Composite porous current collector and manufacturing method thereof

Abstract

The invention discloses a composite porous current collector which comprises an insulating layer, a positive electrode current collector and a negative electrode current collector are attached to the two sides of the insulating layer respectively, micropores for ions to pass through penetrate through the interiors of the positive electrode current collector and the negative electrode current collector, and the surface of the positive electrode current collector is coated with microencapsulated lithium salt; the invention further provides a manufacturing method of the composite porous current collector. By arranging the positive and negative current collectors with different metal layers, the micropores and the microencapsulated lithium salt, metal components in the current collectors provide a good conduction path, and the micropores can provide more channels, so that ions are more smoothly transmitted in the current collectors, the charging and discharging efficiency, the rate capability and the energy density of the battery are improved, and the service life of the battery is prolonged. The battery is higher in flexibility and wider in application range; and when the surface of the current collector is damaged and short-circuited due to a needling phenomenon, lithium salt is released at the damaged part, and the lithium salt reacts with aluminum metal on the surface of the current collector to generate lithium-aluminum alloy, so that the damaged part is repaired.

Description

Technical Field

[0001] The present invention relates to the technical field of current collectors, and in particular to a composite porous current collector and a manufacturing method thereof. Background Art

[0002] Composite current collector is a new type of battery current collector material, which is composed of polymer materials and metals. It mainly plays the role of collecting current and carrying positive and negative electrode active substances.

[0003] The structure of the existing composite current collector is similar to a "sandwich" structure, with a base film (such as PP, PET, PI and other polymer materials) in the middle and two outer layers of copper-plated metal film; the base film of this composite current collector has the same material on both sides, the battery flexibility is low, the applicability is narrow, and the current collectors currently on the market may experience puncture during battery use, with the risk of local short circuit, affecting the battery's performance and life.

[0004] Therefore, those skilled in the art provide a composite porous current collector to solve the problems raised in the above background technology. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a composite porous current collector and a method for manufacturing the same.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] First, a composite porous current collector is provided, comprising an insulating layer, with a positive electrode current collector and a negative electrode current collector attached to both sides of the insulating layer respectively;

[0008] The positive electrode current collector and the negative electrode current collector are penetrated by micropores for ion passage;

[0009] The surface of the positive electrode current collector is coated with microencapsulated lithium salt.

[0010] Preferably, the insulating layer is made of a polymer material such as PP, PET or PI, and has a thickness of 0.1um to 100um; the positive electrode current collector is made of aluminum or aluminum alloy, and has a thickness of 0.01 to 10um;

[0011] The negative electrode current collector is made of copper or copper alloy, and has a thickness of 0.01 to 10 μm.

[0012] Preferably, the micropores for ion passage are punched mechanically or chemically, and the diameter is set to 0.01 to 5 μm.

[0013] Preferably, the microencapsulated lithium salt forms a film on the surface of the lithium salt, and the particle size is set to 1 to 5 μm.

[0014] Secondly, a method for manufacturing a composite porous current collector is provided, including a method for preparing an insulating layer base film, a method for preparing a positive electrode base film, and a method for preparing a negative electrode base film;

[0015] The method for preparing the insulating layer base film comprises the following steps:

[0016] S1: Select PP, PET or PI polymer material as the base film as the insulation layer;

[0017] S2: Aluminum is selected as the target material. Through PVD coating, the target atoms are sputtered out using a magnetron sputtering device and deposited on one side of the insulating layer to form a metal film as the positive electrode current collector;

[0018] S3: Select copper as the target material, and use PVD coating to sputter out the target atoms using magnetron sputtering equipment. The target atoms are then deposited on the other side of the insulating layer to form a metal film, which serves as the negative electrode current collector.

[0019] S4: Use a high-energy laser beam to focus on the surface of the current collector to punch holes to form micropores, or use a micro needle to drill micropores on the surface of the current collector through mechanical force;

[0020] S5: After pretreatment on the surface of the positive electrode current collector, avoid micropores and scan and spray microencapsulate lithium salt.

[0021] Preferably, the method for preparing the positive electrode base film comprises the following steps:

[0022] A. Select aluminum foil as the base film and as the positive electrode current collector;

[0023] B. Select a polymer material such as PP, PET or PI and deposit it on one side of the positive electrode current collector using a magnetron sputtering device by PVD coating to form an insulating layer;

[0024] C. Select copper as the target material, and use PVD coating to sputter target atoms using magnetron sputtering equipment. The target atoms are then deposited on one side of the insulating layer to form a metal film, which serves as the negative electrode current collector.

[0025] D. Use a high-energy laser beam to focus on the surface of the current collector to punch holes to form micropores, or use a micro needle to drill micropores on the surface of the current collector through mechanical force;

[0026] E. After pre-treatment, the surface of the positive electrode current collector is scanned and sprayed with microencapsulated lithium salt, avoiding micropores.

[0027] Preferably, the method for preparing the positive electrode base film comprises the following steps:

[0028] 1) Select copper foil as the base film and as the negative electrode current collector;

[0029] 2) Selecting a polymer material of PP, PET or PI, and depositing it on one side of the negative electrode current collector by PVD coating using a magnetron sputtering device to form an insulating layer;

[0030] 3) Aluminum is selected as the target material, and the target atoms are sputtered out using a magnetron sputtering device through PVD coating. The target atoms are then deposited on one side of the insulating layer to form a metal film, which serves as the positive electrode current collector;

[0031] 4) Using a high-energy laser beam to focus on the surface of the current collector to drill holes to form micropores, or using a micro needle to drill micropores on the surface of the current collector through mechanical force;

[0032] 5) After pre-treatment, the surface of the positive electrode current collector is scanned and sprayed with microencapsulated lithium salt, avoiding micropores.

[0033] Preferably, when the composite porous current collector has an insulating layer, it is prepared according to the above steps; when it does not have an insulating layer, the step of preparing the insulating layer is omitted.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention provides positive and negative electrode current collectors and micropores with different metal layers. The metal components in the current collector provide a good conduction path, ensuring that the ions inside the battery can be quickly transmitted from one electrode to the other. The micropores can provide more channels, making the ions transmit more smoothly inside the battery, reducing the transmission resistance, and improving the efficiency and rate performance of battery charge and discharge. At the same time, the micropores can increase the surface area of the current collector, thereby increasing the loading amount of the electrode active material, and then increasing the energy density of the battery, making the composed battery more flexible and applicable to a wider range of applications.

[0036] 2. The present invention sets a microencapsulated lithium salt with a particle size of 1 to 5 μm and coats it on the surface of the positive electrode current collector. When a needle puncture occurs and the current collector surface is damaged, the heat accumulation at the damaged part will increase due to the local short circuit. When the melting point of the outer film of the microencapsulated lithium salt is reached, the microencapsulated lithium salt will release the lithium salt at the local short circuit. The lithium salt reacts with the aluminum metal on the surface of the current collector to form a lithium-aluminum alloy, thereby repairing the damaged part of the current collector surface, which can extend the cycle life of the battery by 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the composite porous current collector structure with an insulating layer of the present invention;

[0038] Figure 2 This is a schematic diagram of the structure of the composite porous current collector without an insulating layer of the present invention;

[0039] Figure 3Schematic diagram of the manufacturing process of the composite porous current collector using foil as the base membrane of the present invention;

[0040] Figure 4 Schematic diagram of the manufacturing process of the composite porous current collector using an insulating film as a base film of the present invention;

[0041] Figure 5 Schematic diagram of the manufacturing process of the composite porous current collector without an insulating film of the present invention;

[0042] Figure 6 This is a schematic diagram of a method for using the composite porous current collector of the present invention in an existing conventional lithium battery;

[0043] Figure 7 This is a schematic diagram of a method for using the composite porous current collector of the present invention in a solid-state lithium battery. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0045] See also Figure 1 - Figure 7 The present invention provides an embodiment: first, a composite porous current collector is provided, including an insulating layer, with a positive electrode current collector and a negative electrode current collector attached to both sides of the insulating layer, the positive electrode current collector and the negative electrode current collector are penetrated by micropores for ion passage, and the surface of the positive electrode current collector is coated with microencapsulated lithium salt.

[0046] Furthermore, the insulating layer is made of a polymer material such as PP, PET or PI, with a thickness of 0.1um to 100um. The positive electrode current collector is made of aluminum or aluminum alloy, with a thickness of 0.01 to 10um. The negative electrode current collector is made of copper or copper alloy, with a thickness of 0.01 to 10um. The micropores for ion passage are punched mechanically or chemically, with a diameter of 0.01 to 5um.

[0047] Specifically, the composite porous current collector is used for existing conventional lithium batteries or solid-state lithium batteries. The interior of the positive current collector and the negative current collector is penetrated by micropores for ion passage, wherein the insulating layer can be ignored. The micropores can provide more channels, and the metal components in the current collector provide a good conduction path, ensuring that the ions inside the battery can be quickly transmitted from one electrode to another, making the ions more smoothly transmitted inside, reducing transmission resistance, and improving the efficiency and rate performance of battery charging and discharging. At the same time, the micropores can increase the surface area of the current collector, thereby increasing the loading amount of the electrode active material, and then increasing the energy density of the battery, making the composed battery more flexible and applicable.

[0048] Specifically, the microencapsulated lithium salt forms a film on the surface of the lithium salt with a particle size of 1 to 5 μm, which is coated on the surface of the positive electrode current collector. When the surface of the current collector is damaged due to a needle puncture phenomenon, the heat accumulation at the damaged part will increase due to the local short circuit. When the melting point of the outer film of the microencapsulated lithium salt is reached, the microencapsulated lithium salt will release the lithium salt at the local short circuit. The lithium salt reacts with the aluminum metal on the surface of the current collector to generate a lithium-aluminum alloy, thereby repairing the damaged part of the current collector surface, which can extend the cycle life of the battery by 30%.

[0049] Secondly, a method for manufacturing a composite porous current collector is provided, including a method for preparing an insulating layer base film, a method for preparing a positive electrode base film, and a method for preparing a negative electrode base film.

[0050] (1) A method for preparing an insulating layer base film, comprising the following steps:

[0051] S1: Select PP, PET or PI polymer material as the base film as the insulation layer;

[0052] S2: Aluminum is selected as the target material. Through PVD coating, the target atoms are sputtered out using a magnetron sputtering device and deposited on one side of the insulating layer to form a metal film as the positive electrode current collector;

[0053] S3: Select copper as the target material, and use PVD coating to sputter out the target atoms using magnetron sputtering equipment. The target atoms are then deposited on the other side of the insulating layer to form a metal film, which serves as the negative electrode current collector.

[0054] S4: Use a high-energy laser beam to focus on the surface of the current collector to punch holes to form micropores, or use a micro needle to drill micropores on the surface of the current collector through mechanical force;

[0055] S5: After pretreatment on the surface of the positive electrode current collector, avoid micropores and scan and spray microencapsulate lithium salt.

[0056] (2) A method for preparing a positive electrode base film, comprising the following steps:

[0057] A. Select aluminum foil as the base film and as the positive electrode current collector;

[0058] B. Select a polymer material such as PP, PET or PI and deposit it on one side of the positive electrode current collector using a magnetron sputtering device by PVD coating to form an insulating layer;

[0059] C. Select copper as the target material, and use PVD coating to sputter target atoms using magnetron sputtering equipment. The target atoms are then deposited on one side of the insulating layer to form a metal film, which serves as the negative electrode current collector.

[0060] D. Use a high-energy laser beam to focus on the surface of the current collector to punch holes to form micropores, or use a micro needle to drill micropores on the surface of the current collector through mechanical force;

[0061] E. After pre-treatment, the surface of the positive electrode current collector is scanned and sprayed with microencapsulated lithium salt, avoiding micropores.

[0062] (3) A method for preparing a negative electrode base film, comprising the following steps:

[0063] 1) Select copper foil as the base film and as the negative electrode current collector;

[0064] 2) Selecting a polymer material of PP, PET or PI, and depositing it on one side of the negative electrode current collector by PVD coating using a magnetron sputtering device to form an insulating layer;

[0065] 3) Aluminum is selected as the target material, and the target atoms are sputtered out using a magnetron sputtering device through PVD coating. The target atoms are then deposited on one side of the insulating layer to form a metal film, which serves as the positive electrode current collector;

[0066] 4) Using a high-energy laser beam to focus on the surface of the current collector to drill holes to form micropores, or using a micro needle to drill micropores on the surface of the current collector through mechanical force;

[0067] 5) After pre-treatment, the surface of the positive electrode current collector is scanned and sprayed with microencapsulated lithium salt, avoiding micropores.

[0068] In the preparation methods of (2) and (3), the composite porous current collector is prepared according to the steps described therein when it has an insulating layer, and the step of preparing the insulating layer is omitted when it does not have an insulating layer.

[0069] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description. It is intended that all variations within the meaning and range of equivalents of the claims be embraced herein, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

Claims

1. A composite porous current collector, characterized in that: An insulating layer is provided, with a positive electrode current collector and a negative electrode current collector attached to both sides of the insulating layer; The positive electrode current collector and the negative electrode current collector are penetrated by micropores for ion passage; The surface of the positive electrode current collector is coated with microencapsulated lithium salt.

2. A composite porous current collector according to claim 1, characterized in that: The insulating layer is made of a polymer material such as PP, PET or PI, and has a thickness of 0.1um to 100um; The positive electrode current collector is made of aluminum or aluminum alloy, and the thickness is set to 0.01 to 10 μm; The negative electrode current collector is made of copper or copper alloy, and has a thickness of 0.01 to 10 μm.

3. The composite porous current collector according to claim 1, wherein: The micropores for ion passage are punched mechanically or chemically, and the diameter is set to 0.01 to 5 μm.

4. The composite porous current collector according to claim 1, wherein: The microencapsulated lithium salt forms a film on the surface of the lithium salt, and the particle size is set to 1-5 μm.

5. A method for manufacturing a composite porous current collector according to any one of claims 1 to 4, characterized in that: Including the preparation method of insulating layer base film, positive electrode base film and negative electrode base film; The method for preparing the insulating layer base film comprises the following steps: S1: Select PP, PET or PI polymer material as the base film as the insulation layer; S2: Aluminum is selected as the target material. Through PVD coating, the target atoms are sputtered out using a magnetron sputtering device and deposited on one side of the insulating layer to form a metal film as the positive electrode current collector; S3: Select copper as the target material, and use PVD coating to sputter out the target atoms using magnetron sputtering equipment. The target atoms are then deposited on the other side of the insulating layer to form a metal film, which serves as the negative electrode current collector. S4: Use a high-energy laser beam to focus on the surface of the current collector to punch holes to form micropores, or use a micro needle to drill micropores on the surface of the current collector through mechanical force; S5: After pretreatment on the surface of the positive electrode current collector, avoid micropores and scan and spray microencapsulate lithium salt.

6. The method for manufacturing a composite porous current collector according to claim 5, characterized in that: The method for preparing the positive electrode base film comprises the following steps: A. Select aluminum foil as the base film and as the positive electrode current collector; B. Select a polymer material such as PP, PET or PI and deposit it on one side of the positive electrode current collector using a magnetron sputtering device by PVD coating to form an insulating layer; C. Select copper as the target material, and use PVD coating to sputter target atoms using magnetron sputtering equipment. The target atoms are then deposited on one side of the insulating layer to form a metal film, which serves as the negative electrode current collector. D. Use a high-energy laser beam to focus on the surface of the current collector to punch holes to form micropores, or use a micro needle to drill micropores on the surface of the current collector through mechanical force; E. After pre-treatment, the surface of the positive electrode current collector is scanned and sprayed with microencapsulated lithium salt, avoiding micropores.

7. The method for manufacturing a composite porous current collector according to claim 5, wherein: The method for preparing the positive electrode base film comprises the following steps: 1) Select copper foil as the base film and as the negative electrode current collector; 2) Selecting a polymer material of PP, PET or PI, and depositing it on one side of the negative electrode current collector by PVD coating using a magnetron sputtering device to form an insulating layer; 3) Aluminum is selected as the target material, and the target atoms are sputtered out using a magnetron sputtering device through PVD coating. The target atoms are then deposited on one side of the insulating layer to form a metal film, which serves as the positive electrode current collector; 4) Using a high-energy laser beam to focus on the surface of the current collector to form micropores, or using a micro needle to drill micropores on the surface of the current collector through mechanical force; 5) After pre-treatment, the surface of the positive electrode current collector is scanned and sprayed with microencapsulated lithium salt, avoiding micropores.

8. A method for manufacturing a composite porous current collector according to any one of claims 6 to 7, characterized in that: When the composite porous current collector is provided with an insulating layer, the above steps are followed to prepare the composite porous current collector. When the composite porous current collector is provided with no insulating layer, the insulating layer preparation step is omitted.

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