to further improve the strength and toughness of the metal strip and reduce the risk of short circuit of the electrochemical device.

[0020] Optionally, along the second direction, the width of the first insulating layer is W1, 0.1 mm≤W1≤0.17 mm.

[0021] Optionally, along the second direction, the width of the second insulating layer is W2, 0.1 mm ≤ W2 ≤ 0.17 mm.

[0022] In some preferred embodiments, the electrochemical device includes at least two metal strips, at least one of which is a positive electrode metal strip and at least one of which is a negative electrode metal strip, with the positive and negative electrode metal strips extending from the same side of a housing. The presence of the insulating assembly reduces contact between the positive and negative electrode metal strips, allowing the positive and negative electrode metal strips to be extended directly from the same side of the housing, thereby reducing the space required along the length of the electrochemical device.

[0023] In some preferred embodiments, along the first direction, the thickness of the metal strip is H3, 0.06 mm ≤ H3 ≤ 0.1 mm.

[0024] Optionally, along the second direction, the width of the metal strip is W3, 0.2 mm ≤ W3 ≤ 2 mm;

[0025] Optionally, along the second direction, the width of the accommodating portion is W4, 1mm≤W4≤4mm, and the insulating component can isolate the positive and negative metal strips of the electrochemical device, thereby reducing the spacing between the positive and negative metal strips to meet the ultra-narrow design requirements of the electrochemical device.

[0026] In a second aspect, the present application further proposes an electronic device comprising the electrochemical device as described in any embodiment of the first aspect above.

[0027] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below.

Brief Description of the Drawings

[0028] One or more embodiments are exemplarily illustrated by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0029] FIG1 is a schematic structural diagram of an electrochemical device according to some embodiments of the present application;

[0030] FIG2 is a schematic cross-sectional view of the second portion along the second direction and a partial enlarged view of point A of some embodiments of the present application;

[0031] FIG3 is a schematic diagram of the installation of a metal belt and a sealing member according to some embodiments of the present application;

[0032] FIG4 is a schematic structural diagram of a receiving portion and a partial enlarged view of point B in some embodiments of the present application;

[0033] FIG5 is a schematic diagram of the installation of a metal strip and an insulating assembly according to some embodiments of the present application;

[0034] FIG6 is a schematic diagram of the installation of a metal belt and a sealing member according to some embodiments of the present application;

[0035] FIG7 is a schematic diagram of the installation of a metal strip and an insulating assembly according to some embodiments of the present application;

[0036] FIG8 is a schematic diagram of the installation of a metal strip and an insulating assembly according to some embodiments of the present application;

[0037] FIG9 is a schematic cross-sectional view of a third portion along a second direction of some embodiments of the present application;

[0038] FIG10 is a schematic diagram of the installation of metal strips and insulating components according to some embodiments of the present application.

[0039] Description of reference numerals:

[0040] 1000. Electrochemical device;

[0041] 10. Electrode assembly;

[0042] 20. Metal strip; 20a. Long side; 20b. Wide side; 20c. Thick side; 21. First surface; 211. First region; 212. Second region; 213. Conductive region; 22. Second surface; 23. First portion; 24. Second portion; 25. Third portion; 26. Fourth portion; 27. First side; 28. Second side.

[0043] 30. Sealing member; 40. Functional layer; 50. First insulating layer; 60. Second insulating layer; 70. Third insulating layer; 80. Fourth insulating layer; 90. Fifth insulating layer;

[0044] 100, accommodating portion; 101, extending hole; 102, top sealing edge; 110, sixth insulating layer;

[0045] 200, insulation components;

[0046] X, second direction; Y, third direction; Z, first direction. [Specific implementation method]

[0047] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0048] It should be noted that when an element is described as being “fixed to” or “disposed on” another element, it may be directly on the other element, or one or more intervening elements may be present therebetween. When an element is described as being “connected to” another element, it may be directly connected to the other element, or one or more intervening elements may be present therebetween.

[0049] In the description of the embodiments of this application, the technical terms "first," "second," etc. are used only to distinguish different objects and should not be understood to indicate or imply relative importance or to implicitly indicate the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise specifically defined.

[0050] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0051] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive with other embodiments. Furthermore, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not conflict with each other.

[0052] First, the present application provides an electrochemical device 1000. Referring to Figures 1 and 2, the electrochemical device 1000 includes a housing 100, an electrode assembly 10, a metal strip 20, a seal 30, and a functional layer 40. The electrode assembly 10 is housed within the housing 100. One end of the metal strip 20 is electrically connected to the electrode assembly 10, and the other end extends outside the housing 100. The seal 30 seals the installation gap between the metal strip 20 and the housing 100. The functional layer 40 is located between the metal strip 20 and the seal 30.

[0053] Regarding the electrode assembly 10, please refer to FIG1 . The electrode assembly 10 includes a first electrode sheet (not shown), a second electrode sheet (not shown), and a separator (not shown). The first electrode sheet and the second electrode sheet have opposite polarities, one being a positive electrode sheet and the other a negative electrode sheet. The separator is disposed between the first electrode sheet and the second electrode sheet to separate the two. The electrode assembly 10 may adopt a wound structure, that is, the first electrode sheet, the separator, and the second electrode sheet are stacked and wound in sequence to form a wound electrode assembly 10. In other embodiments, the electrode assembly 10 may also adopt a laminated structure, that is, the first electrode sheet, the separator, and the second electrode sheet are alternately stacked in sequence to form a laminated electrode assembly 10.

[0054] Regarding the metal strip 20, referring to Figure 1 , the metal strip 20 can be made of a conductive metal such as aluminum, copper, or nickel, and is used to electrically connect to the electrode assembly 10. For example, if the first electrode is a positive electrode and the second electrode is a negative electrode, two metal strips 20 can be provided: one metal strip 20 electrically connected to the first electrode to lead out the positive electrode, and the other metal strip 20 electrically connected to the second electrode to lead out the negative electrode. The metal strip 20 can be connected to the electrode sheets by welding or conductive adhesive to ensure electrical continuity between the metal strips 20 and the electrode sheets.

[0055] Referring to Figures 1 to 3 , the metal strip 20 can be configured as a flat strip structure, including a long side 20a, a wide side 20b, and a thick side 20c. Along a first direction Z, the thickness of the metal strip 20 is H3, with a range of 0.06 mm ≤ H3 ≤ 0.1 mm. Along a second direction X, the width of the metal strip 20 is W3, with a range of 0.2 mm ≤ W3 ≤ 2 mm. This facilitates the ultra-narrow design requirements of the electrochemical device 1000. For example, along the first direction X, the width of the receiving portion is W4, with a range of 1 mm ≤ W4 ≤ 4 mm.

[0056] The metal strip 20 includes a first portion 23, a second portion 24, and a third portion 25. The second portion 24 is disposed between the first and second portions 23, 24. For example, in the case where the seal 30 is sleeved on the metal strip 20, the seal 30 divides the metal strip 20 into two portions along the length direction (third direction Y) of the metal strip 20: the first portion 23 and the third portion 25. The portion where the metal strip 20 is sleeved is the second portion 24.

[0057] The metal strip 20 has a first surface 21 and a second surface 22 disposed opposite each other in a first direction Z. The first surface 21 and the second surface 22 are defined by the long side 20a and the wide side 20b. The first surface 21 and the second surface 22 extend from a first portion 23 through a second portion 24 to a third portion 25. The first portion 23 can be electrically connected to the electrode assembly 10, and the third portion 25 can be connected to the end of the second portion 24 remote from the first portion 23. For example, the first portion 23 is electrically connected to the electrode assembly 10 within the housing 100. The housing 100 defines an extension hole 101 (see FIG. 4 ). The second portion 24 is disposed within the extension hole 101. The third portion 25 can be connected to the end of the second portion 24 remote from the first portion 23. The third portion 25 is configured to conduct electricity to an external circuit, thereby enabling electrical connection between the electrode assembly 10 and the external circuit. Optionally, along the third direction Y, the length of the third portion 25 is L, 6 mm ≤ L ≤ 10 mm, to ensure that the third portion 25 has sufficient strength and sufficient connection area for stable electrical connection with an external circuit.

[0058] With reference to Figures 1 to 4 , the seal 30 is disposed between the second portion 24 and the inner wall of the extension hole 101, thereby sealing the installation gap between the second portion 24 and the inner wall of the extension hole 101 and thereby ensuring the sealing of the electrochemical device 1000. For example, the seal 30 may be disposed between the first surface 21 and / or the second surface 22 of the second portion 24 and the inner wall of the extension hole 101. Alternatively, the seal 30 may be sleeved on the surface of the metal strip 20 and located between the second portion 24 and the inner wall of the extension hole 101. Alternatively, the housing 100 may be packaged in an aluminum-plastic film bag, and the seal 30 may be directly bonded to the bag. The seal 30 may then be secured to the housing 100 by heat-pressing the bag. As for the above-mentioned extension hole 101, the accommodating portion 100 has a top sealing edge 102, and the second portion 24 of the above-mentioned metal strip 20 is arranged in the top sealing edge 102. When the aluminum-plastic film packaging bag is hot-pressed, the extension hole 101 is formed at the top sealing edge 102 where the second portion 24 is located. At this time, it can be considered that the metal strip 20 extends out of the accommodating portion 100 from the extension hole 101.

[0059] Regarding the functional layer 40, referring to Figures 2 and 3, the functional layer 40 can be disposed between the seal 30 and the metal strip 20. For example, the functional layer 40 is disposed in the second portion 24 and is located between the second portion 24 and the seal 30. The functional layer 40 is configured to melt when the temperature rises to a first threshold. The first threshold is T1, and 110°C ≤ T1 ≤ 115°C. When the electrochemical device 1000 is in a short circuit or thermal shock test, the temperature inside the electrochemical device 100 rises to the first threshold, and the internal heat is rapidly transferred to the functional layer 40, causing the temperature around the functional layer 40 to rise to the first threshold. At this time, the functional layer 40 melts to form an exhaust channel connecting the inside and outside of the container 100, thereby quickly exhausting the gas and heat within the container 100, effectively reducing the risk of explosion of the electrochemical device 1000.

[0060] Preferably, the material of the functional layer 40 can be selected from low-density polyethylene (LDPE), which is different from conventional high-density polyethylene (density 0.941 g / cm 3 ~0.965g / cm 3 ) compared to low-density polyethylene, which has a density of 0.910 g / cm 3 ~0.925g / cm 3Low-density polyethylene is a white resin with a waxy feel and a non-linear structural characteristic. Its molecular weight is generally between 1000 and 5000. It has a low crystallinity (10% to 30%) and a softening point (105°C to 115°C), and has good softness and elongation (370%). It also has good electrical insulation, transparency, and high impact resistance. Its physical and chemical properties are stable at room temperature. It also has certain toughness and strength and can melt at a temperature of 105°C to 115°C. Optionally, in some other embodiments, the functional layer 40 can also be made of polypropylene, which meets the density of 0.910g / cm 3 ~0.925g / cm 3 , and the melting point is 110℃~115℃.

[0061] The seal 30 may be made of at least one of polypropylene (PP), high-density polyethylene (HDPE), o-phenylphenol (OPP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyamide resin (PA), or phenolic resin (PF) with a relatively high melting point (melting point T2 of the seal 30 is greater than 120°C, for example, 120°C ≤ T2 ≤ 190°C). Taking the melting of the functional layer 40 as an example, when the temperature reaches a first threshold, the seal 30 remains solid, isolating the housing 200 from the metal strip 20. Furthermore, when the temperature drops and the functional layer 40 solidifies, the housing 100 can be resealed by adding melted functional layer 40 to the exhaust passage. This arrangement facilitates the reuse of the electrochemical device 100 and increases its service life. The sealing member 30 can be bonded to the functional layer 40 . When the temperature reaches a first threshold, the functional layer 40 melts, and the solid sealing member 30 still bonds to the partially melted functional layer 40 , thereby reducing the spread of the melted functional layer 40 to the surroundings.

[0062] Referring to Figure 5 , the electrochemical device 1000 further includes an insulating assembly 200. The insulating assembly 200 is disposed on the outer surface of the third portion 25. The third portion 25 has a conductive region 213, which is not covered by the insulating assembly 200. Providing the insulating assembly 200 on the third portion 25 outside the housing 100 improves the strength and toughness of the metal strip 20, thereby reducing bending of the metal strip 20.

[0063] For a single electrochemical device 100, the insulating assembly 200 can separate the positive and negative metal strips of the single electrochemical device 1000 to reduce the risk of short circuit due to direct contact between the positive and negative metal strips. In addition, when preparing multiple electrochemical devices 1000, the insulating assembly 200 also isolates the metal strips 20 of other electrochemical devices 1000 to further reduce the risk of short circuit.

[0064] Referring to Figures 5 and 6 , along the second direction X, the third portion 25 has a first region 211 and a second region 212 at either end of the first surface 21, with the conductive region 213 located between the first region 211 and the second region 212. The insulating assembly 200 includes a first insulating layer 50 and a second insulating layer 60. The first insulating layer 50 is disposed in the first region 211, and the second insulating layer 60 is disposed in the second region 212. The first portion 23, the second portion 24, and the third portion 25 are sequentially disposed along the third direction Y, with the first direction Z, the second direction X, and the third direction Y being perpendicular to each other.

[0065] In this embodiment, the first insulating layer 50 and the second insulating layer 60 are respectively provided only in the first region 211 and the second region 212 of the metal strip 20. On the one hand, the amount of insulating layer used can be reduced, thereby reducing costs. On the other hand, the first region 211 and the second region 212 are portions of the metal strip 20 that are easily in contact with external conductive parts. Providing insulating layers in the first region 211 and the second region 212 can improve the strength and toughness of the metal strip 20 and reduce the risk of short circuits due to accidental contact of the positive and negative metal strips 20 during the preparation process of the electrochemical device 1000. Taking the above-mentioned electrochemical device 1000 with a width or diameter of 6 mm as an example, the distance between the positive and negative metal strips of the electrochemical device 1000 (the positive metal strip leading out of the positive electrode of the electrode assembly 10 and the negative metal strip leading out of the negative electrode of the electrode assembly 10) is extremely short (about 2 mm). By respectively providing the first insulating layer 50 and the second insulating layer 60 in the first region 211 and the second region 212 of the metal strip 20, short circuits caused by accidental contact between the positive and negative metal strips can be effectively reduced; alternatively, when preparing multiple electrochemical devices 1000, contact between the metal strips 20 of different electrochemical devices 1000 can also be reduced, thereby further reducing the occurrence of short circuits.

[0066] Optionally, the first insulating layer 50 and the second insulating layer 60 may be extended from the functional layer 40, that is, the first insulating layer 50 and the second insulating layer 60 are integrally formed with the functional layer 40. The first insulating layer 50 and the second insulating layer 60 are both made of the LDPE, and the integrally formed arrangement ensures the strength and toughness of each insulating layer, thereby ensuring the strength and toughness of the metal strip 20.

[0067] Furthermore, referring to Figure 5 , along the second direction X, the first insulating layer 50 has a width W1, 0.1 mm ≤ W1 ≤ 0.17 mm; and / or the second insulating layer 60 has a width W2, 0.1 mm ≤ W2 ≤ 0.17 mm. A portion of the conductive area 213 is reserved between the first insulating layer 50 and the second insulating layer 60. Within this width range, the conductive area 213 is reserved while ensuring that the third portion 25 of the metal strip 20 has sufficient strength and toughness to facilitate electrical connection between the third portion 25 and an external circuit.

[0068] The electrochemical device 100 includes at least two metal strips 20, at least one of which is a positive electrode metal strip and at least one of which is a negative electrode metal strip. The positive and negative electrode metal strips 20 and 20 extend from the same side of a housing 200 (see FIG1 ). The presence of the insulating assembly 200 reduces contact between the positive and negative electrode metal strips. Therefore, the positive and negative electrode metal strips can be directly extended from the same side of the housing 200, thereby reducing the space in the length direction of the electrochemical device 100.

[0069] In addition, referring to FIG7 , a fourth portion 26 may be provided at the end of the third portion 25 facing away from the second portion 24 . During the fabrication of the electrochemical device 1000 , the entire surface of the fourth portion 26 may be provided with an insulating layer. This reduces the need for a sleeve during the production process (conventional solutions require sleeves to be placed over the ends of the metal strips 20 to prevent contact between the positive and negative metal strips. The sleeves must then be removed after production, a process that exposes the metal strips 20 to significant stress and, due to their relative fragility, can easily lead to tearing). This improves production efficiency and further reduces bending and tearing of the metal strips 20 caused by sleeve removal. After fabrication of the electrochemical device 1000 , the fourth portion 26 can be trimmed to facilitate electrical connection of the third portion 25 to an external circuit.

[0070] A conductive region 213 is formed between the first region 211 and the second region 212. This portion of the conductive region 213 can be used for electrical connection to an external circuit. Thus, the entire second surface 22 of the third portion 25 of the metal strip 20 can be provided with an insulating layer. Referring further to Figures 8 and 9 , the electrochemical device 1000 further includes a third insulating layer 70, also made of the aforementioned LDPE. This third insulating layer 70 covers the second surface 22 of the third portion 25. This structure further enhances the strength and toughness of the metal strip 20 and reduces the risk of short circuits in the electrochemical device 1000.

[0071] In some other embodiments, referring to FIG. 9 , the third portion 25 further includes a first side surface 27 and a second side surface 28 disposed opposite to each other in the second direction X, and the insulating component 200 further includes a fourth insulating layer 80 disposed on the first side surface 27 ; and / or, the insulating component 200 further includes a fifth insulating layer 90 disposed on the second side surface 28 , thereby further isolating the positive and negative metal strips to reduce the risk of short circuiting of the electrochemical device 1000 .

[0072] Optionally, the first insulating layer 50, the second insulating layer 60, the third insulating layer 70, the fourth insulating layer 80, and the fifth insulating layer 90 can be integrally formed with the functional layer 40 to ensure the bonding strength between each insulating layer and the functional layer 40. The materials of the insulating layers can be the same or different, as long as they meet the insulation requirements and improve the strength of the metal strip 20, and this application does not impose any restrictions.

[0073] Referring to Figure 9 , in some embodiments, along the first direction Z, the thickness of the first insulating layer 50 is H1, 30 μm ≤ H1 ≤ 40 μm; and / or the thickness of the second insulating layer 60 is H2, 30 μm ≤ H2 ≤ 40 μm; and / or the thickness of the third insulating layer 70 is H5, 30 μm ≤ H5 ≤ 40 μm. Each of these insulating layers has sufficient thickness to enhance the strength and toughness of the metal ribbon 20 while meeting the ultra-narrow design of the electrochemical device 1000. Furthermore, the presence of the functional layer 40 enhances the heat dissipation performance of the electrochemical device 1000 and reduces the risk of explosion. Therefore, a small metal ribbon with a large capacity can be employed. For example, the width W3 of the metal ribbon 20 is 0.2 mm ≤ W3 ≤ 2 mm, and the capacity C is 1880 mAh ≤ C ≤ 2200 mAh. The operating voltage U can also be increased accordingly, for example, to 4.45 V ≤ U ≤ 4.48 V.

[0074] In some embodiments, the insulation assembly 200 further includes a sixth insulation layer 110 (see FIG10 ). The sixth insulation layer 110 may be disposed on the first surface 21 and / or the second surface 22 of the first portion 23 (see FIG2 ). The melting point of the sixth insulation layer 110 is T3, where 110°C ≤ T3 ≤ 115°C. The sixth insulation layer 110 may also be made of the aforementioned LDPE. The sixth insulation layer 110 may be disposed independently or integrally formed with the aforementioned first insulation layer 50, second insulation layer 60, third insulation layer 70 (see FIG9 ), and functional layer 40 (see FIG2 ). When the temperature reaches T3, the sixth insulation layer 110 melts and absorbs some of the heat generated by the electrode assembly 10. Together with the aforementioned functional layer 40, this layer 110 can rapidly dissipate heat from the electrochemical device 100, reducing expansion or explosion of the electrochemical device 100. It is understandable that the first portion 23 needs to be provided with a partial conductive area, that is, the sixth insulating layer 110 does not completely cover the first portion 23 , so as to facilitate electrical connection between the first portion 23 and the electrode assembly 10 .

[0075] In an embodiment of the present application, a functional layer 40 is provided between the second portion 24 and the seal 30. When the electrochemical device 1000 is in a short circuit or thermal shock test, its temperature rises to a first threshold value. At this time, the functional layer 40 melts to form an exhaust channel connected to the inside and outside of the accommodating portion 100, thereby quickly discharging the gas and heat in the accommodating portion 100 to alleviate the expansion of the electrochemical device 1000, thereby effectively reducing the risk of explosion of the electrochemical device 1000. At the same time, the first insulating layer 50 and the second insulating layer 60 are respectively provided in the first region 211 and the second region 212 of the metal strip 20, which can improve the strength and toughness of the metal strip 20, thereby reducing the bending of the metal strip 20; and the first insulating layer 50 and the second insulating layer 60 can separate the positive and negative metal strips of the electrochemical device 1000 to reduce the risk of short circuit due to direct contact between the positive and negative metal strips 20; in addition, when preparing multiple electrochemical devices 1000, the first insulating layer 50 and the second insulating layer 60 can also isolate the metal strips 20 of other electrochemical devices 1000 to further reduce the risk of short circuit of the electrochemical device 1000.

[0076] In a second aspect, the present application further proposes an electronic device, comprising the electrochemical device described in any embodiment of the first aspect. The electronic device of the embodiment of the present application is not particularly limited, and it can be any electronic device known in the prior art. For example, electronic devices include but are not limited to Bluetooth headsets, mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric cars, ships, spacecraft, and the like. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0077] In the embodiments of the present application, a lithium-ion battery (electrochemical device) is taken as an example and subjected to a high-temperature short-circuit test and a drop test.

[0078] Preparation of lithium-ion batteries

[0079] Example 1

[0080] (1) Preparation of negative electrode sheet: Using graphite as the negative electrode active material, the negative electrode active material graphite, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) were mixed in a weight ratio of 96:2:2. Deionized water was added as a solvent to prepare a slurry with a solid content of 70 wt%, and the mixture was stirred evenly. The slurry was evenly coated on one surface of a 10 μm thick copper foil and dried to obtain a negative electrode sheet coated with a negative electrode active layer on one side. The above steps were repeated on the other surface of the copper foil to obtain a negative electrode sheet coated with a negative electrode active layer on both sides.

[0081] (2) Preparation of positive electrode sheet: The positive electrode active material lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly. The slurry is evenly coated on one surface of an aluminum foil with a thickness of 12μm and dried to obtain a positive electrode sheet coated with a positive electrode active layer on one side. The above steps are repeated on the other surface of the aluminum foil to obtain a positive electrode sheet coated with a positive electrode active layer on both sides.

[0082] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were 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) was added to the basic organic solvent to dissolve and mix evenly to obtain an electrolyte with a LiPF6 mass concentration of 12.5%.

[0083] (4) Preparation of isolation membrane: A polyethylene porous membrane is used as a substrate layer, and a ceramic layer containing alumina ceramic and PVDF binder is coated on one surface of the substrate layer as a separator (CCS), wherein the mass percentage of alumina ceramic in the ceramic layer is 95%.

[0084] (5) Preparation of electrode assembly: The above-mentioned positive electrode sheet, separator and negative electrode sheet are stacked and wound. Nickel sheets and aluminum sheets with a specification of 12mm×1mm are selected as metal strips. The aluminum sheet metal strip is welded to the positive electrode sheet (aluminum foil of the positive electrode sheet), and the nickel sheet metal strip is welded to the negative electrode sheet (copper foil of the negative electrode sheet) to form an electrode assembly for standby use. In particular, an LDPE functional layer is coated on each surface of the second part of the metal strip, and an LDPE first insulating layer and an LDPE second insulating layer are coated on the first area and the second area of ​​the third part respectively. In particular, the thickness of the functional layer and the first insulating layer and the second insulating layer are all 30μm, and the width of the first insulating layer and the second insulating layer is 0.1mm.

[0085] (6) Electrode assembly: Place the aluminum-plastic film with the cavities formed in it into an assembly fixture, with the cavities facing upwards. Place the electrode assembly in the cavities and apply external force to compress it. Then, place another aluminum-plastic film with the cavities formed in it, with the cavities facing downwards, over the electrode assembly. Heat-seal the two aluminum-plastic films around their edges using hot pressing to obtain an assembled electrode assembly.

[0086] (7) Liquid injection packaging: The assembled electrode assembly is injected with electrolyte, and after vacuum packaging, static, hot pressing, shaping and other processes, a lithium-ion battery is obtained. The width of the lithium-ion battery is 4 mm.

[0087] Example 2

[0088] The difference from Example 1 is that the thickness of the functional layer, the first insulating layer and the second insulating layer is 35 μm.

[0089] Example 3

[0090] The difference from Example 1 is that the thickness of the functional layer, the first insulating layer and the second insulating layer is 40 μm.

[0091] Example 4

[0092] The difference from Example 1 is that the thickness of the functional layer, the first insulating layer and the second insulating layer is 45 μm.

[0093] Example 5

[0094] The difference from Example 1 is that the thickness of the functional layer, the first insulating layer and the second insulating layer is 25 μm.

[0095] Example 6

[0096] The difference from Example 1 is that the width of the first insulating layer and the second insulating layer is 0.15 mm.

[0097] Example 7

[0098] The difference from Example 1 is that the width of the first insulating layer and the second insulating layer is 0.17 mm.

[0099] Example 8

[0100] The difference from Example 1 is that the width of the first insulating layer and the second insulating layer is 0.08 mm.

[0101] Example 9

[0102] The difference from Example 1 is that a first insulating layer is provided in the first area of ​​the first surface, a second insulating layer is provided in the second area, and a third insulating layer is provided on the second surface. The thickness of the third insulating layer is 30 μm.

[0103] Comparative Example 1

[0104] The difference from Example 1 is that there is no functional layer and no insulating layer.

[0105] High-temperature test: Charge the lithium-ion battery at a constant current of 0.2C to 4.45V, then charge it at a constant voltage of 4.45V to 0.02C. Allow the battery to stand at room temperature for 4 hours and then perform a short-circuit test using an 80±20mΩ resistor at 55±2°C. The test terminates when the temperature drops to 20% of the maximum temperature rise, or when the short-circuit duration reaches 24 hours. The battery passes the test if it does not ignite or explode.

[0106] Drop test: The lithium-ion battery is charged at a constant current of 0.2C to 4.45V, then at a constant voltage of 4.45V to 0.02C. The OCV (open circuit voltage) and IMP (internal resistance) are recorded. The battery is placed at a height of 1.5m, with all six sides and four corners facing downward, and tested twice. Pass criteria include no damage or leakage, no broken metal straps, and no significant voltage drop (<20mV). The test results are shown in Table 1 below.

[0107] Table 1

[0108] According to Table 1 above, combined with Comparative Example 1 and Examples 1 to 9, it can be seen that when the functional layer is used, the high-temperature failure rate of the lithium-ion battery can be effectively reduced. The functional layer can melt at high temperatures and increase the exhaust channel, and quickly discharge gas and heat, thereby reducing the high-temperature failure rate of the lithium-ion battery.

[0109] In Example 5, the thickness of the functional layer is 25 μm, and there is a possibility of high-temperature failure. This is because the functional layer is too thin, and the exhaust channel generated is too small to quickly exhaust gas and heat. In combination with Examples 1 to 4, the thickness of the functional layer in this application is preferably 30 μm to 45 μm. In addition, when the thickness of the first insulating layer and the second insulating layer exceeds 45 μm, the reduction in the production short circuit ratio is not obvious. In this application, it is preferred that the thickness of the first insulating layer and the second insulating layer does not exceed 40 μm, that is, H1 ≤ 40 μm and H2 ≤ 40 μm. The functional layer can be integrally formed with the first insulating layer and the second insulating layer, and the thickness of the three can be set to be consistent, that is, the thickness of the functional layer is preferably 30 μm to 40 μm.

[0110] In Example 5, the thickness of the first and second insulating layers was 25 μm. This could result in failure in the drop test. The thinness of the insulating layer resulted in insufficient strength of the metal strip, leading to tearing upon drop. In this application, the thickness of the first and second insulating layers is preferably 30 μm to 40 μm, i.e., 30 μm ≤ H1 ≤ 40 μm, and 30 μm ≤ H2 ≤ 40 μm.

[0111] Combining Example 1 and Example 8, the widths of the first insulating layer and the second insulating layer in Example 8 are both relatively small, which may also lead to insufficient strength of the metal strip, and the production short circuit ratio and drop failure ratio are both improved compared with Example 1. In this application, it is preferred that the widths of the first insulating layer and the second insulating layer are both 0.1mm to 0.17mm.

[0112] In addition, a first insulating layer is provided in the first area of ​​the first surface, a second insulating layer is provided in the second area, and a third insulating layer is provided on the second surface, which can further improve the strength of the metal strip and isolate the metal strip, thereby further reducing the production short circuit ratio and drop failure ratio.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Based on the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present application as described above. For the sake of simplicity, they are not provided in detail. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrochemical device, comprising a housing and an electrode assembly received in the housing, characterized in that: The electrochemical device further comprises: The metal strip comprises a first portion, a second portion and a third portion connected to each other, wherein the first portion is connected to the electrode assembly in the receiving portion, the receiving portion is provided with a protruding hole, the second portion is arranged in the protruding hole, and the third portion protrudes out of the receiving portion; A sealing member, disposed between the second portion and the inner wall of the extension hole, the sealing member being bonded to the accommodating portion; A functional layer is disposed on an outer surface of the second portion and located between the second portion and the seal, wherein the functional layer is configured to melt when the temperature rises to a first threshold.

2. The electrochemical device according to claim 1, characterized in that The electrochemical device also includes an insulating component; The insulating component is disposed on the outer surface of the third portion. The third portion has a conductive area, and the insulating component does not cover the conductive area.

3. The electrochemical device according to claim 2, characterized in that The metal strip includes a first surface and a second surface disposed opposite to each other in a first direction; On the first surface, along the second direction, two ends of the third portion respectively have a first area and a second area, and the conductive area is located between the first area and the second area; The insulating assembly includes a first insulating layer and a second insulating layer, the first insulating layer is arranged in the first area, and the second insulating layer is arranged in the second area; The first part, the second part and the third part are arranged in sequence along the third direction, and the first direction, the second direction and the third direction are perpendicular to each other.

4. The electrochemical device according to claim 3, characterized in that The first insulating layer, the second insulating layer and the functional layer are integrally formed.

5. The electrochemical device according to claim 2, characterized in that The electrochemical device further includes a third insulating layer disposed on the second surface of the third portion.

6. The electrochemical device according to claim 2, characterized in that The third portion further includes a first side surface and a second side surface disposed opposite to each other in the second direction; The insulating component further includes a fourth insulating layer, which is disposed on the first side surface; and / or the insulating component further includes a fifth insulating layer, which is disposed on the second side surface.

7. The electrochemical device according to claim 1, characterized in that The material of the functional layer includes low-density polyethylene and / or polypropylene, and the density of the functional layer is ρ, 0.910 g / cm 3 ≤ρ≤0.925g / cm 3 .

8. The electrochemical device according to claim 1, characterized in that The first threshold is T1, 110°C≤T1≤115°C.

9. The electrochemical device according to claim 1, characterized in that The material of the sealing component includes at least one of polypropylene, o-phenylphenol, polyvinyl chloride, polyethylene terephthalate, polyamide resin and phenolic resin, and the melting point of the sealing component is T2, T2≥120°C.

10. The electrochemical device according to claim 1, characterized in that The sealing member is bonded to the functional layer.

11. The electrochemical device according to claim 3, characterized in that: The electrochemical device satisfies at least one of the following conditions: a. Along the first direction, the thickness of the first insulating layer is H1, 30 μm≤H1≤40 μm; b. Along the first direction, the thickness of the second insulating layer is H2, 30 μm≤H2≤40 μm; c. Along the second direction, the width of the first insulating layer is W1, 0.1 mm≤W1≤0.17 mm; d. Along the second direction, the width of the second insulating layer is W2, 0.1 mm≤W2≤0.17 mm.

12. The electrochemical device according to claim 2, characterized in that The electrochemical device comprises at least two metal strips, at least one of which is a positive metal strip and at least one of which is a negative metal strip. The positive metal strip and the negative metal strip extend from the same side of the accommodation portion.

13. The electrochemical device according to claim 2, characterized in that The metal strip satisfies at least one of the following conditions: a. Along the first direction, the thickness of the metal strip is H3, 0.06 mm ≤ H3 ≤ 0.1 mm; b. Along the second direction, the width of the metal strip is W3, 0.2 mm ≤ W3 ≤ 2 mm; c. Along the second direction, the width of the accommodation portion is W4, 1mm≤W4≤4mm.

14. An electronic device, characterized in that: Comprising the electrochemical device according to any one of claims 1 to 13.

Images