Current collector, pole piece, secondary battery and electric device

Abstract

The utility model discloses a current collector, a pole piece, a secondary battery and an electric device, and belongs to the technical field of batteries, the current collector comprises a base body layer and a conducting layer located on at least one surface of the base body layer, and the conducting layer comprises metal layers and metal oxide layers which are alternately stacked; the base body layer is provided with a plurality of through holes penetrating through the base body layer. According to the utility model, the conductive layer is arranged on at least one surface of the base body layer, and the metal layers and the metal oxide layers which are alternately laminated are used as the conductive layer, so that when mechanical abuse conditions such as impact, needling or extrusion occur, the metal layers have higher ductility, and the metal oxide layers have lower ductility, so that the metal oxide layers can be prevented from being damaged. And the ductility of the metal layer is not matched with that of the metal oxide layer, so that the conductive layer generates cracks and is fractured, further a current path is blocked, the risk of internal short circuit is reduced, the safety is improved, and violent fire and explosion of the secondary battery are avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a current collector, a pole piece, a secondary battery and an electrical device. Background Art

[0002] Secondary batteries, also known as rechargeable batteries, differ from primary batteries in that they can be recharged through a reversible electrochemical reaction. They offer advantages such as high energy density, excellent power performance, low self-discharge, and long cycle life. They are widely used in consumer electronics, electric vehicles, energy storage power stations, and other fields.

[0003] Currently, current collectors in secondary batteries primarily consist of metal foils and composite current collectors with metal layers plated on both sides of a polymer layer. When a battery cell is subjected to mechanical abuse (such as impact, puncture, or extrusion), conventional metal foil and composite current collectors can break, leading to direct contact between the positive and negative electrodes. This can cause a transient internal short circuit in the battery cell, a sharp rise in internal battery temperature, and potentially lead to violent fires and explosions, posing a significant safety hazard.

[0004] In view of this, this application is filed. Utility Model Content

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a current collector, a pole piece, a secondary battery and an electrical device, which can effectively block the current path when mechanical abuse such as impact, puncture or extrusion occurs, reduce the risk of internal short circuit, improve safety, and avoid violent fire and explosion of the secondary battery.

[0006] To achieve the above-mentioned object, the first aspect of the present application provides a current collector comprising a base layer and a conductive layer located on at least one surface of the base layer, wherein the conductive layer comprises a metal layer and a metal oxide layer alternately stacked;

[0007] The base layer is provided with a plurality of through holes penetrating the base layer.

[0008] As an embodiment of the present application, the diameter of the through hole is d, 1 μm≤d≤100 μm.

[0009] As an embodiment of the present application, the distance between any two adjacent through holes is s, and 500 μm≤s≤5000 μm.

[0010] As an implementation scheme of the present application, the following is satisfied: 25≤s / d≤200.

[0011] As an embodiment of the present application, in the conductive layer, the metal layer is closest to the base layer, and the metal oxide layer is farthest from the base layer.

[0012] As an embodiment of the present application, the thickness of the conductive layer is 0.5 to 3 μm.

[0013] As an embodiment of the present application, the thickness of the metal layer is 20 to 100 nm.

[0014] As an embodiment of the present application, the thickness of the metal oxide layer is 2 to 10 nm.

[0015] As an embodiment of the present application, the thickness of the base layer is 1 to 10 μm.

[0016] As an embodiment of the present application, the base layer is a polymer film.

[0017] As an embodiment of the present application, the metal layer includes one of aluminum, copper, silver, nickel, zinc, magnesium, zirconium, and cobalt.

[0018] As an embodiment of the present application, the metal oxide layer includes one of aluminum oxide, copper oxide, silver oxide, nickel oxide, zinc oxide, magnesium oxide, zirconium oxide, and cobalt oxide.

[0019] As an embodiment of the present application, the polymer film includes one of polypropylene, polyethylene, polyvinylidene fluoride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene, polyacrylonitrile, and polyimide.

[0020] The second aspect of the present application provides a pole piece, comprising a current collector and an active material layer located on at least one surface of the current collector; the current collector comprises the current collector described above; the active material layer comprises one of a positive electrode active material layer and a negative electrode active material layer.

[0021] A third aspect of the present application provides a secondary battery comprising the electrode sheet described above.

[0022] A fourth aspect of the present application provides an electrical device comprising the secondary battery described above.

[0023] The beneficial effect of the present invention is that: by arranging a conductive layer on at least one surface of the base layer, and using metal layers and metal oxide layers alternately stacked as the conductive layer, when mechanical abuse such as impact, puncture or extrusion occurs, since the metal layer has higher ductility and the metal oxide layer has lower ductility, the ductility of the metal layer and the metal oxide layer is mismatched, causing the conductive layer to crack and break, thereby blocking the current path, reducing the risk of internal short circuit, improving safety, and avoiding violent fire and explosion of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of the current collector of the present invention.

[0025] Figure 2 This is a schematic structural diagram of the base layer of the present invention.

[0026] Markings in the figure: 1, substrate layer; 2, metal layer; 3, metal oxide layer; 4, through hole. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0028] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0029] Unless otherwise specified, the components and raw materials used in the embodiments and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0031] See also Figures 1 and 2 The present invention provides a current collector comprising a base layer 1 and a conductive layer located on at least one surface of the base layer, wherein the conductive layer comprises a metal layer 2 and a metal oxide layer 3 alternately stacked;

[0032] The base layer is provided with a plurality of through holes 4 penetrating the base layer.

[0033] The utility model provides a conductive layer on at least one surface of a base layer, and uses metal layers and metal oxide layers alternately stacked as the conductive layer. When mechanical abuse such as impact, puncture or extrusion occurs, the conductive layer will crack and break due to the mismatch between the ductility of the metal layer and the metal oxide layer, as the metal layer has higher ductility and the metal oxide layer has lower ductility, thereby blocking the current path, reducing the risk of internal short circuit, improving safety, and avoiding violent fire and explosion of the secondary battery.

[0034] Among them, a plurality of through holes passing through the base layer are provided in the base layer, and the metal filled in the through holes serves to connect the conductive layers on both sides of the base layer, which is beneficial to improving the conductivity of the current collector and reducing the internal resistance of the battery. The design of filling the through holes with metal enhances the bonding strength between the conductive layer and the base layer, which can reduce the risk of the conductive layer falling off when the electrode is rolled, thereby improving the safety performance of the secondary battery.

[0035] In one embodiment, the diameter of the through hole is d, 1μm≤d≤100μm, for example, it can be 1μm, 2μm, 5μm, 8μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm or a range consisting of any two of these values.

[0036] In one embodiment, 1 μm≤d≤20 μm.

[0037] In one embodiment, the distance between each two adjacent through holes is s, 500μm≤s≤5000μm, for example, it can be 500μm, 600μm, 700μm, 800μm, 1000μm, 2000μm, 3000μm, 4000μm, 5000μm or a range consisting of any two values ​​therein.

[0038] In particular, when the diameter of the through hole and the distance between two adjacent through holes are within this range, the weight of the secondary battery can be more effectively reduced, the energy density can be increased, and a good buffering effect can be played, thereby improving the safety performance of the secondary battery.

[0039] In one embodiment, the following is satisfied: 25≤s / d≤200, for example, it can be 25, 30, 40, 50, 80, 100, 120, 150, 180, 200 or a range consisting of any two of these values. In particular, when the ratio of the distance between two adjacent through holes to the through hole diameter is within this range, it can more effectively play a buffering role, more effectively reduce the volume expansion caused by external forces, and more effectively improve safety performance.

[0040] In one embodiment, in the conductive layer, the metal layer is closest to the base layer, and the metal oxide layer is farthest from the base layer. Among them, the metal layer closest to the base layer has a ductility that is more compatible with the base layer, and the metal oxide layer is farthest from the base layer, which can inhibit the negative ions in the electrolyte from corroding the conductive layer.

[0041] In one embodiment, the thickness of the conductive layer is 0.5 to 3 μm, for example, it can be 0.5 μm, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm or a range consisting of any two values ​​therein.

[0042] In one embodiment, the thickness of the metal layer is 20 to 100 nm, for example, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm or a range consisting of any two values ​​therein.

[0043] In one embodiment, the thickness of the metal oxide layer is 2 to 10 nm, for example, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, or a range consisting of any two values ​​thereof.

[0044] In one embodiment, the base layer has a thickness of 1 to 10 μm.

[0045] In one embodiment, the base layer is a polymer film.

[0046] As an embodiment of the present application, the metal layer includes one of aluminum, copper, silver, nickel, zinc, magnesium, zirconium, and cobalt.

[0047] In one embodiment, the metal oxide layer includes one of aluminum oxide, copper oxide, silver oxide, nickel oxide, zinc oxide, magnesium oxide, zirconium oxide, and cobalt oxide.

[0048] In one embodiment, the polymer film includes one of polypropylene, polyethylene, polyvinylidene fluoride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene, polyacrylonitrile, and polyimide.

[0049] It should be noted that the metal layer and the metal oxide layer are formed on the surface of the base layer by using an evaporation method.

[0050] The metal layer is evaporated in an inert gas or vacuum environment, and the metal oxide layer can be evaporated by introducing oxygen into the environment.

[0051] In one embodiment, the through hole is filled with metal; when the metal layer closest to the base layer is evaporated, part of the metal will enter the through hole, so that the through hole is filled with metal, and the filled metal can connect the conductive layers on both sides of the base layer, thereby improving the conductive performance of the current collector.

[0052] One embodiment of the present application provides a pole piece, comprising a current collector and an active material layer located on at least one surface of the current collector; the current collector comprises the current collector described above; the active material layer comprises one of a positive electrode active material layer and a negative electrode active material layer.

[0053] In one embodiment, the electrode sheet is a positive electrode sheet, which includes a current collector and a positive electrode active material layer located on at least one surface of the current collector, and the current collector includes the current collector described above.

[0054] In one embodiment, the positive electrode active material layer includes a positive electrode active material.

[0055] In one embodiment, the positive electrode active material can be selected from various electrode active materials commonly used in the art. For example, for lithium batteries, the positive electrode active material can be selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, transition metal phosphate, lithium iron phosphate, etc. However, this application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more.

[0056] In one embodiment, the positive electrode active material further includes a conductive agent and a binder.

[0057] In one embodiment, the electrode sheet is a negative electrode sheet, and the negative electrode sheet includes a current collector and a negative electrode active material layer located on at least one surface of the current collector, and the current collector includes the current collector described above.

[0058] In one embodiment, the negative electrode active material layer includes a negative electrode active material.

[0059] In one embodiment, the negative electrode active material further includes a conductive agent and a binder.

[0060] In one embodiment, the negative electrode active material can be natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, spinel structure lithium titanate Li4Ti5O12 , at least one of Li-Al alloy and metallic lithium.

[0061] In one embodiment, the type of the conductive agent mentioned in the present application is not limited, and any known conductive agent can be used.

[0062] In one embodiment, the conductive agent includes at least one carbon material such as acetylene black, needle coke, carbon nanotubes, and graphene.

[0063] In one embodiment, the type of binder mentioned in this application is not limited, and any known positive electrode binder can be used.

[0064] In one embodiment, the binder includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose, styrene-butadiene rubber, nitrile rubber, fluororubber, isoprene rubber, polybutadiene rubber, and ethylene-propylene rubber.

[0065] One embodiment of the present application provides a secondary battery, comprising the electrode sheet described above.

[0066] In the secondary battery mentioned in this application, a separator is usually provided between the positive electrode and the negative electrode to prevent short circuit. There is no particular limitation on the material and shape of the separator, as long as it does not significantly impair the effect of this application.

[0067] In one embodiment, the separator comprises a porous sheet or non-woven fabric having excellent liquid retention. Materials for the resin or glass fiber separator include, but are not limited to, polyolefin, aromatic polyamide, polytetrafluoroethylene, polyethersulfone, and the like.

[0068] In one embodiment, the polyolefin is polyethylene or polypropylene. In some embodiments, the polyolefin is polypropylene. The materials of the above-mentioned diaphragm can be used alone or in any combination.

[0069] In one embodiment, the secondary battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0070] In one embodiment, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0071] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape.

[0072] One embodiment of the present application provides an electrical device including the secondary battery described above.

[0073] Exemplarily, the above-mentioned electrical devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.

[0074] The present application is further described below with specific examples:

[0075] Example 1

[0076] like Figures 1 and 2 As shown, this embodiment provides a positive electrode plate, including a current collector and a positive electrode active material layer located on the upper and lower surfaces of the current collector, the current collector includes a base layer and a conductive layer located on the upper and lower surfaces of the base layer, the conductive layer includes a metal layer and a metal oxide layer alternately stacked, the metal layer is closest to the base layer, and the metal oxide layer is farthest from the base layer, and the base layer is provided with a plurality of through holes penetrating the base layer.

[0077] Specifically, the diameter of the through hole is d, d=10 μm; the distance between any two adjacent through holes is s, s=1000 μm; s / d=100.

[0078] Specifically, the thickness of the conductive layer is 2 μm; the thickness of the metal layer is 45 nm; the thickness of the metal oxide layer is 5 nm; and the thickness of the base layer is 8 μm.

[0079] More specifically, the metal layer is aluminum, the metal oxide layer is aluminum oxide, and the base layer is a polymer including polypropylene.

[0080] Example 2

[0081] This embodiment provides a negative electrode plate, including a current collector and negative electrode active material layers located on the upper and lower surfaces of the current collector. The current collector is different from that in Example 1 in that the metal layer is copper and the metal oxide layer is copper oxide.

[0082] Example 3

[0083] The difference between Example 3 and Example 1 is that the thickness of the conductive layer is 0.55 μm; the thickness of the metal layer is 20 nm; and the thickness of the metal oxide layer is 2 nm.

[0084] Example 4

[0085] The difference between Example 4 and Example 1 is that the thickness of the conductive layer is 2.75 μm; the thickness of the metal layer is 100 nm; and the thickness of the metal oxide layer is 10 nm.

[0086] Example 5

[0087] The difference between Example 5 and Example 1 is that the diameter of the through hole is d, d=20 μm; the distance between each two adjacent through holes is s, s=500 μm; and s / d=25.

[0088] Example 6

[0089] The difference between Example 6 and Example 1 is that the diameter of the through hole is d, d=15 μm; the distance between each two adjacent through holes is s, s=3000 μm; and s / d=200.

[0090] Example 7

[0091] The difference between Example 7 and Example 1 is that the diameter of the through hole is d, d=100 μm; the distance between each two adjacent through holes is s, s=500 μm; and s / d=5.

[0092] Example 8

[0093] The difference between Example 8 and Example 1 is that the diameter of the through hole is d, d=10 μm; the distance between each two adjacent through holes is s, s=5000 μm; s / d=500.

[0094] Comparative Example 1

[0095] The difference between Comparative Example 1 and Example 1 is that the conductive layer in Comparative Example 1 is an aluminum metal layer.

[0096] Test Case

[0097] The square resistance of the current collectors and the safety performance of the battery cells prepared in the examples and comparative examples were tested, and the test results are shown in Table 1. The specific test methods are as follows:

[0098] 1. Current collector square resistance test

[0099] The prepared flat composite current collector sample is placed on a sample table, and the square resistance of the sample is tested using a four-probe square resistance meter.

[0100] 2. Battery cell safety performance test

[0101] Lithium-ion battery assembly

[0102] The positive electrode sheet, negative electrode sheet and separator prepared in each embodiment and comparative example are wound to obtain an electrode assembly with a wound structure, which is wrapped with an aluminum-plastic film, injected with electrolyte after drying, and subjected to packaging, standing, formation, trimming and other processes to obtain a lithium-ion battery.

[0103] Acupuncture test

[0104] Place a fully charged battery cell with the dent facing upward. Use a 4mm diameter steel needle at a speed of 40mm / s to completely pierce the cell at once without removing it. The needle should be placed on the left, center, and right sides of the cell's largest surface. The cell should be left for 1 hour. The test is considered passed if the cell does not catch fire, explode, or expand during the process. In each example, 10 cells were pierced at each of the left, center, and right sides of the cell's largest surface, for a total of 30 cells. The pass rate of the needle penetration test was recorded during the test.

[0105] Table 1

[0106] Square resistance (mΩ) Acupuncture test pass rate (%) Example 1 36 86.7％ Example 2 35 83.3％ Example 3 42 90.0％ Example 4 33 80.0％ Example 5 34 86.7％ Example 6 35 90.0％ Example 7 32 80.0％ Example 8 39 83.3％ Comparative Example 1 32 76.7％

[0107] As can be seen from Table 1, by comparing the square resistance data of Examples 1-2 and Comparative Example 1, it can be found that when the total thickness of the conductive layer in the current collector is basically the same, the alternating stacking structure formed by the metal layer and the metal oxide layer in Examples 1-2 does not significantly affect the conductivity of the current collector. By comparing Example 1 with Examples 3-4, it can be found that the greater the thickness of the conductive layer, the higher the conductivity of the current collector. By comparing Example 1 with Examples 5-8, it can be found that the smaller the s / d value, the higher the conductivity of the current collector, which is caused by the increase in the proportion of the metal layer in the through-hole.

[0108] Compared with Comparative Example 1, the pass rate of the acupuncture test of the battery cells prepared in Examples 1-8 is significantly improved, indicating that the alternating stacking of metal layers and metal oxide layers improves the stability and safety of the current collector, thereby improving the safety of the battery cells.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A current collector, characterized in that: The method comprises a base layer and a conductive layer located on at least one surface of the base layer, wherein the conductive layer comprises a metal layer and a metal oxide layer alternately stacked; The base layer is provided with a plurality of through holes penetrating the base layer.

2. The current collector according to claim 1, characterized in that The diameter of the through hole is d, 1 μm≤d≤100 μm; and / or The distance between any two adjacent through holes is s, and 500 μm≤s≤5000 μm.

3. The current collector according to claim 2, characterized in that Satisfies: 25≤s / d≤200.

4. The current collector according to claim 1, characterized in that In the conductive layer, the metal layer is closest to the base layer, and the metal oxide layer is farthest from the base layer.

5. The current collector according to claim 1, characterized in that The thickness of the conductive layer is 0.5 to 3 μm; and / or The thickness of the base layer is 1 to 10 μm.

6. The current collector according to claim 1, characterized in that The thickness of the metal layer is 20 to 100 nm; and / or The thickness of the metal oxide layer is 2-10 nm.

7. The current collector according to claim 1, characterized in that The base layer is a polymer film.

8. A pole piece, characterized in that: It comprises a current collector and an active material layer located on at least one surface of the current collector; the current collector comprises the current collector according to any one of claims 1 to 7; the active material layer comprises one of a positive electrode active material layer and a negative electrode active material layer.

9. A secondary battery, characterized in that: Including the pole piece according to claim 8.

10. An electrical device, characterized in that: The secondary battery according to claim 9 is included.

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