High-performance composite silicon-based negative electrode material and preparation method thereof

Abstract

The invention provides a high-performance composite silicon-based negative electrode material and a preparation method thereof, and relates to the technical field of preparation of silicon-based negative electrode materials. The composite silicon-based negative electrode material comprises a silicon material; and the self-adaptive telescopic layer is positioned on the outer surface of the silicon material. The material can effectively improve the volume expansion of the silicon material in the charging and discharging process, so that the cycling stability and the service life of the silicon-based negative electrode material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of silicon-based negative electrode materials, and in particular to a high-performance composite silicon-based negative electrode material and a preparation method thereof. Background Art

[0002] With the development of new energy electric vehicles, power lithium-ion batteries will have a huge market for a long time. Electrode materials are a major factor affecting the performance of power lithium-ion batteries, and negative electrode materials are one of the key factors that determine the performance of lithium-ion batteries. At present, the negative electrode materials of commercial lithium-ion batteries are mainly graphite-based carbon materials, which have good cycle performance, but low capacity and poor rate performance, which are difficult to meet the demand. Silicon materials have high specific capacity, making them a research hotspot.

[0003] However, the volume of silicon materials expands greatly during the process of lithium insertion and extraction, and repeated charging and discharging can easily cause the active materials bonded to the current collector to crack directly and even peel off, resulting in poor cycle performance. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a high-performance composite silicon-based negative electrode material and a preparation method thereof, which solves the technical problem that the active material bonded to the current collector cracks and peels off due to the large volume expansion of the silicon material during lithium insertion and deinsertion.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a composite silicon-based negative electrode material, comprising:

[0009] Silicon materials;

[0010] The adaptive stretching layer is located on the outer surface of the silicon material.

[0011] A composite silicon-based negative electrode material of the present invention includes an adaptive telescopic layer, which is scalable and repairable. The volume expansion of the silicon material formed by the deintercalation and extraction of lithium ions can reaggregate the broken silicon material together through the elasticity of the adaptive telescopic layer. Therefore, the adaptive telescopic layer provides a volume expansion protection zone for the silicon material, effectively improving the volume expansion of the silicon material during the charging and discharging process, thereby improving the cycle stability and service life of the silicon-based negative electrode material.

[0012] Preferably, the adaptive scaling layer satisfies at least one of the following conditions:

[0013] The adaptive telescopic layer material includes graphene, and graphene wrapping can effectively improve the conductivity of silicon materials and improve their rate performance.

[0014] The thickness of the adaptive telescopic layer is 1 to 150 nm.

[0015] Preferably, the graphene satisfies at least one of the following conditions:

[0016] The graphene includes three-dimensional graphene balls, which are stretchable. The volume expansion of the silicon material formed by the deintercalation of lithium ions can reassemble the broken silicon material through the stretchability of the three-dimensional graphene balls, thereby improving the cycle stability of the negative electrode material.

[0017] The mass percentage of the graphene in the adaptive telescopic layer is 1-10%.

[0018] Preferably, the three-dimensional graphene spheres are graphene hyperbranched polyurethane composite materials, which are retractable and self-healing. The volume expansion of the silicon material caused by the insertion and extraction of lithium ions can repolymerize the broken silicon material through its retractable and self-healing properties, thereby improving the cycle stability of the negative electrode material.

[0019] Preferably, the graphene hyperbranched polyurethane composite material is obtained by covalent reaction of amino-functionalized graphene and polyurethane, the reaction raw materials are easily available, and the reaction process is easy to control.

[0020] Preferably, the polyurethane is a polyurethane containing a reversible covalent bond segment and a dynamic non-covalent bond segment, wherein the reversible covalent bond segment is one or more of a disulfide bond segment, a Diels-Alder reaction segment, and a borate bond segment, and the dynamic non-covalent bond segment is one or more of a hydrogen bond segment, an ionic bond segment, a metal coordination bond segment, and a host-guest structure. The polyurethane is formed by the interaction of reversible covalent bonds and dynamic non-covalent bonds so that the polyurethane spontaneously moves and re-entangles together without external force, thereby forming a self-healing function.

[0021] Preferably, the silicon material is selected from pure silicon, silicon-carbon material, silicon-oxygen material, silicon nanowire composite material, and silicon alloy material. The material has high specific capacity and the raw materials are easily available.

[0022] Preferably, the silicon-oxygen material is selected from silicon oxide, which has high specific capacity, abundant reserves and is easy to process as a negative electrode material.

[0023] In a second aspect, the present invention provides a method for preparing the composite silicon-based negative electrode material as described in the first aspect, comprising the following steps:

[0024] S1, mixing the aminoazobenzene derivative and the graphene sieve by ultrasonic dispersion to obtain a mixture;

[0025] S2, reacting the mixture at high temperature to obtain an amino-functionalized graphene sieve;

[0026] S3, adding the amino-functionalized graphene sieve and the silicon material into a solvent and reacting them by ultrasonic stirring to obtain a silicon-based material coated with amino-functionalized graphene;

[0027] S4, adding polyurethane to S3 for dispersion, and then irradiating with microwaves to obtain a silicon-based negative electrode material coated with three-dimensional graphene balls.

[0028] The preparation method of the present invention firstly adopts an aminoazobenzene derivative and a graphene sieve to carry out a solvent thermal reaction to produce an amino-functionalized graphene sieve, disperses the obtained amino-functionalized graphene sieve and a silicon material by ultrasonic, and then adds polyurethane to make the functionalized graphene sieve wrapped on the surface of the silicon material covalently react with the polyurethane to form a three-dimensional graphene ball by microwave radiation, and the three-dimensional graphene ball wraps the silicon material inside, so as to obtain a silicon-based negative electrode material wrapped by a three-dimensional graphene ball. The three-dimensional graphene ball is formed by cross-linking a self-healing graphene hyperbranched polyurethane composite material formed by covalently forming functionalized graphene and polyurethane, and has scalability. The volume expansion of the silicon material formed by the deintercalation and extraction of lithium ions can repolymerize the broken silicon material together through the expansion and contraction and self-healing properties of the three-dimensional graphene ball, thereby improving the material cycle stability. In addition, the three-dimensional graphene ball wrapping can effectively improve the conductivity of the silicon material and improve its rate performance.

[0029] Preferably, the aminoazobenzene derivative is selected from one or more of p-aminoazobenzene and 4-diethylaminoazobenzene.

[0030] Preferably, S2 satisfies at least one of the following conditions:

[0031] The high temperature is 70-180°C;

[0032] The reaction time is 6 to 24 hours.

[0033] Preferably, S3 satisfies at least one of the following conditions:

[0034] Ultrasonic stirring time is 1 to 36 hours.

[0035] The solvent is selected from any one of butanediol and ethanol;

[0036] In S4, the microwave radiation power is 100 to 1000 W, and the radiation time is 1 to 10 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 The cycle performance test results of the silicon oxide negative electrode material wrapped with three-dimensional graphene balls obtained in Example 1 and the silicon oxide negative electrode material of Comparative Example 1 were obtained. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The embodiments of the present application provide a high-performance composite silicon-based negative electrode material and a preparation method thereof, thereby solving the technical problem that the volume expansion of silicon materials during lithium insertion and extraction causes cracking and peeling of active materials bonded to the current collector, thereby improving the cycle performance and service life of the battery.

[0041] The technical solution in the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows:

[0042] The high-performance composite silicon-based negative electrode material of the present invention includes a silicon material and an adaptive telescopic layer uniformly coated on its surface. The preparation method thereof firstly adopts an aminoazobenzene derivative and a graphene sieve to carry out a solvent thermal reaction to produce an amino-functionalized graphene sieve, disperses the obtained amino-functionalized graphene sieve and the silicon material by ultrasonic, and then adds polyurethane to make the functionalized graphene sieve wrapped on the surface of the silicon material covalently react with the polyurethane to form a three-dimensional graphene ball by microwave radiation, and the three-dimensional graphene ball wraps the silicon material inside to obtain a silicon material negative electrode material wrapped by a three-dimensional graphene ball. The three-dimensional graphene ball is formed by cross-linking a self-repairable graphene hyperbranched polyurethane composite material formed by covalently forming functionalized graphene and polyurethane, and has telescopicity. The volume expansion of the silicon material formed by the deintercalation of lithium ions can repolymerize the broken silicon material together through the telescopicity of the three-dimensional graphene ball, thereby improving the cycle stability of the negative electrode material. In addition, the graphene wrapping can effectively improve the conductivity of the silicon material and improve its rate performance.

[0043] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0044] Example 1

[0045] This embodiment provides a method for preparing a high-performance composite silicon-based negative electrode material, comprising the following steps:

[0046] S1. Ultrasonically disperse 8 mmol of p-aminoazobenzene and 100 mg of graphene sieve;

[0047] S2. Add the mixture obtained in S1 into a reactor and react at 120° C. for 12 h to obtain amino-functionalized graphene sieve.

[0048] S3. Add 75 ml of butanediol to the amino-functionalized graphene sieve obtained in S2 and 5 g of silicon dioxide, and react for 24 hours by ultrasonic stirring to obtain silicon dioxide coated with amino-functionalized graphene.

[0049] S4. Add polyurethane to S3 and disperse it evenly, then irradiate it with microwaves at a power of 500 W for 6 h to obtain a silicon oxide negative electrode material wrapped with three-dimensional graphene balls.

[0050] The above obtained three-dimensional graphene ball wrapped silicon oxide negative electrode material: SP: LA133 = 8:1:1 was mixed and coated to assemble CR2032 button batteries. The electrolyte used was 1 mol / L LiPF6 EC + DMC solution, and the electrochemical performance test was carried out. The results are shown in Figure 1 .

[0051] Example 2

[0052] A method for preparing a high-performance composite silicon-based negative electrode material comprises the following steps:

[0053] S1. Ultrasonically disperse 8 mmol 4-diethylaminoazobenzene and 100 mg graphene sieve uniformly;

[0054] S2. Add the mixture obtained in S1 into a reactor and react at 70° C. for 24 h to obtain amino-functionalized graphene sieve.

[0055] S3. Add 75 ml of butanediol to the amino-functionalized graphene sieve obtained in S2 and 5 g of pure silicon, and react by ultrasonic stirring for 36 h to obtain amino-functionalized graphene-coated silicon.

[0056] S4. Add polyurethane to S3 and disperse it evenly, then irradiate it with microwaves at a power of 100 W for 10 h to obtain a silicon negative electrode material wrapped with three-dimensional graphene balls.

[0057] Example 3

[0058] A method for preparing a high-performance composite silicon-based negative electrode material comprises the following steps:

[0059] S1. Ultrasonically disperse 10 mmol of p-aminoazobenzene and 100 mg of graphene sieve;

[0060] S2. Add the mixture obtained in S1 into a reactor and react at 180° C. for 6 h to obtain amino-functionalized graphene sieve.

[0061] S3. Add 75 ml of butanediol to the amino-functionalized graphene sieve obtained in S2 and 6 g of silicon carbide, and react by ultrasonic stirring for 1 h to obtain amino-functionalized graphene-coated silicon carbide.

[0062] S4. Add polyurethane to S3 and disperse evenly, then irradiate with microwaves at a power of 200 W for 3 h to obtain a silicon carbide negative electrode material wrapped with three-dimensional graphene balls.

[0063] Example 4

[0064] A high-performance composite silicon-based negative electrode material and a preparation method thereof, comprising the following steps:

[0065] S1. Ultrasonically disperse 10 mmol of p-aminoazobenzene and 100 mg of graphene sieve;

[0066] S2. Add the mixture obtained in S1 into a reactor and react at 160° C. for 10 h to obtain amino-functionalized graphene sieve.

[0067] S3. Add 75 ml of butanediol to the amino-functionalized graphene sieve obtained in S2 and 6 g of gold nanoparticle-modified silicon nanowire composite material, and react by ultrasonic stirring for 24 hours to obtain amino-functionalized graphene-coated gold nanoparticle-modified silicon nanowires.

[0068] S4. Add polyurethane to S3 and disperse it evenly, then irradiate with microwaves at a power of 1000 W for 1 h to obtain a silicon nanowire negative electrode material modified with gold nanoparticles wrapped in three-dimensional graphene spheres.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that silicon dioxide anode material is used to replace silicon dioxide anode material wrapped in three-dimensional graphene spheres to assemble CR2032 button batteries, and the rest is the same as Example 1. The electrochemical performance test is performed on it, and the results are shown in Figure 1 .

[0071] from Figure 1It can be seen that the cycle performance of the battery prepared by the three-dimensional graphene ball-wrapped silicon oxide negative electrode material of Example 1 is significantly better than that of the silicon oxide negative electrode material of Comparative Example 1. This is because the three-dimensional graphene ball-wrapped silicon oxide composite material obtained by microwave radiation of graphene hyperbranched polyurethane composite material and silicon oxide material, wherein the three-dimensional graphene ball is obtained by cross-linking the self-repairing graphene hyperbranched polyurethane composite material, has scalability and repairability, and can self-regulate to adapt to the volume expansion formed by silicon oxide when lithium ions are inserted, and the broken silicon oxide is repolymerized after silicon oxide removes lithium ions, thereby providing a volume expansion protection zone during the repeated charge and discharge process of silicon oxide, and improving the cycle performance and service life of the battery.

[0072] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0073] 1. A composite silicon-based negative electrode material of the present invention includes an adaptive telescopic layer, which is scalable and repairable. The volume expansion of the negative electrode material formed by the deintercalation and extraction of lithium ions can reaggregate the broken silicon material together through the elasticity of the adaptive telescopic layer. Therefore, the adaptive telescopic layer provides a volume expansion protection zone for the silicon material, effectively improving the volume expansion of the silicon material during the charging and discharging process, thereby improving the cycle stability and service life of the silicon-based negative electrode material.

[0074] 2. The preparation method of the present invention first uses an aminoazobenzene derivative and a graphene sieve to perform a solvent thermal reaction to produce an amino-functionalized graphene sieve, disperses the obtained amino-functionalized graphene sieve and a silicon material by ultrasonic, and then adds polyurethane to covalently react with the functionalized graphene sieve wrapped on the surface of the silicon material to form a three-dimensional graphene ball by microwave radiation. The three-dimensional graphene ball wraps the silicon material inside to obtain a silicon-based negative electrode material wrapped in a three-dimensional graphene ball. The three-dimensional graphene ball is formed by cross-linking a self-repairable graphene hyperbranched polyurethane composite material formed by covalently forming functionalized graphene and polyurethane, and has scalability. The volume expansion of the silicon material formed by the deintercalation of lithium ions can repolymerize the broken silicon material through the scalability of the three-dimensional graphene ball, thereby improving the material cycle stability. In addition, the three-dimensional graphene ball wrapping can effectively improve the conductivity of the silicon material and improve its rate performance.

[0075] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite silicon-based negative electrode material, characterized in that: include, Silicon materials; The adaptive stretching layer is located on the outer surface of the silicon material.

2. The composite silicon-based negative electrode material according to claim 1, characterized in that: The adaptive scaling layer meets at least one of the following conditions: The adaptive telescopic layer material includes graphene; The thickness of the adaptive telescopic layer is 1 to 150 nm.

3. The composite silicon-based negative electrode material according to claim 2, characterized in that: The graphene satisfies at least one of the following conditions: The graphene is selected from three-dimensional graphene spheres; The mass percentage of the graphene in the adaptive telescopic layer is 1-10%.

4. The composite silicon-based negative electrode material according to claim 3, characterized in that: The three-dimensional graphene sphere is a graphene hyperbranched polyurethane composite material.

5. The composite silicon-based negative electrode material according to claim 4, characterized in that: The graphene hyperbranched polyurethane composite material is obtained by covalent reaction of amino-functionalized graphene and polyurethane.

6. The composite silicon-based negative electrode material according to claim 1, characterized in that: The silicon material is selected from pure silicon, silicon-carbon material, silicon-oxygen material, silicon nanowire composite material, and silicon alloy material; Preferably, the silicon-oxygen material is selected from silicon monoxide.

7. A method for preparing a composite silicon-based negative electrode material according to any one of claims 1 to 6, characterized in that: The steps include: S1, mixing the aminoazobenzene derivative and the graphene sieve by ultrasonic dispersion to obtain a mixture; S2, reacting the mixture at high temperature to obtain an amino-functionalized graphene sieve; S3, adding the amino-functionalized graphene sieve and the silicon material into a solvent and reacting them by ultrasonic stirring to obtain a silicon-based material coated with amino-functionalized graphene; S4, adding polyurethane to S3 for dispersion, and then irradiating with microwaves to obtain a silicon-based negative electrode material coated with three-dimensional graphene balls.

8. The preparation method according to claim 7, characterized in that: The aminoazobenzene derivative is selected from one or more of p-aminoazobenzene and 4-diethylaminoazobenzene.

9. The preparation method according to claim 7, characterized in that: S2 satisfies at least one of the following conditions: The high temperature is 70-180°C; The reaction time is 6 to 24 hours.

10. The preparation method according to claim 7, characterized in that: S3 satisfies at least one of the following conditions: Ultrasonic stirring time is 1 to 36 hours. The solvent is selected from any one of butanediol and ethanol; In S4, the microwave radiation power is 100 to 1000 W, and the radiation time is 1 to 10 hours.

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