A functional current collector, a pole sheet applying the same, and a battery

Abstract

This invention provides a functional current collector, an electrode using the same, and a battery. The functional current collector includes a substrate and a first copper layer and a second copper layer sequentially disposed on at least one surface of the substrate. The first copper layer is prepared by magnetron sputtering, and the second copper layer is prepared by electroplating. The X-ray diffraction peak intensity I of the first copper layer at the (111) crystal plane is... (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) Satisfying 6≤I (111) / I (200) ≤8. The first copper layer of the functional current collector provided by this invention satisfies 6≤I (111) / I (200) ≤8 can improve defects such as dislocations and interfaces caused by grain growth and thermal deformation during the forming process when the second copper layer is laminated on the surface of the first copper layer. This reduces defects in the second copper layer and increases its density, thereby lowering the resistivity of the functional current collector and improving the energy density, cycle life, and safety performance of the battery using it.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a functional current collector, an electrode using the same, and a battery. Background Technology

[0002] With the rapid development of new energy and electronic technology, battery cycle life, safety performance, and energy density have become paramount. As a crucial component of a battery, the current collector gathers the current generated by the battery's active materials to form a larger output current; its performance directly impacts the battery's cycle life, energy density, and safety performance.

[0003] Currently, copper foil is often used as the current collector in the negative electrode of lithium and sodium batteries. This type of current collector has high cost and quality, which is not conducive to controlling battery cost and improving energy density. Summary of the Invention

[0004] To address the issues of low energy density and high cost in existing batteries that use traditional copper foil as the negative electrode current collector, this invention provides a functional current collector, an electrode sheet using it, and a battery.

[0005] According to a first aspect of the present invention, a functional current collector is provided, comprising a substrate and a first copper layer disposed on at least one surface of the substrate, the first copper layer being prepared by a magnetron sputtering process, wherein the X-ray diffraction peak intensity of the first copper layer at the (111) crystal plane is I. (111) I is the X-ray diffraction peak intensity of the first copper layer at the (200) crystal plane. (200) I (111) I (200) Satisfies that 6≤I (111) / I (200) ≤8.

[0006] Compared with traditional copper foil, the functional current collector provided by this invention has an inner layer as a substrate and at least one side as a copper layer. Applying the functional current collector provided by this invention to electrodes and batteries can, on the one hand, improve the energy density of the battery and reduce the battery cost. On the other hand, when the battery experiences thermal runaway, the copper layer on the surface of the functional current collector is more likely to break, thereby isolating the connection between the active material and the functional current collector, effectively preventing the continued thermal runaway of the battery, and improving the safety performance of the battery.

[0007] The parameters of the current, electroplating solution concentration, and electroplating time during the electroplating process of the functional current collector do not regularly affect the recrystallization time and recrystallization quality of the metal layer of the functional current collector. Therefore, it is difficult to control the recrystallization time through the above-mentioned preparation process parameters of the functional current collector. The metal coating on the functional current collector has a face-centered cubic structure with diffraction peaks of crystal planes such as (111), (200), (220), and (311). The inventors of this application have found that the recrystallization time and quality of the metal layer in the functional current collector are closely related to the ratio of the crystal plane orientation of the metal layer at (111) and (200).

[0008] Based on the above findings, the present invention obtains the X-ray diffraction peak intensity I at the (111) crystal plane of the first copper layer obtained by magnetron sputtering on the substrate surface of the functional current collector. (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) The ratio I (111) / I (200) Controlling the value within the range of 6 to 8 has several advantages. First, when plating a second copper layer onto the surface of the first copper layer using electroplating, the recrystallization time during the bonding process of the second copper layer with the first copper layer can be reduced, thus lowering the production cycle, storage costs, and product cycle time associated with the functional current collector. Second, it improves the formation process by mitigating defects such as dislocations and interfaces caused by grain growth and thermal deformation during the bonding of the second copper layer with the first copper layer. This results in fewer defects and higher density in the second copper layer produced by electroplating, improving the reliability of the functional current collector and consequently enhancing the safety performance of batteries using it. Third, the reduced defects in the second copper layer improve the quality of the metal layer, increasing the strength and quality of the functional current collector, reducing its resistivity, and thus increasing the energy density of batteries using it. It also reduces the risk of copper layer detachment when the functional current collector is used in batteries, significantly improving the cycle life and safety performance of batteries using it.

[0009] If the X-ray diffraction peak intensity I of the first copper layer on the substrate surface of the functional current collector at the (111) crystal plane is... (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) The ratio I (111) / I (200) >8, the recrystallization time during the process of the second copper layer being composited on the surface of the first copper layer will increase, which will reduce the recrystallization quality of the second copper layer, leading to an increase in defects in the second copper layer, and thus increasing the resistivity of the functional current collector; if the X-ray diffraction peak intensity I of the first copper layer on the substrate surface of the functional current collector at the (111) crystal plane is (111) X-ray diffraction peak intensity I at the (200) crystal plane (200)The ratio I (111) / I (200) <6. During the surface recrystallization process of the second copper layer on the first copper layer, the recrystallization time of the second copper layer may increase and the recrystallization quality of the second copper layer may decrease, resulting in an increase in defects in the second copper layer, which in turn increases the resistivity of the functional current collector.

[0010] Preferably, 6.2≤I (111) / I (200) ≤7.7.

[0011] Preferably, 6.2≤I (111) / I (200) ≤7.5.

[0012] Further, the X-ray diffraction peak intensity I of the first copper layer on the substrate surface of the functional current collector at the (111) crystal plane is increased. (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) The ratio I (111) / I (200) By controlling the resistivity within the range of 6.2 to 7.5, the resistivity of the functional current collector can be further reduced, thereby further improving the cycle energy density of the battery using this functional current collector.

[0013] Preferably, the thickness of the first copper layer is 30–80 nm.

[0014] Preferably, the thickness of the second copper layer is 0.5 to 2 μm.

[0015] Preferably, the substrate is selected from at least one of polyethylene terephthalate (PET) film, polypropylene (PP) film, and polyimide (PI) film.

[0016] Preferably, the thickness of the substrate is 3 to 10 μm.

[0017] The thickness of the first copper layer, sequentially laminated onto the two surfaces of the substrate of the current collector, is controlled within the range of 30–80 nm, the thickness of the second copper layer is controlled within the range of 0.5–2 μm, and the thickness of the substrate is controlled within the range of 3–10 μm. Because the surface metal layer of the functional current collector is thin and the internal polymer substrate is light, it can effectively reduce the overall weight of the functional current collector, thereby improving the energy density of the battery using this functional current collector.

[0018] According to a second aspect of the present invention, a method for preparing a functional current collector is provided, comprising the following steps: depositing a first copper layer on at least one surface of a substrate using a magnetron sputtering process, and depositing a second copper layer on the surface of the first copper layer using an electroplating process to obtain a functional current collector; in the magnetron sputtering process, the substrate bias voltage is controlled within the range of -(185~265)V, the power is 12~16kW, and the argon flow rate is 40~80sccm.

[0019] The first copper layer and the second copper layer are deposited on the surface of the substrate by magnetron sputtering and electroplating, respectively. During the forming process of bonding the second copper layer to the surface of the first copper layer by electroplating, the second copper layer will undergo recrystallization due to self-repair of micro-defects.

[0020] In the method for preparing the functional current collector provided in this scheme, a first copper layer is composited on at least one surface of a substrate using magnetron sputtering. By controlling the substrate bias voltage of the magnetron sputtering within the range of -265V to -185V, while controlling the power between 12 and 16kW and the argon flow rate between 40 and 80 sccm, the X-ray diffraction peak intensity I of the first copper layer on the substrate surface of the final functional current collector at the (111) crystal plane can be achieved. (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) The ratio satisfies 6≤I (111) / I (200) ≤8 can effectively improve the density of the second copper layer obtained after electroplating, reduce the resistivity of the functional current collector, and thus improve the energy density and safety performance of the battery using this functional current collector.

[0021] According to a third aspect of the present invention, an electrode is provided, the electrode comprising the above-described functional current collector or a functional current collector prepared by the above-described method for preparing the functional current collector.

[0022] According to a fourth aspect of the present invention, a battery is provided, the battery comprising the aforementioned electrode.

[0023] Applying the functional current collector provided by this invention to electrodes and batteries can endow batteries with excellent energy density, cycle performance and safety performance. Attached Figure Description

[0024] Figure 1 A schematic diagram of the structure of the functional current collector provided by the present invention.

[0025] The attached figures are labeled as follows: 1 substrate, 2 first copper layer, 3 second copper layer. Detailed Implementation

[0026] The technical features of the technical solution provided by the present invention will be further clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0027] Example 1

[0028] A functional current collector, the structure of which is as follows Figure 1 As shown, the functional current collector includes a substrate 1 and a first copper layer 2 and a second copper layer 3 sequentially disposed on two surfaces of the substrate 1, wherein the substrate 1 is a polypropylene (PP) film.

[0029] The functional current collector provided in this embodiment is prepared through the following steps:

[0030] S1. Equipment Preparation

[0031] Prepare a high-vacuum winding magnetron sputtering equipment and ensure that the equipment is operating normally. Also prepare an electroplating line and ensure that it is operating normally.

[0032] S2. Target preparation

[0033] Choose copper with a smooth surface and no impurities as the target material;

[0034] S3. Base Preparation

[0035] A PP film with a thickness of 4.5μm and a smooth, impurity-free surface was selected as substrate 1;

[0036] S4. Magnetron sputtering

[0037] Start the magnetron sputtering equipment, control the substrate bias voltage of the magnetron sputtering equipment to -225V, the power to 14kW, the argon flow rate to 60sccm, and the winding coating speed to 5m / min, and deposit a first copper layer 2 with a thickness of 60nm on the two surfaces of the PP film.

[0038] S5. Electroplating

[0039] A second copper layer 3 with a thickness of 1 μm is deposited on the surface of the first copper layer 2 using an electroplating process to obtain the functional current collector of this embodiment.

[0040] Example 2

[0041] This embodiment provides a functional current collector. Compared with Embodiment 1, the difference in configuration is that in step S4 of the preparation of the functional current collector, the substrate bias voltage of the magnetron sputtering equipment is controlled to be -185V. Apart from the above differences, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Embodiment 1.

[0042] Example 3

[0043] This embodiment provides a functional current collector. Compared with Embodiment 1, the difference in configuration is that in step S4 of the preparation of the functional current collector, the substrate bias voltage of the magnetron sputtering equipment is controlled to be -265V. Apart from the above differences, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Embodiment 1.

[0044] Example 4

[0045] This embodiment provides a functional current collector. Compared with Embodiment 1, the difference in configuration is that in step S4 of the preparation of the functional current collector, the power of the magnetron sputtering equipment is controlled to be 16kW. Apart from the above differences, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Embodiment 1.

[0046] Example 5

[0047] This embodiment provides a functional current collector. Compared with Embodiment 1, the difference in configuration is that in step S4 of the preparation of the functional current collector, the power of the magnetron sputtering equipment is controlled to be 12kW. Apart from the above differences, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Embodiment 1.

[0048] Example 6

[0049] This embodiment provides a functional current collector. Compared with Embodiment 1, the difference in configuration is that in step S4 of the preparation of the functional current collector, the argon flow rate is controlled to be 80 sccm. Apart from the above differences, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Embodiment 1.

[0050] Example 7

[0051] This embodiment provides a functional current collector. Compared with Embodiment 1, the difference in configuration is that in step S4 of the preparation of the functional current collector, the argon flow rate is controlled at 40 sccm. Apart from the above differences, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Embodiment 1.

[0052] Comparative Example 1

[0053] This comparative example provides a functional current collector. Compared with Example 1, the difference in configuration is that in step S4 of the preparation of the functional current collector, the substrate bias voltage of the magnetron sputtering equipment is controlled to be -115V, the power to be 18kW, and the argon flow rate to be 30sccm. Apart from the above differences, the materials, formulation ratios, and preparation operations used in this comparative example are strictly consistent with those in Example 1.

[0054] Comparative Example 2

[0055] This comparative example provides a functional current collector. Compared with Example 1, the difference in configuration is that in step S4 of the preparation of the functional current collector, the substrate bias voltage of the magnetron sputtering equipment is controlled to be -325V, the power is 10kW, and the argon flow rate is 90sccm. Apart from the above differences, the materials, formulation ratios, and preparation operations used in this comparative example are strictly consistent with those in Example 1.

[0056] Test case

[0057] 1. Participants

[0058] This test example uses the functional current collectors prepared in Examples 1-7 and Comparative Examples 1-2 as test objects to conduct relevant performance tests.

[0059] 2. Test Content

[0060] (1) Crystal plane orientation

[0061] The "crystal plane orientation" mentioned in this test example refers to the X-ray diffraction peak intensity at different crystal planes of the first copper layer obtained by magnetron sputtering in the functional current collector, i.e., the integrated area of ​​the X-ray diffraction peak. The X-ray diffraction peak intensity at the (111) crystal plane of the first copper layer obtained by magnetron sputtering is taken as I. (111) The X-ray diffraction peak intensity at the (200) crystal plane is I. (200) X-ray crystal diffraction was used to measure the diffraction angle and intensity of the first copper layer to X-rays. Different crystal planes produced specific diffraction peaks. The crystal orientation of the first copper layer could be analyzed based on the position and intensity of the diffraction peaks. The lattice parameters and crystal orientation of the crystal could be determined using the diffraction angle and intensity, thereby obtaining I... (111) and I (200) And the ratio between the two.

[0062] (2) Resistivity

[0063] The resistivity of the functional current collector was tested using a BEST-300C automatic four-probe resistivity meter (purchased from Beijing Beiguang Precision Instrument Equipment Co., Ltd.). During the recrystallization process of the copper layer, the resistivity changes over time. After electroplating is completed and the plated is left to stand for 30 minutes, the resistivity is measured every 6 minutes until the resistivity no longer changes after 10 consecutive measurements. This resistivity is the resistivity after recrystallization is completed, which is the final resistivity measured.

[0064] The resistivity of a functional current collector indirectly reflects the energy density and safety performance of a battery using that current collector. Specifically, firstly, during battery charging and discharging, low resistivity reduces energy transmission losses, allowing more energy to be stored and released effectively, thus increasing the battery's actual usable energy. Furthermore, lower resistivity helps reduce ohmic polarization within the battery, lowering the heat generated by internal resistance and improving charging and discharging efficiency. This means that with the same volume and weight, the battery can store and release more energy, thereby increasing energy density. In other words, the lower the resistivity of the functional current collector, the higher the energy density of the battery using it. Secondly, a short recrystallization time and low resistivity in the second copper layer of the functional current collector indicate good recrystallization quality. A high-quality second copper layer reduces the risk of peeling and detachment, and also reduces relative stress, thereby improving the safety performance of the functional current collector.

[0065] (3) Recrystallization time

[0066] The resistivity of the functional current collector also changes during the recrystallization process. After electroplating is completed and left to stand for 30 minutes, the resistivity is tested every 6 minutes until the resistivity no longer changes after 10 consecutive measurements. The time of the first measurement among the 10 consecutive measurements without change is taken as the recrystallization end time. The time difference between this and the time when electroplating is completed is the recrystallization time of the second copper layer.

[0067] 3. Experimental Results

[0068] Table 1. Performance test results of functional current collectors

[0069]

[0070] The relevant performance test results of the functional current collector are shown in Table 1.

[0071] The functional current collectors prepared in Examples 1-7 and Comparative Examples 1-2 all include a substrate and copper layers disposed on two surfaces of the substrate. The difference is that the X-ray diffraction peak intensity I of the first copper layer of the functional current collector prepared in Comparative Example 1 at the (111) crystal plane is... (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) The ratio I (111) / I (200) <6, The X-ray diffraction peak intensity I of the first copper layer of the functional current collector prepared in Comparative Example 2 at the (111) crystal plane (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) The ratio I (111) / I (200)>8, while the X-ray diffraction peak intensity I of the first copper layer of the functional current collector prepared in Examples 1-7 at the (111) crystal plane is >8. (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) The ratio satisfies 6 ≤ I (111) / I (200) ≤8.

[0072] Compared to Comparative Examples 1-2, the recrystallization time of the second copper layer in Examples 1-7 during the preparation of the functional current collector was between 2.6 and 3.5 hours, which was shorter than that in Comparative Examples 1-2. Furthermore, the resistivity of the functional current collectors prepared in Examples 1-7 was (2.65-3.53) × 10⁻⁶. -8 The X-ray diffraction peak intensity I at the (111) crystal plane is significantly lower than that in Comparative Examples 1-2, where the substrate bias voltage of the magnetron sputtering is controlled within the range of -265V to -185V during the preparation of the functional current collector in Examples 1-7. (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) The ratio satisfies 6≤I (111) / I (200) The relationship ≤8 can reduce the recrystallization time during the process of the second copper layer being bonded to the surface of the first copper layer during electroplating, and can also improve the defects such as dislocations and interfaces caused by grain growth and thermal deformation during the forming process when the second copper layer is bonded to the surface of the first copper layer. This results in fewer defects and higher density in the second copper layer obtained by electroplating, thus reducing the resistivity of the functional current collector. In contrast, the substrate bias voltage of the functional current collectors in Comparative Examples 1 and 2 during the preparation process was not within the range of -265 to -185V. The X-ray diffraction peak intensity I of the first copper layer on the substrate surface of the final functional current collector at the (111) crystal plane was significantly lower. (111) X-ray diffraction peak intensity I at the (200) crystal plane (200) The ratio does not satisfy 6≤I (111) / I (200) The relationship ≤8 increases the recrystallization time during the process of the second copper layer being laminated onto the surface of the first copper layer, leading to an increase in defects during the forming process of the second copper layer. This results in a significant increase in the resistivity of the functional current collector, which in turn leads to a significant decrease in the energy density of the battery using the functional current collectors of Comparative Examples 1 to 2.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention, but such modifications or substitutions are all within the scope of protection of the present invention.

Claims

1. A functional current collector, characterized in that: The functional current collector includes a substrate and a first copper layer and a second copper layer sequentially disposed on at least one surface of the substrate. The first copper layer is prepared by magnetron sputtering, and the second copper layer is prepared by electroplating. I is the X-ray diffraction peak intensity of the first copper layer at the (111) crystal plane. (111) I is the X-ray diffraction peak intensity of the first copper layer at the (200) crystal plane. (200) The I (111) The I (200) Satisfies 6.2≤I (111) / I (200) ≤7.5; The method for preparing the functional current collector includes the following steps: depositing a first copper layer on at least one surface of the substrate using a magnetron sputtering process, and depositing a second copper layer on the surface of the first copper layer using an electroplating process to obtain the functional current collector; In the magnetron sputtering process, the substrate bias voltage is controlled within the range of -(185~225)V, the power is 12~16 kW, and the argon flow rate is 40~80 sccm.

2. The functional current collector as described in claim 1, characterized in that: The thickness of the first copper layer is 30~80 nm.

3. The functional current collector as described in claim 1, characterized in that: The thickness of the second copper layer is 0.5~2 μm.

4. The functional current collector as described in claim 1, characterized in that: The substrate is selected from at least one of polyethylene terephthalate film, polypropylene film, and polyimide film.

5. The functional current collector as described in claim 1, characterized in that: The thickness of the substrate is 3~10 μm.

6. An electrode sheet, characterized in that: The electrode includes the functional current collector as described in any one of claims 1 to 5.

7. A battery, characterized in that: The battery includes the electrode as described in claim 6.

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