Cobalt disulfide / carbon micro-nano fiber composite material and preparation method thereof

Abstract

The invention discloses a cobalt disulfide / carbon micro-nano fiber composite material, which is a composite material formed by in-situ growth of cobalt disulfide nano-particles with uniform size and uniform distribution on the surface of carbon fiber. The cobalt disulfide / carbon micro-nano fiber composite material prepared by the invention is used as an adhesive-free electrode, side reaction of an electrolyte and an adhesive is avoided, and the cycling stability of a battery is improved.

Description

Technical Field

[0001] The invention relates to the field of electrode materials, and in particular to a cobalt disulfide / carbon micro-nano fiber composite material and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are the most widely used batteries at present. At the same time, lithium-ion batteries are facing safety issues such as limited lithium resource supply and flammability and explosion. Therefore, there are many studies on the new generation of metal-ion batteries to replace lithium-ion batteries. It is very necessary to develop a new type of secondary battery system with safety and low cost.

[0003] Aluminum-ion batteries based on aluminum negative electrodes have a theoretical storage capacity of about four times that of lithium ions due to their three-electron transfer redox reaction. In addition, aluminum is the most abundant metal on earth and its price is much lower than lithium. Moreover, aluminum secondary batteries based on chloroaluminate ionic liquid electrolytes will not spontaneously combust, which greatly improves the safety of the battery. Aluminum-ion batteries are considered to be one of the most promising candidate batteries due to their low cost, high safety, and high theoretical specific capacity. However, the lack of suitable positive electrode materials is one of the main factors restricting the development of aluminum-ion batteries: Al3+ has a high charge density and will produce strong electrostatic interactions with the positive electrode active material, requiring the positive electrode material to have high electron and ion transport capabilities and good structural stability.

[0004] For example, patent No. 202410321419.0, named a modified carbon nanofiber composite material and its preparation method, includes nitrogen-doped carbon nanofibers and cobalt-nickel bimetallic sulfide coated on the surface of nitrogen-doped carbon nanofibers. The modified carbon nanofiber composite material has high electron and ion transmission capabilities and good structural stability. As a positive electrode material for aluminum ion batteries, it can further improve the cycle stability of aluminum ion batteries.

[0005] For example, patent No. 202010040668.4 is entitled a method for preparing a cobalt disulfide / carbon fiber composite material and its application. The cobalt disulfide / carbon fiber composite material is used for the in-situ generation of hydrogen peroxide at the electrocatalytic cathode. Summary of the invention

[0006] Based on the above description, a cobalt disulfide / carbon micro-nano fiber composite material proposed in the present invention is a composite material in which cobalt disulfide nanoparticles of uniform size and uniform distribution are grown in situ on the surface of carbon fiber. The cobalt disulfide / carbon micro-nano fiber composite material is used as an adhesive-free electrode to avoid side reactions between electrolyte and adhesive and improve the battery cycle stability.

[0007] The technical solution adopted is: a cobalt disulfide / carbon micro-nano fiber composite material, which is to in-situ grow cobalt disulfide nanoparticles with uniform size and uniform distribution on the surface of carbon fiber; the mass content of cobalt disulfide in the cobalt disulfide / carbon micro-nano fiber composite material is 50%, and the diameter of the cobalt disulfide nanoparticles is 30nm.

[0008] A method for preparing a cobalt disulfide / carbon micro-nano fiber composite material, comprising the following steps: 1) Cobalt acetate, N,N-dimethylformamide and polyacrylonitrile are mixed to obtain an electrospinning precursor; 2) electrospinning the electrospinning precursor obtained in step 1) to obtain fibers; 3) pretreating the fiber obtained in step 2) in air; 4) reducing the pretreated fibers obtained in step 3) to Co@CNFs at high temperature; 5) mixing the Co@CNFs obtained in step 4) with sublimed sulfur and subjecting them to molten sulfur treatment to form a Co@CNFs / S mixture; 6) calcining the Co@CNFs / S mixture obtained in step 5) to obtain a cobalt disulfide / carbon micro-nano fiber composite material CoS2@CNFs, in which the mass content of cobalt disulfide is 50% and the diameter of cobalt disulfide is 30 nm.

[0009] Furthermore, in step 1), 2 g of cobalt acetate, 30 ml of N,N-dimethylformamide, and 3 g of polyacrylonitrile are mixed to obtain an electrospinning precursor.

[0010] Furthermore, in step 2), the parameters of electrospinning include: voltage of 15 kV, distance between needle and collector of 18 cm, and propulsion speed of 0.06 ml / min.

[0011] Furthermore, in step 3), the pretreatment is to heat the temperature from room temperature to 280° C., the heating rate is 1° C. / min, and the heat treatment time is 2 h.

[0012] Furthermore, in step 4), the high temperature reduction is performed from room temperature to 900°C, the heating rate is 5°C / min, and the heat treatment time is 2h.

[0013] Furthermore, in step 5), the mass ratio of Co@CNFs and sulfur powder is 4:1, and the heat treatment temperature is 155°C.

[0014] The cobalt disulfide / carbon micro-nano fiber prepared by the present invention is used as a self-supporting adhesive-free electrode to avoid side reactions between electrolyte and adhesive, thereby improving the battery cycle stability; the composite material uses carbon fiber as a supporting substrate, which alleviates the destruction of the electrode structure during the cycle; the cobalt disulfide nanoparticles evenly distributed on the fiber surface form a three-dimensional conductive network structure, which increases the reaction interface and shortens the kinetic barrier of ion transmission, and can be charged and discharged under high current conditions, providing feasibility for the development of low-cost, safe aluminum ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the XRD diagram of the CoS2@CNFs three-dimensional network composite material of the present invention; Figure 2 It is a desorption curve diagram of the CoS2@CNFs three-dimensional network composite material of the present invention; Figure 3 This is the electron energy spectrum of the XPS full spectrum element analysis of the CoS2@CNFs three-dimensional network composite material of the present invention; Figure 4 This is a scanning electron microscope image (SEM) of the CoS2@CNFs three-dimensional network composite material of the present invention; Figure 5 The CoS2@CNFs three-dimensional network composite material of the present invention is used as an electrode at 500mA g -1 Battery cycling performance diagram at different current densities. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0017] See also Figures 1 to 5 As shown, a cobalt disulfide / carbon micro-nano fiber composite material is obtained by in-situ growing cobalt disulfide nanoparticles with uniform size and uniform distribution on the surface of carbon fiber; the mass content of cobalt disulfide in the cobalt disulfide / carbon micro-nano fiber composite material is 50%, and the diameter of the cobalt disulfide nanoparticles is 30nm.

[0018] A method for preparing a cobalt disulfide / carbon micro-nano fiber composite material, comprising the following steps: 1) Dissolve 2 g of cobalt acetate and 3 g of polyacrylonitrile in 30 ml of N,N-dimethylformamide and stir until a clear and uniform mixed solution is obtained to obtain an electrospinning precursor; 2) electrospinning the electrospinning precursor obtained in step 1) with the following parameters: voltage of 15 kV, distance between needle and collector of 18 cm, propulsion speed of 0.06 ml / min, to obtain fibers; 3) pre-treating the fiber obtained in step 2) in air; the conditions are: heating from room temperature to 280°C, the heating rate is 1°C / min, and the heat treatment time is 2h; 4) The fibers pretreated in step 3) were reduced to Co@CNFs by high temperature, with the temperature rising from room temperature to 900°C, the heating rate being 5°C / min, and the heat treatment time being 2h; 5) heat treating the Co@CNFs and sulfur powder obtained in step 4) at a mass ratio of 4:1 at 155°C for 12h to form a Co@CNFs / S mixture; 6) The Co@CNFs / S mixture obtained in step 5) is heat treated at 450°C for 4h with a heating rate of 2°C / min to obtain a cobalt disulfide / carbon micro-nano fiber composite material (CoS2@CNFs), i.e., cobalt disulfide nanoparticles are in situ grown on the surface of carbon fiber; the cobalt disulfide / carbon micro-nano fiber composite material CoS2@CNFs is obtained, wherein the mass content of cobalt disulfide is 50%, the diameter of cobalt disulfide is 30nm, and the fiber diameter is 500nm.

[0019] The crystal structure of the prepared cobalt disulfide / carbon micro-nano fiber composite material was determined by X-ray diffractometer (XRD). Figure 1 As shown, the XRD spectrum shows that several characteristic peaks of the cobalt disulfide / carbon micro-nano fiber composite material match the characterization card (JCPDS No. 41-1471), indicating that CoS2 is the main phase. Figure 2 The N2 desorption isotherm of the cobalt disulfide / carbon nanofiber composite prepared in Example 1 is used to analyze the pore structure of the CoS2@CNFs composite. The results show that the BET specific surface area of ​​CoS2@CNFs is 13.42 and 123.63 m 2 g -1 . Figure 3 The electron energy spectrum of the full spectrum elements of the cobalt disulfide / carbon micro-nano fiber composite material prepared in Example 1 is shown in the XPS analysis. Figure 3 It can be seen that the prepared samples are mainly composed of C, Co and S elements. Figure 4 This is a SEM image of the cobalt disulfide / carbon micro-nano fiber composite material prepared in Example 1, which shows that the cobalt disulfide nanoparticles can be evenly distributed on the surface of the carbon fiber, the diameter of the cobalt disulfide nanoparticles is 30nm, and the morphology is uniform. In addition, the cobalt disulfide / carbon micro-nano fiber composite material continuously and uniformly forms a three-dimensional network, and the fiber diameter is 500nm.

Claims

1. A cobalt disulfide / carbon micro-nano fiber composite material, characterized in that: A cobalt disulfide / carbon micro-nano fiber composite material with cobalt disulfide nanoparticles of uniform size and uniform distribution is in situ grown on the surface of carbon fiber; the mass content of cobalt disulfide in the cobalt disulfide / carbon micro-nano fiber composite material is 50%, and the diameter of the cobalt disulfide nanoparticles is 30nm.

2. A method for preparing a cobalt disulfide / carbon micro-nano fiber composite material, characterized in that Here are the steps: 1) Cobalt acetate, N,N-dimethylformamide and polyacrylonitrile are mixed to obtain an electrospinning precursor; 2) electrospinning the electrospinning precursor obtained in step 1) to obtain fibers; 3) pretreating the fiber obtained in step 2) in air; 4) reducing the pretreated fibers obtained in step 3) to Co@CNFs at high temperature; 5) mixing the Co@CNFs obtained in step 4) with sublimed sulfur and subjecting them to molten sulfur treatment to form a Co@CNFs / S mixture; 6) calcining the Co@CNFs / S mixture obtained in step 5) to obtain a cobalt disulfide / carbon micro-nano fiber composite material CoS2@CNFs, in which the mass content of cobalt disulfide is 50% and the diameter of cobalt disulfide is 30 nm.

3. The method for preparing a cobalt disulfide / carbon micro-nano fiber composite material according to claim 2, characterized in that In the step 1), 2 g of cobalt acetate, 30 ml of N,N-dimethylformamide and 3 g of polyacrylonitrile are mixed to obtain an electrospinning precursor.

4. The method for preparing a cobalt disulfide / carbon micro-nano fiber composite material according to claim 2, characterized in that In the step 2), the electrospinning parameters include: voltage of 15 kV, distance between the needle and the collector of 18 cm, and propulsion speed of 0.06 ml / min.

5. The method for preparing a cobalt disulfide / carbon micro-nano fiber composite material according to claim 2, characterized in that In the step 3), the pretreatment is to heat the temperature from room temperature to 280°C, the heating rate is 1°C / min, and the heat treatment time is 2h.

6. The method for preparing a cobalt disulfide / carbon micro-nano fiber composite material according to claim 2, characterized in that In the step 4), the high temperature reduction is carried out from room temperature to 900° C., the heating rate is 5° C. / min, and the heat treatment time is 2 h.

7. The method for preparing a cobalt disulfide / carbon micro-nano fiber composite material according to claim 2, characterized in that In the step 5) molten sulfur treatment, the mass ratio of Co@CNFs and sulfur powder is 4:1, and the heat treatment temperature is 155°C.

Images