Preparation method of MnS / carbon composite material for sodium battery

Abstract

The invention discloses a preparation method of a MnS / carbon composite material for a sodium battery and belongs to the field of sodium ion batteries. The MnS / carbon composite material is prepared by adopting a rapid sol-gel method and annealing treatment, taking ethanol as a solvent, polyvinylpyrrolidone as a carbon source, dicyandiamide as a pore-forming agent, manganese nitrate tetrahydrate as a manganese source and thiourea as a sulfur source, rapidly stirring at room temperature, drying, directly annealing at 580 DEG C, and sintering for 1 hour. The material is composed of a carbon plate and nanoparticles growing on the carbon plate. When the material is used as a negative electrode material of a sodium battery for an electrochemical performance test, the initial specific capacity of the material is 439.6 mAh / g (0.1 A / g), the specific capacity is still 324.1 mAh / g after 100 times of circulation, and the specific capacity of 142.1 mAh / g can still be provided when the specific capacity is 2.0 A / g. The MnS / carbon composite material prepared by the invention has high specific capacity and good cycle performance, and the preparation method has the characteristics of simplicity, rapidness, safety and the like.

Description

Technical Field

[0001] A method for preparing a MnS / carbon composite material for sodium batteries belongs to the field of sodium-ion batteries. Background Technology

[0002] With the improvement of people's living standards and the widespread use of new energy electric vehicles for home use, the research and application of energy storage devices have been greatly promoted. Compared with lead-acid batteries, lithium-ion batteries have advantages such as relatively small size and weight, as well as high energy density, and have been widely used. However, due to the uneven distribution and large-scale consumption of lithium resources, the price of lithium sources is high, making it difficult to meet the requirements of large-scale energy storage applications. Conversely, sodium resources are relatively abundant in my country and relatively inexpensive. In addition, sodium and lithium have similar physicochemical properties, making sodium-ion batteries more suitable for large-scale energy storage applications.

[0003] The realization of high-performance anode materials is one of the key factors driving the large-scale application of sodium batteries. Currently, commercially available graphite cannot meet the demands of sodium batteries. Transition metal sulfides, especially manganese sulfide, have received extensive research due to their high specific capacity and good electrochemical stability. However, their low conductivity and severe particle pulverization result in unsatisfactory rate performance and cycle performance. In recent years, methods combining nanoparticles with carbon-based materials have been employed to attempt to improve the electrochemical performance of manganese sulfide anodes. These methods include hydrothermal or solvothermal treatments, or a combination of annealing; ball milling combined with annealing; or sol-gel methods combined with annealing. Hydrothermal or solvothermal methods mostly require reaction vessels, which are time-consuming, especially for large-scale preparation where the equipment requirements are high and the process is unsafe, thus hindering large-scale preparation (CN202211307329; CN202210501943; CN114229902A). Ball milling is difficult to guarantee the homogeneity of the composite, and the process is also relatively cumbersome, thus it is also not conducive to industrial-scale preparation (CN114014368A). The existing sol-gel method is time-consuming, the process is relatively cumbersome, and it uses a toxic hydrogen sulfide / argon mixture as a sulfur source, thus it is also not conducive to industrial-scale preparation (CN113415827A). Summary of the Invention

[0004] This invention provides a method that is short in preparation cycle, simple in operation and safe. By using a rapid sol-gel method and a one-step annealing treatment, a MnS / carbon composite material was successfully prepared. When used as a negative electrode for sodium-ion batteries, it exhibits good electrochemical performance.

[0005] The present invention provides a method for preparing a MnS / carbon composite material for sodium electrolysis, comprising the following steps: a) In a 50 mL beaker, add 95 vol% ethanol, polyvinylpyrrolidone (molecular weight 40000) and dicyandiamine. Stir at 500 rpm at room temperature for 20 min. Then add manganese nitrate tetrahydrate and thiourea. Continue stirring at 500 rpm at room temperature for 10 min. Pour the entire solution in the beaker into a ceramic boat with dimensions of 60 x 30 mm. Then transfer it to an 85°C oven and dry for 30 min. b) A ceramic boat carrying the precursor is placed in a tube furnace, heated to a specific temperature, and kept at that temperature for a period of time under a nitrogen atmosphere. Then, it is cooled down to room temperature with the furnace to obtain MnS / carbon composite material. c) The above-mentioned MnS / carbon composite material is used as an electrode material in sodium-ion batteries.

[0006] In step a), the amounts of ethanol, polyvinylpyrrolidone, dicyandiamine, manganese nitrate tetrahydrate, and thiourea added are 8.0 mL, 0.8 g, 0.4 g, 0.5 g, and 2.0 g, respectively.

[0007] In step b), under the condition that the argon gas flow rate is 18 sccm, the temperature is increased from 20°C to 580°C at a heating rate of 8°C / min, and then held for 60 min.

[0008] In step c), during the sodium-ion battery cycle performance test, the initial specific capacity was 439.6 mAh / g at 0.1 A / g, and the specific capacity remained at 324.1 mAh / g even after 100 cycles.

[0009] Compared with other methods for preparing manganese sulfide-based materials, this method is safer, has a shorter cycle time, is simpler to operate, and is suitable for large-scale mass production. When the MnS / carbon composite material is used in sodium-ion batteries, it exhibits high specific capacity and cycle performance.

[0010] The X-ray powder diffractometer (Cu Ka) was used for radiation, l = 1.5406 Å, 2 q The structure of the prepared material was determined at 10-80°. The surface morphology of the prepared material was observed using a Hitachi S-4800 scanning electron microscope. The battery performance was tested using an electrochemical workstation (CHI 660E) and a Neware battery testing system.

[0011] Depend on Figure 1It can be seen that, under the condition of annealing time of 60 min, when the annealing temperature is 500℃ and 580℃, the strong diffraction peaks of the obtained products are all attributed to the diffraction peaks of the cubic phase of pure MnS (JCPDS card No. 89-4952), among which no other impurity peaks were detected besides the diffraction peaks of MnS and carbon; when the annealing temperature is 660℃, in addition to the cubic phase of MnS, the diffraction peaks of the tetragonal phase of Mn3O4 are also clearly present (JCPDS card No. 80-0382). Figure 2 It can be seen that, without the addition of dicyandiamine, after annealing at 580℃ for 60 min, the diffraction peaks of the product obtained in Example 4 are classified as mixed-phase diffraction peaks of MnSO4 (JCPDS card No. 29-0898), MnSO4·2H2O (JCPDS card No. 38-0602), and Mn3O4 (JCPDS card No. 24-0734), indicating that it is difficult to prepare pure-phase MnS materials without the addition of dicyandiamine. Figure 3 As can be seen from AC, the MnS / carbon composite material obtained in Scheme 5 is composed of carbon sheets and nanoparticles embedded thereon, wherein the nanoparticles have varying sizes, ranging from approximately 10 to 100 nm. Figure 3 As can be seen from df, the MnS / carbon composite material obtained in embodiment 2 is composed of carbon sheets and nanoparticles embedded thereon, and its nanoparticle distribution is denser than that in embodiment 5. Figure 3 As can be seen from gi, with the further increase of the amount of manganese nitrate tetrahydrate added, the distribution of MnS nanoparticles on the carbon sheet obtained by Example 6 not only becomes denser, but also precipitates larger bulk particles. Figure 4 It can be seen that the MnS / carbon composite material obtained in Implementation Scheme 2, as an electrode material for sodium-ion batteries, exhibits essentially overlapping cycle curves from the second to the fourth cycle during cyclic voltammetry testing at a scan rate of 0.2 mV / s, indicating stable electrochemical performance. Figure 5 It can be seen that the MnS / carbon composite material prepared in Scheme 2, as a sodium electrode material, has an initial specific capacity of 439.6 mAh / g at 0.1 A / g. The charge-discharge curves of the second and third cycles are basically overlapping, indicating that it has stable electrochemical performance. Even after 100 cycles, the specific capacity is still 324.1 mAh / g. Figure 6 At 580℃); meanwhile, when the MnS / carbon composite material prepared in Implementation Scheme 1 is used as a sodium electrode material, the initial specific capacity is 367.5 mAh / g ( Figure 6 At 500℃, after 100 cycles, the specific capacity was 251.5 mAh / g. The specific capacity of Scheme 1 was lower than that of Scheme 2. Figure 7It can be seen that the MnS / carbon composite material prepared in Scheme 2 can still provide a specific capacity of 142.1 mAh / g when used as a sodium electrode material at 2.0 A / g, and can provide a specific capacity of 100.0 mAh / g even at 5.0 A / g. Attached Figure Description

[0012] Figure 1 The X-ray diffraction patterns are of the products obtained from implementation schemes 1, 2, and 3. Figure 2 This is the X-ray diffraction pattern of the product obtained in implementation scheme 4; Figure 3 These are scanning electron microscope images of the products obtained from implementation schemes 2, 5, and 6; Figure 4 This is the CV curve of the product obtained in implementation scheme 2; Figure 5 It is a charge-discharge curve of the product obtained in Implementation Scheme 2; Figure 6 This is a cycle curve of the products obtained from implementation schemes 2 and 3; Figure 7 This is a magnification chart of the product obtained from implementation scheme 2. Detailed Implementation

[0013] 1. In a 50 mL beaker, add 8.0 mL of 95 vol% ethanol, 0.8 g of polyvinylpyrrolidone (molecular weight 40,000), and 0.4 g of dicyandiamine. Stir at 500 rpm at room temperature for 20 min. Then add 0.5 g of manganese nitrate tetrahydrate and 2.0 g of thiourea. Continue stirring at 500 rpm at room temperature for 10 min. Pour the entire solution from the beaker into a ceramic boat with dimensions of 60 x 30 mm. Transfer the boat to an 85°C oven and dry for 30 min. Place the ceramic boat containing the precursor in a tube furnace. Under an argon gas flow rate of 18 sccm, heat the furnace from 20°C to 500°C at a rate of 8°C / min. Hold the temperature for 60 min, then cool the furnace to room temperature to obtain the MnS / carbon composite material (see...). Figure 1 500°C and Figure 6 (500°C).

[0014] 2. In a 50 mL beaker, add 8.0 mL of 95 vol% ethanol, 0.8 g of polyvinylpyrrolidone (molecular weight 40,000), and 0.4 g of dicyandiamine. Stir at 500 rpm at room temperature for 20 min. Then add 0.5 g of manganese nitrate tetrahydrate and 2.0 g of thiourea. Continue stirring at 500 rpm at room temperature for 10 min. Pour the entire solution from the beaker into a ceramic boat with dimensions of 60 x 30 mm. Transfer the boat to an 85°C oven and dry for 30 min. Place the ceramic boat containing the precursor in a tube furnace. Under an argon gas flow rate of 18 sccm, heat the furnace from 20°C to 580°C at a rate of 8°C / min. Hold the temperature for 60 min, then cool the furnace to room temperature to obtain the MnS / carbon composite material (see...). Figure 1 580°C Figure 3 df, Figure 4 , Figure 5 , Figure 6 580°C and Figure 7 ).

[0015] 3. In a 50 mL beaker, add 8.0 mL of 95 vol% ethanol, 0.8 g of polyvinylpyrrolidone (molecular weight 40,000), and 0.4 g of dicyandiamine. Stir at 500 rpm at room temperature for 20 min. Then add 0.5 g of manganese nitrate tetrahydrate and 2.0 g of thiourea. Continue stirring at 500 rpm at room temperature for 10 min. Pour the entire solution from the beaker into a ceramic boat with dimensions of 60 x 30 mm. Transfer the boat to an 85°C oven and dry for 30 min. Place the ceramic boat containing the precursor in a tube furnace. Under an argon gas flow rate of 18 sccm, heat the furnace from 20°C to 660°C at a rate of 8°C / min. Hold the temperature for 60 min, then cool the furnace to room temperature to obtain the MnS / carbon composite material (see...). Figure 1 (660°C).

[0016] 4. In a 50 mL beaker, add 8.0 mL of 95 vol% ethanol and 0.8 g of polyvinylpyrrolidone (molecular weight 40,000). Stir at 500 rpm at room temperature for 20 min. Then add 0.5 g of manganese nitrate tetrahydrate and 2.0 g of thiourea. Continue stirring at 500 rpm at room temperature for 10 min. Pour the entire solution from the beaker into a ceramic boat with dimensions of 60 x 30 mm. Transfer the boat to an 85°C oven and dry for 30 min. Place the ceramic boat containing the precursor in a tube furnace. Under an argon gas flow rate of 18 sccm, heat the furnace from 20°C to 580°C at a rate of 8°C / min. Hold the temperature for 60 min, then cool the furnace to room temperature to obtain the product (see...). Figure 2 ).

[0017] 5. In a 50 mL beaker, add 8.0 mL of 95 vol% ethanol, 0.8 g of polyvinylpyrrolidone (molecular weight 40,000), and 0.4 g of dicyandiamine. Stir at 500 rpm at room temperature for 20 min. Then add 0.4 g of manganese nitrate tetrahydrate and 2.0 g of thiourea. Continue stirring at 500 rpm at room temperature for 10 min. Pour the entire solution from the beaker into a ceramic boat with dimensions of 60 x 30 mm. Transfer the boat to an 85°C oven and dry for 30 min. Place the ceramic boat containing the precursor in a tube furnace. Under an argon gas flow rate of 18 sccm, heat the furnace from 20°C to 580°C at a rate of 8°C / min. Hold the temperature for 60 min, then cool the furnace to room temperature to obtain the MnS / carbon composite material (see...). Figure 3 (c).

[0018] 6. In a 50 mL beaker, add 8.0 mL of 95 vol% ethanol, 0.8 g of polyvinylpyrrolidone (molecular weight 40,000), and 0.4 g of dicyandiamine. Stir at 500 rpm at room temperature for 20 min. Then add 0.6 g of manganese nitrate tetrahydrate and 2.0 g of thiourea. Continue stirring at 500 rpm at room temperature for 10 min. Pour the entire solution from the beaker into a ceramic boat with dimensions of 60 x 30 mm. Transfer the boat to an 85°C oven and dry for 30 min. Place the ceramic boat containing the precursor in a tube furnace. Under an argon gas flow rate of 18 sccm, heat the furnace from 20°C to 580°C at a rate of 8°C / min. Hold the temperature for 60 min, then cool the furnace to room temperature to obtain the MnS / carbon composite material (see...). Figure 3 in gi).

Claims

1.A method for preparing MnS / carbon composite material for sodium battery, comprising the following steps: a) in a 50 mL beaker, 95 vol% ethanol, polyvinylpyrrolidone (molecular weight 40000) and dicyandiamide are added, stirred at a speed of 500 rpm at room temperature for 20 min, then manganese nitrate tetrahydrate and thiourea are added, and stirred at a speed of 500 rpm at room temperature for 10 min, then the solution in the beaker is poured into a ceramic square boat with a length of 60 mm and a width of 30 mm, and then the ceramic square boat is transferred to an oven at 85°C for drying treatment for 30 min; b) the ceramic square boat loaded with the precursors is placed in a tube furnace, heated to a specific temperature, and then kept at the specific temperature for a period of time under a nitrogen atmosphere, and then cooled to room temperature with the furnace, to obtain the MnS / carbon composite material; the amounts of the ethanol, polyvinylpyrrolidone, dicyandiamide, manganese nitrate tetrahydrate and thiourea added in the step a) are 8.0 mL, 0.8 g, 0.4 g, 0.5 g and 2.0 g respectively; in the step b), the temperature is raised from 20°C to 580°C at a rate of 8°C / min under an argon flow rate of 18 sccm, and then kept at 580°C for 60 min. ​ ​ ​ 2. The method for preparing a MnS / carbon composite material for sodium electrolysis according to claim 1, characterized in that, ​

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