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

Abstract

The application 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 a self-adapting expansion layer located on the outer surface of the silicon material.The material can effectively improve 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.

Description

Technical Field

[0001] This invention relates to the field of silicon-based anode material preparation technology, specifically to a high-performance composite silicon-based anode material and its preparation method. Background Technology

[0002] With the development of new energy electric vehicles, power lithium-ion batteries will have a huge market for a considerable period of time. Electrode materials are a major factor affecting the performance of power lithium-ion batteries, and anode materials are one of the key factors determining lithium-ion battery performance. Currently, commercially available lithium-ion battery anode materials are mainly graphite-based carbon materials, which have good cycle performance but low capacity and poor rate performance, making it difficult to meet the demand. Silicon materials have high specific capacity, making them a research hotspot.

[0003] However, silicon materials expand significantly during lithium insertion / extraction, and repeated charging and discharging can cause the active material bonded to the current collector to crack and eventually peel off, resulting in poor cycle performance. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a high-performance composite silicon-based anode material and its preparation method, solving the technical problem of cracking and peeling of active material bonded to the current collector due to large volume expansion of silicon material during lithium insertion / extraction.

[0006] (II) Technical Solution

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

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

[0009] Silicon materials;

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

[0011] The present invention provides a composite silicon-based anode material including an adaptive stretching layer. The adaptive stretching layer is stretchable and repairable. The volume expansion of silicon material caused by lithium ion insertion / extraction can be re-aggregated by the stretching of the adaptive stretching layer. Therefore, the adaptive stretching layer provides a volume expansion protection zone for silicon material, effectively improving the volume expansion of silicon material during charge and discharge, thereby improving the cycle stability and service life of silicon-based anode material.

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

[0013] The adaptive stretching layer material includes graphene. Graphene encapsulation can effectively improve the conductivity of silicon materials and enhance their rate performance.

[0014] The thickness of the adaptive stretching layer is 1–150 nm.

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

[0016] The graphene includes three-dimensional graphene spheres, which are stretchable. The volume expansion of silicon material caused by lithium ion insertion / extraction can be re-aggregated by the stretchability of the three-dimensional graphene spheres, thereby improving the cycle stability of the anode material.

[0017] The graphene accounts for 1 to 10% of the mass of the adaptive stretching layer.

[0018] Preferably, the three-dimensional graphene spheres are graphene hyperbranched polyurethane composite materials. Graphene hyperbranched polyurethane composite materials have stretchability and self-healing properties. The volume expansion of silicon material caused by lithium ion insertion / extraction can be used to re-aggregate the broken silicon material through its stretchability 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 raw materials for this reaction are readily available and the reaction process is easy to control.

[0020] Preferably, the polyurethane is a polyurethane containing reversible covalent bond segments and dynamic non-covalent bond segments, wherein the reversible covalent bond segments are one or more of disulfide bond segments, Diels-Alder reaction segments, and borate ester bond segments, and the dynamic non-covalent bond segments are one or more of hydrogen bond segments, ionic bond segments, metal coordination bond segments, and host-guest structures. The polyurethane spontaneously re-entangles itself through the interaction of reversible covalent bonds and dynamic non-covalent bonds, without the need for external force, thus forming a self-healing function.

[0021] Preferably, the silicon material is selected from pure silicon, silicon-carbon materials, silicon-oxygen materials, silicon nanowire composite materials, and silicon alloy materials, which have high specific capacity and readily available raw materials.

[0022] Preferably, the silicon-oxygen material is selected from silicon suboxide, 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 a composite silicon-based anode material as described in the first aspect, comprising the following steps:

[0024] S1, an aminoazobenzene derivative, and a graphene sieve were ultrasonically dispersed and mixed to obtain a mixture;

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

[0026] S3. The amino-functionalized graphene sieve and silicon material are added to a solvent and reacted by ultrasonic stirring to obtain an amino-functionalized graphene-coated silicon-based material.

[0027] S4. After adding polyurethane dispersion to S3, microwave irradiation is performed to obtain silicon-based anode material coated with three-dimensional graphene spheres.

[0028] The preparation method of this invention first uses an amino-azobenzene derivative to produce an amino-functionalized graphene sieve through a solvothermal reaction with a graphene sieve. The obtained amino-functionalized graphene sieve is then ultrasonically dispersed with silicon material. Polyurethane is then added, and the functionalized graphene sieve coated on the silicon material surface undergoes a covalent reaction with the polyurethane using microwave radiation to form three-dimensional graphene spheres. These three-dimensional graphene spheres encapsulate the silicon material, resulting in a silicon-based anode material encapsulated in three-dimensional graphene spheres. The three-dimensional graphene spheres are formed by the cross-linking of functionalized graphene and polyurethane into a self-healing graphene hyperbranched polyurethane composite material. This cross-linking provides extensibility, allowing the volume expansion of silicon material during lithium ion insertion / extraction to be re-aggregated by the extensibility and self-healing properties of the three-dimensional graphene spheres, thus improving the material's cycle stability. Furthermore, the three-dimensional graphene sphere encapsulation effectively improves the conductivity of the silicon material, enhancing 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] The ultrasonic stirring time is 1–36 hours.

[0035] The solvent is selected from either butanediol or ethanol;

[0036] In S4, the microwave radiation power is 100-1000W and the radiation time is 1-10h. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 The cycle performance test results of the silicon suboxide anode material encapsulated in three-dimensional graphene spheres obtained in Example 1 and the silicon suboxide anode material in Comparative Example 1 are shown. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This application provides a high-performance composite silicon-based anode material and its preparation method, which solves the technical problem of cracking and peeling of active material bonded to the current collector due to large volume expansion of silicon material during lithium insertion / extraction process, thereby improving the cycle performance and service life of the battery.

[0041] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0042] This invention relates to a high-performance composite silicon-based anode material comprising silicon material and an adaptive stretching layer uniformly coated on its surface. The preparation method involves first producing amino-functionalized graphene sieves through a solvothermal reaction of an amino-azobenzene derivative with a graphene sieve. The obtained amino-functionalized graphene sieves are then ultrasonically dispersed with silicon material. Polyurethane is then added, and the functionalized graphene sieves coated on the silicon material surface undergo a covalent reaction with the polyurethane using microwave radiation to form three-dimensional graphene spheres. These three-dimensional graphene spheres encapsulate the silicon material, resulting in a silicon anode material encapsulated in three-dimensional graphene spheres. The three-dimensional graphene spheres are formed by the cross-linking of functionalized graphene and polyurethane into a self-healing graphene hyperbranched polyurethane composite material. This cross-linking provides stretchability, allowing the volume expansion of silicon material during lithium-ion insertion / extraction to be reassembled by the stretchability of the three-dimensional graphene spheres, thus improving the cycle stability of the anode material. Furthermore, the graphene encapsulation effectively enhances the conductivity of the silicon material, improving its rate performance.

[0043] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions 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 anode material, including the following steps:

[0046] S1. Disperse 8 mmol of p-aminoazobenzene and 100 mg of graphene sieve evenly by ultrasonication.

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

[0048] S3. The amino-functionalized graphene sieve obtained in S2 and 5g of silicon suboxide were added to 75ml of butanediol and reacted by ultrasonic stirring for 24h to obtain amino-functionalized graphene-coated silicon suboxide.

[0049] S4. After adding polyurethane to S3 and dispersing it evenly, the silicon suboxide anode material encapsulated by three-dimensional graphene spheres is obtained by microwave irradiation with 500W power for 6 hours.

[0050] The silicon suboxide anode material (SP:LA133 = 8:1:1) encapsulated with the obtained three-dimensional graphene spheres was slurry-coated and then used to assemble CR2032 coin cells. A 1 mol / L LiPF6 EC + DMC solution was used as the electrolyte, and electrochemical performance was tested. The results are shown in [Figure number missing]. Figure 1 .

[0051] Example 2

[0052] A method for preparing a high-performance composite silicon-based anode material includes the following steps:

[0053] S1. Disperse 8 mmol of 4-diethylaminoazobenzene and 100 mg of graphene sieve evenly by ultrasonication.

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

[0055] S3. The amino-functionalized graphene sieve obtained in S2 and 5g of pure silicon were added to 75ml of butanediol and reacted by ultrasonic stirring for 36h to obtain amino-functionalized graphene-coated silicon.

[0056] S4. After adding polyurethane to S3 and dispersing it evenly, the silicon anode material encapsulated with three-dimensional graphene spheres is obtained by microwave irradiation with 100W power for 10 hours.

[0057] Example 3

[0058] A method for preparing a high-performance composite silicon-based anode material includes the following steps:

[0059] S1. Disperse 10 mmol of p-aminoazobenzene and 100 mg of graphene sieve evenly by ultrasonication.

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

[0061] S3. The amino-functionalized graphene sieve obtained in S2 and 6g of silicon carbide were added to 75ml of butanediol and reacted by ultrasonic stirring for 1h to obtain amino-functionalized graphene-coated silicon carbide.

[0062] S4. After adding polyurethane to S3 and dispersing it evenly, the silicon carbide anode material encapsulated in three-dimensional graphene spheres is obtained by microwave irradiation with 200W power for 3 hours.

[0063] Example 4

[0064] A high-performance composite silicon-based anode material and its preparation method, comprising the following steps:

[0065] S1. Disperse 10 mmol of p-aminoazobenzene and 100 mg of graphene sieve evenly by ultrasonication.

[0066] S2. Add the mixture obtained from S1 to a reactor and react at 160℃ for 10 hours to obtain amino-functionalized graphene sieves.

[0067] S3. The amino-functionalized graphene sieve obtained in S2 and 6g of silicon nanowires modified with gold nanoparticles were added to 75ml of butanediol and reacted by ultrasonic stirring for 24h to obtain amino-functionalized graphene-coated silicon nanowires modified with gold nanoparticles.

[0068] S4. After adding polyurethane to S3 and dispersing it uniformly, the silicon nanowire anode material modified with gold nanoparticles and encapsulated in three-dimensional graphene spheres is obtained by microwave irradiation with 1000W power for 1 hour.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that silicon suboxide anode material was used instead of the three-dimensional graphene sphere-encapsulated silicon suboxide anode material for assembling the CR2032 coin cell; otherwise, the assembly was the same as in Example 1. Electrochemical performance tests were performed, and the results are shown below. Figure 1 .

[0071] from Figure 1It is evident that the battery prepared from the three-dimensional graphene sphere-encapsulated silicon suboxide anode material in Example 1 exhibits significantly better cycle performance than the silicon suboxide anode material in Comparative Example 1. This is because the three-dimensional graphene sphere-encapsulated silicon suboxide composite material, obtained by microwave radiation method using graphene hyperbranched polyurethane composite material and silicon suboxide material, has three-dimensional graphene spheres that are obtained by crosslinking self-healing graphene hyperbranched polyurethane composite material. These spheres possess stretchability and repairability, enabling them to self-regulate to adapt to the volume expansion of silicon suboxide during lithium-ion insertion and to re-aggregate the broken silicon suboxide after lithium-ion removal. This provides a volume expansion protection zone during repeated charge-discharge processes of silicon suboxide, improving the battery's cycle performance and lifespan.

[0072] In summary, compared with existing technologies, it has the following beneficial effects:

[0073] 1. A composite silicon-based anode material of the present invention includes an adaptive stretching layer. The adaptive stretching layer has stretchability and repairability. The volume expansion of the anode material caused by lithium ion insertion / extraction can be re-aggregated by the stretching of the adaptive stretching layer. Therefore, the adaptive stretching 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 anode material.

[0074] 2. The preparation method of this invention first uses an amino-azobenzene derivative to produce an amino-functionalized graphene sieve through a solvothermal reaction with a graphene sieve. The obtained amino-functionalized graphene sieve is then ultrasonically dispersed with silicon material. Polyurethane is then added, and the functionalized graphene sieve coated on the silicon material surface undergoes a covalent reaction with the polyurethane using microwave radiation to form three-dimensional graphene spheres. These three-dimensional graphene spheres encapsulate the silicon material, resulting in a silicon-based anode material encapsulated in three-dimensional graphene spheres. The three-dimensional graphene spheres are formed by the cross-linking of functionalized graphene and polyurethane into a self-healing graphene hyperbranched polyurethane composite material. This cross-linking provides extensibility, allowing the volume expansion of silicon material during lithium ion insertion / extraction to be re-aggregated by the extensibility of the three-dimensional graphene spheres, thus improving the material's cycle stability. Furthermore, the three-dimensional graphene sphere encapsulation effectively improves the conductivity of the silicon material, enhancing its rate performance.

[0075] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite silicon-based anode material, characterized in that, include, Silicon materials; An adaptive stretchable layer is located on the outer surface of the silicon material; The adaptive stretching layer material includes graphene; the graphene is selected from three-dimensional graphene spheres; the three-dimensional graphene spheres are graphene hyperbranched polyurethane composite materials; The graphene hyperbranched polyurethane composite material is obtained by covalent reaction of amino-functionalized graphene and polyurethane; the polyurethane is a polyurethane containing reversible covalent bond segments and dynamic non-covalent bond segments, wherein the reversible covalent bond segments are one or more of Diels-Alder reaction segments and borate ester bond segments, and the dynamic non-covalent bond segments are one or more of hydrogen bond segments, ionic bond segments, metal coordination bond segments, and host-guest structures.

2. The composite silicon-based anode material as described in claim 1, characterized in that, The thickness of the adaptive stretching layer is 1–150 nm.

3. The composite silicon-based anode material as described in claim 1, characterized in that, The graphene accounts for 1 to 10% of the mass of the adaptive stretching layer.

4. The composite silicon-based anode material as described in claim 1, characterized in that, The silicon material is selected from pure silicon, silicon-carbon materials, silicon-oxygen materials, silicon nanowire composite materials, and silicon alloy materials; The silicon-oxygen material is selected from silicon suboxide.

5. A method for preparing a composite silicon-based anode material as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1, an aminoazobenzene derivative, and a graphene sieve were ultrasonically dispersed and mixed to obtain a mixture; S2. React the mixture at high temperature to obtain an amino-functionalized graphene sieve; S3. The amino-functionalized graphene sieve and silicon material are added to a solvent and reacted by ultrasonic stirring to obtain an amino-functionalized graphene-coated silicon-based material. S4. After adding polyurethane dispersion to S3, microwave irradiation is performed to obtain silicon-based anode material coated with three-dimensional graphene spheres.

6. The preparation method according to claim 5, characterized in that, The aminoazobenzene derivative is selected from one or more of p-aminoazobenzene and 4-diethylaminoazobenzene.

7. The preparation method according to claim 5, 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.

8. The preparation method according to claim 5, characterized in that, S3 satisfies at least one of the following conditions: The ultrasonic stirring time is 1–36 hours. The solvent is selected from either butanediol or ethanol; In S4, the microwave radiation power is 100-1000W and the radiation time is 1-10h.

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