Edge-sealed pole piece based on functional current collector, preparation method of edge-sealed pole piece and battery

Abstract

The invention belongs to the technical field of battery manufacturing, and relates to an edge-sealed pole piece based on a functional current collector, a preparation method of the edge-sealed pole piece and a battery, the edge-sealed pole piece comprises the functional current collector and an active material layer arranged on at least one side surface of the functional current collector, the functional current collector at least comprises a transition layer, a sealing layer is arranged on the edge end surface of the edge-sealed pole piece and completely covers the edge end surface of the transition layer. By arranging the sealing layer on the edge end face of the pole piece, the transition layer in the functional current collector is effectively prevented from being in contact with electrolyte, so that the structural stability of the pole piece and the cycle performance of the battery are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery manufacturing and relates to a pole piece, and in particular to an edge-sealed pole piece based on a functional current collector, a preparation method thereof, and a battery. Background Art

[0002] Currently, functional current collectors based on polymer membranes are widely used in the battery industry. Compared with traditional current collectors, functional current collectors have the advantages of low cost, light weight, and good internal insulation. These characteristics enable the use of functional current collectors in batteries to significantly reduce battery costs while improving battery energy density and safety.

[0003] To improve the adhesion between the polymer film and the metal layer within the functional current collector, technicians typically place a transition layer between the polymer film and the metal layer. However, during battery cycling, this transition layer comes into contact with and corrodes the electrolyte, reducing the adhesion between the metal layer and the polymer film and even causing delamination. This deteriorates the structural stability of the electrode and ultimately the cycling performance of the resulting battery.

[0004] Therefore, how to prevent the transition layer in the functional current collector from contacting the electrolyte and improve the structural stability of the electrode and the cycle performance of the battery has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a sealed edge electrode based on a functional current collector, a preparation method and a battery. By setting a sealing layer on the edge end face of the electrode, the transition layer in the functional current collector is effectively prevented from contacting the electrolyte, thereby significantly improving the structural stability of the electrode and the cycle performance of the battery.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an edge-sealed pole piece based on a functional current collector, comprising a functional current collector and an active material layer arranged on at least one side surface of the functional current collector, wherein the functional current collector contains at least a transition layer, and the edge end face of the edge-sealed pole piece is provided with a sealing layer, and the sealing layer completely covers the edge end face of the transition layer.

[0008] The present invention provides a sealing layer on the edge end face of the electrode and ensures that the sealing layer completely covers the edge end face of the transition layer, that is, the sealing treatment is achieved by fully integrating the sealing layer with the end face of the functional current collector, which effectively avoids the transition layer in the functional current collector from contacting the electrolyte, thereby improving the interface stability between the polymer film and the metal layer and the structural stability of the electrode during the battery cycle, significantly improving the cycle performance of the battery. At the same time, the presence of the sealing layer avoids the internal short circuit problem caused by the overlap of burrs on the edge of the current collector of the positive and negative electrode sheets, thereby improving the safety performance of the battery.

[0009] Preferably, the sealing layer is made of at least one of polyolefin, polyurethane or polyamide.

[0010] Preferably, the polyolefin comprises at least one of polyethylene, polypropylene or ethylene-propylene copolymer.

[0011] Preferably, the thickness of the sealing layer is 5-500 μm, more preferably 50-200 μm.

[0012] Preferably, the functional current collector comprises a polymer film and a transition layer, a metal layer and a passivation layer provided on at least one surface of the polymer film, and the transition layer is located between the polymer film and the metal layer.

[0013] Preferably, the material of the polymer film includes at least one of polyolefin, polyester, polyamide, polyimide, polyphenylene ether or polyphenylene sulfide.

[0014] Preferably, the polyolefin includes at least one of polyethylene, polypropylene, polypropylene, polyvinyl chloride, polyvinylidene fluoride or polytetrafluoroethylene.

[0015] Preferably, the polyester comprises at least one of polyethylene terephthalate, polybutylene terephthalate or polyethylene naphthalate.

[0016] Preferably, the material of the polymer film and the material of the sealing layer satisfy any one of the following conditions:

[0017] (A) The difference in surface energy is ≤10mJ / m 2 ;

[0018] (B) The difference between the number average molecular weights is ≤ 50,000 g / mol.

[0019] Preferably, the polymer film includes a base film region and transition regions arranged on both sides of the base film region, and the transition region is located between the base film region and the sealing layer.

[0020] Preferably, the material of the transition zone includes at least two of polyolefin, polyester, polyurethane, polyamide, polyimide, polyphenylene ether or polyphenylene sulfide.

[0021] Preferably, the width of the transition zone is 0.05-1 mm.

[0022] Preferably, the ratio of the thickness of the transition zone to the thickness of the base film zone is (90-110):100.

[0023] Preferably, the sealing layer is partially sealed or fully sealed at the edge end surface of the pole piece.

[0024] Preferably, when the sealing layer is partially sealed, the width of the sealing layer is greater than or equal to the thickness of the functional current collector, and less than or equal to the total thickness of the edge-sealed electrode.

[0025] Preferably, when the sealing layer is fully sealed, the sealing layer goes over the edge ridge of the pole piece and overlaps at least one side surface of the pole piece, and the overlap width is ≤1 mm.

[0026] In a second aspect, the present invention provides a method for preparing the edge-sealed electrode according to the first aspect, the method comprising the following steps:

[0027] (1) preparing a functional current collector comprising at least a transition layer;

[0028] (2) providing an active material layer on at least one side surface of the functional current collector to obtain a pole piece;

[0029] (3) A sealing layer is provided on the edge end face of the electrode, and the sealing layer is controlled to completely cover the edge end face of the transition layer, thereby obtaining an edge-sealed electrode based on a functional current collector.

[0030] Preferably, the method for preparing the functional current collector in step (1) comprises: depositing a transition layer, a metal layer and a passivation layer in sequence on at least one surface of a polymer film.

[0031] Preferably, the method for setting the active material layer in step (2) comprises homogenization, coating, rolling and die cutting in sequence.

[0032] Preferably, the method for setting the sealing layer in step (3) includes precision spraying or slit coating.

[0033] Preferably, the coating liquid temperature used in the precision spraying or slit coating is set to T c , then: T m ≤T c ≤T m +50℃.

[0034] If the melting point of the sealing layer material is less than or equal to the melting point of the polymer film material, then T m Refers to the melting point of the polymer film material, ℃; if the melting point of the sealing layer material is greater than the melting point of the polymer film material, then T mRefers to the melting point of the sealing layer material, ℃.

[0035] In a third aspect, the present invention provides a battery comprising an edge-sealed electrode based on a functional current collector as described in the first aspect.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention provides a sealing layer on the edge end face of the electrode and ensures that the sealing layer completely covers the edge end face of the transition layer, that is, the sealing treatment is achieved by fully integrating the sealing layer with the end face of the functional current collector, which effectively avoids the transition layer in the functional current collector from contacting the electrolyte, thereby improving the interface stability between the polymer film and the metal layer and the structural stability of the electrode during the battery cycle, significantly improving the cycle performance of the battery. At the same time, the presence of the sealing layer avoids the internal short circuit problem caused by the overlap of burrs on the edge of the current collector of the positive and negative electrode sheets, thereby improving the safety performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the edge-sealed electrode structure provided by the present invention (partially sealed);

[0039] Figure 2 Schematic diagram of the edge-sealed electrode structure provided by the present invention (fully sealed);

[0040] Figure 3 This is a schematic diagram of the functional current collector structure in the edge-sealed electrode provided by the present invention;

[0041] Figure 4 This is a partial enlarged view of the edge-sealed electrode provided by the present invention.

[0042] Among them: 10 - functional aluminum current collector; 11 - polymer film; 11a - base film region; 11b - transition region; 12 - transition layer; 13 - metal layer; 14 - passivation layer; 20 - active material layer; 30 - sealing layer. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] An embodiment of the present invention provides an edge-sealed pole piece based on a functional current collector, comprising a functional current collector and an active material layer arranged on at least one side surface of the functional current collector, the functional current collector containing at least a transition layer, and the edge end face of the edge-sealed pole piece being provided with a sealing layer, and the sealing layer completely covers the edge end face of the transition layer.

[0045] The present invention provides a sealing layer on the edge end face of the electrode and ensures that the sealing layer completely covers the edge end face of the transition layer, that is, the sealing treatment is achieved by fully integrating the sealing layer with the end face of the functional current collector, which effectively avoids the transition layer in the functional current collector from contacting the electrolyte, thereby improving the interface stability between the polymer film and the metal layer and the structural stability of the electrode during the battery cycle, significantly improving the cycle performance of the battery. At the same time, the presence of the sealing layer avoids the internal short circuit problem caused by the overlap of burrs on the edge of the current collector of the positive and negative electrode sheets, thereby improving the safety performance of the battery.

[0046] In some embodiments, the functional current collector is specifically a functional aluminum current collector or a functional copper current collector, and the corresponding edge-sealed electrode is specifically a positive electrode or a negative electrode. Since the transition layer in these two types of functional current collectors has the risk of contacting the electrolyte, they are both applicable to the present invention.

[0047] In some embodiments, the sealing layer is made of at least one of polyolefin, polyurethane, or polyamide.

[0048] In certain embodiments, the polyolefin includes at least one of polyethylene, polypropylene, or ethylene-propylene copolymer.

[0049] In some embodiments, the thickness of the sealing layer is 5-500 μm, for example, it can be 5 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm, and more preferably 50-200 μm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0050] By limiting the thickness of the sealing layer to a reasonable range, the present invention balances the sealing performance of the sealing layer with the energy density of the battery. When the sealing layer thickness is less than 5μm, the sealing performance of the sealing layer is poor, causing the transition layer in the functional current collector to contact the electrolyte, which in turn leads to poor interface stability between the polymer film and the metal layer, and thus poor structural stability of the pole piece. When the sealing layer thickness exceeds 500μm, it is not conducive to smooth pole piece processing, increasing production costs and reducing the energy density of the battery.

[0051] In some embodiments, the functional current collector includes a polymer film and a transition layer, a metal layer, and a passivation layer disposed on at least one surface of the polymer film, and the transition layer is located between the polymer film and the metal layer.

[0052] In some embodiments, the polymer film is made of at least one of polyolefin, polyester, polyamide, polyimide, polyphenylene ether, or polyphenylene sulfide, and is used to provide support for the functional current collector.

[0053] In certain embodiments, the polyolefin includes at least one of polyethylene, polypropylene, polypropylene, polyvinyl chloride, polyvinylidene fluoride, or polytetrafluoroethylene.

[0054] In certain embodiments, the polyester includes at least one of polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate.

[0055] In certain embodiments, the material of the polymer film and the material of the sealing layer satisfy any one of the following conditions:

[0056] (A) The difference in surface energy is ≤10mJ / m 2 , for example, it can be 1mJ / m 2 , 2mJ / m 2 、3mJ / m 2 4mJ / m 2 5mJ / m 2 , 6mJ / m 2 , 7mJ / m 2 , 8mJ / m 2 , 9mJ / m 2 or 10mJ / m 2 , but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] (B) The difference between the number average molecular weights is ≤ 50,000 g / mol, for example, 10 g / mol, 100 g / mol, 10000 g / mol, 20,000 g / mol, 30,000 g / mol, 40,000 g / mol or 50,000 g / mol, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0058] Exemplarily, in order to meet the above conditions, when the material of the polymer film is polyolefin, the material of the sealing layer can be polyolefin; when the material of the polymer film is polyester, the material of the sealing layer can be polyurethane and / or polyamide; when the material of the polymer film is polyamide and / or polyimide, the material of the sealing layer can be polyurethane and / or polyamide; when the material of the polymer film is polyphenylene ether and / or polyphenylene sulfide, the material of the sealing layer can be polyurethane and / or polyamide.

[0059] The present invention specifically limits the material of the sealing layer according to the specific material of the polymer film, ensuring that the surface energy and molecular weight of the two materials are close to each other, improving the hot melt effect and interface stability of both, and further achieving full fusion between the sealing layer and the polymer film, thereby improving the sealing performance of the sealing layer and significantly improving the barrier performance of the sealing layer to the electrolyte.

[0060] In certain embodiments, the polymer film includes a base film region and transition regions disposed on both sides of the base film region, and the transition regions are located between the base film region and the sealing layer.

[0061] In some embodiments, the material of the transition zone includes at least two of polyolefin, polyester, polyurethane, polyamide, polyimide, polyphenylene ether, or polyphenylene sulfide.

[0062] In some embodiments, the width of the transition zone is 0.05-1 mm, for example, it can be 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] In the present invention, the width of the transition zone is crucial for balancing the barrier performance and production cost of the sealing layer. If the width of the transition zone is less than 0.05 mm, it indicates that the sealing layer and the polymer film are not fully integrated, reducing the sealing layer's barrier performance to the electrolyte. If the width of the transition zone is greater than 1 mm, the barrier performance of the sealing layer is not significantly improved, and the production cost is unnecessarily increased.

[0064] In some embodiments, the ratio of the thickness of the transition zone to the thickness of the base film zone is (90-110):100, for example, it can be 90:100, 92:100, 94:100, 96:100, 98:100, 100:100, 102:100, 104:100, 106:100, 108:100 or 110:100, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0065] In the present invention, the thickness of the transition region and the thickness of the base film region both refer to average thickness.

[0066] In some embodiments, the metal layer is made of aluminum or aluminum alloy, which functions as a conductor.

[0067] In some embodiments, the passivation layer is made of aluminum oxide to prevent further oxidation of the metal layer.

[0068] In some embodiments, the thickness of the polymer film is 1-10 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] In some embodiments, the thickness of the transition layer is 2-20 nm, for example, it can be 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm or 20 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0070] By limiting the thickness of the transition layer to a reasonable range, the present invention balances adhesion and bonding stability between the film layers. When the thickness of the transition layer is less than 2nm, the uniformity of the transition layer is poor, resulting in low adhesion between the polymer film and the metal layer. When the thickness of the transition layer is greater than 20nm, it is not conducive to further improving the bonding stability between the polymer film and the metal layer.

[0071] In some embodiments, the thickness of the metal layer is 500-2000 nm, for example, it can be 500 nm, 600 nm, 800 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm or 2000 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0072] By limiting the thickness of the metal layer to a reasonable range, the present invention balances the conductivity of the metal layer with the energy density of the battery. When the thickness of the metal layer is less than 500nm, the conductivity of the metal layer is poor; when the thickness of the metal layer is greater than 2000nm, it is not conducive to further improving the energy density of the battery.

[0073] In some embodiments, the thickness of the passivation layer is 5-100 nm, for example, it can be 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0074] In some embodiments, the sealing layer is partially sealed or fully sealed at the edge end surface of the pole piece.

[0075] In some embodiments, when the sealing layer is partially sealed, the width of the sealing layer is greater than or equal to the thickness of the functional current collector, and less than or equal to the total thickness of the edge-sealed electrode.

[0076] In some embodiments, when the sealing layer is fully sealed, the sealing layer passes over the edge ridge of the pole piece and overlaps at least one side surface of the pole piece, and the overlap width is ≤1mm, for example, it can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0077] The present invention limits the overlap width of the sealing layer on the electrode surface to less than 1 mm, thereby avoiding the loss of energy storage function of part of the electrode material due to excessive overlap of the sealing layer, thereby ensuring that the battery capacity is at a high level.

[0078] An embodiment of the present invention further provides a method for preparing the edge-sealed electrode according to any of the above embodiments, the method comprising the following steps:

[0079] (1) preparing a functional current collector comprising at least a transition layer;

[0080] (2) providing an active material layer on at least one side surface of the functional current collector to obtain a pole piece;

[0081] (3) A sealing layer is provided on the edge end face of the electrode, and the sealing layer is controlled to completely cover the edge end face of the transition layer, thereby obtaining an edge-sealed electrode based on a functional current collector.

[0082] In certain embodiments, the method for preparing the functional current collector in step (1) includes: depositing a transition layer, a metal layer, and a passivation layer in sequence on at least one surface of a polymer film.

[0083] In certain embodiments, the method for providing the active material layer in step (2) comprises sequentially performing slurrying, coating, rolling, and die-cutting.

[0084] In some embodiments, the active material layer in step (2) includes an active material, a binder, and a conductive agent.

[0085] For example, the active material includes lithium iron phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium titanium oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, transition metal phosphate, sodium-transition metal oxide (Na x MO2, M is a transition metal), any one of sodium iron phosphate, sodium vanadium phosphate, sodium iron sulfate, sodium ferric fluorophosphate, Prussian blue compounds, polyanthraquinone, perylenetetracarboxylic dianhydride, polyaniline, polypyrrole, sodium sulfide or sodium tin, or a combination of at least two thereof, with a content of 90-98wt%, for example, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt% or 98wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0086] Exemplarily, the binder includes any one of polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, sodium carboxymethyl cellulose, polyacrylic acid, conductive polymers (such as polyaniline, polypyrrole, etc.), sodium alginate or chitosan, or a combination of at least two of them, with a content of 1-5wt%, for example, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0087] Exemplarily, the conductive agent includes any one of carbon black, conductive graphite, carbon fiber, carbon nanotube, graphene, silver nanowire, copper nanowire or conductive polymer (such as polyaniline, polypyrrole, etc.) or a combination of at least two, with a content of 1-5wt%, for example, it can be 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0088] In some embodiments, the thickness of the active material layer in step (2) is 30-300 μm, for example, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm or 300 μm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0089] In certain embodiments, the method for providing the sealing layer in step (3) includes precision spraying or slit coating.

[0090] In some embodiments, the coating liquid temperature used in the precision spray coating or slit coating is set to T c , then: T m ≤T c ≤T m +50℃, for example, it can be T c =T m 、T m +5℃、T m +10℃、T m +15℃、T m +20℃、T m +25℃、T m +30℃、T m +35℃、T m +40℃、T m +45℃ or T m +50℃, but is not limited to the listed values, other values ​​not listed in this numerical range are also applicable.

[0091] If the melting point of the sealing layer material is less than or equal to the melting point of the polymer film material, then T m Refers to the melting point of the polymer film material, ℃; if the melting point of the sealing layer material is greater than the melting point of the polymer film material, then T m Refers to the melting point of the sealing layer material, ℃.

[0092] The present invention limits the coating liquid temperature to be higher than the highest melting point of the sealing layer and the polymer film, and limits the difference between the two to within 50°C. This not only achieves full fusion of the sealing layer and the end face of the electrode, but also avoids unnecessary damage to the edge of the electrode due to excessively high coating liquid temperature and unnecessary increase in preparation cost.

[0093] A certain embodiment of the present invention further provides a battery, wherein the battery comprises an edge-sealed electrode based on a functional current collector as described in any of the above embodiments.

[0094] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0095] Example 1

[0096] This embodiment provides a sealed edge electrode based on a functional aluminum current collector, such as Figure 1 As shown, the edge-sealed electrode comprises a functional aluminum current collector 10 and an active material layer 20 disposed on both sides of the functional aluminum current collector 10. Figure 3 As shown, the functional aluminum current collector 10 includes a polymer film 11 and a transition layer 12, a metal layer 13 and a passivation layer 14 arranged on both sides of the polymer film 11, and the transition layer 12 is located between the polymer film 11 and the metal layer 13; the edge end surface of the edge-sealed electrode is provided with a sealing layer 30, and the sealing layer 30 completely covers the edge end surface of the transition layer 12 (see FIG. Figure 1 ).

[0097] In this embodiment, the material of the polymer film 11 is polyethylene terephthalate (number average molecular weight of 14600 g / mol) with a thickness of 6 μm; the material of the transition layer 12 is aluminum oxide with a thickness of 10 nm; the material of the metal layer 13 is aluminum with a thickness of 1 μm; the material of the passivation layer 14 is aluminum oxide with a thickness of 5 nm; the material of the sealing layer 30 is polyethylene (number average molecular weight of 20000 g / mol) with a thickness d1 of 5 μm, and the difference in surface energy between the material of the sealing layer 30 and the material of the polymer film 11 is ≤10 mJ / m 2 .like Figure 1As shown, the sealing layer 30 is partially sealed at the edge end face of the pole piece, and the width of the sealing layer 30 is equal to the total thickness of the pole piece, that is, the sealing layer 30 completely covers the end of the pole piece without overlap.

[0098] like Figure 4 As shown, the polymer film 11 includes a base film area 11a and a transition area 11b arranged on both sides of the base film area 11a, and the transition area 11b is located between the base film area 11a and the sealing layer 30; the material of the transition area 11b is a mixture of polyethylene terephthalate and polyethylene, the width d2 is 0.5mm, and the ratio of the average thickness of the transition area 11b to the average thickness of the base film area 11a is 105:100.

[0099] This embodiment also provides a method for preparing the edge-sealed electrode, which specifically includes the following steps:

[0100] (1) Preparation of a functional aluminum current collector 10 containing a transition layer 12:

[0101] (1.1) The polymer film 11 is placed in an evaporation machine, and aluminum oxide is deposited on both sides of the film to form a transition layer 12. The specific process is as follows: high-purity aluminum wire (purity of 99.93wt%) is used as the evaporation source, the evaporation boat is heated to 1500°C, the gas source is oxygen, the flow rate is 80mL / min, and the vacuum degree of the vacuum chamber is 0.1Pa.

[0102] (1.2) A metal layer 13 is deposited on the surface of the transition layer 12 by an evaporation coating process. The specific process is as follows: a high-purity aluminum wire (purity of 99.93 wt%) is used as an evaporation source, the evaporation boat is heated to 1500°C, and the vacuum degree of the vacuum chamber is 0.08 Pa.

[0103] (1.3) The obtained functional aluminum current collector 10 is exposed to air and aged for 24 hours to form a passivation layer 14 made of aluminum oxide on its surface.

[0104] (2) Active material layers 20 are provided on both sides of the functional aluminum current collector 10:

[0105] (2.1) Homogenization: a. Premixing (dry mixing): Add NCM811 (LiNi 0.8 Co 0.1 Mn 0.1O2) and a conductive agent (carbon nanotubes: Super P = 1:1), stirred for 10 minutes at a vacuum degree of -0.08 MPa and a rotation speed of 500 rpm; b. primary wet mixing: adding polyvinyl pyrrolidone (NMP) to the above mixture and stirring for 30 minutes at a rotation speed of 1500 rpm and a temperature of 40°C; c. secondary wet mixing: adding polyvinylidene fluoride (PVDF) to the above mixture and stirring for 60 minutes at a rotation speed of 2000 rpm; d. defoaming treatment: stirring for 20 minutes at a vacuum degree of -0.095 MPa and a rotation speed of 500 rpm to finally obtain a slurry with a solid content of 65wt% and a viscosity of 4500 cP (25°C), wherein the contents of NCM, conductive agent and PVDF are 96wt%, 2wt% and 2wt%, respectively.

[0106] (2.2) Coating: Using the functional aluminum current collector 10 obtained in step (1) as a base, the slurry obtained in step (2.1) was placed in a coating machine for double-sided coating. The coating speed was controlled to be 25 m / min and the surface density was 23.5 mg / cm 2 ; Drying temperature is: 80℃ (Zone 1) → 110℃ (Zone 2) → 90℃ (Zone 3), wind speed is 12m / s (cross flow hot air).

[0107] (2.3) Rolling: Place the baked electrode obtained in step (2.2) in a roller press for rolling. The line pressure is controlled to be 3000 N / mm and the compaction density is 3.5 g / cm 3 , and obtain a pole piece with a thickness of 200 μm.

[0108] (2.4) Die-cutting: Place the electrode obtained in step (2.3) in a die-cutting machine and cut it into 40 mm × 60 mm samples.

[0109] (3) The sample obtained in step (2.4) is placed in a precision slot extrusion sprayer. Polyethylene is used as the raw material, melted at 280°C, and kept warm while passing through the sprayer die (the die lip gap is 196 μm). The edge end face of the sample is sprayed to form a sealing layer 30, and the sealing layer 30 is controlled to completely cover the edge end face of the transition layer 12 to obtain an edge-sealed electrode.

[0110] Example 2

[0111] This embodiment provides an edge-sealed electrode based on a functional aluminum current collector. Except that the material of the sealing layer 30 is changed to polyamide (number average molecular weight is 20,000 g / mol), the rest of the structure and conditions are the same as those in Example 1, so they are not described here.

[0112] Example 3

[0113] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except for changing the material of the polymer film 11 to polyamide (number average molecular weight of 20,000 g / mol) and changing the material of the sealing layer 30 to polyurethane (number average molecular weight of 30,000 g / mol), the rest of the structure and conditions are the same as those in Example 1, so they are not repeated here.

[0114] Example 4

[0115] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except for changing the material of the polymer film 11 to polyimide (number average molecular weight of 30,000 g / mol) and changing the material of the sealing layer 30 to polyamide (number average molecular weight of 20,000 g / mol), the rest of the structure and conditions are the same as those in Example 1, so they are not repeated here.

[0116] Example 5

[0117] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except for changing the material of the polymer film 11 to polyphenylene ether (number average molecular weight of 40,000 g / mol) and changing the material of the sealing layer 30 to polyurethane (number average molecular weight of 30,000 g / mol), the remaining structures and conditions are the same as those in Example 1, so they are not repeated here.

[0118] Example 6

[0119] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except for changing the material of the polymer film 11 to polyphenylene sulfide (number average molecular weight of 40,000 g / mol) and changing the material of the sealing layer 30 to polyamide (number average molecular weight of 20,000 g / mol), the remaining structures and conditions are the same as those in Example 1, so they are not repeated here.

[0120] Example 7

[0121] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except for changing the material of the polymer film 11 to polyethylene (number average molecular weight of 20,000 g / mol) and changing the material of the sealing layer 30 to polypropylene (number average molecular weight of 20,000 g / mol), the remaining structures and conditions are the same as those in Example 1, so they are not repeated here.

[0122] Example 8

[0123] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except for changing the material of the polymer film 11 to polyethylene terephthalate with a number average molecular weight of 80,000 g / mol, so that the difference between the number average molecular weight of the material of the sealing layer 30 and the material of the polymer film 11 is greater than 50,000 g / mol, the rest of the structure and conditions are the same as those in Example 1, so they are not repeated here.

[0124] Example 9

[0125] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except for changing the material of the sealing layer 30 to a polyamide with a number average molecular weight of 80,000 g / mol, so that the difference between the number average molecular weight of the material of the sealing layer 30 and the material of the polymer film 11 is greater than 50,000 g / mol, the remaining structures and conditions are the same as those in Example 4, so they are not repeated here.

[0126] Example 10

[0127] This embodiment provides an edge-sealed electrode based on a functional aluminum current collector. Except that the material of the sealing layer 30 is changed to polyurethane (number average molecular weight is 30,000 g / mol), the rest of the structure and conditions are the same as those in Example 1, so they are not repeated here.

[0128] Example 11

[0129] This embodiment provides an edge-sealed electrode based on a functional aluminum current collector. In addition to changing the material of the polymer film 11 to polytetrafluoroethylene (number average molecular weight of 20,000 g / mol), and changing the material of the sealing layer 30 to polyamide (number average molecular weight of 30,000 g / mol), the difference between the surface energies of the two materials is greater than 10 mJ / m 2 The remaining structures and conditions are the same as those in Example 1, so they will not be described here.

[0130] Example 12

[0131] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except for changing the ratio of the average thickness of the transition area 11b to the average thickness of the base film area 11a to 80:100, the remaining structures and conditions are the same as those in Example 1, so they are not repeated here.

[0132] Example 13

[0133] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except that the ratio of the average thickness of the transition region 11b to the average thickness of the base film region 11a is changed to 90:100, the rest of the structure and conditions are the same as those in Example 1, so they are not described here.

[0134] Example 14

[0135] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except that the ratio of the average thickness of the transition region 11b to the average thickness of the base film region 11a is changed to 100:100, the rest of the structure and conditions are the same as those in Example 1, so they are not described here.

[0136] Example 15

[0137] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except that the ratio of the average thickness of the transition region 11b to the average thickness of the base film region 11a is changed to 110:100, the rest of the structure and conditions are the same as those in Example 1, so they are not described here.

[0138] Example 16

[0139] This embodiment provides an edge-sealed electrode based on a functional aluminum current collector. Except that the thickness d1 of the sealing layer 30 is changed to 2 μm, the rest of the structure and conditions are the same as those in Example 1, and therefore will not be described in detail here.

[0140] Example 17

[0141] This embodiment provides an edge-sealed electrode based on a functional aluminum current collector. Except that the thickness d1 of the sealing layer 30 is changed to 50 μm, the rest of the structure and conditions are the same as those in Example 1, and therefore will not be described in detail here.

[0142] Example 18

[0143] This embodiment provides an edge-sealed electrode based on a functional aluminum current collector. Except that the thickness d1 of the sealing layer 30 is changed to 200 μm, the rest of the structure and conditions are the same as those in Example 1, and therefore will not be described in detail here.

[0144] Example 19

[0145] This embodiment provides an edge-sealed electrode based on a functional aluminum current collector. Except that the thickness d1 of the sealing layer 30 is changed to 500 μm, the rest of the structure and conditions are the same as those in Example 1, and therefore will not be described in detail here.

[0146] Example 20

[0147] This embodiment provides an edge-sealed electrode based on a functional aluminum current collector. Except that the thickness d1 of the sealing layer 30 is changed to 600 μm, the rest of the structure and conditions are the same as those in Example 1, and therefore will not be described in detail here.

[0148] Example 21

[0149] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except for adjusting the width of the sealing layer 30 so that it only completely covers the end of the transition layer 12, the rest of the structure and conditions are the same as those in Example 1, so they are not repeated here.

[0150] Example 22

[0151] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. In addition to adjusting the sealing layer 30 to be fully sealed at the edge end surface of the electrode, that is, the sealing layer 30 passes over the edge ridge of the electrode and overlaps the two side surfaces of the electrode (see Figure 2), and the overlap width is controlled to be 0.5 mm. The remaining structures and conditions are the same as those in Example 1, so they are not described here.

[0152] Example 23

[0153] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except that the overlap width of the sealing layer 30 on the electrode surface is changed to 1 mm, the rest of the structure and conditions are the same as those in Example 22, so they will not be repeated here.

[0154] Example 24

[0155] This embodiment provides a sealed edge electrode based on a functional aluminum current collector. Except that the overlap width of the sealing layer 30 on the electrode surface is changed to 1.3 mm, the rest of the structure and conditions are the same as those in Example 22, so they will not be repeated here.

[0156] Example 25

[0157] This embodiment provides a functional aluminum current collector-based edge-sealed electrode. In addition to changing the material of the sealing layer 30 to polypropylene (number average molecular weight of 150,000 g / mol), the difference between the number average molecular weight of the sealing layer 30 and the polymer film 11 is greater than 50,000 g / mol, and the difference between the surface energies of the two materials is greater than 10 mJ / m 2 At the same time, the thickness d1 of the sealing layer 30 is changed to 2 μm, and the ratio of the average thickness of the transition area 11 b to the average thickness of the base film area 11 a is changed to 120:100. The remaining structures and conditions are the same as those in Example 1, so they are not repeated here.

[0158] Comparative Example 1

[0159] This comparative example provides a pole piece based on a functional aluminum current collector. Except that the sealing layer 30 is not provided on the edge end surface of the pole piece, the rest of the structure and conditions are the same as those of Example 1, so they are not described here in detail.

[0160] Performance testing:

[0161] (1) Adhesion test:

[0162] At room temperature (25°C), take a 20mm wide and 120mm long double-sided tape and stick it on the surface of the stainless steel plate, cut the collector sample with a size of 50mm×125mm (the collector before and after the cycle), and then evenly stick the cut measurement sample on the double-sided tape, and the double-sided tape is located in the center of the test sample, and use a 2kg standard small pressure roller to squeeze it back and forth twice; after the extrusion is completed, take a tape of the same size as the tape on the stainless steel plate, stick it to the sample surface, align it with the tape under the sample, and use a 2kg standard small pressure roller to squeeze it back and forth twice, then fix the prepared sample to the clamping distance of the peel force testing device, stretch it at an angle of 180° and a speed of 100mm / min, and set the width to the tape width. After the test is completed, read the peel force value.

[0163] (2) Cyclic performance test:

[0164] (A) Battery assembly: The electrode prepared in the present invention was used as the positive electrode; copper foil (thickness 6 μm) was used as the negative electrode current collector, and artificial graphite was used as the negative electrode active material; a polyethylene diaphragm coated with alumina ceramic (thickness 25 μm) was used as the diaphragm; the electrolyte was 1 mol·L -1 A carbonate solution of LiPF6, wherein the carbonate is a mixture of propylene carbonate, ethylene carbonate and ethyl methyl carbonate, with a mass ratio of 1:1:1; using the above materials, a lithium-ion battery is assembled according to the relevant process.

[0165] (B) The battery was cycled for 1000 times at a charge / discharge rate of 1 C, and the battery capacity retention rate after 1000 cycles was recorded, that is, the battery capacity after 1000 cycles / the initial capacity of the battery × 100%.

[0166] The test results of the electrodes obtained in Examples 1-20 and Comparative Example 1 are shown in Table 1 below.

[0167] Table 1

[0168]

[0169]

[0170] It can be seen that the present invention provides a sealing layer on the edge end face of the electrode and ensures that the sealing layer completely covers the edge end face of the transition layer, that is, the sealing treatment is achieved by fully integrating the sealing layer with the end face of the functional current collector, which effectively avoids the transition layer in the functional current collector from contacting the electrolyte, thereby improving the interface stability between the polymer film and the metal layer and the structural stability of the electrode during the cycle of the battery, significantly improving the cycle performance of the battery, and at the same time, the presence of the sealing layer avoids the internal short circuit problem of the positive and negative electrode sheets caused by the burr overlap of the current collector edge, thereby improving the safety performance of the battery.

[0171] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A sealed edge electrode based on a functional current collector, comprising a functional current collector and an active material layer disposed on at least one side of the functional current collector, wherein the functional current collector comprises at least a transition layer, characterized in that: The edge end surface of the edge-sealed electrode is provided with a sealing layer, and the sealing layer completely covers the edge end surface of the transition layer.

2. The edge-sealed electrode based on the functional current collector according to claim 1, characterized in that: The material of the sealing layer includes at least one of polyolefin, polyurethane or polyamide; wherein the polyolefin comprises at least one of polyethylene, polypropylene or ethylene-propylene copolymer; And / or, the thickness of the sealing layer is 5-500 μm, more preferably 50-200 μm.

3. The edge-sealed electrode based on the functional current collector according to claim 2, characterized in that: The functional current collector includes a polymer film and a transition layer, a metal layer and a passivation layer arranged on at least one side of the polymer film, and the transition layer is located between the polymer film and the metal layer; Wherein, the material of the polymer film includes at least one of polyolefin, polyester, polyamide, polyimide, polyphenylene ether or polyphenylene sulfide; And / or, the polyolefin comprises at least one of polyethylene, polypropylene, polypropylene, polyvinyl chloride, polyvinylidene fluoride or polytetrafluoroethylene; And / or, the polyester includes at least one of polyethylene terephthalate, polybutylene terephthalate or polyethylene naphthalate.

4. The edge-sealed electrode based on the functional current collector according to claim 3, characterized in that: The material of the polymer film and the material of the sealing layer satisfy any one of the following conditions: (A) The difference in surface energy is ≤10mJ / m 2 ; (B) The difference between the number average molecular weights is ≤ 50,000 g / mol.

5. The edge-sealed electrode based on the functional current collector according to claim 3 or 4, characterized in that: The polymer film includes a base film area and transition areas arranged on both sides of the base film area, and the transition areas are located between the base film area and the sealing layer; The material of the transition zone includes at least two of polyolefin, polyester, polyurethane, polyamide, polyimide, polyphenylene ether or polyphenylene sulfide; and / or, the width of the transition zone is 0.05-1 mm; And / or, the ratio of the thickness of the transition zone to the thickness of the basement membrane zone is (90-110):

100.

6. The edge-sealed electrode based on the functional current collector according to claim 5, characterized in that: The sealing layer is partially sealed or fully sealed at the edge end surface of the pole piece; Wherein, when the sealing layer is partially sealed, the width of the sealing layer is greater than or equal to the thickness of the functional current collector, and less than or equal to the total thickness of the edge-sealed electrode; Alternatively, when the sealing layer is fully sealed, the sealing layer goes over the edge ridge of the pole piece and overlaps at least one side surface of the pole piece, and the overlap width is ≤1 mm.

7. A method for preparing an edge-sealed electrode according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: (1) preparing a functional current collector comprising at least a transition layer; (2) providing an active material layer on at least one side surface of the functional current collector to obtain a pole piece; (3) A sealing layer is provided on the edge end face of the electrode, and the sealing layer is controlled to completely cover the edge end face of the transition layer, thereby obtaining an edge-sealed electrode based on a functional current collector.

8. The preparation method according to claim 7, characterized in that The method for preparing the functional current collector in step (1) comprises: depositing a transition layer, a metal layer and a passivation layer in sequence on at least one surface of a polymer film; And / or, the method for setting the active material layer in step (2) includes sequentially performing slurrying, coating, rolling and die cutting.

9. The preparation method according to claim 8, characterized in that The method for setting the sealing layer in step (3) includes precision spraying or slit coating; Set the coating liquid temperature used in the precision spraying or slit coating to T c , then: T m ≤T c ≤T m +50℃; If the melting point of the sealing layer material is less than or equal to the melting point of the polymer film material, then T m Refers to the melting point of the polymer film material, ℃; if the melting point of the sealing layer material is greater than the melting point of the polymer film material, then T m Refers to the melting point of the sealing layer material, ℃.

10. A battery, characterized in that: The battery comprises an edge-sealed electrode based on a functional current collector as claimed in any one of claims 1 to 6.

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