Preparation method and application of polystyrene resin-based spherical carbonaceous porous material

Abstract

The invention provides a preparation method and application of a polystyrene resin-based spherical carbonaceous porous material, and belongs to the technical field of new energy materials. The method comprises the following steps: firstly, pre-mixing styrene with a cross-linking agent, a pore-forming agent, an initiator and a surfactant at a first preset temperature, then continuously stirring at a first preset stirring speed at a second preset temperature for a first preset time, and carrying out organic polymerization to prepare a polystyrene-based resin microsphere emulsion; then separating and drying the emulsion to obtain polystyrene-based resin microspheres; then oxidizing for a second preset time at a third preset temperature in an air atmosphere to prepare oxidized polystyrene-based resin microspheres; and finally, oxidizing at a fourth preset temperature for a third preset time to prepare the polystyrene resin-based spherical carbonaceous porous material. The method is simple in process and easy to implement, the preparation cost is effectively reduced while the yield is increased, and the method has wide application value and popularization prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials, and in particular relates to a preparation method and application of a polystyrene resin-based spherical carbonaceous porous material. Background Art

[0002] Although lithium-ion batteries have been widely used in electronics, electric vehicles, mechanical equipment, and solar and wind energy storage, their energy density is less than 450Wh / kg due to the theoretical capacity of graphite-based anode materials being only 372mAh / g. With the urgent demand for high-energy-density lithium-ion batteries in high-tech applications such as electric vehicles and drones, the ultra-high theoretical capacity of nano-Si makes Si / C anodes an inevitable development trend in the field of lithium-ion battery anode materials.

[0003] When nano-Si is used directly as the negative electrode material for lithium-ion batteries, it suffers from problems such as low electrical conductivity and severe volume expansion. To address this, functional carbon materials such as graphene, carbon nanotubes, and porous carbon have excellent electrical conductivity, designable micro-nanostructures, and composite properties to address the shortcomings of nano-Si. When nano-Si microspheres with a diameter of 50-100 nm are directly physically mixed with carbonaceous functional materials with good electrical conductivity, such as graphene, carbon nanotubes, graphite, and porous carbon, the capacity of the resulting Si / C negative electrode is indeed higher than that of a single graphite-based negative electrode material. However, due to the large size of the nano-Si microspheres, the capacity of the Si / C negative electrode decays extremely severely during long cycles. To address this, the use of chemical vapor deposition to deposit nano-Si on the pore surface of carbonaceous porous materials to construct Si / C negative electrode materials has become the mainstream development direction in this new energy material field.

[0004] When carbonaceous porous materials are used as carrier carbon for Si / C negative electrodes, their appearance, morphology, pore size distribution, and specific surface area all have a significant impact on the deposition amount of nano-Si, the microstructure, and the electrochemical performance of the Si / C negative electrode. First, spherical carbonaceous porous materials not only have a high packing density, but also facilitate the uniform deposition of nano-Si on the pore surface during chemical vapor deposition. Second, although a higher specific surface area of ​​a carbonaceous porous material is more conducive to increasing the deposition amount of nano-Si, when nano-Si is deposited on the surface of mesopores or macropores, the thicker nano-Si layer will inevitably expand in volume during the charge and discharge process, thereby affecting the long-cycle stability of the Si / C negative electrode. Finally, when the surface of the spherical carbonaceous porous material is relatively smooth, it will be detrimental to the binder performing its bonding function.

[0005] At present, the carrier carbon used as Si / C negative electrode is generally a polystyrene resin-based spherical carbonaceous porous material. Polystyrene resin-based spherical carbonaceous porous materials are usually prepared from styrene and p-divinylbenzene using organic polymerization, sulfuric acid sulfonation, carbonization, and water vapor activation processes. The preparation system of this material, first of all, sulfuric acid sulfonation will not only cause high waste acid treatment costs, but also extremely serious equipment corrosion, resulting in high equipment replacement costs. Secondly, this raw material synthesis system not only has a low yield of the final resin-based spherical carbonaceous porous material, but also the market price of p-divinylbenzene remains high. This factor will inevitably affect the promotion and large-scale application of polystyrene resin-based spherical carbonaceous porous materials in the field of lithium-ion battery Si / C negative electrodes.

[0006] In summary, how to provide a method for preparing polystyrene resin-based spherical carbonaceous porous materials that is conducive to reducing costs is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a preparation method and application of a polystyrene resin-based spherical carbonaceous porous material, which can be prepared to obtain a polystyrene resin-based spherical carbonaceous porous material with grooves on the surface and is suitable as a carrier carbon for the Si / C negative electrode of a lithium-ion battery.

[0008] The present invention provides a method for preparing a polystyrene resin-based spherical carbonaceous porous material, comprising the following steps: S1: pre-mixing styrene with a cross-linking agent, a pore-forming agent, an initiator, and a surfactant at a first preset temperature, and then stirring at a first preset stirring speed for a first preset time at a second preset temperature to cause organic polymerization to produce a polystyrene-based resin microsphere emulsion; S2 separates and then dries the polystyrene resin-based resin microsphere emulsion prepared in S1 to obtain polystyrene-based resin microspheres; S3 oxidizes the polystyrene-based resin microspheres prepared in S2 at a third preset temperature for a second preset time in an air atmosphere to prepare oxidized polystyrene-based resin microspheres; S4: oxidizing the oxidized polystyrene-based resin microspheres in S3 at a fourth preset temperature for a third preset time to obtain a polystyrene resin-based spherical carbonaceous porous material.

[0009] Furthermore, the cross-linking agent in S1 is one or more of butadiene, propylene, and acrylonitrile; The pore-forming agent in S1 is one or more of liquid paraffin, naphtha, and coal tar.

[0010] Furthermore, the pore-forming agent in S1 is one or more of liquid paraffin, naphtha, and coal tar.

[0011] Furthermore, in S1, the mixing ratio of styrene and cross-linking agent is 1:1-5:1; The mixing ratio of styrene and pore-forming agent is 1:9-2:8; The initiator accounts for 0.1-1% of the mixed raw materials of styrene, crosslinking agent and pore-forming agent; The surfactant accounts for 0.01-1% of the mixed raw materials of styrene, cross-linking agent and pore-forming agent.

[0012] Furthermore, in S1, the first preset temperature is 30-40° C., and the first preset time is 2-6 hours; In S1, the second preset temperature is 70-98° C., and the first preset stirring speed is 800-1000 r / min.

[0013] Furthermore, in S3, the third preset temperature is 800-1000° C., and the second preset time is 2-4 hours.

[0014] Furthermore, the fourth preset temperature in S4 is 800-1000° C., and the third preset time is 2-6 hours.

[0015] The present invention provides a polystyrene resin-based spherical carbonaceous porous material prepared by any of the above methods, the surface of which has grooves.

[0016] Furthermore, the polystyrene resin-based spherical carbonaceous porous material has a spherical diameter of 5-15 μm and a specific surface area of ​​1500-2000 m 2 / g, pore volume is 0.52~1.08cm 3 / g, and the micropore content is higher than 90%.

[0017] The present invention provides a lithium ion battery, the negative electrode of which comprises the polystyrene resin-based spherical carbonaceous porous material as described above as carrier carbon.

[0018] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art, as an example: The preparation method provided by the present invention eliminates the sulfuric acid sulfonation step, saving the cost required for waste acid treatment, and avoids the problem of equipment corrosion, extending the service life of the equipment and indirectly saving equipment replacement costs. Overall, the preparation method provided by the present invention is easy to implement, improves the yield, and can effectively reduce the cost of preparing resin-based spherical carbonaceous porous materials, thus having broad application value and promotion prospects.

[0019] The polystyrene resin-based spherical carbonaceous porous material provided by the present invention has many advantages as a carrier carbon for Si / C negative electrodes. This material not only has excellent electrical conductivity and can effectively make up for the defect of low electrical conductivity of nano-Si, but also can limit the deposition thickness of nano-Si through its microporous structure, thereby alleviating the volume expansion problem of nano-Si during charging and discharging. In addition, its ultra-high specific surface area provides sufficient deposition sites for nano-Si, which helps to increase the deposition amount of nano-Si and give full play to its theoretical capacity advantage. The micron-scale spherical structure of the material not only increases the density of the Si / C negative electrode material, but also enhances the coupling effect with the binder. At the same time, since it does not contain metal substances and has an extremely low ash content, it can effectively inhibit the self-discharge behavior of lithium-ion batteries, thereby comprehensively improving the performance and energy density of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1a This is the SEM image of the polystyrene resin-based spherical carbonaceous porous material provided in Comparative Example 1.

[0021] Figure 1b This is the nitrogen adsorption-desorption curve of the polystyrene resin-based spherical carbonaceous porous material provided in Comparative Example 1.

[0022] Figure 2a The SEM image and nitrogen adsorption-desorption curve of the polystyrene resin-based spherical carbonaceous porous material provided in Example 1.

[0023] Figure 2b This is the nitrogen adsorption-desorption curve of the polystyrene resin-based spherical carbonaceous porous material provided in Example 1.

[0024] Figure 3a This is an SEM image of the polystyrene resin-based spherical carbonaceous porous material provided in Example 2.

[0025] Figure 3b This is the nitrogen adsorption-desorption curve of the polystyrene resin-based spherical carbonaceous porous material provided in Example 2.

[0026] Figure 4a This is an SEM image of the polystyrene resin-based spherical carbonaceous porous material provided in Example 3.

[0027] Figure 4b This is the nitrogen adsorption-desorption curve of the polystyrene resin-based spherical carbonaceous porous material provided in Example 3.

[0028] Figure 5a This is an SEM image of the polystyrene resin-based spherical carbonaceous porous material provided in Example 4.

[0029] Figure 5b This is the nitrogen adsorption-desorption curve of the polystyrene resin-based spherical carbonaceous porous material provided in Example 4. DETAILED DESCRIPTION

[0030] The technical solutions disclosed in the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects.

[0031] Techniques, methods, and apparatus known to persons of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0032] The present invention provides a method for preparing a polystyrene resin-based spherical carbonaceous porous material, as shown in FIG1 , comprising the following steps: S1: After pre-mixing styrene with a cross-linking agent, a pore-forming agent, an initiator and a surfactant at a first preset temperature, stirring is continued at a first preset stirring speed at a second preset temperature for a first preset time to cause organic polymerization to occur, thereby preparing a polystyrene-based resin microsphere emulsion.

[0033] Preferably, the cross-linking agent in S1 is one or more of butadiene, propylene, and acrylonitrile.

[0034] Preferably, the pore-forming agent in S1 is one or more of liquid paraffin, naphtha, and coal tar.

[0035] Preferably, in S1, the mixing ratio of styrene and cross-linking agent is 1:1-5:1; The mixing ratio of styrene and pore-forming agent is 1:9-2:8; The initiator accounts for 0.1-1% of the mixed raw materials of styrene, crosslinking agent and pore-forming agent; The surfactant accounts for 0.01-1% of the mixed raw materials of styrene, cross-linking agent and pore-forming agent.

[0036] Preferably, in S1, the first preset temperature is 30-40° C., and the first preset time is 2-6 hours.

[0037] Preferably, in S1, the second preset temperature is 70-98° C., and the first preset stirring speed is 800-1000 r / min.

[0038] S2 separates and then dries the polystyrene resin-based resin microsphere emulsion prepared in S1 to obtain polystyrene-based resin microspheres.

[0039] Preferably, S2 includes drying the separated polystyrene resin-based resin microsphere emulsion at 150-250° C. for 2-4 hours.

[0040] S3 oxidizes the polystyrene-based resin microspheres prepared in S2 at a third preset temperature for a second preset time in an air atmosphere to prepare oxidized polystyrene-based resin microspheres.

[0041] Preferably, the third preset temperature in S3 is 800-1000° C., and the second preset time is 2-4 hours.

[0042] S4: oxidizing the oxidized polystyrene-based resin microspheres in S3 at a fourth preset temperature for a third preset time to obtain a polystyrene resin-based spherical carbonaceous porous material.

[0043] Preferably, the fourth preset temperature in S4 is 800-1000° C., and the third preset time is 2-6 hours.

[0044] The following are examples of the specific implementation process: Comparative Example 1 1g of benzoyl peroxide initiator was added to 100g of styrene and 100g of p-divinylbenzene, stirred uniformly until completely dissolved, and then added to 500g of a 0.3% aqueous solution of polyvinyl alcohol. Prepolymerization was carried out at 30°C for 2h, followed by organic polymerization at 80°C and 1000 rpm for 4h. The resulting polystyrene resin microsphere emulsion was separated and dried at 150°C for 2h. The dried polystyrene resin microspheres were then oxidized at 280°C in air for 2h to produce oxidized polystyrene resin microspheres. The oxidized polystyrene resin microspheres were then carbonized at 950°C for 2h under a nitrogen atmosphere, followed by activation at 950°C for 3h, switching the nitrogen atmosphere to water vapor. This resulted in a polystyrene resin-based spherical carbonaceous porous material.

[0045] Under the above preparation conditions, the specific surface area of ​​the prepared polystyrene resin-based spherical carbonaceous porous material is 1250m2 / g. The sphere diameter of the prepared material is concentrated in the range of 5-15μm, but the surface is smooth ( Figure 1a ).from Figure 1b The nitrogen adsorption-desorption curve shows that the material obviously has mesopores and macropores, of which the micropore content is 67%. Example 1

[0046] Except that p-divinylbenzene in [Comparative Example] is replaced by butadiene, all other conditions are the same as those in [Comparative Example]. Under these conditions, if Figure 2a As shown, a polystyrene resin-based spherical carbonaceous porous material with a spherical diameter distribution of 5-15 μm was obtained, and the surface was still relatively smooth.

[0047] Due to the influence of the cross-linked molecular structure of butadiene and styrene, under the same preparation conditions, the specific surface area of ​​the prepared polystyrene resin-based spherical carbonaceous porous material was increased to 1650m 2 / g. From Figure 2b It can be seen from the nitrogen adsorption-desorption curve that the material is mainly composed of micropores with only a small amount of mesopores, of which the micropore content is 91%. Example 2

[0048] 5g of liquid paraffin pore-forming agent was added to the raw materials of [Example 1], and all other conditions were the same as [Example 1]. Under this condition, Figure 3a As shown in FIG, a polystyrene resin-based spherical carbonaceous porous material with a spherical diameter distribution of 5-15 μm and a rough surface was obtained. Figure 3b As shown in the figure, the specific surface area of ​​the prepared polystyrene resin-based spherical carbonaceous porous material is 1647m 2 / g, but due to the influence of pore-forming agent, the micropore content of the material is 93%. Example 3

[0049] In the raw materials of [Example 1], 15g of liquid paraffin pore-forming agent was added, and all other conditions were the same as [Example 1]. Under this condition, Figure 4a As shown in FIG, a polystyrene resin-based spherical carbonaceous porous material with a spherical diameter distribution of 5-15 μm was obtained, but the difference is that the surface has grooves. The grooves here refer to the surface having raised grooves and sunken grooves, which is a fold structure. Figure 4b As shown in the figure, the specific surface area of ​​the prepared polystyrene resin-based spherical carbonaceous porous material is 1674m 2 / g, but due to the influence of pore-forming agent, the micropore content of the material is 91%. Example 4

[0050] The steam activation temperature in [Example 3] was lowered from 950°C to 850°C, but the activation time was extended from 2h to 4h. All other conditions were the same as [Example 3]. Figure 5a As shown in FIG, a polystyrene resin-based spherical carbonaceous porous material with a spherical diameter distribution of 5-15 μm and grooves on the surface was obtained. Figure 5b As shown in the figure, the change of water vapor activation conditions not only increases the specific surface area of ​​polystyrene resin-based spherical carbonaceous porous materials to 1910m 2 / g, and the micropore content is also increased to 94%.

[0051] In summary, the polystyrene resin-based spherical carbonaceous porous material prepared by the preparation method provided by the present invention has grooves on its surface. The grooves here refer to the surface having raised grooves and sunken grooves, which is a wrinkled structure.

[0052] The polystyrene resin-based spherical carbonaceous porous material has a spherical diameter of 5-15 μm and a specific surface area of ​​1500-2000 m 2 / g, pore volume is 0.52~1.08cm 3 / g, and the micropore content is higher than 90%.

[0053] The present invention provides a lithium-ion battery, wherein the Si / C negative electrode thereof adopts the polystyrene resin-based spherical carbonaceous porous material as the carrier carbon, including but not limited to the following advantages: 1) The excellent electrical conductivity of the carbon matrix material can make up for the low electrical conductivity of nano-Si.

[0054] 2) When nano-Si is deposited on the microporous surface of polystyrene resin-based spherical carbonaceous porous materials, the narrow pore size of 1-2 nm will limit the deposition thickness of nano-Si to a certain extent, thereby solving the problem of volume expansion of nano-Si during the charging and discharging process.

[0055] 3) The ultra-high specific surface area of ​​the polystyrene resin-based spherical carbonaceous porous material provides a deposition site for nano-Si, which can effectively increase the deposition amount of nano-Si in the negative electrode material, thereby fully exerting the ultra-high theoretical capacity advantage of nano-Si.

[0056] 4) The micron-sized spherical structure can effectively increase the density of Si / C negative electrode materials, thereby helping to improve the energy density in lithium-ion batteries.

[0057] 5) It will have a better bonding effect with the adhesive.

[0058] 6) Since there are no metal substances in the raw material system, the ash content of the polystyrene resin-based spherical carbonaceous porous material is extremely low, which can inhibit the self-discharge behavior of lithium-ion batteries to a certain extent.

[0059] Within the scope of protection intended by the present disclosure, terms such as "including" and "comprising" should be interpreted as inclusive or open-ended rather than exclusive or closed by default, unless expressly defined to the contrary. All technical, scientific, or other terms have the meanings understood by those skilled in the art unless expressly defined to the contrary. Common terms found in dictionaries should not be interpreted in an overly idealistic or unrealistic manner in the context of relevant technical documents, unless expressly defined to that extent by the present disclosure.

[0060] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0061] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a polystyrene resin-based spherical carbonaceous porous material, characterized in that: The steps include: S1: pre-mixing styrene with a cross-linking agent, a pore-forming agent, an initiator, and a surfactant at a first preset temperature, and then stirring at a first preset stirring speed for a first preset time at a second preset temperature to cause organic polymerization to produce a polystyrene-based resin microsphere emulsion; S2 separates and then dries the polystyrene resin-based resin microsphere emulsion prepared in S1 to obtain polystyrene-based resin microspheres; S3 oxidizes the polystyrene-based resin microspheres prepared in S2 at a third preset temperature for a second preset time in an air atmosphere to prepare oxidized polystyrene-based resin microspheres; S4: oxidizing the oxidized polystyrene-based resin microspheres in S3 at a fourth preset temperature for a third preset time to obtain a polystyrene resin-based spherical carbonaceous porous material.

2. The method for preparing a polystyrene resin-based spherical carbonaceous porous material according to claim 1, characterized in that: S1 The crosslinking agent is one or more of butadiene, propylene, and acrylonitrile.

3. The method for preparing a polystyrene resin-based spherical carbonaceous porous material according to claim 1, wherein: The pore-forming agent in S1 is one or more of liquid paraffin, naphtha, and coal tar.

4. The method according to claim 1, wherein: In S1, the mixing ratio of styrene and cross-linking agent is 1:1-5:1; The mixing ratio of styrene and pore-forming agent is 1:9-2:8; The initiator accounts for 0.1-1% of the mixed raw materials of styrene, crosslinking agent and pore-forming agent; The surfactant accounts for 0.01-1% of the mixed raw materials of styrene, cross-linking agent and pore-forming agent.

5. The method according to claim 1, wherein: In S1, the first preset temperature is 30-40°C, and the first preset time is 2-6 hours; In S1, the second preset temperature is 70-98° C., and the first preset stirring speed is 800-1000 r / min.

6. The method according to claim 1, wherein: In S3, the third preset temperature is 800-1000° C., and the second preset time is 2-4 hours.

7. The method according to claims 1-7, characterized in that: The fourth preset temperature in S4 is 800-1000° C., and the third preset time is 2-6 hours.

8. A polystyrene resin-based spherical carbonaceous porous material prepared by the method according to any one of claims 1 to 8, characterized in that: The surface of the polystyrene resin-based spherical carbonaceous porous material has grooves.

9. The polystyrene resin-based spherical carbonaceous porous material according to claim 8, characterized in that: The polystyrene resin-based spherical carbonaceous porous material has a spherical diameter of 5-15 μm and a specific surface area of ​​1500-2000 m 2 / g, pore volume of 0.52-1.08cm 3 / g, and the micropore content is higher than 90%.

10. A lithium ion battery, characterized in that: The negative electrode adopts the polystyrene resin-based spherical carbonaceous porous material as claimed in claim 9 as the carrier carbon.

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