Silicon-based copper negative pole piece as well as preparation method and application thereof

Abstract

The invention provides a silicon-based copper negative electrode plate as well as a preparation method and application thereof, and relates to the technical field of battery negative electrodes. The silicon-based copper negative pole piece provided by the invention comprises a copper substrate with at least one surface provided with a plurality of micropores, silicon-carbon composite layers are deposited in the micropores, aluminum composite layers are deposited on at least one surface of the copper substrate, and the aluminum composite layers at least seal openings of the micropores; the silicon-carbon composite layer comprises a silicon-based layer and a carbon-based layer which are circularly deposited. The silicon-carbon material is circularly deposited in the micropores in the surface of the porous copper foil, and the aluminum composite layer is used for sealing, so that the loading capacity and the contact area of the copper foil on the silicon-carbon material can be improved, and the stability of the silicon-carbon material on the surface of the copper foil can be improved, thereby effectively improving the energy density and the cycle life of the battery.

Description

Technical Field

[0001] This invention relates to the field of battery anode technology, and mainly to a silicon-based copper anode sheet, its preparation method and application. Background Technology

[0002] In lithium-ion battery systems, the negative electrode is one of the core components determining the battery's energy density. During charging and discharging, the negative electrode stores and releases energy through reversible lithium-ion insertion / extraction reactions. Silicon (Si)-based negative electrode materials are considered key to breaking through existing energy density bottlenecks due to their extremely high theoretical specific capacity (approximately 4200 mAh / g, far exceeding the ~372 mAh / g of traditional graphite). In the negative electrode, the current collector acts as a conductive bridge between the active material and the external circuitry, requiring it to meet core requirements such as high conductivity, electrochemical stability, mechanical strength, and interfacial compatibility. Copper foil is widely used in current collectors due to its strong electrochemical inertness, high conductivity, ductility, and mechanical strength within the operating potential.

[0003] In existing technologies, commonly used negative electrode sheets primarily utilize current collectors to load active materials. The active slurry is coated onto the current collector using methods such as roller coating or slot extrusion coating, and then dried and cured. However, this preparation process is relatively complex, requiring steps such as active slurry mixing, coating, drying, and rolling, resulting in low production efficiency. Furthermore, the bonding strength between the active slurry and the current collector is limited, making it prone to detachment during cycling and causing capacity decay. Therefore, there is an urgent need to provide a solution to address these issues. Summary of the Invention

[0004] The purpose of this invention is to provide a silicon-based copper negative electrode sheet and its preparation method. By cyclically depositing silicon-carbon material in the micropores on the surface of porous copper foil and sealing it with an aluminum composite layer, not only can the loading capacity and contact area of ​​the silicon-carbon material on the copper foil be increased, but the stability of the silicon-carbon material on the surface of the copper foil can also be improved, thereby effectively improving the energy density and cycle life of the battery.

[0005] In a first aspect, the present invention provides a silicon-based copper negative electrode sheet, comprising at least one copper substrate having a plurality of micropores on its surface and a silicon-carbon composite layer deposited within the micropores, wherein at least one surface of the copper substrate is deposited with an aluminum composite layer, and the aluminum composite layer at least seals the opening of the micropores; the silicon-carbon composite layer comprises a silicon substrate and a carbon substrate deposited in a cycle.

[0006] The negative electrode provided by the present invention can effectively improve the loading and positional stability of the silicon-carbon composite layer on the surface of the copper substrate by depositing a silicon-carbon composite layer in the micropores of the copper substrate. At the same time, the use of an aluminum composite layer to seal the silicon-carbon composite layer can improve the positional stability of the silicon-carbon composite layer in the micropores and limit the volume change of silicon during charging and discharging.

[0007] Optionally, the pore size of the micropore is 1nm-400nm.

[0008] Optionally, the density of the micropores on the surface of the copper substrate is 50,000 per cm². 2 -100,000 pieces / cm 2 .

[0009] Optionally, the total pore volume of the micropores is 0.15 cm³. 3 -0.35cm 3 .

[0010] Optionally, the thickness of the aluminum composite layer is 1nm-300nm.

[0011] Optionally, the thickness of the copper substrate is 8 μm.

[0012] Optionally, the silicon substrate comprises amorphous silicon or amorphous silicon suboxide.

[0013] Optionally, the thickness of the silicon substrate is 0.1 μm-1.2 μm.

[0014] Optionally, the thickness of the carbon base layer is 0.1 μm-0.6 μm.

[0015] Optionally, the silicon substrate and the carbon substrate are cyclically deposited 1 to 3 times.

[0016] Optionally, the thickness of the silicon-carbon composite layer is 0.5 μm-3.0 μm.

[0017] Optionally, the aluminum composite layer is formed by composite deposition of aluminum oxide and aluminum fluoride.

[0018] Secondly, the present invention provides a method for preparing a silicon-based copper anode sheet, comprising: cyclically depositing silicon-based materials and carbon-based materials on the surface of a copper substrate having micropore openings for a preset number of cycles, then polishing the surface of the copper substrate and depositing an aluminum composite layer to obtain a silicon-based copper anode sheet.

[0019] Optionally, when depositing silicon-based materials, one of plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, high-power pulsed magnetron sputtering, or chemical vapor deposition is used to deposit copper substrates on silicon-based materials.

[0020] Optionally, when depositing carbon-based materials, one of plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, high-power pulsed magnetron sputtering, or chemical vapor deposition is used to deposit copper substrates on carbon-based materials.

[0021] Optionally, when depositing the aluminum composite layer, one of the following methods can be used to prepare the aluminum composite layer on the aluminum-based material: magnetron sputtering, metal-organic chemical vapor deposition, atomic layer deposition, or vapor deposition.

[0022] Thirdly, the present invention provides an application of a silicon-based copper negative electrode sheet in a battery. Attached Figure Description

[0023] Figure 1 A schematic diagram of the structure of a silicon-based copper negative electrode sheet provided by the present invention; Figure 2 The flowchart illustrates a method for preparing a silicon-based copper negative electrode sheet provided by this invention.

[0024] Explanation of reference numerals in the attached figures: 1. Copper substrate; 2. Silicon-carbon composite layer; 21. Silicon base layer; 22. Carbon base layer; 3. Aluminum composite layer. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0026] See Figure 1 The present invention provides a silicon-based copper negative electrode sheet, comprising at least one copper substrate 1 having a plurality of micropores on its surface and a silicon-carbon composite layer 2 deposited in the micropores, and an aluminum composite layer 3 deposited on at least one surface of the copper substrate 1, wherein the aluminum composite layer 3 is at least capable of sealing the opening of the micropores.

[0027] In fact, using a copper substrate 1 as the conductive framework and mechanical support for the negative electrode can effectively utilize the high conductivity and high ductility of the copper substrate 1. At the same time, micropores are opened on the surface of the copper substrate 1 to accommodate the silicon-carbon composite layer 2, which is beneficial to increase the loading of silicon-carbon material on the negative electrode. Meanwhile, the aluminum composite layer 3 deposited on the surface can seal the micropores, thereby improving the positional stability of the silicon-carbon composite layer 2 within the negative electrode sheet.

[0028] In fact, by depositing the silicon-carbon composite layer 2 within micropores, the micropores can effectively accommodate the silicon-carbon composite layer 2, mitigating the volume change of silicon material during charging and discharging. This improves the structural integrity of the silicon-carbon composite layer 2 within the micropores, preventing pulverization and enhancing the cycle performance of the negative electrode. Furthermore, the silicon-carbon composite layer 2 comprises a cycle-deposited silicon substrate 21 and a carbon substrate 22. The silicon substrate 21 is made of amorphous silicon or amorphous silicon suboxide.

[0029] Specifically, a copper substrate 1 can be obtained by pre-calendering copper material, and micropores can be fabricated on the surface of the copper substrate 1 using chemical etching, electrochemical etching, laser processing, or a template method, thereby producing a copper substrate 1 with multiple micropores on its surface. In some embodiments, the micropore diameter on the surface of the copper substrate 1 is 1 nm-400 nm, and the micropore density is 50,000 / cm². 2 -100,000 pieces / cm 2 The pore volume is 0.15cm. 3 - 0.35cm 3 .

[0030] In some embodiments, the thickness of the copper substrate 1 used is 8 μm. In practice, the thickness of the copper substrate 1 can be controlled by rolling the copper material according to actual needs. At the same time, the thickness of the copper substrate 1 is necessary to ensure that the micropores do not completely penetrate the copper substrate. This is beneficial for the silicon-carbon composite layer 2 to enter the micropores and be contained by the micropores during deposition.

[0031] In some embodiments, the thickness of the aluminum composite layer 3 is 1nm-300nm. In fact, the aluminum composite layer 3 is formed by composite deposition of aluminum oxide and aluminum fluoride. Specifically, by composite deposition of aluminum compounds on the surface of the copper substrate, the silicon-carbon composite layer 2 inside the micropores can be protected, effectively preventing the silicon-carbon composite layer 2 from detaching from the micropores when volume changes occur.

[0032] In some embodiments, during the cyclic deposition of silicon substrate 21 and carbon substrate 22 in micropores, the thickness of each silicon substrate 21 layer is independently 0.1 μm-1.2 μm, and the thickness of each carbon substrate 22 layer is independently 0.1 μm-0.6 μm. In fact, by performing cyclic deposition, the thickness of each silicon substrate 21 and carbon substrate 22 layer can be effectively reduced, and the silicon and carbon substrates can be encouraged to form an interleaved stacked structure, which is beneficial to improving the composite structure between the silicon substrate 21 and carbon substrate 22. Specifically, the total thickness of the silicon-carbon composite layer 2 in the micropores is 0.5 μm-3.0 μm.

[0033] In fact, the present invention also provides a method for preparing a silicon-based copper negative electrode sheet, comprising: cyclically depositing silicon-based materials and carbon-based materials on the surface of a copper substrate 1 with micropore openings for a preset number of cycles, then polishing the surface of the copper substrate 1 and depositing an aluminum composite layer 3 to obtain a silicon-based copper negative electrode sheet. Specifically, after cyclically depositing silicon-based materials and carbon-based materials, a silicon-carbon composite layer 2 can be formed in the micropores. At the same time, polishing removes the silicon-carbon material deposited on the surface of the copper substrate, thereby facilitating the deposition of the aluminum composite layer 3 and improving the bonding strength between the aluminum composite layer 3 and the copper substrate 1.

[0034] In some embodiments, see Figure 2 The preparation method provided by the present invention includes the following steps: S1. A copper substrate 1 with micropore openings on its surface is obtained by chemical etching on the surface of a copper sheet; S2. Cyclicly deposit silicon-based materials and carbon-based materials on the surface of porous copper substrate 1 for a preset number of cycles; S3. Polish the surface of the copper substrate 1 and deposit an aluminum composite layer 3 to obtain a silicon-based copper negative electrode sheet.

[0035] In fact, when preparing porous copper foil in step S1, rolling is performed, and micropores are processed on the surface of the copper sheet by chemical etching, electrochemical etching, laser processing technology or template method.

[0036] In fact, when performing step S2 to deposit silicon-based materials and carbon-based materials, one of the following methods can be used independently to deposit copper substrates: plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, high-power pulsed magnetron sputtering, and chemical vapor deposition.

[0037] In fact, when performing step S3 to deposit the aluminum composite layer, one of the following methods is used to prepare the aluminum composite layer on the aluminum-based material: magnetron sputtering, metal-organic chemical vapor deposition, atomic layer deposition, or vapor deposition.

[0038] Specifically, this invention also provides an application of a silicon-based copper negative electrode sheet in a battery. In fact, the copper negative electrode sheet can be directly loaded into a lithium-ion battery as the negative electrode, and a layer of silicon-carbon material can be solidified on the negative electrode sheet to further increase the surface silicon-carbon loading. Example 1

[0039] This embodiment 1 provides a method for preparing a silicon-based copper negative electrode sheet, including the following steps: preparing a microporous copper foil current collector (thickness 8μm, average micropore diameter 200nm, average micropore density 80,000 / cm²). 2The material (purchased from Foshan Zhongji Ximi New Materials Co., Ltd.) was ultrasonically cleaned in anhydrous ethanol, dried in a vacuum environment at 80°C, and then transferred to the vacuum sputtering chamber of a magnetron sputtering equipment. An N-type silicon target was used as the target material to sputter a silicon base layer with an average thickness of 0.2 μm. Then, the current collector was transferred to a chemical vapor deposition equipment to deposit a carbon base layer with an average thickness of 0.1 μm on the surface. After repeating the above operation twice, the surface was polished and an aluminum composite layer with a thickness of 0.2 μm composed of aluminum oxide and aluminum fluoride in a 1:1 molar ratio was deposited on the surface to obtain a silicon-based copper negative electrode sheet. Example 2

[0040] This embodiment 2 provides a method for preparing a silicon-based copper negative electrode sheet, including the following steps: preparing a microporous copper foil current collector (thickness 8μm, average micropore diameter 200nm, average micropore density 80,000 / cm²). 2 The material (purchased from Foshan Zhongji Ximi New Materials Co., Ltd.) was ultrasonically cleaned in anhydrous ethanol, dried in a vacuum environment at 80°C, and then transferred to the vacuum sputtering chamber of a magnetron sputtering equipment. An N-type silicon target was used as the target material to sputter a silicon base layer with an average thickness of 0.6 μm. Then, the current collector was transferred to a chemical vapor deposition equipment to deposit a carbon base layer with an average thickness of 0.3 μm on the surface. After polishing the surface and depositing an aluminum composite layer with a thickness of 0.2 μm composed of aluminum oxide and aluminum fluoride in a 1:1 molar ratio, a silicon-based copper negative electrode sheet was obtained.

[0041] Comparative Example 1 Comparative Example 1 provides a method for preparing a silicon-based copper negative electrode sheet, including the following steps: preparing a microporous copper foil current collector (thickness 8 μm, average micropore diameter 200 nm, average micropore density 80,000 / cm²). 2 The material (purchased from Foshan Zhongji Ximi New Materials Co., Ltd.) was ultrasonically cleaned in anhydrous ethanol, dried in a vacuum environment at 80°C, and then transferred to the vacuum sputtering chamber of a magnetron sputtering equipment. An N-type silicon target was used as the target material to sputter a silicon base layer with an average thickness of 0.2 μm. Then, the current collector was transferred to a chemical vapor deposition equipment to deposit a carbon base layer with an average thickness of 0.1 μm on the surface. The above operation was repeated twice to obtain a silicon-based copper negative electrode sheet.

[0042] Comparative Example 2 Comparative Example 2 provides a method for preparing a silicon-based copper negative electrode sheet, comprising the following steps: after ultrasonically cleaning an 8 μm thick copper foil current collector in anhydrous ethanol, drying it in a vacuum environment at 80°C, and then transferring it to the vacuum sputtering chamber of a magnetron sputtering device, using an N-type silicon target as the target material to sputter a silicon base layer with an average thickness of 0.1 μm, and then transferring the current collector to a chemical vapor deposition device to deposit a carbon base layer with an average thickness of 0.05 μm on the surface; after repeating the above operation twice, the surface is polished and an aluminum composite layer with a thickness of 0.2 μm composed of an aluminum oxide and an aluminum fluoride molar ratio of 1:1 is deposited on the surface to obtain the silicon-based copper negative electrode sheet.

[0043] Performance testing The silicon-based copper negative electrode sheets from Examples 1 and 2, and Comparative Examples 1 to 2 were assembled into coin cells. Lithium sheets were used as counter electrodes, lithium hexafluorophosphate as electrolytes, and Celgard 250 as separators. Electrochemical tests were conducted under the Newway test environment to detect the initial coulombic efficiency, initial reversible capacity, and capacity retention rate after 100 cycles. The results are shown in Table 1 below.

[0044] Table 1 Performance Test Data First Coulomb efficiency % First reversible capacity mAh / g Capacity retention rate % Example 1 91.42 1769.32 86.56 Example 2 88.95 1713.80 83.73 Comparative Example 1 75.46 1489.13 58.36 Comparative Example 2 92.54 1838.48 47.25 While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A silicon-based copper negative electrode sheet, characterized in that, The invention includes a copper substrate having at least one surface with multiple micropores and a silicon-carbon composite layer deposited within the micropores; an aluminum composite layer is deposited on at least one surface of the copper substrate, and the aluminum composite layer at least seals the opening of the micropores; the silicon-carbon composite layer includes a cyclically deposited silicon base layer and a carbon base layer.

2. The silicon-based copper negative electrode sheet according to claim 1, characterized in that, The pore size of the micropores is 1 nm-400 nm; and / or, the density of the micropores on the surface of the copper substrate is 50,000 per cm². 2 -100,000 pieces / cm 2 ; and / or, the total pore volume of the micropores is 0.15 cm³. 3 -0.35cm 3 ; and / or, the thickness of the aluminum composite layer is 1nm-300nm; and / or, the thickness of the copper substrate is 8μm; and / or, the silicon substrate comprises amorphous silicon or amorphous silicon suboxide.

3. The silicon-based copper negative electrode sheet according to claim 1, characterized in that, The thickness of the silicon substrate is 0.1 μm-1.2 μm; and / or, the thickness of the carbon substrate is 0.1 μm-0.6 μm; and / or, the silicon substrate and the carbon substrate are cyclically deposited 1 to 3 times; and / or, the thickness of the silicon-carbon composite layer is 0.5 μm-3.0 μm; and / or, the aluminum composite layer is formed by composite deposition of alumina and aluminum fluoride.

4. A method for preparing a silicon-based copper negative electrode sheet as described in any one of claims 1 to 3, characterized in that, include: After a preset number of cycles of cyclic deposition of silicon-based and carbon-based materials on the surface of a copper substrate with micropore openings, the surface of the copper substrate is polished and an aluminum composite layer is deposited to obtain a silicon-based copper negative electrode sheet.

5. The preparation method according to claim 4, characterized in that, When depositing silicon-based materials, one of the following methods is used to deposit copper substrates on silicon-based materials: plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, high-power pulsed magnetron sputtering, and chemical vapor deposition.

6. The preparation method according to claim 4, characterized in that, When depositing carbon-based materials, one of the following methods is used to deposit copper substrates on carbon-based materials: plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, high-power pulsed magnetron sputtering, and chemical vapor deposition.

7. The preparation method according to claim 4, characterized in that, When depositing an aluminum composite layer, one of the following methods is used to prepare the aluminum composite layer on the aluminum-based material: magnetron sputtering, metal-organic chemical vapor deposition, atomic layer deposition, or vapor deposition.

8. The application of a silicon-based copper anode sheet as described in any one of claims 1 to 3 or a silicon-based copper anode sheet prepared by any one of claims 4 to 7 in a battery.

Images