CN115020670A - A kind of MOFs modified silicon-based negative electrode material and preparation method thereof - Google Patents

Abstract

The invention discloses a MOFs modified silicon-based negative electrode material and a preparation method thereof, wherein the preparation method comprises the following steps: preparing a precursor liquid containing a silicon source and a metal salt; adding a first organic ligand into the precursor liquid for reaction to carry out MOFs modification, drying the coated plate, and carrying out heat treatment to obtain a MOFs modified silicon-based precursor material; and (3) placing the MOFs modified silicon-based precursor material into a zinc salt solution, adding a second organic ligand for hydrophobic modification, and drying to obtain the MOFs modified silicon-based negative electrode material. According to the invention, the conductive performance of the silicon-based negative electrode material can be obviously improved by introducing the alloy element and the carbon skeleton, the conductive performance of the silicon-based negative electrode material is enhanced, and the electrochemical performance of the silicon-based negative electrode material is favorably improved after the metal ions are reasonably doped; the dispersibility of the silicon-based negative electrode material is improved through hydrophobic modification, so that the volume expansion hazard of the silicon-carbon negative electrode material is reduced.

Description

A kind of MOFs modified silicon-based negative electrode material and preparation method thereof

technical field

The invention relates to the technical field of lithium batteries, in particular to a silicon-based negative electrode material modified by MOFs and a preparation method thereof.

Background technique

Lithium-ion batteries have the advantages of high energy storage density, high open-circuit voltage, and low self-discharge rate, and have been widely used in recent years. At present, the commercial lithium batteries use graphite-like carbon as the negative electrode material, but the theoretical capacity of graphite is only 372mAh/g, and the rate performance is not good. The theoretical specific capacity of silicon is as high as 4200mAh/g, which is an order of magnitude higher than the specific capacity of graphite-based anode materials, and its intercalation/delithiation potential is moderate, and its reactivity with electrolyte is low. Ideal for anode materials for Li-ion batteries.

However, during the alloying reaction between silicon and lithium, the silicon material will have a violent volume expansion (>300%), which may easily lead to the rapid pulverization and shedding of the active material during the cycle, and the electrical contact between the electrode active material and the current collector is weakened. , so that the battery cycle life rapidly declines. At the same time, due to the volume expansion effect of the silicon material, the silicon material cannot produce a solid surface solid electrolyte (SEI) film in the electrolyte, the electrode structure is destroyed, and the newly exposed silicon surface will continue to form new SEI. film, resulting in reduced charge-discharge efficiency and accelerated capacity decay. Therefore, how to improve the electrical conductivity of silicon anode materials and reduce the expansion during cycling is a major research focus in this field. The Chinese patent application document with publication number CN109671928A discloses a preparation method of a silicon-based negative electrode material coated by carbonization of MOFs, which utilizes the ordered and stable structure of metal-organic framework materials to coat highly dispersed nano-silicon, and then Carbonization is carried out by heat treatment in an inert atmosphere to obtain a silicon-based negative electrode material. At the same time, the system also contains uniformly dispersed metal nanoparticles, which can effectively alleviate the volume change of nano-silicon and improve the conductivity of the system. However, only one organic compound is used for coordination, and the obtained negative electrode material still has the defects of poor cycle life and large volume expansion effect.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention lies in how to solve the problems of poor cycle life and large volume expansion effect of the existing silicon-based negative electrode materials, and poor dispersion when actually forming a silicon-carbon negative electrode with carbon materials, resulting in poor quality controllability. Provided are a MOFs-modified silicon-based negative electrode material and a preparation method thereof.

The present invention realizes and solves the above-mentioned technical problems through the following technical means:

A preparation method of a silicon-based negative electrode material modified by MOFs, comprising the following steps:

S1. Prepare a precursor liquid containing silicon source and metal salt;

S2, adding the first organic ligand to the precursor solution described in S1 to react with MOFs, and heat-treating the coated plate after drying to obtain the MOFs-modified silicon-based precursor material;

S3, placing the MOFs-modified silicon-based precursor material in S2 in a zinc salt solution, adding a second organic ligand for hydrophobic modification, and drying to obtain the MOFs-modified silicon-based negative electrode material.

Beneficial effects: In the technical solution of the present invention, by introducing a networked MOFs structure, the silicon negative electrode material with carbon as the network skeleton greatly improves the electrical conductivity, and the alloying can effectively avoid the serious volume expansion problem caused by conventional alloying. , to realize the organic coordination of silicon-based materials and metals. At the same time, the modified MOFs particles introduced with metal salts can greatly improve the electrical conductivity and electrochemical properties of silicon-based anode materials, so that the rate performance and cycle performance can be significantly improved; The secondary modification with MOFs particles makes the silicon-based anode material have a certain degree of hydrophobicity, which can significantly improve its dispersibility. No contact to reduce the detrimental effects of silicon volume expansion.

Preferably, in S1, the silicon source includes a mixture of one or more of trichlorosilane, silicon tetrachloride, ethyl orthosilicate, and sodium silicate; the metal salt includes silver salt, manganese One or more mixtures of salts and iron salts.

Preferably, in S1, the metal salt includes silver nitrate, silver chloride, silver bromide, manganese chloride, manganese sulfate, manganese acetate, potassium permanganate, ferric chloride hexahydrate, ferric nitrate, ferric sulfate one or more mixtures.

Preferably, in S1, a silicon source is dissolved in a type A solvent to obtain a silicon solution, and a metal salt is dissolved in a type B solvent to obtain a salt solution; the silicon solution is mixed with the salt solution to obtain a precursor liquid containing the silicon source and the metal salt. ; Described A class solvent includes one or more mixtures in benzene, chloroform, ether, petroleum ether; Described B class solvent includes benzene, toluene, pentane, hexane, cyclohexane, cyclohexanone, methyl alcohol cyclohexanone, ether, propylene oxide, methyl acetate, ethyl acetate, propyl acetate, acetone, methyl butanone, methyl isobutyl ketone, ethylene glycol monomethyl ether, acetonitrile, pyridine, phenol one or more mixtures.

Preferably, the molar concentration of silicon element in the silicon solution is 0.1-1.0 mol/L; the molar concentration of metal ions in the salt solution is 0.1-1.0 mol/L; the precursor after the silicon solution and the salt solution are mixed The molar ratio of silicon and metal ions in the body fluid is 1:0.5-2.

Preferably, in S2, the first organic ligand is a mixture of one or more of carboxylic acid organic ligands, ammonia organic ligands, and pyridine organic ligands; the first organic ligand The molar dosage of S1 is 0.125-0.5 times the total molar amount of silicon element and metal ions in the precursor liquid in S1.

Preferably, the first organic ligand is 5,15-bis(4'-carboxyphenyl)porphyrin, 1,2-bis(4-carboxyphenyl)-1,2-stilbene, 5,10 ,15,20-Tetrakis(4-carboxyphenyl)porphyrin, 1,3,5,7-adamantanetetracarboxylic acid, 1,2-diphenyl-1,2-bis(4-carboxyphenyl)ethylene , 1,3,5-tris(4-carboxyphenylethynyl)benzene, 1,3,5-tris(4'-aminophenoxy)benzene, 1,4-bis(2',6,'- A mixture of one or more of dicarboxyphenyl-4'-pyridine)benzene.

Preferably, in S2, the heat treatment is performed in a protective atmosphere, the temperature of the heat treatment is 800-1200°C, and the time is 2-10h.

Preferably, in the heat treatment process, the temperature is raised to 800-1200° C. for 2-10 hours at a heating rate of 1° C./min.

Preferably, in S2, the method of the reaction is a solvothermal method, a seed crystal method or a microwave method.

Preferably, in S3, the molar concentration of zinc in the zinc salt solution is 0.10-0.35mol/L; in the zinc salt solution, the zinc salt used is one or both of zinc nitrate and zinc chloride mixture, the solvent used is one of methanol and ethanol or a mixture of both; the second organic ligand is 2-methylimidazole; the 2-methylimidazole is prepared as 0.5-2.0g/L alcohol solution And add the zinc salt solution in an amount of 1.0-2.5 times the volume.

Preferably, in S2, the MOFs-modified silicon-based precursor material in S2 is placed in a zinc salt solution in an amount of 30-50 g/100 ml.

The present invention also proposes a MOFs-modified silicon-based negative electrode material, which is prepared by using the preparation method of the MOFs-modified silicon-based negative electrode material.

In the technical solution of the present invention, by introducing the network-like MOFs structure, the silicon anode material with carbon as the network skeleton greatly improves the electrical conductivity, and the alloying can effectively avoid the serious volume expansion problem caused by conventional alloying, and realize silicon Organic coordination of base materials and metals. At the same time, the introduction of silver and/or manganese and/or iron MOFs particle modification can greatly improve the electrical conductivity and electrochemical performance of silicon-based anode materials, and their rate performance and cycle performance can be significantly improved. Further, the technical solution of the present invention is to perform secondary modification with MOFs particles on the formed granular silicon MOFs carrier, so that the silicon-based negative electrode material has a certain degree of hydrophobicity, which can significantly improve its dispersibility. During the preparation of silicon dioxide, a gap core-shell structure can be effectively formed, that is, the core-shell separation is not in contact with each other, so as to reduce the adverse effects caused by the volume expansion of silicon.

The advantages of the present invention are:

1) Through technical improvement, the huge volume expansion problem of the silicon-based negative electrode material during the alloying process is avoided, and the structural stability of the alloyed silicon-based negative electrode material is improved;

2) By introducing alloying elements and carbon skeleton, the electrical conductivity of silicon-based anode materials can be significantly improved, and the electrical conductivity of silicon-based anode materials can be strengthened, and rational doping of metal ions is beneficial to improve the electrochemical performance of silicon-based anode materials;

3) Improve the dispersibility of silicon-based anode materials through hydrophobic modification to reduce the harm of volume expansion of silicon-carbon anode materials;

4) The rate performance and cycle performance of the overall silicon-based anode material are significantly improved in practical use.

Description of drawings

1 is a comparison diagram of the 100mA cycle discharge capacity curves at room temperature of batteries prepared from silicon-based negative electrode materials prepared in Example 2 of the present invention and Comparative Example 2;

FIG. 2 is a comparison diagram of discharge capacity curves of batteries prepared from silicon-based negative electrode materials prepared in Example 2 of the present invention and Comparative Example 2 under different rate conditions.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the present invention. examples, but not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The test materials and reagents used in the following examples can be obtained from commercial sources unless otherwise specified.

If the specific technology or condition is not indicated in the embodiment, it can be carried out according to the technology or condition described in the literature in this field or according to the product specification.

Example 1

A MOFs-modified silicon-based negative electrode material is prepared by the following method:

1) respectively prepare 0.2mol/L ethyl orthosilicate ether solution and 0.1mol/L silver nitrate acetone solution, and mix in equal volume to obtain precursor liquid;

2) 1,3,5-tris(4-carboxyphenylethynyl)benzene was added to the precursor solution at a ratio of 0.04 mol per liter, MOFs were modified by a solvothermal reaction at 200°C for 10 h, and the plate was dried at 80°C Then, under nitrogen protection, the temperature was heated to 800 °C for 10 h at a heating rate of 1 °C/min to obtain the MOFs-modified silicon-based precursor material;

3) The silicon-based precursor material modified by MOFs is placed in a 0.15mol/L zinc nitrate ethanol solution at a ratio of 50g:100mL, and the concentration is 1.0g/L by adding 1.5L per liter of the zinc nitrate ethanol solution. The 2-methylimidazole ethanol solution of 2-methylimidazole was added in three equal amounts during the addition process. After each addition, the reaction was mixed for 4 hours. After the addition and the reaction was complete, the solid was filtered out and the solid was heat-treated at 60 °C for 12 hours and dried to obtain MOFs. Modified silicon-based anode material.

Example 2

A MOFs-modified silicon-based negative electrode material is prepared by the following method:

1) respectively prepare the propyl acetate solution of the silicon tetrachloride petroleum ether solution of 0.75mol/L and the ferric chloride hexahydrate of 0.375mol/L, and equal volume mixing obtains the precursor liquid;

2) 1,3,5-tris(4-carboxyphenylethynyl)benzene was added to the precursor solution at a ratio of 0.25 mol per liter, MOFs were modified by a solvothermal reaction at 200°C for 12h, and the plate was dried at 80°C Then, under nitrogen protection, the temperature was heated to 1000 °C for 8 h at a heating rate of 1 °C/min to obtain the MOFs-modified silicon-based precursor material;

3) The silicon-based precursor material modified by MOFs is placed in a 0.30 mol/L zinc nitrate ethanol solution at a ratio of 50 g: 100 mL, and the concentration is 1.5 g/L by adding 2.0 L per liter of the zinc nitrate ethanol solution. The 2-methylimidazole ethanol solution of 2-methylimidazole was added in three equal amounts during the addition process. After each addition, the reaction was mixed for 4 hours. After the addition and the reaction was complete, the solid was filtered out and the solid was heat-treated at 60 °C for 12 hours and dried to obtain MOFs. Modified silicon-based anode material.

Example 3

A MOFs-modified silicon-based negative electrode material is prepared by the following method:

1) respectively prepare the methyl acetate solution of the silicon tetrachloride chloroform solution of 1.0mol/L and the manganese sulfate of 0.5mol/L, and equal volume mixing obtains the precursor liquid;

2) 1,4-bis(2',6,'-dicarboxyphenyl-4'-pyridine)benzene was added to the precursor liquid at a ratio of 0.3 mol per liter, and MOFs were carried out by a solvothermal reaction at 200°C for 14 h Modified, the coated plate was dried at 80 °C and then heated to 1000 °C for 6.5 h at a heating rate of 1 °C/min under nitrogen protection to obtain the MOFs-modified silicon-based precursor material;

3) The silicon-based precursor material modified by MOFs is placed in a 0.1 mol/L zinc nitrate ethanol solution at a ratio of 30 g: 100 mL, and the concentration is 2.0 g/L by adding 1.0 L per liter of the zinc nitrate ethanol solution. The 2-methylimidazole ethanol solution was added in three equal amounts during the addition process. After each addition, the reaction was mixed for 4 hours. After the addition and the reaction was completed, the solid was filtered out and the solid was heat-treated at 60 °C for 12 hours. Dry to obtain MOFs modified Silicon-based anode material.

Example 4

A MOFs-modified silicon-based negative electrode material is prepared by the following method:

1) respectively prepare the ethyl orthosilicate ether solution of 1.0mol/L and the silver nitrate acetone solution of 1.0mol/L, and equal volume mixing obtains the precursor liquid;

2) Add 1,3,5-tris(4-carboxyphenylethynyl)benzene to the precursor liquid at a ratio of 0.5 mol per liter, carry out MOFs modification through a solvothermal reaction at 200°C for 14h, and dry the plate at 80°C Then, under nitrogen protection, the temperature was heated to 1000 °C for 9 h at a heating rate of 1 °C/min to obtain the MOFs-modified silicon-based precursor material;

3) The silicon-based precursor material modified by MOFs is placed in a 0.35mol/L zinc nitrate ethanol solution at a ratio of 50g:100mL, and the concentration is 1.5g/L by adding 2.5L per liter of the zinc nitrate ethanol solution. The 2-methylimidazole ethanol solution of 2-methylimidazole was added in three equal amounts during the addition process. After each addition, the reaction was mixed for 4 hours. After the addition and the reaction was completed, the solid was filtered out and the solid was heat-treated at 60 °C for 12 hours and dried to obtain MOFs modification. silicon-based anode material.

Example 5

A MOFs-modified silicon-based negative electrode material is prepared by the following method:

1) respectively prepare 0.1mol/L ethyl orthosilicate ether solution and 0.2mol/L silver nitrate acetone solution, and mix in equal volume to obtain precursor liquid;

2) 1,3,5-tris(4-carboxyphenylethynyl)benzene was added to the precursor liquid at a ratio of 0.05 mol per liter, MOFs were modified by a solvothermal reaction at 200°C for 14h, and the plate was dried at 80°C Then, under nitrogen protection, the temperature was heated to 1200 °C for 2 h at a heating rate of 1 °C/min to obtain the MOFs-modified silicon-based precursor material;

3) The silicon-based precursor material modified by MOFs is placed in a 0.35mol/L zinc chloride ethanol solution at a ratio of 50g:100mL, and the concentration is 0.5g by adding 2.4L per liter of zinc chloride ethanol solution. /L 2-methylimidazole ethanol solution was added in three equal amounts during the addition process. After each addition, the reaction was mixed for 4 hours. After the addition and the reaction was complete, the solid was filtered out and the solid was heat-treated at 60 °C for 12 hours and dried to obtain MOFs. Modified silicon-based anode material.

Example 6

A MOFs-modified silicon-based negative electrode material is prepared by the following method:

1) respectively prepare 0.1mol/L trichlorosilane ether solution and 0.1mol/L silver chloride pyridine solution, and mix in equal volume to obtain precursor liquid;

2) 5,15-bis(4'-carboxyphenyl) porphyrin was added to the precursor liquid at a ratio of 0.0125 mol per liter, MOFs were modified by a solvothermal reaction at 200 °C for 12 h, and the coated plate was dried at 80 °C for 12 h. Under nitrogen protection, the temperature was heated to 1100 °C at a heating rate of 1 °C/min for 5.5 h to obtain MOFs-modified silicon-based precursor materials;

3) The MOFs-modified silicon-based precursor material was placed in a 0.17 mol/L zinc chloride ethanol solution at a ratio of 50 g: 100 mL, and 2- 2- Methylimidazole ethanol solution, in the process of adding, add 0.8L per liter of zinc chloride ethanol solution each time, mix and react for 3h after each addition, filter out the solid after adding and react completely and remove the solid After heat treatment at 70 °C for 10 h and drying, the MOFs-modified silicon-based anode material was obtained.

Example 7

A MOFs-modified silicon-based negative electrode material is prepared by the following method:

1) respectively prepare the benzene and petroleum ether solution of 0.2mol/L ethyl orthosilicate and the silver nitrate acetone solution of 0.1mol/L, and equal volume mixing obtains the precursor liquid;

2) 1,3,5-tris(4-carboxyphenylethynyl)benzene was added to the precursor solution at a ratio of 0.04 mol per liter, MOFs were modified by a solvothermal reaction at 200°C for 10 h, and the plate was dried at 80°C Then, under nitrogen protection, the temperature was heated to 800 °C for 10 h at a heating rate of 1 °C/min to obtain the MOFs-modified silicon-based precursor material;

3) The silicon-based precursor material modified by MOFs is placed in a 0.15mol/L zinc nitrate ethanol solution at a ratio of 50g:100mL, and the concentration is 1.0g/L by adding 1.5L per liter of the zinc nitrate ethanol solution. The 2-methylimidazole ethanol solution of 2-methylimidazole was added in three equal amounts during the addition process. After each addition, the reaction was mixed for 4 hours. After the addition and the reaction was complete, the solid was filtered out and the solid was heat-treated at 60 °C for 12 hours and dried to obtain MOFs. Modified silicon-based anode material.

Example 8

A MOFs-modified silicon-based negative electrode material is prepared by the following method:

1) respectively prepare the ether solution of 0.2mol/L ethyl orthosilicate and the toluene and ether solution of 0.1mol/L silver nitrate, and mix equal volume to obtain precursor liquid;

2) 1,3,5-tris(4-carboxyphenylethynyl)benzene was added to the precursor solution at a ratio of 0.04 mol per liter, MOFs were modified by a solvothermal reaction at 200°C for 10 h, and the plate was dried at 80°C Then, under nitrogen protection, the temperature was heated to 800 °C for 10 h at a heating rate of 1 °C/min to obtain the MOFs-modified silicon-based precursor material;

3) The silicon-based precursor material modified by MOFs is placed in a 0.15mol/L zinc nitrate ethanol solution at a ratio of 50g:100mL, and the concentration is 1.0g/L by adding 1.5L per liter of the zinc nitrate ethanol solution. The 2-methylimidazole ethanol solution of 2-methylimidazole was added in three equal amounts during the addition process. After each addition, the reaction was mixed for 4 hours. After the addition and the reaction was complete, the solid was filtered out and the solid was heat-treated at 60 °C for 12 hours and dried to obtain MOFs. Modified silicon-based anode material.

Comparative Example 1

The specific preparation process is the same as that in Example 2, the difference is that in step 2), the first organic ligand is not added to modify the MOFs particles.

Comparative Example 2

The silicon-based negative electrode material was obtained by directly applying 0.75 mol/L silicon tetrachloride petroleum ether solution at 80 °C and drying the plate under nitrogen protection at 1000 °C (heating rate of 1 °C/min) for 8 h.

Comparative Example 3

The specific preparation process is the same as that of Example 2, except that step 3) is not performed, and the silicon-based precursor material modified with MOFs is directly used as the silicon-based negative electrode material.

Blank control group (CK group)

Commercially available silicon-based anode materials.

test:

The silicon-based negative electrode materials prepared in the above Examples 1-8 and Comparative Examples 1-3 and the commercially available silicon-based negative electrode materials were assembled into button cells. The obtained silicon-based negative electrode material, CMC-Na, SBR and SP were mixed in a mass ratio of 95:1.5:2:1.5, and the negative electrode was prepared by a conventional process, and a pure lithium sheet was used as the counter electrode. PE diaphragm, the electrolyte active material is 1mol/L LiPF6, the electrolyte solvent is the volume ratio EC:EMC=1:1, an appropriate amount of foam nickel gasket can be added according to the remaining space of the button battery, and finally put in an argon-filled glove box The button battery with the model number CR2032 assembled in China, the battery number corresponds to the source of its silicon-based negative electrode material.

The cycle performance and rate performance of the prepared CR2032 button battery were tested.

Among them, the comparison chart of the 100mA cycle discharge capacity curves of the batteries prepared from the negative materials of Example 2 and Comparative Example 2 at room temperature is shown in Figure 1, and the comparison chart of the discharge capacity curves under different rate conditions is shown in Figure 2. In the figure: silicon-MOFs refers to the Instead of Example 2, silicon refers to Comparative Example 2; it can be seen from Figures 1 and 2 that the silicon-based anode material modified by the double MOFs of the present invention is significantly better than the one without MOFs modification in terms of cycle performance and rate performance. Silicon-based anode material.

Specifically, the cycle performance and rate performance of each CR2032 coin cell battery are shown in the following table

Among them, the rate performance test is: 0.1C (100mA), 0.2C (200mA), 0.3C (300mA), 0.4C (400mA) and 0.5C (500mA) rate conditions for 10 cycles respectively, and then at 0.1 10 cycles (51st to 60th cycles) were performed under the condition of C (100 mA). In the table, the 0.5C rate cycle retention rate is the capacity retention rate of the 50th cycle, and the 51-60 cycle capacity retention rate of the rate test is the capacity retention rate of the 60th cycle.

It can be seen from the data in the above table that the two MOFs particle modifications in the actual technical solution of the present invention have a significant impact on the performance of the silicon-based negative electrode material. Relatively speaking, the first modification of MOFs particles is more excellent and significant for directly improving the electrical conductivity and electrochemical performance of silicon-based anode materials. Comparative Example 3 has both 80% capacity and room temperature cycles and 0.5C rate cycle retention. It is better than Comparative Example 1, but it can be seen that the performance of Comparative Example 1 is better than that of Comparative Example 3 in the 51-60 cycle capacity retention test of the rate test. Therefore, in fact, the main role of Ag/Mn/Fe-MOFs particle modification is to improve the direct conductivity and direct electrochemical performance of silicon-based anode materials, while the purpose of Zn-MOFs particle modification is to improve the mixing of silicon-based anode materials and carbon materials. The adaptability of the silicon carbon anode material formed later to the rate, switching to a low rate cycle after a high rate cycle can quickly restore its capacity; and the effect produced by the combination of the two is better than either of them. , resulting in a certain synergy, with a significant performance improvement.

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The recorded technical solutions are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A preparation method of a MOFs modified silicon-based negative electrode material is characterized by comprising the following steps: the method comprises the following steps:

s1, preparing a precursor liquid containing a silicon source and a metal salt;

s2, adding a first organic ligand into the precursor liquid in the S1 to react to perform MOFs modification, and carrying out heat treatment after coating and drying to obtain a MOFs modified silicon-based precursor material;

s3, placing the MOFs modified silicon-based precursor material in the S2 in a zinc salt solution, adding a second organic ligand for hydrophobic modification, and drying to obtain the MOFs modified silicon-based negative electrode material.

2. The method for preparing a MOFs-modified silicon-based negative electrode material according to claim 1, wherein: in S1, the silicon source includes one or more of trichlorosilane, silicon tetrachloride, ethyl orthosilicate, and sodium silicate; the metal salt comprises one or more of silver salt, manganese salt and ferric salt.

3. The method for preparing a MOFs-modified silicon-based negative electrode material according to claim 1 or 2, wherein: at S1, the metal salt includes one or more of silver nitrate, silver chloride, silver bromide, manganese chloride, manganese sulfate, manganese acetate, potassium permanganate, ferric chloride hexahydrate, ferric nitrate, and ferric sulfate.

4. The method for preparing a MOFs-modified silicon-based negative electrode material according to claim 1 or 2, wherein: in S1, dissolving a silicon source in a solvent A to obtain a silicon solution, and dissolving a metal salt in a solvent B to obtain a salt solution; mixing a silicon solution with a salt solution to obtain a precursor solution containing a silicon source and a metal salt; the A-type solvent comprises one or more of benzene, chloroform, diethyl ether and petroleum ether; the B-type solvent comprises one or more of benzene, toluene, pentane, hexane, cyclohexane, cyclohexanone, methylcyclohexanone, diethyl ether, epoxypropane, methyl acetate, ethyl acetate, propyl acetate, acetone, methyl butanone, methyl isobutyl ketone, ethylene glycol monomethyl ether, acetonitrile, pyridine and phenol.

5. The method for preparing MOFs-modified silicon-based negative electrode material according to claim 4, wherein: the molar concentration of the silicon element in the silicon solution is 0.1-1.0 mol/L; the molar concentration of metal ions in the salt solution is 0.1-1.0 mol/L; the molar ratio of silicon element to metal ion in the precursor liquid after the silicon solution and the salt solution are mixed is 1: 0.5-2.

6. The method for preparing a MOFs-modified silicon-based negative electrode material according to claim 1, wherein: in S2, the first organic ligand is one or a mixture of more of carboxylic acid organic ligands, ammonia organic ligands, and pyridine organic ligands; the molar usage of the first organic ligand is 0.125-0.5 times of the total molar weight of the silicon element and the metal ions in the precursor liquid in S1.

7. The preparation method of the MOFs-modified silicon-based anode material according to claim 1, wherein the preparation method comprises the following steps: the first organic ligand is one or a mixture of more of 5, 15-di (4' -carboxyphenyl) porphyrin, 1, 2-di (4-carboxyphenyl) -1, 2-stilbene, 5,10,15, 20-tetra (4-carboxyphenyl) porphyrin, 1,3,5, 7-adamantanetetracarboxylic acid, 1, 2-diphenyl-1, 2-di (4-carboxyphenyl) ethylene, 1,3, 5-tri (4-carboxyphenylethynyl) benzene, 1,3, 5-tri (4' -aminophenoxy) benzene, 1, 4-bis (2',6, ' -dicarboxyphenyl-4 ' -pyridine) benzene.

8. The method for preparing a MOFs-modified silicon-based negative electrode material according to claim 1, wherein: in S2, the heat treatment is carried out in a protective atmosphere, and the temperature of the heat treatment is 800-1200 ℃ for 2-10 h.

9. The method for preparing a MOFs-modified silicon-based negative electrode material according to claim 1, wherein: in S3, the molar concentration of zinc in the zinc salt solution is 0.10-0.35 mol/L; in the zinc salt solution, the zinc salt is one or a mixture of two of zinc nitrate and zinc chloride, and the solvent is one or a mixture of two of methanol and ethanol; the second organic ligand is 2-methylimidazole; the 2-methylimidazole is prepared into 0.5-2.0g/L alcoholic solution and added in an amount which is 1.0-2.5 times of the volume of the zinc salt solution.

10. A MOFs modified silicon-based negative electrode material is characterized in that: the preparation method of the MOFs-modified silicon-based negative electrode material as claimed in any one of claims 1 to 9.

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