A dynamic self-healing composite micrometer silicon electrode and a preparation method and application thereof

Abstract

The application belongs to the technical field of lithium ion battery negative electrode materials, and particularly relates to a dynamic self-healing composite micron silicon electrode and a preparation method and application thereof. The method comprises the following steps: (1) micron silicon powder, carbon black and a binder are prepared into electrode slurry according to a certain proportion, are coated on a current collector, and are vacuum dried to obtain a micron silicon electrode; (2) the micron silicon electrode is placed in a magnetron sputtering device for magnetron sputtering, and a copper layer is sputtered on the micron silicon electrode; (3) gallium-based liquid metal is added dropwise on the surface of the micron silicon electrode with the sputtered copper layer, and then the micron silicon electrode is placed in hydrochloric acid vapor for reaction wetting of the gallium-based liquid metal on the surface of the electrode, to obtain the dynamic self-healing composite micron silicon electrode. The micron silicon electrode prepared by the application has a dynamic self-healing interface layer, and based on the fluidity and self-healing property of the liquid metal, the cracking of the micron silicon electrode in the cycle process can be realized, and the shedding of the active material is effectively prevented.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lithium ion battery negative electrode materials, and particularly relates to a dynamic self-healing composite micron silicon electrode and a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of increasing the understanding of the background of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art with respect to any country.

[0003] Silicon material, especially micron silicon, is one of the most potential lithium ion battery negative electrode materials and has attracted widespread attention in recent years. Compared with graphite negative electrode and lithium metal negative electrode, the silicon negative electrode has a higher theoretical specific capacity, a lower discharge platform, is not easy to precipitate lithium dendrites, and has better safety performance. However, the micron silicon produces a huge volume expansion during lithium extraction and insertion, which causes the material to pulverize and fall off, resulting in a decrease in the cycle performance of the battery. The volume expansion of the micron silicon makes it difficult for silicon to form a stable solid electrolyte interface film in the electrolyte, which reduces the coulombic efficiency and exacerbates the capacity decay.

[0004] In recent years, various methods such as electrolyte optimization and active material optimization have been used to modify micron silicon. The modified micron silicon is further prepared into a micron silicon electrode, and good results have been achieved. However, the preparation cost of the modified micron silicon is high, which leads to an increase in the electrode preparation cost. Direct electrode design for the micron silicon electrode has not yet received widespread attention. Room-temperature liquid metal, as a new material with self-healing function, is expected to be applied to the repair and healing of the electrode surface interface. However, the wettability of the liquid metal to the micron silicon electrode is poor, and a stable liquid metal interface cannot be formed on the micron silicon electrode. SUMMARY

[0005] In order to solve the problems of the prior art, the present application aims to provide a dynamic self-healing composite micron silicon electrode and a preparation method and application thereof.

[0006] In order to achieve the above-mentioned purpose, the present application is realized by the following technical solutions:

[0007] In the first aspect, the present application provides a preparation method of a dynamic self-healing composite micron silicon electrode, comprising the following steps:

[0008] (1) micron silicon powder, carbon black and a binder are prepared into electrode slurry according to a certain proportion, which is coated on a current collector, and a micron silicon electrode is obtained after vacuum drying;

[0009] (2) the micron silicon electrode is placed in a magnetron sputtering device for magnetron sputtering, and a copper layer is sputtered on the micron silicon electrode;

[0010] (3) dripping gallium-based liquid metal on the surface of the micron silicon electrode layer of the sputtered copper layer, and then placing it in hydrochloric acid vapor to react and wet the gallium-based liquid metal on the surface of the electrode, thereby obtaining the dynamic self-healing composite micron silicon electrode.

[0011] In a second aspect, the application provides a dynamic self-healing composite micron silicon electrode, which is obtained by the preparation method of the first aspect.

[0012] In a third aspect, the application provides the use of the dynamic self-healing composite micron silicon electrode of the second aspect in a lithium ion battery.

[0013] In a fourth aspect, the application provides a lithium ion battery, wherein the negative electrode material of the lithium ion battery is the dynamic self-healing composite micron silicon electrode of the second aspect.

[0014] The application achieves the following beneficial effects through one or more technical solutions described above:

[0015] (1) The silicon powder used in the application is commercialized micron silicon, which does not need to be further modified and has the advantage of low price, and is the most commercially potential silicon negative electrode.

[0016] (2) The micron silicon electrode prepared by the application has a dynamic self-healing interface layer, and based on the fluidity and self-healing property of the liquid metal, the cracking of the micron silicon electrode during the cycle process can be alleviated, and the shedding of the active material is effectively prevented.

[0017] (3) The application introduces a nanoscale copper layer to realize the wetting of the liquid metal to the micron silicon electrode, and has a certain universality to other electrodes. DETAILED DESCRIPTION

[0018] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated herein for purposes of illustration. The embodiments of the application, together with its drawings, disclose the application and its principles of operation, and are not intended to limit the application.

[0019] Figure 1 FIG. 1 is an XRD spectrum of the composite micron silicon electrode in Example 1 of the application;

[0020] Figure 2 FIG. 2 is an SEM image of the composite micron silicon electrode in Example 1 of the application;

[0021] Figure 3 FIG. 3 is a graph of the cycle stability test results of the composite micron silicon electrode in Example 1 of the application. DETAILED DESCRIPTION

[0022] In a first typical embodiment of the application, a preparation method of a dynamic self-healing composite micron silicon electrode comprises the following steps:

[0023] (1) micron silicon powder, carbon black and binder are prepared into electrode slurry according to a certain proportion, which is coated on a current collector, and then vacuum dried to obtain a micron silicon electrode;

[0024] (2) the micron silicon electrode is placed in a magnetron sputtering device for magnetron sputtering, and a copper layer is sputtered on the micron silicon electrode;

[0025] (3) gallium-based liquid metal is added dropwise on the surface of the micron silicon electrode with the sputtered copper layer, and then the micron silicon electrode is placed in hydrochloric acid vapor for reaction wetting of the gallium-based liquid metal on the surface of the electrode, thereby obtaining the dynamic self-healing composite micron silicon electrode.

[0026] In one or more embodiments of the embodiment, the size of the micron silicon powder is 1-10 μm.

[0027] In one or more embodiments of the embodiment, the ratio of the micron silicon powder, carbon black and binder is 3-8:1:1.

[0028] In one or more embodiments of the embodiment, the temperature of the vacuum drying is 75-85℃, and the time is 12-24h.

[0029] In one or more embodiments of the embodiment, the power of the magnetron sputtering is 50W, and the time is 5-20min.

[0030] In one or more embodiments of the embodiment, the gallium-based liquid metal is metallic gallium or gallium alloy.

[0031] In one or more embodiments of the embodiment, during the reaction wetting process, the gallium in the gallium-based liquid metal is alloyed with the copper layer on the surface of the electrode to form a dynamic self-healing interface layer composed of CuGa2 and the remaining liquid metal.

[0032] The second typical embodiment of the present application is a dynamic self-healing composite micron silicon electrode, which is obtained by the preparation method of the first typical embodiment.

[0033] The third typical embodiment of the present application is the application of the dynamic self-healing composite micron silicon electrode of the second typical embodiment in a lithium ion battery.

[0034] The fourth typical embodiment of the present application is a lithium ion battery, characterized in that the negative electrode material of the lithium ion battery is the dynamic self-healing composite micron silicon electrode of the second typical embodiment.

[0035] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific examples and comparative examples.

[0036] Example 1

[0037] (1) Using 1 μm silicon powder, carbon black, binder, electrode slurry is prepared according to the ratio of 6:2:2, coated on the current collector, after vacuum drying at 80°C for 12h, micron silicon electrode is obtained;

[0038] (2) The micron silicon electrode is placed in a magnetron sputtering device to sputter a copper layer at a power of 50W for 20min;

[0039] (3) Liquid metal gallium indium tin is added dropwise on the surface of the micron silicon electrode with sputtered copper layer, and then placed in hydrochloric acid vapor to realize the reactive wetting of the liquid metal on the electrode surface, form a dynamic self-healing interface layer, and obtain a dynamic self-healing composite micron silicon electrode.

[0040] As shown in Figure 1 , the copper layer reacts with gallium in the liquid metal gallium indium tin to form CuGa2, and the remaining liquid metal and CuGa2 form a dynamic self-healing interface layer. The XRD spectrum of the dynamic self-healing interface layer contains Cu, CuGa2 and the characteristic peaks of the liquid metal, proving the formation process. As shown in Figure 2 , the surface of the dynamic self-healing interface layer is flat and uniformly covers the micron silicon electrode.

[0041] As shown in Figure 3 , the dynamic self-healing composite micron silicon electrode has excellent cycle stability.

[0042] Example 2

[0043] (1) Using 5 μm silicon powder, carbon black, binder, electrode slurry is prepared according to the ratio of 6:2:2, coated on the current collector, after vacuum drying at 75°C for 24h, micron silicon electrode is obtained;

[0044] (2) The micron silicon electrode is placed in a magnetron sputtering device to sputter a copper layer at a power of 50W for 10min;

[0045] (3) Liquid metal gallium is added dropwise on the surface of the micron silicon electrode with sputtered copper layer, and then placed in hydrochloric acid vapor to realize the reactive wetting of the liquid metal on the electrode surface, form a dynamic self-healing interface layer, and obtain a dynamic self-healing composite micron silicon electrode.

[0046] Example 3

[0047] (1) Using 10 μm silicon powder, carbon black, binder, electrode slurry is prepared according to the ratio of 8:1:1, coated on the current collector, after vacuum drying at 85°C for 12h, micron silicon electrode is obtained;

[0048] (2) The micron silicon electrode is placed in a magnetron sputtering device to sputter a copper layer at a power of 50W for 5min;

[0049] (3) on the surface of the micron silicon electrode with sputtered copper layer, drop liquid metal gallium indium, then placed in hydrochloric acid vapor, to achieve the reaction wetting of liquid metal on the electrode surface, forming a dynamic self-healing interface layer, to get a dynamic self-healing composite micron silicon electrode.

[0050] Example 4

[0051] (1) using 1 μm silicon powder, carbon black, binder, prepared electrode slurry according to the proportion of 6:2:2, coated on the current collector, after drying at 80℃ for 12h to get micron silicon electrode;

[0052] (2) micron silicon electrode was placed in the magnetron sputtering device at 50W power sputtering copper layer for 15min;

[0053] (3) on the surface of the micron silicon electrode with sputtered copper layer, drop liquid metal gallium indium tin, then placed in hydrochloric acid vapor, to achieve the reaction wetting of liquid metal on the electrode surface, forming a dynamic self-healing interface layer, to get a dynamic self-healing composite micron silicon electrode.

[0054] Example 5

[0055] (1) using 1 μm silicon powder, carbon black, binder, prepared electrode slurry according to the proportion of 6:2:2, coated on the current collector, after drying at 80℃ for 12h to get micron silicon electrode;

[0056] (2) micron silicon electrode was placed in the magnetron sputtering device at 50W power sputtering copper layer for 15min;

[0057] (3) on the surface of the micron silicon electrode with sputtered copper layer, drop liquid metal gallium indium tin zinc, then placed in hydrochloric acid vapor, to achieve the reaction wetting of liquid metal on the electrode surface, forming a dynamic self-healing interface layer, to get a dynamic self-healing composite micron silicon electrode.

[0058] The above only for the preferred embodiments of the present application, and not for limiting the present application, for those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. A method for preparing a dynamic self-healing composite micron-sized silicon electrode, characterized in that, Includes the following steps: (1) Prepare an electrode slurry by mixing micron-sized silicon powder, carbon black and binder in a certain proportion, coat it on the current collector, and dry it under vacuum to obtain a micron-sized silicon electrode; (2) Place the micron-sized silicon electrode in a magnetron sputtering apparatus for magnetron sputtering, and sputter a copper layer onto the micron-sized silicon electrode; (3) Gallium-based liquid metal is dropped onto the surface of a micron-sized silicon electrode with a sputtered copper layer, and then placed in hydrochloric acid vapor to react and wet the surface of the electrode with the gallium-based liquid metal, thereby obtaining the dynamic self-healing composite micron-sized silicon electrode; During the reactive wetting process, gallium in the gallium-based liquid metal alloys with the copper layer on the electrode surface, forming a dynamic self-healing interface layer composed of CuGa2 and the remaining liquid metal.

2. The preparation method according to claim 1, characterized in that, The size of the micron-sized silicon powder is 1-10 μm.

3. The preparation method according to claim 1, characterized in that, The ratio of the micron-sized silicon powder, carbon black, and binder is 3-8:1:

1.

4. The preparation method according to claim 1, characterized in that, The vacuum drying temperature is 75-85 ℃, and the time is 12-24 h.

5. The preparation method according to claim 1, characterized in that, The magnetron sputtering power is 50 W, and the time is 5-20 min.

6. The preparation method according to claim 1, characterized in that, The gallium-based liquid metal is metallic gallium or a gallium alloy.

7. A dynamically self-healing composite micron-sized silicon electrode, characterized in that, Obtained by the preparation method according to any one of claims 1-6.

8. The application of the dynamic self-healing composite micron silicon electrode as described in claim 7 in lithium-ion batteries.

9. A lithium-ion battery, characterized in that, The negative electrode material of the lithium-ion battery is the dynamic self-healing composite micron silicon electrode as described in claim 7.

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