Metal current collector with multi-scale microstructure

Abstract

The utility model discloses a metal current collector with a multi-scale microstructure, which comprises a substrate and a coating, grooves are formed on the surfaces of two sides of the substrate, the width of the opening of each groove is 5-50 microns, the width of the bottom of each groove is 5-50 microns, and the depth of each groove is 0.1-5 microns; the inner surface of the groove is a rough net-shaped surface. The utility model has the beneficial effects that the orthogonal grooves are arranged on the surface of the metal foil, so that the surface of the formed current collector is provided with a periodic boss and groove array, and the structure increases the contact area between the current collector and an electrode active material, thereby reducing the contact resistance of the whole electrode; and the staggered structure of the grooves and the square bosses also strengthens the mechanical bonding between the electrode active material and the current collector, and enhances the bonding strength between the current collector and the carbon electrode, so as to prevent the peeling and layering phenomena between the active material and the current collector under extreme working conditions, especially alternate high temperature and low temperature, and improve the cycling stability.

Description

Technical Field

[0001] This utility model relates to the field of electrochemical energy storage materials technology, specifically to a metal current collector with a multi-scale microstructure. Background Technology

[0002] Supercapacitors possess high power density and ultra-long cycle life, making them irreplaceable in certain specialized applications. Lithium-ion batteries, on the other hand, offer high energy density and excellent cycle performance. Supercapacitors and lithium-ion batteries complement each other in applications, forming the core system of electrochemical energy storage. In principle, a typical electrochemical system includes electrode materials and an electrolyte. Energy storage and release in both capacitors and lithium-ion batteries rely on the reaction of ions and electrons at the electrodes. The electrochemical properties of the electrodes directly determine the electrochemical performance of the capacitor or lithium-ion battery. Electrodes are generally composed of active materials, conductive agents, and binders; these three components are uniformly coated onto a conductive current collector to form the electrode material. The anode and cathode current collectors in electrochemical energy storage devices are typically made of metal foil, playing two important roles: collecting and conducting current from the electrodes to the power source or appliance, and supporting the active material. Therefore, an ideal current collector should possess high conductivity, low contact resistance with the active material, and a strong and stable bond with the active material.

[0003] However, in practical applications, it has been found that in activated carbon-based supercapacitors using organic electrolytes, the carbon layer peels off from the aluminum foil current collector after long-term aging and processing, leading to a decline in electrochemical performance. A similar phenomenon exists in lithium-ion batteries. After long-term charge-discharge cycles, the active materials on the cathode and anode of lithium-ion batteries also peel off from the current collector, causing problems such as increased internal resistance and a severe decline in electrochemical performance. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] The technical problem to be solved by this utility model is to provide a metal current collector with a multi-scale microstructure by setting orthogonal grooves on the surface of a metal foil, so that the surface has periodic "protrusions" and groove arrays, and the surface inside the grooves has a rough nano-mesh surface, thereby modifying the metal surface, reducing the contact resistance between the metal and the active material, and increasing the bonding strength between the active material and the current collector.

[0006] (II) Technical Solution

[0007] This utility model is achieved through the following technical solution: This utility model proposes a metal current collector with a multi-scale microstructure, including a substrate and a coating. The substrate has grooves formed on both sides of its surface. The width of the groove opening is 5-50 μm, the width of the bottom is 5-50 μm, and the depth is 0.1-5 μm. The surface inside the groove is a rough mesh surface with a surface roughness Ra of 0.01-0.5 μm. The coating consists of two layers, which are respectively disposed on both sides of the substrate in the thickness direction. The thickness of the coating is 0.01-1 μm, and the coating is a diamond-like carbon film deposited on the substrate surface.

[0008] Furthermore, the total thickness of the substrate and the coating is 6-200 μm.

[0009] Furthermore, the groove is further divided into a first groove and a second groove. Multiple first grooves are arranged at intervals along a first direction and are parallel to each other. The interval between two adjacent first grooves is 10-150μm.

[0010] Furthermore, the plurality of second grooves are arranged at intervals along the second direction and are parallel to each other, with the interval between two adjacent second grooves being 10-150μm.

[0011] Furthermore, the ratio of the width of the bottom of the groove to the width of the groove opening is 0.5-1.

[0012] Furthermore, the bottom surface of the groove is randomly distributed with pits and protrusions, and the average hole diameter of the pits is 5-500 nm.

[0013] Furthermore, the angle between the first direction and the width direction of the substrate has the following relationship: 5° ≤ angle ≤ 90°.

[0014] Furthermore, the first direction is perpendicular to the second direction.

[0015] (III) Beneficial Effects

[0016] Compared with the prior art, this utility model has the following advantages:

[0017] 1. This utility model creates orthogonal grooves on the surface of a metal foil, resulting in a periodic array of "protrusions" and grooves on the surface of the current collector. This structure increases the contact area between the current collector and the electrode active material, thereby reducing the contact resistance of the entire electrode. Furthermore, the staggered structure of the grooves and square protrusions strengthens the mechanical bond between the electrode active material and the current collector, enhancing the bonding strength between the current collector and the carbon electrode. This prevents peeling and delamination of the active material and the current collector under extreme working conditions, especially under alternating high and low temperatures, thus improving cycle stability.

[0018] 2. This utility model features a rough mesh surface with randomly distributed pits and protrusions on the inner surface of the groove. The average pore diameter of the pits is 5-500 nm, which is smaller than the aforementioned "protrusions" and groove array. Together, they form a multi-scale microstructure on the surface of the current collector, which can further enhance the contact area between the current collector and the electrode active material. At the same time, the rough mesh surface has a high specific surface area. When this current collector is used in a capacitor, the multi-scale microstructure formed by the nanometer and micrometer scales on its surface can provide a huge surface area, which can increase the specific capacitance of the capacitor.

[0019] 3. The current collector disclosed in this utility model has a protective coating on both sides of the substrate in the thickness direction. The purpose is to protect the metal substrate, prevent oxidation and corrosion, and improve the corrosion resistance of the current collector in the battery, thereby providing good cycle stability. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of a metal current collector with a multi-scale microstructure as described in this utility model;

[0021] Figure 2 This is a top view of a metal current collector with a multi-scale microstructure as described in this utility model.

[0022] The annotations in the attached figures are explained as follows:

[0023] 1. Substrate; 2. Coating; 3. Groove; 31a. First groove; 32a. Second groove; D1. First direction; D2. Second direction; θ. Angle. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0025] like Figures 1-2As shown, a metal current collector with a multi-scale microstructure in this embodiment includes a substrate 1 and a coating 2. The substrate 1 is an aluminum foil with a purity greater than 99%. Grooves 3 are formed on both sides of the substrate 1. The width of the opening of the groove 3 is 5-50 μm, the width of the bottom is 5-50 μm, and the depth is 0.1-5 μm. The surface inside the groove 3 is a rough mesh surface with a surface roughness Ra of 0.01-0.5 μm. The substrate 1 is an aluminum foil with a purity greater than 99%. The coating 2 has two layers, which are respectively disposed on both sides of the substrate 1 in the thickness direction. The thickness of the coating 2 is 0.01-1 μm. The coating 2 is a diamond-like film deposited on the surface of the substrate 1. Observation of the substrate 1 as is shows that the surface of the substrate 1 without etching is relatively flat, providing a limited surface area. Its relatively flat surface also makes it difficult to provide enough anchoring points, resulting in a relatively low mechanical bonding strength between the electrode active material coated on its surface and the aluminum foil.

[0026] like Figures 1-2 As shown, in this embodiment, the total thickness of the substrate 1 and the coating 2 is 6-200 μm.

[0027] Furthermore, the groove 3 is further divided into a first groove 31a and a second groove 32a. Multiple first grooves 31a are arranged at intervals along the first direction D1 and are parallel to each other. The interval S1 between two adjacent first grooves 31a is 10-150μm. Multiple second grooves 32a are arranged at intervals along the second direction D2 and are parallel to each other. The interval S2 between two adjacent second grooves 32a is 10-150μm.

[0028] like Figures 1-2 As shown, in this embodiment, the ratio of the width of the bottom of the groove 3 to the width of the opening of the groove 3 is 0.5-1. The groove 3 can be formed by laser etching, chemical etching, mechanical processing, etc. The groove 3 is obtained by femtosecond laser etching. Micro-nano-scale pits and protrusions are randomly distributed on the bottom and inner surface of the groove 3. The average hole diameter of the micro-nano-scale pits formed on its surface is 5-500nm. The bottom surface of the groove 3 is randomly distributed with pits and protrusions. The average hole diameter of the pits is 5-500nm. The angle θ between the first direction D1 and the width direction of the substrate 1 has the following relationship: 5°≤θ≤90°. The first direction D1 is perpendicular to the second direction D2.

[0029] The specific implementation process of this embodiment is as follows: In use, simply install the metal current collector at the corresponding position on the lithium battery and the container to put it into use. By setting orthogonal grooves 3 on the surface of the metal foil, the current collector surface has a periodic array of "protrusions" and grooves 3. This structure increases the contact area between the current collector and the electrode active material, thereby reducing the overall electrode contact resistance. Furthermore, the staggered structure of the grooves 3 and square protrusions strengthens the mechanical bonding between the electrode active material and the current collector, enhancing the bonding strength between the current collector and the carbon electrode. This prevents peeling and delamination of the active material and the current collector under extreme working conditions, especially under alternating high and low temperatures, thus improving cycle stability. Simultaneously, the rough surface inside the grooves 3... The rough mesh surface is randomly distributed with pits and protrusions. The average pore diameter of the pits is 5-500 nm, which is smaller than the aforementioned array of "protrusions" and grooves 3. Together, they form a multi-scale microstructure on the current collector surface, which can further enhance the contact area between the current collector and the electrode active material. At the same time, the rough mesh surface has a high specific surface area. When this current collector is used in a capacitor, the multi-scale microstructure formed by its nanometer and micrometer scales can provide a huge surface area, which can increase the specific capacitance of the capacitor. In addition, a protective coating 2 is provided on both sides of the substrate 1 in the thickness direction to protect the substrate 1 from oxidation and corrosion, thereby improving the corrosion resistance of the current collector in the battery and providing good cycle stability.

[0030] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A metal current collector with a multi-scale microstructure, characterized in that: The substrate (1) includes a substrate (1) and a coating (2). The substrate (1) has grooves (3) formed on both sides of its surface. The grooves (3) have a width of 5-50 μm at the opening, a width of 5-50 μm at the bottom, and a depth of 0.1-5 μm. The surface inside the grooves (3) is a rough mesh surface with a surface roughness Ra of 0.01-0.5 μm. The coating (2) has two layers, which are respectively disposed on both sides of the substrate (1) in the thickness direction. The coating (2) has a thickness of 0.01-1 μm and is a diamond-like film deposited on the surface of the substrate (1).

2. A metal current collector with a multi-scale microstructure according to claim 1, characterized in that: The total thickness of the substrate (1) and the coating (2) is 6-200 μm.

3. A metal current collector with a multi-scale microstructure according to claim 1, characterized in that: The groove (3) is further divided into a first groove (31a) and a second groove (32a). Multiple first grooves (31a) are arranged at intervals along a first direction (D1) and are parallel to each other. The interval between two adjacent first grooves (31a) is 10-150μm.

4. A metal current collector with a multi-scale microstructure according to claim 3, characterized in that: Multiple second grooves (32a) are arranged at intervals along the second direction (D2) and are parallel to each other, with a spacing of 10-150 μm between two adjacent second grooves (32a).

5. A metal current collector with a multi-scale microstructure according to claim 1, characterized in that: The ratio of the width of the bottom of the groove (3) to the width of the opening of the groove (3) is 0.5-1.

6. A metal current collector with a multi-scale microstructure according to claim 2, characterized in that: The bottom surface of the groove (3) is randomly distributed with pits and protrusions, and the average hole diameter of the pits is 5-500 nm.

7. A metal current collector with a multi-scale microstructure according to claim 3, characterized in that: The angle (θ) between the first direction (D1) and the width direction of the substrate (1) has the following relationship: 5°≤θ≤90°.

8. A metal current collector with a multi-scale microstructure according to claim 4, characterized in that: The first direction (D1) is perpendicular to the second direction (D2).

Images