Preparation method of nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material

Abstract

This invention relates to a method for preparing a nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material, comprising the following steps: 1) dissolving gelatin in deionized water and stirring to obtain solution A; 2) dissolving Bi(NO3)3·5H2O in dilute nitric acid and stirring to obtain solution B; 3) dissolving (NH4)2S2O8 in deionized water and naming it solution C; 4) slowly adding solution B to solution A while stirring continuously, adding solution C to the mixture of solutions A and B while stirring; drying in a constant temperature drying oven; and calcining at high temperature under a nitrogen atmosphere to obtain the final product. The advantages are: using inexpensive and readily available gelatin as the carbon source greatly reduces costs, and the simple preparation process enables large-scale production. The Bi-C composite material prepared by this invention improves its lithium storage performance and electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery anode materials, and particularly relates to a method for preparing a nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material. Background Technology

[0002] Lithium-ion batteries (LIBs) have a promising future in the field of sustainable energy, serving as excellent energy storage and portable devices. However, the theoretical capacity of currently commercially available graphite electrodes is relatively low (372 mAh / g), which cannot meet society's demand for high-capacity, high-density batteries, thus limiting their further development. Therefore, developing new anode materials is crucial to meeting the requirements of next-generation lithium-ion batteries for high capacity, long cycle life, and cycle stability.

[0003] Bismuth-based materials have a slightly higher specific capacity than graphite, but a higher volumetric capacity of 3765 mA·h·cm. -3 Bi has a much higher conductivity than graphite, Si, Sn, and Sb, giving it a significant advantage as a negative electrode material. However, when Bi is used as a negative electrode material in lithium-ion batteries, it is prone to large volume changes during multiple charge-discharge cycles, leading to capacity decay, poor cycle stability, and low conductivity, resulting in poor rate performance at high current densities.

[0004] Currently, common methods for improving the electrochemical performance of bismuth-based materials include nanostructuring, compositing with carbon materials, and introducing other elements for modification. Among these three methods, compositing with carbon materials is the most common and effective way to address the poor conductivity of bismuth-based electrode materials. Furthermore, some carbon-coated materials can help solve the problem of large volume changes in bismuth-based materials during electrochemical processes, further improving their lithium storage performance. However, existing technologies mostly use graphene, carbon nanotubes, etc., as carbon sources in composite materials, but these materials are often expensive and complex to process, making large-scale use difficult.

[0005] Gelatin is an amphoteric colloid that forms a gel system in hot water and returns to its original state after the temperature drops. Applying this property to the preparation of carbon-coated composite materials can lead to the development of composite materials with high capacity and good conductivity, which has broad prospects in the preparation of new energy materials. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing a nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material. The method uses gelatin carbon to coat metallic Bi to prepare the lithium-ion battery anode material, which can effectively suppress the problems of metallic Bi as a lithium-ion battery anode electrode material alone.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing a nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material includes the following steps:

[0009] 1) Dissolve gelatin in deionized water and stir at 60-90℃ to obtain a slightly yellow gelatin solution, named solution A;

[0010] 2) Dissolve Bi(NO3)3·5H2O in dilute nitric acid and stir for 20-40 minutes until completely dissolved. This solution is named B.

[0011] 3)(NH4)2S2O8 dissolved in deionized water is named solution C;

[0012] 4) Slowly add solution B to solution A and stir continuously at 60-90℃ for 20-30 minutes. While stirring, add solution C to the mixture of A and B and continue stirring for 0.5-1.5 hours. After stirring, transfer the mixture to a constant temperature drying oven and dry at 70-90℃ for 24-36 hours. Once the solution has completely solidified, calcine it at 500-800℃ for 2-3 hours under a nitrogen atmosphere to obtain the final product.

[0013] In step 1), the ratio of gelatin to deionized water is (8-30)g:40ml.

[0014] In step 2), the ratio of Bi(NO3)3·5H2O to dilute nitric acid is (1-5)g:10ml.

[0015] In step 3), the ratio of (NH4)2S2O8 to deionized water is (0.1-2)g:20ml.

[0016] The mixing ratio of solution A, solution B, and solution C is (40-70) ml: (10-15) ml: (20-25) ml.

[0017] The concentration of the dilute nitric acid is 1 mol / L.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] Compared to existing methods that use graphene, carbon nanotubes, etc., as carbon sources in lithium-ion battery composite materials, this invention uses inexpensive and readily available gelatin as the carbon source, greatly reducing costs. Furthermore, the simple preparation process enables large-scale production. The Bi-C composite material prepared by this invention solves the problem of large volume changes in bismuth-based materials during electrochemical processes, improving its lithium storage performance and significantly enhancing its electrochemical performance. It also provides new ideas and approaches for the preparation of other electrode materials. Attached Figure Description

[0020] Figure 1 This is the process route diagram of the present invention.

[0021] Figure 2 This is a flowchart of lithium-ion battery assembly and testing.

[0022] Figure 3 This is the XRD pattern of the Bi-C composite material.

[0023] Figure 4 This is a SEM image of the Bi-C composite material.

[0024] Figure 5 This is the EDS diagram of the Bi-C composite material.

[0025] Figure 6 This is a rate performance graph for Bi-C.

[0026] Figure 7 This is a graph showing the cycling performance of Bi-C. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] See Figure 1 The preparation method of nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material includes the following steps:

[0030] 1) Dissolve 10g of gelatin in 40ml of deionized water, heat and stir at 70℃ to obtain a slightly yellow gelatin solution, and name it solution A;

[0031] 2) Weigh 4.85g of Bi(NO3)3·5H2O and dissolve it in dilute nitric acid. Stir for 30 minutes until it is completely dissolved and name it solution B. At the same time, take 1g of (NH4)2S2O8 and dissolve it in deionized water and name it solution C.

[0032] 3) Preparation of Bi / gelatin carbon composite material

[0033] Solution B was slowly added to solution A, and the mixture was stirred continuously at 70°C for 30 minutes. While stirring, solution C was added to the mixture of solutions A and B, and stirring continued for 0.5–1.5 hours. After stirring, the mixture was transferred to a constant-temperature drying oven and dried at 70–90°C for 24–36 hours. Once the solution had completely solidified, it was calcined at 500–800°C for 2–3 hours under a nitrogen atmosphere to obtain the final product, named the Bi-C-10 composite material.

[0034] Bi-C-10 composite material according to Figure 2Lithium-ion batteries were assembled sequentially and then tested. From Figure 3 It can be seen that the characteristic peaks of the Bi-C-10 composite material at 27.2°, 37.9°, 39.6° and 48.7° are in perfect agreement with the standard card ICDD 01-085-1329, which correspond to the Bi(012), (104), (110) and (202) crystal planes, respectively, indicating that the Bi-C-10 composite material was successfully prepared.

[0035] Figure 4 Images (a) and (b) are SEM images of the Bi-C-10 composite material at different magnifications. It can be seen that all Bi-C-10 composite materials exhibit blocky solid structures of varying sizes, with relatively smooth surfaces and no metal particles, indicating that Bi particles are encapsulated within C. Figure 5 As can be seen, the elements Bi, C, O, N, and S in the composite material are all uniformly distributed on the material surface.

[0036] See Figure 6 The rate performance of the Bi-C-10 composite material at current densities of 0.1 A / g, 0.2 A / g, 0.5 A / g, 1.0 A / g, 2.0 A / g, and 5.0 A / g is given by... Figure 6 It can be seen that the Bi-C-10 composite material exhibits a discharge specific capacity of 396 mAh / g after ten cycles at a current density of 0.1 A / g. Even at a high current density of 5 A / g, the Bi-C-10 composite material still maintains a discharge specific capacity of 139 mAh / g. When the current density returns to 0.1 A / g, the discharge specific capacity of the Bi-C-10 composite material reaches 371.4 mAh / g, demonstrating good rate performance.

[0037] Example 2

[0038] See Figure 1 The preparation method of nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material includes the following steps:

[0039] 1) Dissolve 15g of gelatin in 40ml of deionized water, heat and stir at 70℃ to obtain a slightly yellow gelatin solution, and name it solution A;

[0040] 2) Weigh 4.85g of Bi(NO3)3·5H2O and dissolve it in dilute nitric acid. Stir for 30 minutes until it is completely dissolved and name it solution B. At the same time, take 1g of (NH4)2S2O8 and dissolve it in deionized water and name it solution C.

[0041] 3) Preparation of Bi / gelatin carbon composite material

[0042] Solution B was slowly added to solution A, and the mixture was stirred continuously at 70°C for 30 minutes. While stirring, solution C was added to the mixture of solutions A and B, and stirring continued for 0.5–1.5 hours. After stirring, the mixture was transferred to a constant temperature drying oven and dried at 70–90°C for 24–36 hours. Once the solution had completely solidified, it was calcined at 500–800°C for 2–3 hours under a nitrogen atmosphere to obtain the final product, named Bi-C-15 composite material.

[0043] from Figure 3 It can be seen that the characteristic peaks of the Bi-C-15 composite material at 27.2°, 37.9°, 39.6° and 48.7° are in perfect agreement with the standard card ICOD 01-085-1329, which correspond to the Bi(012), (104), (110) and (202) crystal planes, respectively, indicating that the Bi-C-15 composite material was successfully prepared.

[0044] Figure 4 SEM images (c) and (d) of the Bi-C-15 composite material at different magnifications show that all Bi-C-15 composite materials exhibit blocky solid structures of varying sizes. The surfaces of these blocky structures are relatively smooth and lack metallic particles, indicating that the Bi particles are encapsulated within the C atoms. Figure 5 As can be seen, the elements Bi, C, O, N, and S in the composite material are all uniformly distributed on the material surface.

[0045] See Figure 6 Rate performance of Bi-C-15 composite materials at current densities of 0.1 A / g, 0.2 A / g, 0.5 A / g, 1.0 A / g, 2.0 A / g, and 5.0 A / g. (Based on...) Figure 6 It can be seen that the Bi-C-15 composite material exhibits better rate performance than other materials. After ten cycles at a current density of 0.1 A / g, the discharge specific capacity is 457.6 mAh / g. Even at a high current density of 5 A / g, the Bi-C-15 composite material still exhibits good lithium storage performance, with a discharge specific capacity as high as 143.5 mAh / g. When the current density returns to 0.1 A / g, the discharge specific capacity of the Bi-C-15 composite material is 436.1 mAh / g, significantly higher than other materials, demonstrating excellent rate performance.

[0046] Example 3

[0047] See Figure 1 The preparation method of nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material includes the following steps:

[0048] 1) Dissolve 20g of gelatin in 40ml of deionized water, heat and stir at 70℃ to obtain a slightly yellow gelatin solution, and name it solution A;

[0049] 2) Weigh 4.85g of Bi(NO3)3·5H2O and dissolve it in dilute nitric acid. Stir for 30 minutes until it is completely dissolved and name it solution B. At the same time, take 1g of (NH4)2S2O8 and dissolve it in deionized water and name it solution C.

[0050] 3) Preparation of Bi / gelatin carbon composite material

[0051] Solution B was slowly added to solution A, and the mixture was stirred continuously at 70°C for 30 minutes. While stirring, solution C was added to the mixture of solutions A and B, and stirring continued for 0.5–1.5 hours. After stirring, the mixture was transferred to a constant temperature drying oven and dried at 70–90°C for 24–36 hours. Once the solution had completely solidified, it was calcined at 500–800°C for 2–3 hours under a nitrogen atmosphere to obtain the final product, named Bi-C-20 composite material.

[0052] from Figure 3 It can be seen that the characteristic peaks of the Bi-C-20 composite material at 27.2°, 37.9°, 39.6° and 48.7° are in perfect agreement with the standard card ICOD 01-085-1329, which correspond to the Bi(012), (104), (110) and (202) crystal planes, respectively. This indicates that the Bi-C-20 composite material was successfully prepared, and the narrowing of its peak half-width proves that the Bi particles in the Bi-C-20 composite material are small.

[0053] Figure 4 (e) and (f) are SEM images of Bi-C-20 composite materials at different magnifications. As can be seen from the images, all Bi-C-20 composite materials exhibit blocky solid structures of varying sizes, and the surface of the blocky structures is relatively smooth with no metal particles, indicating that Bi particles are encapsulated in C.

[0054] See Figure 6 Rate performance of Bi-C-20 composite materials at current densities of 0.1 A / g, 0.2 A / g, 0.5 A / g, 1.0 A / g, 2.0 A / g, and 5.0 A / g. (Based on...) Figure 6 It can be seen that the Bi-C-20 composite material exhibits a discharge specific capacity of 380.9 mAh / g after ten cycles at a current density of 0.1 A / g. At a high current density of 5 A / g, the discharge specific capacity of the Bi-C-20 composite material is 81 mAh / g. When the current density returns to 0.1 A / g, the discharge specific capacity of the Bi-C-20 composite material is 376.9 mAh / g.

[0055] Example 4

[0056] See Figure 1The preparation method of nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material includes the following steps:

[0057] 1) Dissolve 25g of gelatin in 40ml of deionized water, heat and stir at 70℃ to obtain a slightly yellow gelatin solution, which is named solution A;

[0058] 2) Weigh 4.85g of Bi(NO3)3·5H2O and dissolve it in dilute nitric acid. Stir for 30 minutes until it is completely dissolved and name it solution B. At the same time, take 1g of (NH4)2S2O8 and dissolve it in deionized water and name it solution C.

[0059] 3) Preparation of Bi / gelatin carbon composite material

[0060] Solution B was slowly added to solution A, and the mixture was stirred continuously at 70°C for 30 minutes. While stirring, solution C was added to the mixture of solutions A and B, and stirring continued for 0.5–1.5 hours. After stirring, the mixture was transferred to a constant temperature drying oven and dried at 70–90°C for 24–36 hours. Once the solution had completely solidified, it was calcined at 500–800°C for 2–3 hours under a nitrogen atmosphere to obtain the final product, named Bi-C-25 composite material.

[0061] from Figure 3 It can be seen that the characteristic peaks of the Bi-C-25 composite material at 27.2°, 37.9°, 39.6° and 48.7° are in perfect agreement with the standard card ICOD 01-085-1329, corresponding to the Bi(012), (104), (110) and (202) crystal planes, respectively. This indicates that the Bi-C-25 composite material was successfully prepared and its peak half-width narrowed, proving that the Bi particle size in the Bi-C-25 composite material is as small as that in the Bi-C-25 composite material.

[0062] Figure 4 SEM images of (g) and (h) Bi-C-25 composites at different magnifications show that all Bi-C-25 composites exhibit blocky solid structures of varying sizes, with relatively smooth surfaces and no metal particles, indicating that Bi particles are encapsulated within C.

[0063] See Figure 6 Rate performance of Bi-C-25 composite materials at current densities of 0.1 A / g, 0.2 A / g, 0.5 A / g, 1.0 A / g, 2.0 A / g, and 5.0 A / g. (Based on...) Figure 6It can be seen that after ten cycles at a current density of 0.1 A / g, the Bi-C-25 composite material exhibits a discharge specific capacity of 395.2 mAh / g. At a higher current density of 5 A / g, the Bi-C-25 composite material still maintains a discharge specific capacity of 82.9 mAh / g. When the current density returns to 0.1 A / g, the discharge specific capacity of the Bi-C-25 composite material is 396.8 mAh / g.

Claims

1. A method for preparing a nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material, characterized in that, Includes the following steps: 1) Dissolve gelatin in deionized water and stir at 60-90℃ to obtain a slightly yellow gelatin solution, named solution A; 2) Dissolve Bi(NO3)3·5H2O in dilute nitric acid and stir for 20-40 minutes until completely dissolved. This solution is named B. 3)(NH4)2S2O8 dissolved in deionized water is named solution C; 4) Slowly add solution B to solution A and stir continuously at 60-90℃ for 20-30 minutes. While stirring, add solution C to the mixture of A and B and continue stirring for 0.5-1.5 hours. After stirring, transfer the mixture to a constant temperature drying oven and dry at 70-90℃ for 24-36 hours. Once the solution has completely solidified, calcine it at 500-800℃ for 2-3 hours under a nitrogen atmosphere to obtain the final product.

2. The preparation method of the nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material according to claim 1, characterized in that, In step 1), the ratio of gelatin to deionized water is (8-30)g:40ml.

3. The preparation method of the nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material according to claim 1, characterized in that, In step 2), the ratio of Bi(NO3)3·5H2O to dilute nitric acid is (1-5)g:10ml.

4. The preparation method of the nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material according to claim 1, characterized in that, In step 3), the ratio of (NH4)2S2O8 to deionized water is (0.1-2)g:20ml.

5. The preparation method of a nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material according to claim 1, characterized in that, The mixing ratio of solution A, solution B, and solution C is (40-70) ml: (10-15) ml: (20-25) ml.

6. The preparation method of a nitrogen-sulfur co-doped Bi / gelatin carbon lithium-ion battery anode composite material according to claim 1, characterized in that, The concentration of the dilute nitric acid is 1 mol / L.

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