A method for preparing a three-dimensional porous cobalt-indium alloy electrode

Abstract

The invention discloses a preparation method of a three-dimensional porous cobalt-indium alloy electrode, comprising the following steps: the first step, measuring a certain volume ratio of acid and distilled water and placing them in a beaker to form a dilute acid solution; foamed cobalt (Co) is placed in a dilute acid solution as a magnetic matrix to remove impurities such as surface oxides; the foamed cobalt (Co) is washed with anhydrous ethanol and distilled water, and is placed in a vacuum drying oven after washing 3 to 5 times; the second step, indium (In) is rolled on a roller machine for 2 to 5 times to form an In flake; the third step, the In flake obtained by step S2 is placed on the foamed cobalt (Co) obtained by step S1, and rolled in a roller machine for 2 to 5 times to obtain a Co-In sheet; the fourth step, the Co-In sheet obtained by step S3 is heated in high-purity argon for several hours, and a Co-In composite material is obtained after cooling to room temperature. A preparation method of a three-dimensional porous cobalt-indium alloy electrode provided by the present invention effectively avoids uneven lithium nucleation, deposition and the formation of dendritic lithium.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and in particular relates to a method for preparing a three-dimensional porous cobalt-indium alloy electrode. Background Art

[0002] With the advent of the intelligent era, the rapid rise of emerging industries such as AI robots, new energy vehicles, and high-end mobile communication tools has prompted the need to further improve the energy storage efficiency of commercial lithium-ion batteries. However, due to its insertion / extraction mechanism, the energy density of lithium-ion batteries is limited, making it difficult to meet the needs of new fields. Lithium metal electrodes, due to their ultra-high theoretical specific capacity and negative redox potential, are attracting much attention to meet the booming demand for high-energy-density electrodes. However, to date, lithium metal batteries still have limitations that hinder their commercialization, such as low Coulombic efficiency of the metallic lithium anode, short life cycle, large volume expansion, uncontrolled lithium dendrite growth, and unstoppable interfacial reactions. Among them, the most pressing issue is how to alleviate or solve the problems of uncontrolled lithium dendrite growth and anode volume expansion.

[0003] To address the above problems, three main strategies have been proposed to reduce lithium dendrite growth and improve electrode stability: (1) forming a stable SEI film to protect Li from electrolyte corrosion; (2) using electrolyte additives to inhibit lithium dendrite growth; and (3) designing a current collector with a 3D structure to inhibit dendrite growth and volume expansion. Artificial SEI films are prone to cracking at high current densities due to their thinness and brittleness. At the same time, electrolyte additives will be consumed during long-term cycling. Using 3D structural materials as current collectors for Li metal anodes can effectively increase the specific surface area, reduce the surface current density, and uniformly deposit metallic lithium. Such as 3D porous graphene, 3D metal materials, and 3D carbon skeletons. Foam metal is a preferred current collector material with high availability, low cost, and superconductivity. The initial foam framework can provide abundant micron-scale pores that can accommodate a large amount of Li metal and reduce volume expansion. Such as foam copper, foam nickel, etc. Tang et al. in situ grew nickel-cobalt alloy and lithiophilic zinc oxide on a 3D copper-based current collector by electroplating and hydrothermal methods to achieve deep and uniform lithium deposition. Kong et al. used atomic layer deposition (ALD) to prepare a super-assembled surface-modified lithiophilic ZnO film on copper foam and used multilayer copper nanofibers (MCN) as the lithium metal anode substrate. However, when adding the lithiophilic layer by electrodeposition or atomic layer deposition, the steps are cumbersome and the cost is high. At the same time, the lithiophilic three-dimensional current collector used in lithium metal batteries will still cause lithium dendrite growth due to irregular deposition during the transmission process after long-term circulation, thereby piercing the separator and causing the battery to fail. Therefore, there is an urgent need for a three-dimensional skeleton negative electrode that can regulate the lithium ion transmission path, reduce the metal lithium nucleation barrier and inhibit the volume expansion of the negative electrode. Summary of the Invention

[0004] The purpose of the present invention is to solve the above problems and provide a method for effectively avoiding Li + A method for preparing a three-dimensional porous cobalt-indium alloy electrode that reduces uneven deposition and formation of mossy / dendrite lithium while improving the utilization efficiency of lithium ions.

[0005] To solve the above technical problems, the technical solution of the present invention is: a method for preparing a three-dimensional porous cobalt-indium alloy electrode, comprising the following steps:

[0006] S1. A certain volume ratio of acid and distilled water is measured and placed in a beaker to form a dilute acid solution; foamed cobalt (Co) is placed in the dilute acid solution as a magnetic matrix to remove surface oxides and other impurities; the foamed cobalt (Co) is washed with anhydrous ethanol and distilled water for 3 to 5 times and then dried in a vacuum drying oven;

[0007] S2, rolling indium (In) on a roller machine 2 to 5 times to form an In sheet;

[0008] S3, placing the In flakes obtained in step S2 on the cobalt (Co) foam obtained in step S1, and rolling them 2 to 5 times in a double-roller mill to obtain a Co-In sheet;

[0009] S4. Heating the Co-In sheet obtained in step S3 in high-purity argon for several hours and cooling it to room temperature to obtain a Co-In composite material.

[0010] Furthermore, the acid in step S1 is one of hydrochloric acid, sulfuric acid and nitric acid, and its molar concentration is 2 mol / L to 6 mol / L.

[0011] Furthermore, in step S1, the volume ratio of acid to distilled water is 1:1 to 1:10.

[0012] Furthermore, the magnetic matrix in step S1 is foamed cobalt, foamed nickel or one of other magnetic matrices.

[0013] Furthermore, the temperature of the vacuum drying oven in step S1 is 40° C. to 80° C., and the drying time is 6 h to 12 h.

[0014] Furthermore, In in step S2 may be replaced by zinc (Zn), sodium (Na), tin (Sn) or alloys thereof.

[0015] Furthermore, the heating time of the Co-In sheet in step S4 is 1 hour to 10 hours.

[0016] Furthermore, in step S4, the heating temperature of the Co-In sheet is 100° C. to 1200° C., and the high-purity argon gas can be replaced by nitrogen gas.

[0017] The beneficial effects of the present invention are: the preparation method of a three-dimensional porous cobalt-indium alloy electrode provided by the present invention is to compound metal In with foamed Co by a rolling method, and to form lithium-philic CoIn3 particles on the surface of the foamed Co by simple heat treatment, thereby getting rid of complex processes such as electrodeposition and hydrothermal method. At the same time, the prepared Co-In alloy matrix not only has the function of reducing the nucleation overpotential of metallic lithium and the CoIn3 particles with high alloying reversibility on the surface, but also has the function of a magnetic skeleton that can regulate the metallic lithium transmission path and guide the deep deposition of metallic lithium. The interaction between lithium ions and the substrate is of great significance for forming an ideal deposition pattern. It has been proven that the three-dimensional foamed cobalt framework has intrinsic magnetism. During the lithium ion transmission process, it will be affected by the magnetohydrodynamic effect (MHD) generated by the magnetic field, thereby guiding the lithium ions to be uniformly deposited deep into the three-dimensional skeleton. The CoIn3 alloy particles on the surface of the three-dimensional skeleton meet the "lattice matching" strategy. During the lithium ion deposition process, Li + It forms a coherent lattice plane with CoIn3. High lattice matching helps to achieve a coherent interface, where Li atoms can easily combine with CoIn3 and grow uniformly along the substrate layer. After electrochemical testing of half-cells, symmetric cells and full cells assembled with Co-In alloy matrix and lithium, its cycling stability at high current density / high capacity is better than that of 3D lithium-philic foam framework negative electrode materials prepared by Tang, Kong et al. by electrodeposition. Symmetric cells assembled with Co-In alloy and lithium negative electrode have a high cycling stability at 0.5 mA cm -2 / 1mAh cm -2 The cycling stability reached 1600h, and the hysteresis voltage variation range was less than 10mV. A full battery assembled with a Co-In alloy-lithium negative electrode and a commercial lithium iron phosphate electrode exhibited excellent stability for 800 cycles at 1C, while maintaining a coulombic efficiency of approximately 99.8%, which is of great significance for the application of this negative electrode in commercial lithium secondary batteries. Furthermore, compared to complex electrodeposition methods, this method offers advantages such as one-step formation, simple process, wide range of preparation conditions, no need to control the reaction atmosphere during the reaction, simple preparation equipment, reduced costs, and easier industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a comparison of SEM images of the Co-In composite material prepared in Example 1 of the method for preparing a three-dimensional porous cobalt-indium alloy electrode of the present invention at 200 μm and 20 μm;

[0019] Figure 2 is the XRD pattern of the Co-In composite material prepared in Example 1 of the present invention;

[0020] Figure 3 is a CV curve diagram of the Co-In composite material prepared in Example 1 of the present invention;

[0021] Figure 4 1 is a half-cell performance diagram of the Co-In composite material prepared in Example 1 of the present invention;

[0022] Figure 5 1 is a symmetrical battery performance diagram of the Co-In composite material prepared in Example 1 of the present invention;

[0023] Figure 6 This is a full-battery performance diagram of the Co-In composite material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0025] Example 1

[0026] like Figures 1 to 6 As shown, the present invention provides a method for preparing a three-dimensional porous cobalt-indium alloy electrode, comprising the following steps:

[0027] S1. A certain volume ratio of acid and distilled water is measured and placed in a beaker to form a dilute acid solution; foamed cobalt (Co) is placed in the dilute acid solution as a magnetic substrate to remove surface oxides and other impurities; the foamed cobalt (Co) is washed with anhydrous ethanol and distilled water for 3 to 5 times and then dried in a vacuum drying oven.

[0028] In this step, the acid is one of hydrochloric acid, sulfuric acid, and nitric acid, with a molar concentration of 2 mol / L to 6 mol / L. The volume ratio of the acid to distilled water is 1:1 to 1:10. The magnetic substrate is cobalt foam, nickel foam, or another magnetic substrate. The vacuum drying oven temperature is 40°C to 80°C, and the drying time is 6 to 12 hours.

[0029] S2. Roll indium (In) on a double-roller machine 2 to 5 times to form an In sheet.

[0030] In in this step may be replaced with zinc (Zn), sodium (Na), tin (Sn), or alloys thereof.

[0031] S3. Place the In flakes obtained in step S2 on the cobalt (Co) foam obtained in step S1, and roll them 2 to 5 times in a double-roller mill to obtain a Co-In flake.

[0032] S4. Heating the Co-In sheet obtained in step S3 in high-purity argon for several hours and cooling it to room temperature to obtain a Co-In composite material.

[0033] In this step, the Co-In sheet is heated for 1 to 10 hours. The heating temperature for the Co-In sheet is 100°C to 1200°C, and high-purity argon can be replaced with nitrogen. The present invention uses a simple heat treatment to composite the metal In sheet onto the highly porous Co foam, thereby forming a Co-In alloy electrode material. This material, used as the anode of a lithium metal battery, promotes uniform lithium ion deposition on the anode surface, effectively avoiding uneven lithium nucleation and deposition and the formation of dendritic lithium.

[0034] Figure 1 The following are electron microscope scanning images and test images of the Co-In alloy composite material prepared in Example 1. After heat treatment on a temperature-controlled heating platform, the CoIn3 alloy grows uniformly on the surface. Figure 2 The XRD peaks of the synthesized CoIn3 alloy are shown, and the characteristic peak intensity is high, indicating that the synthesized CoIn3 alloy and Co-In alloy composite material have a crystal structure. Figure 3 The figure shows the CV curve test results of a half-cell assembled with the negative electrode prepared in Example 1 and a lithium metal sheet as the positive electrode, with a scan rate of 0.05mV / s. It can be seen that two characteristic peaks appear in the lithiation stage and the delithiation stage, respectively, indicating that the negative electrode (Li@Co-In) formed by melting lithium on the prepared three-dimensional porous Co-In alloy has an excellent reversible alloying reaction. Figure 4 As shown, the negative electrode of Example 1 and the lithium metal sheet as the positive electrode were assembled into a half-cell. -2 , with a specific capacity of 1 mAh cm -2 The efficiency of electrode lithium insertion / delithiation was tested. During the test, the coulombic efficiency of the first cycle was 85.3%, which was due to the pre-lithiation process in the first cycle. In the 350 cycles, the coulombic efficiency of each cycle of the half-cell assembled by the Co-In alloy electrode and metallic lithium was close to 100%, indicating that the efficiency of electrode lithium insertion / delithiation was almost 100%, proving the effect of highly reversible alloying of the Co-In alloy composite electrode. Compared with the same period, the three-dimensional porous nickel-zinc alloy electrode and the iron-nickel-tin alloy electrode should have more stable coulombic efficiency and cycle stability when used as half-cell negative electrode materials. Figure 5 As shown in the figure, the negative electrode and the positive electrode were prepared after melting the lithium in Example 1, and the symmetrical battery was assembled at the same time. -2 , with a specific capacity of 1 mAh cm -2 The stability of the electrode was tested. The battery showed excellent cycling stability over 1600h with an overpotential of approximately 10mV; the hysteresis voltage rise was stable without any irregular fluctuations; for the carbonate electrolyte system, LiFePO4 (LFP) was used as the positive electrode material to demonstrate the advantages of the Li@Co-In negative electrode; Figure 6As shown, at a current density of 1C, 103.2 mAh g was provided after 800 cycles. -1 high specific capacity and high Coulombic efficiency >99%.

[0035] Example 2

[0036] The differences between this embodiment and the first embodiment are that the volume ratio of the acid to distilled water in step S1 is changed to 1:4; the standing time in the solution in step S1 is changed to 2 hours; and the heating temperature in step S4 is changed to 400°C and the heating time is changed to 1 hour. The rest of the process is the same as in the first embodiment.

[0037] Example 3

[0038] The differences between this embodiment and the first embodiment are that the volume ratio of acid to distilled water in step S1 is changed to 1:5; the standing time in the solution in step S1 is changed to 3 hours; and the heating temperature in step S4 is changed to 450°C and the heating time is changed to 2 hours. The rest of the steps are the same as those in the first embodiment.

[0039] Example 4

[0040] The differences between this embodiment and the first embodiment are that the volume ratio of the acid to distilled water in step 1 is changed to 1:6, the standing time in the solution in step 1 is changed to 4 hours, and the heating temperature and heating time in step 4 are changed to 450°C and 4 hours respectively. The rest of the steps are the same as those in the first embodiment.

[0041] Example 5

[0042] The difference between this embodiment and the first embodiment is that the magnetic substrate in step 1 is replaced with nickel (Ni) foam and the indium in step S2 is replaced with zinc (Zn). The rest of the process is the same as the first embodiment.

[0043] Example 6

[0044] The differences between this embodiment and the fifth embodiment are that the volume ratio of the acid to distilled water in step S1 is changed to 1:3; the standing time in the solution in step S1 is changed to 2 hours; and the heating temperature in step S4 is changed to 550°C and the heating time is changed to 3 hours. The rest of the steps are the same as those in the fifth embodiment.

[0045] Example 7

[0046] The differences between this embodiment and the fifth embodiment are that the volume ratio of the acid to distilled water in step S1 is changed to 1:4; the standing time in the solution in step S1 is changed to 3 hours; and the heating temperature in step S4 is changed to 650°C and the heating time is changed to 2 hours. The rest of the steps are the same as those in the fifth embodiment.

[0047] Example 8

[0048] The difference between this embodiment and the first embodiment is that the magnetic substrate in step S1 is changed to foamed iron nickel (FeNi); the indium in step S2 is changed to tin (Sn); the rest is the same as the first embodiment.

[0049] Example 9

[0050] The difference between this embodiment and the eighth embodiment is that the volume ratio of the acid to distilled water in step S1 is changed to 1:2, the standing time in the solution is changed to 1 hour, and the heating temperature in step S4 is changed to 250°C and the heating time is changed to 4 hours. The rest of the steps are the same as those in the eighth embodiment.

[0051] Example 10

[0052] The difference between this embodiment and the eighth embodiment is that the volume ratio of the acid to distilled water in step S1 is changed to 1:3, the standing time in the solution is changed to 2 hours, and the heating temperature in step S4 is changed to 350°C and the heating time is changed to 3 hours. The rest of the steps are the same as those in the eighth embodiment.

[0053] Example 11

[0054] The difference between this embodiment and the eighth embodiment is that the volume ratio of the acid to distilled water in step S1 is changed to 1:3, the standing time in the solution is changed to 3 hours, and the heating temperature in step S4 is changed to 450°C and the heating time is changed to 2 hours. The rest of the steps are the same as those in the eighth embodiment.

[0055] The following table shows the results of using the alloy electrodes obtained in Examples 1 to 11:

[0056]

[0057]

[0058] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. A method for preparing a three-dimensional porous cobalt-indium alloy electrode, characterized in that: The following steps are involved: S1. A certain volume ratio of acid and distilled water is measured and placed in a beaker to form a dilute acid solution; the cobalt foam is placed in the dilute acid solution as a magnetic substrate to remove surface oxide impurities; the cobalt foam is washed with anhydrous ethanol and distilled water for 3 to 5 times and then dried in a vacuum drying oven; S2, rolling indium on a roller machine 2 to 5 times to form an In sheet; S3, placing the In flakes obtained in step S2 on the cobalt foam obtained in step S1, and rolling them 2 to 5 times in a double-roller mill to obtain a Co-In sheet; S4. The Co-In sheet obtained in step S3 is heated in high-purity argon for several hours and cooled to room temperature to obtain a Co-In composite material. The heating temperature of the Co-In sheet is 100° C. to 1200° C., and lithium-philic CoIn3 particles are formed on the surface of the foamed Co.

2. The method for preparing a three-dimensional porous cobalt-indium alloy electrode according to claim 1, characterized in that: The acid in step S1 is one of hydrochloric acid, sulfuric acid and nitric acid, and its molar concentration is 2 mol / L to 6 mol / L.

3. The method for preparing a three-dimensional porous cobalt-indium alloy electrode according to claim 1, characterized in that: In step S1, the volume ratio of acid to distilled water is 1:1 to 1:

10.

4. The method for preparing a three-dimensional porous cobalt-indium alloy electrode according to claim 1, wherein: The temperature of the vacuum drying oven in step S1 is 40° C. to 80° C., and the drying time is 6 h to 12 h.

5. The method for preparing a three-dimensional porous cobalt-indium alloy electrode according to claim 1, characterized in that: The heating time of the Co-In sheet in step S4 is 1 hour to 10 hours.

6. The method for preparing a three-dimensional porous cobalt-indium alloy electrode according to claim 1, characterized in that: The high purity argon gas was replaced with nitrogen gas.

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