Preparation method of reduced graphene oxide / bismuth selenide composite material and application thereof in aqueous zinc ion battery

Abstract

The application belongs to the technical field of aqueous zinc ion batteries, and discloses a preparation method of a graphene oxide / bismuth selenide composite material and application of the graphene oxide / bismuth selenide composite material in an aqueous zinc ion battery. The composite material is synthesized through a simple secondary hydrothermal method. First, bismuth selenide is synthesized by taking bismuth chloride and selenium powder as raw materials, and then graphene oxide is added to perform secondary hydrothermal treatment, so that bismuth selenide uniformly coated with reduced graphene oxide (Bi2Se3@rGO) is obtained. The synthesis process is simple, environment-friendly and low in production cost. Compared with the prior art, the conductivity of bismuth selenide is increased by graphene coating, and the capacity attenuation caused by volume change is relieved. The prepared graphene oxide / bismuth selenide composite material is used as a positive electrode to assemble a battery, and the battery exhibits excellent specific capacity and cycle stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aqueous zinc-ion batteries, and relates to a preparation method of a high-performance positive electrode material of an aqueous zinc-ion battery, in particular to a preparation method of a reduced graphene oxide / bismuth selenide composite material. BACKGROUND

[0002] The large-scale use of fossil energy has caused energy crisis and environmental pollution, and the demand for renewable energy is increasingly urgent, so it is imperative to develop new energy. However, new energy such as wind energy and solar energy has discontinuous power generation time, dispersed geographical location and instability due to climate conditions, which is in conflict with the time concentration and continuity of the use of electric energy. In order to make full use of new energy and solve the problems of energy storage, peak shaving and grid connection, it is of great significance to develop new electrochemical energy storage devices. At present, lithium-ion batteries have become the most widely used energy storage devices in commercial applications due to their high energy density and long cycle life. However, the shortage and high cost of lithium resources limit the development of lithium-ion batteries. In addition, the use of flammable and toxic organic electrolytes in lithium-ion batteries also poses a safety hazard. In recent years, aqueous rechargeable batteries have attracted widespread attention due to their high energy density, low cost, safety and environmental protection, and are expected to become an important supplement to lithium-ion batteries and be applied to new portable energy storage devices. Among the many candidate products of aqueous rechargeable batteries, zinc-ion batteries have become one of the best choices for large-scale energy storage systems.

[0003] So far, only limited materials have been developed as viable zinc-ion positive electrode materials, including manganese-based oxides, vanadium-based oxides and prussian blue analogues. Manganese-based oxides have a high specific capacity, but the positive electrode will cause rapid capacity decay due to dissolution during the cycle process; vanadium-based oxides are limited by low discharge platform and energy density, and prussian blue analogues have a low specific capacity. Therefore, it is crucial to develop a positive electrode with high specific capacity and long cycle stability.

[0004] Bi2Se3 is a semiconductor material, which has good electrical conductivity compared with oxides and sulfides, has a graphite-like layered structure, and has a layer spacing of 0.315 nm, showing great application prospect in energy storage. However, the capacity of Bi2Se3 reported in the present papers is low and the cycle stability is poor, so it is very important to adjust the thickness of flaky Bi2Se3 to improve the specific capacity of the material by adding ethylenediamine, and to improve the cycle stability of Bi2Se3 as a zinc-ion battery positive electrode material by compounding with carbon materials. So far, there is no related report on the preparation of a reduced graphene oxide / bismuth selenide composite material and its use as a zinc-ion battery positive electrode material. SUMMARY

[0005] The application aims to provide a preparation method of reduced graphene oxide / bismuth selenide composite material, which is simple, environment-friendly, has high capacity and long cycle life when used as a zinc ion battery positive electrode material.

[0006] The technical scheme of the application is as follows:

[0007] (1) Dissolve bismuth salt and polyvinylpyrrolidone in an organic solvent and stir to dissolve;

[0008] (2) Add ethylenediamine to the solution obtained in step (1) and stir for 5-10 min;

[0009] (3) Add selenium powder to the solution obtained in step (2) and stir for 8-12 h to mix;

[0010] (4) Put the reaction solution prepared in step (3) into a reaction kettle, react at 150-220 DEG C for 12-36 h, and then cool to room temperature;

[0011] (5) Add graphene oxide to the solution obtained in step (4) and stir for 4-24 h;

[0012] (6) Put the reaction solution prepared in step (5) into a reaction kettle, react at 150-220 DEG C for 2-10 h, and then cool to room temperature, centrifugally collect the obtained black precipitate, repeatedly wash with deionized water and ethanol, and dry to obtain the reduced graphene oxide / bismuth selenide composite material.

[0013] In step (1), the bismuth salt is one of bismuth nitrate pentahydrate or bismuth chloride.

[0014] In step (1), the organic solvent is a mixed solvent of N,N dimethylformamide and ethylene glycol, wherein the volume ratio of N,N dimethylformamide to ethylene glycol is 1:1-3:1.

[0015] In step (1), the mass ratio of bismuth salt to polyvinylpyrrolidone is 3:1-5:1.

[0016] In step (2), the volume of ethylenediamine is 5%-35% of the liquid obtained in step (2).

[0017] In step (3), the molar ratio of selenium powder to bismuth salt is 3:2-3:1.

[0018] In step (5), the mass ratio of graphene oxide to bismuth salt is 1:10-1:2.

[0019] In step (6), the rotation speed of centrifugation is 5000-10000 rpm; the drying temperature is 40-90 DEG C, and the drying time is 6-24 h.

[0020] The application discloses a use of a reduced graphene oxide / bismuth selenide composite prepared by the application as a positive electrode material of a water-based zinc ion battery.

[0021] The application has the following advantages:

[0022] (1) The reduced graphene oxide / bismuth selenide composite is prepared by simple secondary hydrothermal synthesis, and the conductive property of bismuth selenide is increased by coating the reduced graphene oxide, so that the transmission of zinc ions in the positive electrode is promoted.

[0023] (2) The structural collapse caused by volume change during charging and discharging of the material is effectively alleviated, and the possibility of deactivation of the electrode material is ultimately reduced.

[0024] (3) The addition of ethylenediamine changes the thickness of the sheet-shaped bismuth selenide, so that more active sites are exposed to the material, and the capacity of the material is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is an XRD graph of the reduced graphene oxide / bismuth selenide composite obtained according to Example 1 of the application;

[0026] Figure 2 It is an SEM graph of the reduced graphene oxide / bismuth selenide composite obtained according to Example 1 of the application;

[0027] Figure 3 It is an AFM graph of Bi2Se3-1 obtained according to Comparative Example 1;

[0028] Figure 4 It is an AFM graph of Bi2Se3-2 obtained according to Comparative Example 2;

[0029] Figure 5 It is a CV curve of a zinc ion battery assembled by using the reduced graphene oxide / bismuth selenide composite obtained according to Example 1 of the application as a positive electrode;

[0030] Figure 6 It is a cycle curve of a zinc ion battery assembled by using the reduced graphene oxide / bismuth selenide composite obtained according to Example 1 of the application as a positive electrode at a current density of 5 Ag -1 DETAILED DESCRIPTION

[0031] The application will be further described below by means of specific implementation examples, but the scope of the application is not limited thereto. Modifications and replacements of the method, steps or conditions without departing from the essence of the application all belong to the scope of the application.

[0032] Comparative Example 1

[0033] ​(1) A mixed solution of 20 ml of N, N-dimethylformamide and ethylene glycol in a volume ratio of 1:1 was prepared, and 0.315 g of bismuth chloride and 0.1 g of polyvinylpyrrolidone were dissolved in the solution;

[0034] (2) 0.158 g of selenium powder was added to the solution prepared in (2) and stirred for 5 h;

[0035] (3) The above solution was transferred to an autoclave and reacted at 180°C for 24 h, and after cooling to room temperature;

[0036] (4) The black precipitate was collected by centrifugation and washed several times with anhydrous ethanol and deionized water, and dried at 50°C for 12 h.

[0037] (5) The dried precipitate was collected to obtain Bi2Se3-1.

[0038] Comparative Example 2

[0039] (1) A mixed solution of 20 ml of N, N-dimethylformamide and ethylene glycol in a volume ratio of 1:1 was prepared, and 0.315 g of bismuth chloride and 0.1 g of polyvinylpyrrolidone were dissolved in the solution;

[0040] (2) 5 ml of ethylenediamine was added to the above solution and stirred for 10 min;

[0041] (3) 0.158 g of selenium powder was added to the solution prepared in (2) and stirred for 5 h;

[0042] (4) The above solution was transferred to an autoclave and reacted at 180°C for 24 h, and after cooling to room temperature;

[0043] (5) The black precipitate was collected by centrifugation and washed several times with anhydrous ethanol and deionized water, and dried at 50°C for 12 h.

[0044] (6) The dried precipitate was collected to obtain Bi2Se3-2.

[0045] Figure 3 and 4 The AFM images of Bi2Se3-1 and Bi2Se3-2, respectively, can be seen that the thickness of Bi2Se3-1 without ethylenediamine is about 250 nm, and the thickness of Bi2Se3-2 with 5 mL of ethylenediamine is about 30 nm, the material is obviously thinned, and the flake structure can expose more active sites to improve the specific capacity of the battery.

[0046] Example 1

[0047] (1) A mixed solution of 20 ml of N, N-dimethylformamide and ethylene glycol in a volume ratio of 1:1 was prepared, and 0.315 g of bismuth chloride and 0.1 g of polyvinylpyrrolidone were dissolved in the solution;

[0048] (2) Add 5 ml of ethylenediamine to the above solution and stir for 10 min;

[0049] (3) Add 0.158g of selenium powder to the solution prepared in (2) and stir for 5 hours;

[0050] (4) Transfer the above solution to a hydrothermal reactor and react at 180°C for 24 hours. After cooling to room temperature;

[0051] (5) Add 60 mg of graphene oxide to the solution obtained above and stir for 20 h;

[0052] (6) Transfer the above solution to a hydrothermal reactor and react at 180°C for 8 hours. After cooling to room temperature;

[0053] (7) Centrifuge to collect the black precipitate and wash it several times with anhydrous ethanol and deionized water, and dry it at 50°C for 12 hours.

[0054] (8) Collect the dried precipitate to obtain the reduced graphene oxide / bismuth selenide composite material.

[0055] The XRD pattern of the reduced graphene oxide / bismuth selenide composite material obtained in this embodiment is shown below. Figure 1 As shown, it corresponds one-to-one with the standard card PDF#33-0214.

[0056] Figure 2 The image shows a SEM image of reduced graphene oxide / bismuth selenide, with bismuth selenide coated by strips of reduced graphene oxide.

[0057] The obtained reduced graphene oxide / bismuth selenide composite material, conductive carbon black, and polyvinylidene fluoride binder were dispersed in an N-methylpyrrolidone solution at a mass ratio of 70:20:10. After being mixed and ground evenly, the mixture was coated onto titanium foil. The electrode sheet was dried in a vacuum drying oven at 80℃ for 12 hours, and then punched to serve as the positive electrode. A zinc sheet was used as the negative electrode, glass fiber as the separator, and 2 mol L... -1 ZnSO4 was used as the electrolyte and assembled with the positive electrode into a button cell (CR2032 model) for charge-discharge testing. Cyclic voltammetry was performed using a Gmary electrochemical workstation.

[0058] Figure 5 The CV curves for reducing graphene oxide / bismuth selenide show good overlap, indicating that the material has good reversibility.

[0059] Figure 6 It is assembled into a battery at 5A·g -1The cycle curves of the current density, the capacity of Bi2Se3-1 without ethylenediamine is far lower than that of Bi2Se3-2 with 5 mL ethylenediamine, which shows that the capacity of the material can be effectively improved by adding ethylenediamine. However, the cycle stability of Bi2Se3-2 is poor, therefore, we coated the material with reduced graphene oxide on the basis of adding ethylenediamine. The specific capacity of the reduced graphene oxide / bismuth selenide composite material is 141.68 mAh·g -1 after 4000 cycles, which is far higher than that of Bi2Se3-2 without graphene. This shows that the reduced graphene oxide can effectively improve the cycle stability of bismuth selenide.

[0060] Example 2, prepared according to the method of Example 1, the mass of graphene oxide is 30 mg.

[0061] Example 3, prepared according to the method of Example 1, the mass of graphene oxide is 90 mg.

[0062] Example 4, prepared according to the method of Example 1, 0.315 g of bismuth chloride is replaced by 0.485 g of bismuth nitrate pentahydrate.

[0063] Example 5, prepared according to the method of Example 1, the hydrothermal temperature is changed to 200℃.

Claims

1. A method for preparing a reduced graphene oxide / bismuth selenide composite material, characterized in that, The steps include the following: (1) Dissolve bismuth salt and polyvinylpyrrolidone in an organic solvent and stir until dissolved; (2) Add ethylenediamine to the solution obtained in step (1) and stir for 5-10 min; (3) Add selenium powder to the solution obtained in step (2) and stir for 8-12 hours to mix it. (4) The reaction solution obtained in step (3) is loaded into a reaction vessel and reacted at 150-220℃ for 12-36h, and then cooled to room temperature; (5) Add graphene oxide to the solution obtained in step (4) and stir for 4-24 hours; (6) The reaction solution obtained in step (5) is loaded into a reaction vessel and reacted at 150-220℃ for 2-10h. Then it is cooled to room temperature, and the black precipitate is collected by centrifugation. After repeated washing with deionized water and ethanol, it is dried to obtain the reduced graphene oxide / bismuth selenide composite material.

2. The method for preparing the reduced graphene oxide / bismuth selenide composite material as described in claim 1, characterized in that, In step (1), the bismuth salt is either bismuth nitrate pentahydrate or bismuth chloride.

3. The method for preparing the reduced graphene oxide / bismuth selenide composite material as described in claim 1, characterized in that, In step (1), the organic solvent is a mixture of N,N-dimethylformamide and ethylene glycol, wherein the volume ratio of N,N-dimethylformamide and ethylene glycol is 1:1 to 3:

1.

4. The method for preparing the reduced graphene oxide / bismuth selenide composite material as described in claim 1, characterized in that, In step (1), the mass ratio of bismuth salt to polyvinylpyrrolidone is 3:1 to 5:

1.

5. The method for preparing the reduced graphene oxide / bismuth selenide composite material as described in claim 1, characterized in that, In step (2), the volume of ethylenediamine is 5%-35% of the liquid obtained in step (2).

6. The method for preparing the reduced graphene oxide / bismuth selenide composite material as described in claim 1, characterized in that, In step (3), the molar ratio of selenium powder to bismuth salt is 3:2-3:

1.

7. The method for preparing the reduced graphene oxide / bismuth selenide composite material as described in claim 1, characterized in that, In step (5), the mass ratio of graphene oxide to bismuth salt is 1:10-1:

2.

8. The method for preparing the reduced graphene oxide / bismuth selenide composite material as described in claim 1, characterized in that, In step (6), the centrifugation speed is 5000-10000 rpm; the drying temperature is 40-90℃; and the drying time is 6-24h.

9. The use of the reduced graphene oxide / bismuth selenide composite material prepared by the preparation method according to any one of claims 1 to 8 as a positive electrode material for an aqueous zinc-ion battery.

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