A preparation method of conductive polymer modified SiO negative electrode material

Abstract

The present invention discloses a method for preparing a conductive polymer-modified SiO2 negative electrode material, comprising: uniformly mixing a bio-template prepared from Chlorella vulgaris with a Si-containing solvent, first ball-milling the mixture under a certain pressure, then sintering the mixture under an inert atmosphere, and finally coating the product surface with polyaniline via an in-situ polymerization method. The conductive polymer-modified SiO2 negative electrode material prepared by the present invention has excellent physicochemical and electrochemical properties, and has the advantages of a wide range of material sources, stable performance, and excellent cycle performance.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery negative electrode materials, and in particular to a method for preparing a conductive polymer modified SiO negative electrode material. Background Art

[0002] In recent years, lithium-ion battery (LIBs) technology has developed rapidly. Due to its advantages such as long cycle life, environmental friendliness, and high specific energy, it has been widely used in fields such as mobile phone batteries, home energy storage, and power sources such as electric vehicles. At present, the negative electrode material of lithium-ion batteries mainly adopts traditional graphite negative electrode material, but the actual reversible capacity of graphite negative electrode material is only about 350mAh / g, which is difficult to meet people's requirements for long battery life. The theoretical capacity of silicon is as high as 4200mAh / g, which is more than ten times the theoretical capacity of graphite (372mAh / g). However, when Si combines with Li, it will produce a huge volume expansion, which can easily cause the capacity of lithium-ion batteries to decay, greatly limiting its practical application as a negative electrode material.

[0003] In recent years, many researchers have made numerous attempts at Si anode materials. Silicon dioxide (SiO) materials have the advantage of high capacity, but their poor conductivity and large expansion, leading to poor cycling performance, have been difficult to resolve. Mainstream technical solutions include disproportionation treatment, carbon coating, and etching. For example, SEPEHR H et al. (Reference: SEPEHR H, OHKUBO H, KODZUKA M. Evidence for nano-Si clusters in amorphous SiO anode materials for rechargeable Li-ion batteries [J]. Scripta Materialia, 2013, 69: 92-95.) used disproportionation and carbon coating methods to treat SiO precursors, resulting in SiO anode materials with excellent cycling performance. Patent CN112289987A also reports the use of acid etching to etch the SiO surface and create pores to alleviate lithium-insertion expansion. The performance of SiO materials treated with these methods can still meet the actual requirements of battery cell applications, or these methods are difficult to implement in actual mass production. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a method for preparing a conductive polymer modified SiO negative electrode material.

[0005] The present invention provides a method for preparing a conductive polymer modified SiO negative electrode material, comprising the following steps:

[0006] S1, washing the Chlorella with deionized water, soaking it in an organic solvent, and drying it at low temperature to obtain a biological template;

[0007] S2. Evenly mix ethylene glycol, ethanol, a silane coupling agent, hexadecyltrimethylammonium bromide, and ethyl orthosilicate to obtain a mixed solution;

[0008] S3, mixing the biological template and the mixed solution uniformly, ball milling under a certain air pressure, and then separating the solid and liquid, drying the obtained solid material, sintering it under an inert atmosphere, and grinding it after cooling to obtain a powder;

[0009] S4. Coating polyaniline on the surface of the powder by in-situ polymerization to obtain a conductive polymer-modified SiO negative electrode material.

[0010] Preferably, in S1, the organic solvent is obtained by mixing formaldehyde, ethylene glycol and ethanol in a volume ratio of 1:(1-3):(1-3).

[0011] Preferably, in S1, the low-temperature drying temperature is 60-100° C. and the time is 3-5 hours.

[0012] Preferably, in S2, the mass ratio of ethylene glycol, ethanol, silane coupling agent, hexadecyltrimethylammonium bromide and ethyl orthosilicate is (3-5): (1-3): (2-4): 1: (3-6).

[0013] Preferably, the silane coupling agent is KH-550, KH-560 or a combination thereof.

[0014] Preferably, the mass ratio of the biological template to the mixed solution is 1:(5-15).

[0015] Preferably, in S3, the ball milling is performed at an air pressure of 1-2 atmospheres for 8-10 hours.

[0016] Preferably, in S3, the sintering temperature is 450°C-550°C, and the sintering time is 3-5 hours.

[0017] Preferably, in S3, the drying temperature is 60-100° C. and the drying time is 3-5 h.

[0018] Preferably, in S4, the specific method of coating the powder surface with polyaniline by in-situ polymerization is: adding the powder to an acidic solution containing aniline and mixing uniformly, then adding an oxidant at 0-5° C. and performing polymerization reaction for 2-5 hours.

[0019] Preferably, after the polymerization reaction is completed, the following steps are further included: solid-liquid separation, and the obtained solid matter is washed, dried, and ground to obtain the product.

[0020] Preferably, the acidic solution containing aniline has an aniline concentration of 0.5-1 mol / L, H + The concentration is 0.5-3mol / L.

[0021] Preferably, the acidic solution containing aniline is obtained by dissolving aniline in an aqueous acid solution, wherein the acid is at least one of hydrochloric acid, sulfuric acid and nitric acid.

[0022] Preferably, the oxidant is at least one of ammonium persulfate, hydrogen peroxide, and ferric chloride.

[0023] Preferably, the amount of the oxidant is 1-1.3 times the mass of the powder.

[0024] A conductive polymer modified SiO negative electrode material is prepared by the preparation method.

[0025] In the present invention, the water used is deionized water.

[0026] In the present invention, the method for solid-liquid separation is not particularly limited, and conventional methods such as filtration and centrifugation can be used.

[0027] The beneficial effects of the present invention are as follows:

[0028] The present invention uses Chlorella vulgaris as a raw material to prepare a bio-template, and compounding ethylene glycol, ethanol, silane coupling agent, hexadecyltrimethylammonium bromide, and tetraethyl orthosilicate to obtain a liquid Si-containing solvent. The solvent has strong penetration and dissolving power, and can carry Si sources into the molecular layers and internal gaps of the bio-template, thereby achieving uniform mixing of various substances. The mixture of the bio-template and the Si-containing solvent is calcined, and the tetraethyl orthosilicate is hydrolyzed at high temperature to generate SiO. At the same time, the bio-template is carbonized to generate soft / hard carbon and react with Si to obtain SiO particles with uniform size and regular morphology. The soft / hard carbon is interspersed in the bio-template. The interior and exterior surfaces of SiO can effectively inhibit the expansion of SiO when lithium is inserted, and the soft / hard carbon has excellent ion and electron conductivity properties, which can effectively and significantly improve the cycling performance of SiO. Finally, the conductive polymer polyaniline is wrapped on the surface of the particles through in-situ polymerization. The chemical bonds formed by the silane coupling agent with C and the SiO surface are more easily coated by polyaniline, which can better exert synergistic effects with the soft / hard carbon and SiO. The conductive polymer has a certain elastic mechanism, which can further inhibit the rupture of SiO particles and effectively improve the stability of SiO particle insertion / extraction.

[0029] The particle size of the conductive polymer modified SiO negative electrode material prepared by the present invention is 1-3 μm, and the tap density is 0.6-0.8 g / cm 3 , with a specific surface area of ​​1.5-2.5m 2 / g, the lithium removal capacity is 1000-1400mAh / g, the half-cell efficiency is 60-88%, and the present invention has the advantages of wide material sources, stable performance and excellent cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a scanning electron microscope image of the conductive polymer modified SiO negative electrode material prepared in Example 1.

[0031] Figure 2 This is a charge-discharge curve of a lithium-ion battery assembled with the conductive polymer-modified SiO negative electrode material prepared in Example 1.

[0032] Figure 3 This is a charge cycle diagram of a lithium-ion battery assembled with the conductive polymer-modified SiO negative electrode material prepared in Example 1 and the polyaniline-coated commercially available SiO material.

[0033] Figure 4 The charge rate performance of a lithium-ion battery assembled with the conductive polymer-modified SiO negative electrode material prepared in Example 1 and the polyaniline-coated commercially available SiO material. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is described in detail below through specific embodiments.

[0035] Example 1

[0036] A method for preparing a conductive polymer modified SiO negative electrode material comprises the following steps:

[0037] S1. The Chlorella vulgaris was first washed with deionized water, then soaked in an organic solvent obtained by mixing formaldehyde, ethylene glycol, and ethanol in a volume ratio of 1:2:2, and then dried at 60°C for 3 hours to obtain a biological template;

[0038] S2. Ethylene glycol, ethanol, silane coupling agent KH-550, hexadecyltrimethylammonium bromide, and ethyl orthosilicate are uniformly mixed in a mass ratio of 3:1:2:1:6 to obtain a mixed solution;

[0039] S3, 100 g of the bio-template was mixed with 1000 g of the mixed solution, ball-milled at 1 atmosphere for 8 h, and then filtered. The obtained solid material was dried at 100 ° C for 3 h, and then sintered at 450 ° C for 5 h under a nitrogen atmosphere. After cooling, it was ground to obtain 137 g of powder;

[0040] S4. Add the powder to an acidic solution containing aniline and mix evenly, then add 140 g of ammonium persulfate at 0° C. and carry out polymerization reaction for 5 h. Then filter and wash, dry and grind the obtained solid matter to obtain a conductive polymer modified SiO negative electrode material, wherein the acidic solution containing aniline is obtained by dissolving aniline in an aqueous solution of hydrochloric acid, and the aniline concentration in the acidic solution containing aniline is 1 mol / L. + The concentration is 0.5mol / L.

[0041] Example 2

[0042] A method for preparing a conductive polymer modified SiO negative electrode material comprises the following steps:

[0043] S1. The Chlorella vulgaris was first washed with deionized water, then soaked in an organic solvent obtained by mixing formaldehyde, ethylene glycol, and ethanol in a volume ratio of 1:2:2, and then dried at 100°C for 5 hours to obtain a biological template;

[0044] S2. Ethylene glycol, ethanol, silane coupling agent KH-550, hexadecyltrimethylammonium bromide, and ethyl orthosilicate are uniformly mixed in a mass ratio of 3:2:2:1:5 to obtain a mixed solution;

[0045] S3, 100 g of the bio-template was mixed with 1000 g of the mixed solution, ball-milled under 1 atmosphere of pressure for 9 h, and then filtered. The obtained solid material was dried at 60 ° C for 5 h, and then sintered at 450 ° C for 4 h under a nitrogen atmosphere. After cooling, it was ground to obtain 118 g of powder;

[0046] S4. Add the powder to an acidic solution containing aniline and mix evenly, then add 120 g of ammonium persulfate at 0° C. and carry out polymerization reaction for 3 h. Then filter and wash, dry and grind the obtained solid matter to obtain a conductive polymer modified SiO negative electrode material, wherein the acidic solution containing aniline is obtained by dissolving aniline in an aqueous solution of sulfuric acid, and the aniline concentration in the acidic solution containing aniline is 0.8 mol / L. + The concentration is 0.5mol / L.

[0047] Example 3

[0048] A method for preparing a conductive polymer modified SiO negative electrode material comprises the following steps:

[0049] S1. The Chlorella vulgaris was first washed with deionized water, then soaked in an organic solvent obtained by mixing formaldehyde, ethylene glycol, and ethanol in a volume ratio of 1:2:2, and then dried at 100°C for 5 hours to obtain a biological template;

[0050] S2. Ethylene glycol, ethanol, silane coupling agent KH-560, hexadecyltrimethylammonium bromide, and ethyl orthosilicate are uniformly mixed in a mass ratio of 4:2:2:1:4 to obtain a mixed solution;

[0051] S3, 100 g of the bio-template was mixed with 1000 g of the mixed solution, ball-milled under 1 atmosphere of pressure for 10 h, and then filtered. The obtained solid material was dried at 100 ° C for 3 h, and then sintered at 500 ° C for 5 h under a nitrogen atmosphere. After cooling, it was ground to obtain 115 g of powder;

[0052] S4. Add the powder to an acidic solution containing aniline and mix evenly, then add 120 g of ammonium persulfate at 0° C. and carry out polymerization reaction for 3 h. Then filter and wash, dry and grind the obtained solid matter to obtain a conductive polymer modified SiO negative electrode material, wherein the acidic solution containing aniline is obtained by dissolving aniline in an aqueous solution of sulfuric acid, and the aniline concentration in the acidic solution containing aniline is 0.8 mol / L. + The concentration is 1mol / L.

[0053] Example 4

[0054] A method for preparing a conductive polymer modified SiO negative electrode material comprises the following steps:

[0055] S1. The Chlorella vulgaris was first washed with deionized water, then soaked in an organic solvent obtained by mixing formaldehyde, ethylene glycol, and ethanol in a volume ratio of 1:2:2, and then dried at 100°C for 5 hours to obtain a biological template;

[0056] S2. Ethylene glycol, ethanol, silane coupling agent KH-560, hexadecyltrimethylammonium bromide, and ethyl orthosilicate are uniformly mixed in a mass ratio of 4:2:2:1:6 to obtain a mixed solution;

[0057] S3, 100 g of the bio-template was mixed with 1000 g of the mixed solution, ball-milled under 1 atmosphere of pressure for 10 h, and then filtered. The obtained solid material was dried at 100 ° C for 5 h, and then sintered at 550 ° C for 5 h under an inert atmosphere. After cooling, it was ground to obtain 165 g of powder;

[0058] S4. Add the powder to an acidic solution containing aniline and mix evenly, then add 180 g of ammonium persulfate at 0° C. and carry out polymerization reaction for 3 h. Then filter and wash, dry and grind the obtained solid matter to obtain a conductive polymer modified SiO negative electrode material, wherein the acidic solution containing aniline is obtained by dissolving aniline in an aqueous solution of nitric acid, and the aniline concentration in the acidic solution containing aniline is 0.8 mol / L. + The concentration is 1mol / L.

[0059] The performance of the lithium-ion battery was tested by using the conductive polymer modified SiO negative electrode material prepared in the example and the negative electrode material obtained by normal polyaniline coating of commercially available SiO material with a capacity of 1200 mAh / g (i.e., polyaniline-coated commercial SiO material) and the assembled lithium-ion battery. The test methods: particle size, specific surface area, and tapping were in accordance with GB / T 24513-2019, and the buckling test was in accordance with GB / T-24533-2019. The results are as follows: Figure 1-4 and as shown in Table 1.

[0060] Figure 1 The scanning electron microscope image of the conductive polymer modified SiO negative electrode material prepared in Example 1. Figure 1 It can be seen that the prepared conductive polymer modified SiO negative electrode material has a regular morphology and the surface is evenly covered with conductive polyaniline.

[0061] Figure 2 This is the charge-discharge curve of the lithium-ion battery assembled with the conductive polymer modified SiO negative electrode material prepared in Example 1. Figure 2 It can be seen that the conductive polymer modified SiO negative electrode material prepared in Example 1 has a good charge-discharge curve and a specific capacity higher than 1200 mAh / g.

[0062] Figure 3 This is a charge cycle diagram of a lithium-ion battery assembled with the conductive polymer-modified SiO negative electrode material prepared in Example 1 and the polyaniline-coated commercially available SiO material. Figure 4 The charge rate performance of the lithium-ion battery obtained by assembling the conductive polymer modified SiO negative electrode material prepared in Example 1 and the polyaniline coated commercial SiO material. Figure 3 、 Figure 4 It can be seen that the conductive polymer modified SiO negative electrode material prepared in Example 1 is superior to the polyaniline coated commercially available SiO material in terms of rate performance and cycle performance.

[0063] Table 1 shows the physicochemical properties of the conductive polymer modified SiO negative electrode materials and the polyaniline coated commercial SiO materials prepared in Examples 1-4, as well as the electrical performance test results of the lithium ion batteries assembled therefrom.

[0064] Table 1

[0065]

[0066] As can be seen from Table 1, the capacity of the conductive polymer modified SiO negative electrode material prepared in Example is slightly higher than 1200 mAh / g, and the first efficiency is comparable to that of the polyaniline-coated commercial SiO material, but the cycle performance is much higher than that of the polyaniline-coated commercial SiO material.

[0067] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a conductive polymer modified SiO negative electrode material, characterized in that: The following steps are involved: S1, washing the Chlorella with deionized water, soaking it in an organic solvent, and drying it at low temperature to obtain a biological template; S2. Evenly mix ethylene glycol, ethanol, silane coupling agent, hexadecyltrimethylammonium bromide, and ethyl orthosilicate to obtain a mixed solution; the mass ratio of ethylene glycol, ethanol, silane coupling agent, hexadecyltrimethylammonium bromide, and ethyl orthosilicate is (3-5): (1-3): (2-4): 1: (3-6); S3, mixing the bio-template and the mixed solution uniformly, ball milling under a certain air pressure, and then separating the solid and liquid, drying the obtained solid material, sintering under an inert atmosphere, and grinding after cooling to obtain a powder; the mass ratio of the bio-template to the mixed solution is 1: (5-15); the sintering temperature is 450 ° C to 550 ° C, and the time is 3-5 hours; S4. Coating polyaniline on the surface of the powder by in-situ polymerization to obtain a conductive polymer-modified SiO negative electrode material.

2. The method for preparing a conductive polymer modified SiO negative electrode material according to claim 1, wherein: In S1, the organic solvent is obtained by mixing formaldehyde, ethylene glycol, and ethanol in a volume ratio of 1:(1-3):(1-3).

3. The method for preparing a conductive polymer modified SiO negative electrode material according to claim 1, wherein: In S1, the low-temperature drying temperature is 60-100° C. and the time is 3-5 hours.

4. The method for preparing a conductive polymer modified SiO negative electrode material according to claim 1, wherein: In S3, the mixture is ball milled at an atmospheric pressure of 1 to 2 atmospheres for 8 to 10 hours.

5. The method for preparing a conductive polymer modified SiO negative electrode material according to claim 1, wherein: In S3, the drying temperature is 60-100° C. and the drying time is 3-5 hours.

6. The method for preparing a conductive polymer modified SiO negative electrode material according to claim 1, characterized in that: In S4, the specific method of coating the powder surface with polyaniline by in-situ polymerization is: adding the powder to an acidic solution containing aniline and mixing evenly, then adding an oxidant at 0-5° C. and performing polymerization reaction for 2-5 hours.

7. The method for preparing a conductive polymer modified SiO negative electrode material according to claim 6, characterized in that: In the acidic solution containing aniline, the concentration of aniline is 0.5-1 mol / L, H + The concentration is 0.5-3mol / L.

8. The method for preparing a conductive polymer-modified SiO negative electrode material according to claim 6, wherein: The oxidant is at least one of ammonium persulfate, hydrogen peroxide, and ferric chloride.

9. The method for preparing a conductive polymer-modified SiO negative electrode material according to claim 6, wherein: The amount of the oxidant used is 1-1.3 times the mass of the powder.

10. A conductive polymer modified SiO negative electrode material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.

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