Controllable preparation method and application of CaMn (CO3) 2 magnetic powder with layered structure

Abstract

The invention discloses a controllable preparation method and application of CaMn (CO3) 2 magnetic powder with a layered structure, and relates to the field of layered structure material preparation and new energy batteries. The preparation method comprises the following steps: firstly, respectively adding sodium citrate, potassium permanganate and anhydrous calcium chloride into deionized water, and stirring and dispersing to completely dissolve; secondly, adding gelatin, heating, and stirring until the gelatin is completely dissolved to obtain a mixed precursor solution; finally, transferring the mixed precursor solution into a high-pressure reaction kettle for hydrothermal reaction; after the reaction is finished, a reaction product is filtered, washed and dried, and the CaMn (CO3) 2 magnetic powder with the layered structure is obtained. According to the invention, the dicarbonate produced by oxidation or hydrolysis is utilized to form the lamellar-structure microcrystals in a self-assembly form, and a new idea and a new method for effectively preparing the composite material are provided. The prepared product is controllable in shape and size, and the target product is good in magnetism and can be applied to the fields of lithium ion battery materials and electro-catalytic materials.

Description

Technical Field

[0001] The present invention relates to the field of layered structure material preparation and new energy batteries, and in particular to a controllable preparation method of CaMn(CO3)2 magnetic powder with a layered structure and its application. Background Art

[0002] In recent years, with the growing global demand for energy, it has become particularly important to develop more efficient and environmentally friendly energy storage and efficiency conversion technologies. Lithium batteries first originated in the 1970s. With the advantages of high energy density, long cycle life, and environmental friendliness, they have become the mainstream battery technology in new energy vehicles and mobile communications. With the rapid development of related fields, lithium-ion battery technology is also improving.

[0003] CaMn(CO3)2, manganese dolomite, belongs to the trigonal system. The current DFT test results show that CaMn(CO3)2 has excellent electrode properties: theoretical specific capacity is 250mAh / g, calculated average voltage is 3.8V, and volume change rate is 13%. It has the characteristics of non-toxicity and low price, and has attracted the attention of many researchers in the field of batteries and electrocatalysis.

[0004] The present invention combines the structural and performance characteristics of both solid solutions and transition metal carbonates to construct and successfully prepare CaMn(CO3)2 layered microcrystals with novel structure and morphology, which are expected to be used as lithium-ion battery materials. Summary of the invention

[0005] The purpose of the present invention is to propose a controllable preparation method and application of CaMn(CO3)2 magnetic powder with layered structure, to construct and prepare layered structural materials with novel structure and morphology, and to provide new ideas for the selection of lithium battery materials and electrocatalytic materials.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A controllable preparation method of CaMn(CO3)2 magnetic powder with layered structure, the steps are as follows

[0008] Step S1: adding sodium citrate, potassium permanganate and anhydrous calcium chloride to deionized water respectively, stirring and dispersing them to completely dissolve;

[0009] Step S2: adding gelatin, heating and stirring to completely dissolve the gelatin to obtain a mixed precursor solution;

[0010] Step S3: transferring the mixed precursor solution to a high-pressure reactor for hydrothermal reaction; after the reaction is completed, filtering, washing, and drying the reaction product to obtain CaMn(CO3)2 magnetic powder with a layered structure.

[0011] As a preferred technical solution of the present invention, in the preparation method:

[0012] In step S1, the molar ratio of potassium permanganate, sodium citrate and anhydrous calcium chloride is 0.8-1.2:0.8-1.2:0.5-1.5.

[0013] In step S2, the heating temperature is 60-80° C. and the heating time is 1-2 hours.

[0014] The hydrothermal reaction temperature in step S3 is 130-150° C., and the reaction time is 5-15 hours.

[0015] The CaMn(CO3)2 magnetic powder with a layered structure prepared by the present invention is spindle-shaped or dumbbell-shaped, is self-assembled by sheets, and can be used as a lithium battery material and an electrocatalytic material.

[0016] The present invention proposes a controllable preparation method of CaMn(CO3)2 magnetic powder with a layered structure. First, sodium citrate, potassium permanganate and calcium chloride are sequentially added to deionized water and stirred to dissolve. An appropriate amount of gelatin is added to the above solution and heated to dissolve to obtain a brown precursor solution. Then, the prepared precursor solution is transferred to a reactor and subjected to a hydrothermal reaction at a certain temperature. Finally, the reaction product is filtered and washed and dried to obtain CaMn(CO3)2 magnetic powder with a layered structure. Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention utilizes bicarbonate produced by oxidation or hydrolysis to form layered microcrystals through self-assembly, providing a new idea and method for effectively preparing composite materials.

[0018] 2. The morphology and size of the product prepared by the present invention are controllable, the target product has good magnetic properties, and can be applied to the fields of lithium-ion battery materials and electrocatalytic materials.

[0019] 3. The preparation method proposed in the present invention has the advantages of simple operation, low cost, large product volume, safety, reliability and green environmental protection, which provides a guarantee for application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The composition (a), morphology (b) and energy spectrum analysis (c) of the spindle-shaped CaMn(CO3)2 layered structure microcrystals prepared in Example 1.

[0021] Figure 2 The composition (a), morphology (b) and energy spectrum analysis (c) of the rod-shaped MnCO3 layered structure microcrystals prepared in Example 2.

[0022] Figure 3The morphology (a) and energy spectrum analysis (b) of the dumbbell-shaped CaMn(CO3)2 layered structure microcrystals prepared in Example 3 are shown respectively.

[0023] Figure 4 Cyclic voltammetry scanning curves of the spindle-shaped CaMn(CO3)2 layered structure microcrystals (a) prepared in Example 1 and the rod-shaped MnCO3 layered structure microcrystals (b) prepared in Example 2 under hydrogen evolution conditions.

[0024] Figure 5 Cyclic voltammetry scanning curves of the spindle-shaped CaMn(CO3)2 layered structure microcrystals (a) prepared in Example 1 and the rod-shaped MnCO3 layered structure microcrystals (b) prepared in Example 2 under oxygen evolution conditions.

[0025] Figure 6 Impedance fitting diagrams of the spindle-shaped CaMn(CO3)2 layered structure microcrystals prepared in Example 1 and the rod-shaped MnCO3 layered structure microcrystals prepared in Example 2 under hydrogen evolution conditions (a) and oxygen evolution conditions (b).

[0026] Figure 7 Cdl performance diagram of the spindle-shaped CaMn(CO3)2 layered structure microcrystals prepared in Example 1 and the rod-shaped MnCO3 layered structure microcrystals prepared in Example 2 under hydrogen evolution conditions (a) and oxygen evolution conditions (b).

[0027] Figure 8 This is the curve of the electrocatalytic hydrogen production over time of the spindle-shaped CaMn(CO3)2 layered structure microcrystals prepared in Example 1. DETAILED DESCRIPTION

[0028] The controllable preparation method of the layered CaMn(CO3)2 magnetic powder of the present invention and its application are further described in detail below in conjunction with the examples and drawings. The morphology and composition of the product obtained by the method of the present invention are characterized and analyzed using instruments such as a field emission scanning electron microscope (FE-SEM, SU8010) and a high resolution transmission electron microscope (HRTEM, F200).

[0029] Example 1

[0030] The steps of preparing spindle-shaped CaMn(CO3)2 layered structure microcrystals are as follows:

[0031] Step S1: Add 0.980 g of sodium citrate, 0.527 g of potassium permanganate, and 0.185 g of anhydrous calcium chloride to 15 mL of deionized water, respectively, and stir and disperse for 10 minutes to completely dissolve them in the deionized water.

[0032] Step S2: Add gelatin and continue heating in an oven at 70° C. with stirring for 1 hour to completely dissolve the gelatin in the solution to obtain a mixed precursor solution.

[0033] Step S3: The mixed precursor solution is transferred to a high-pressure reactor for hydrothermal reaction at a reaction temperature of 140°C for a reaction time of 10 hours. After the reaction is completed, the reaction product is filtered, washed, and dried at 60°C to obtain spindle-shaped CaMn(CO3)2 layered structure microcrystals.

[0034] Example 2

[0035] The preparation method of rod-shaped MnCO3 layered structure microcrystals is as follows:

[0036] Step S1: Add 0.980 g of sodium citrate and 0.527 g of potassium permanganate to 15 mL of deionized water, respectively, and stir and disperse for 10 minutes to completely dissolve them in the deionized water.

[0037] Step S2: Add gelatin and continue heating in an oven at 70° C. with stirring for 1 hour to completely dissolve the gelatin in the solution to obtain a mixed precursor solution.

[0038] Step S3: The mixed precursor solution is transferred to a high-pressure reactor for hydrothermal reaction at a reaction temperature of 140° C. for a reaction time of 10 h. After the reaction is completed, the reaction product is filtered, washed, and dried at 60° C. to obtain rod-shaped MnCO3 layered structure microcrystals.

[0039] Example 3

[0040] The preparation method of dumbbell-shaped CaMn(CO3)2 layered structure microcrystals is as follows:

[0041] Step S1: Add 0.980 g of sodium citrate, 0.527 g of potassium permanganate, and 0.370 g of anhydrous calcium chloride to 15 mL of deionized water, respectively, and stir and disperse for 10 minutes to completely dissolve them in the deionized water.

[0042] Step S2: Add gelatin and continue heating in an oven at 70° C. with stirring for 1 hour to completely dissolve the gelatin in the solution to obtain a mixed precursor solution.

[0043] Step S3: The mixed precursor solution is transferred to a high-pressure reactor for hydrothermal reaction at a reaction temperature of 140°C for a reaction time of 10 hours. After the reaction is completed, the reaction product is filtered, washed, and dried at 60°C to obtain dumbbell-shaped CaMn(CO3)2 layered structure microcrystals.

[0044] Characterization and performance testing of the products prepared in Examples 1, 2, and 3:

[0045] pass Figure 1(a) It can be seen that the X-ray powder diffraction analysis (XRD) spectrum of the product prepared in Example 1 is completely consistent with the CaMn(CO3)2 standard card. Figure 1 (b) It can be seen that the product is spindle-shaped on a macroscopic scale, with a length of 4 to 7 μm and a width of 1 to 2 μm; on a microscopic scale, the spindle-shaped microcrystals are assembled from sheets. Figure 1 (c) It can be seen that the elements are evenly distributed on the crystal surface.

[0046] Figure 2 , 3 The electron microscope photographs of rod-shaped MnCO3 layered structure microcrystals and dumbbell-shaped CaMn(CO3)2 layered structure microcrystals obtained by a similar method show that they have similar morphologies. The layered MnCO3 and CaMn(CO3)2 form rod-shaped MnCO3 and dumbbell-shaped CaMn(CO3)2 in the form of self-assembly.

[0047] From the perspective of electrochemical testing, Figure 4 The cyclic voltammetry curves shown in the figure show that under hydrogen evolution conditions, the spindle-shaped CaMn(CO3)2 has better cycling performance than the rod-shaped MnCO3. Figure 5 The cyclic voltammetry curves shown in the figure show that under oxygen evolution conditions, the cycling performance of rod-shaped MnCO3 is better than that of spindle-shaped CaMn(CO3)2. Figure 6 It can be seen that the impedance of spindle-shaped CaMn(CO3)2 is relatively large. Figure 7 The double-layer Cdl test results show that under hydrogen evolution conditions, the spindle-shaped CaMn(CO3)2 has more surface active sites than the rod-shaped MnCO3, and under oxygen evolution conditions, the rod-shaped MnCO3 has more surface active sites than the spindle-shaped CaMn(CO3)2.

[0048] Example 4

[0049] The steps of the electrocatalytic hydrogen production experiment are as follows:

[0050] Step S1: 10 mg of the sample (prepared in Example 1) was dissolved in a mixed solution of 600 μL of ethanol and 400 μL of deionized water, and then 60 μL of DuPont membrane solution was added. After ultrasonic dispersion for 10 min, the solution was dropped onto two 1 cm*1.5 cm pieces of nickel foam respectively, and dried in a 60°C oven for 20 min.

[0051] Step S2: Prepare 100mL of 1mol / L KOH solution in a quartz container (three-electrode hole), clamp two pieces of nickel foam on the two working electrodes, and replace the remaining hole with any other electrode (plug the hole to facilitate vacuuming, not actually used). Cover the container lid, immerse the nickel foam working electrode with the sample in the KOH solution, clamp the oxygen evolution working electrode with the green crocodile clip, and clamp the hydrogen evolution working electrode with the red and white clips (both electrodes are fully hydrolyzed), draw vacuum, and the device is built when the vacuum is drawn.

[0052] Step S3: Open the electrochemical station software, set the parameters and start the test.

[0053] As the electrocatalytic time increases, the amount of hydrogen produced is detected by gas chromatography, and then the relationship curve between hydrogen production and time is obtained by calculation. Figure 8 As shown in the figure, it can be seen that as time goes by, the amount of electrocatalytic hydrogen production is in direct proportion to time. This shows that the sample has good hydrogen production performance, which corresponds to the fact that the sample has abundant hydrogen production active sites.

[0054] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A controllable preparation method of CaMn(CO3)2 magnetic powder with layered structure, characterized in that: The steps are as follows Step S1: adding sodium citrate, potassium permanganate and anhydrous calcium chloride to deionized water respectively, stirring and dispersing them to completely dissolve; Step S2: adding gelatin, heating and stirring to completely dissolve the gelatin to obtain a mixed precursor solution; Step S3: transferring the mixed precursor solution to a high-pressure reactor for hydrothermal reaction; after the reaction is completed, filtering, washing, and drying the reaction product to obtain CaMn(CO3)2 magnetic powder with a layered structure.

2. The controllable preparation method according to claim 1, characterized in that: In step S1, the molar ratio of potassium permanganate, sodium citrate and anhydrous calcium chloride is 0.8-1.2:0.8-1.2:0.5-1.

5.

3. The controllable preparation method according to claim 1, characterized in that: In step S2, the heating temperature is 60-80° C. and the heating time is 1-2 hours.

4. The controllable preparation method according to claim 1, characterized in that: The hydrothermal reaction temperature in step S3 is 130-150° C., and the reaction time is 5-15 hours.

5. The CaMn(CO3)2 magnetic powder having a layered structure prepared by the method according to any one of claims 1 to 4, characterized in that: It is spindle-shaped or dumbbell-shaped and is self-assembled from sheets.

6. Use of the CaMn(CO3)2 magnetic powder with a layered structure as claimed in claim 5 as a lithium battery material and an electrocatalytic material.

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