Composite material having concrete structure, preparation method therefor and use thereof

Abstract

Provided in the present invention is a composite material having a concrete structure, the composite material consisting of the following components in mass ratios, the mass ratios of silicon powder: coating agent: graphene: fiber carbon tubes: binder: filling material: auxiliary agent being 1:0.05-10:0.0001-0.02:0.0001-0.02:0.15-1:0.01-0.5:0.001-0.1. The composite material has the cementing property, strength and elasticity of a concrete structure, such that the compactness, tensile strength and crack resistance of the material can be improved, the volume change effect of a silicon material can be reduced during charging and discharging, and the silicon material can be effectively prevented from continuously forming new SEI films and thus consuming lithium ions, thereby improving the stability of the composite material. In addition, a binder is used to tightly bond the surface of the silicon material to a conductive agent such as a fiber carbon tube, thereby improving the conductivity of the composite material. The present disclosure further provides a preparation method for the composite material and the use of the composite material. By applying the composite material to a negative electrode material of a lithium-ion battery, the lithium-ion battery has excellent cycle performance.

Description

A composite material for concrete structures, its preparation method and application Technical Field

[0001] This invention relates to the technical field of material preparation, and in particular to a composite material for concrete structures, its preparation method, and its application. Background Technology

[0002] Micro- and nano-powder materials refer to powder materials with particle sizes at the micrometer and nanometer levels. They have large specific surface areas, high specific surface energy, and low tap density. Furthermore, the smaller the particle size, the greater the van der Waals forces, Coulomb forces, and nanoparticle interactions between particles become compared to the particles' own gravity, making them very prone to agglomeration and often difficult to mix evenly between two or more micro- and nano-powders. Lithium-ion batteries, as a high-performance battery, have been widely adopted in digital products, new energy vehicles, and energy storage over the past two decades, and their technological development has attracted widespread attention. Currently, graphite materials are mainly used as anodes in lithium-ion batteries. After years of in-depth research and development, the capacity of commercially available graphite anode materials has approached their theoretical specific capacity of 372 mAh / g. To further improve the energy density of lithium-ion battery anode materials, current methods generally involve combining silicon, phosphorus, germanium, tin, and other materials with graphite or other carbon materials and additives to create novel high-specific-capacity anode materials. Theoretically, silicon has a specific capacity more than 10 times that of carbon when used as an anode material. However, pure silicon anode materials undergo significant volume changes during the charge and discharge process of lithium-ion batteries. After multiple charge and discharge cycles, the silicon particle structure is easily pulverized and fails, leading to battery performance degradation. In addition, silicon has poor conductivity, making it difficult to achieve high-current charge and discharge as an anode material.

[0003] In view of this, the inventor specifically designed a composite material for concrete structures and its preparation method, which leads to this invention. Summary of the Invention

[0004] To solve the above problems, the technical solution of the present invention is as follows:

[0005] This invention proposes a composite material for concrete structures. The finished composite material is in the form of irregular particles with an internal structure similar to that of concrete. The composite material is composed of any two or more components selected from silicon powder, encapsulating agent, graphene, carbon fiber, adhesive, filler, and additives.

[0006] The mass ratio of silicon powder: encapsulating agent: graphene: carbon fiber tube: adhesive: filler: additive is 1:0.05~10:0.0001~0.02:0.0001~0.02:0.15~1:0.01~0.5:0.001~0.1.

[0007] More preferably, the silicon powder is made of nanoscale or microscale material, and the other components are made of microscale material.

[0008] More preferably, the silicon powder is composed of any one or more of pure silicon (Si), silicon-silica composite (SiOx), and silicon alloy, and the D50 particle size of the silicon powder is in the range of 1nm~500nm or 0.02μm~6μm.

[0009] More preferably, the encapsulating agent is any one or a mixture of two or more of alcohols, ketones, esters and organic acid solvents, and the purity of the encapsulating agent used is analytical grade or higher.

[0010] More preferably, the graphene powder is made of single-layer graphene, multi-layer graphene, or carbon black, and the number of layers in the multi-layer graphene does not exceed 100.

[0011] More preferably, the carbon nanotubes are any one of single-walled carbon nanotubes, multi-walled carbon nanotubes, and vapor-grown carbon fibers.

[0012] More preferably, the filler material is any one or any two or more of the following in any proportion: amorphous hard carbon, flake graphite, spherical graphite, microcrystalline graphite, mesophase carbon microspheres (MCMB), carbon fiber, thermosetting phenolic resin, thermosetting polyurethane, epoxy resin, and polyimide resin.

[0013] More optimally, the filler material D50 has a particle size range of 1μm to 8μm.

[0014] More preferably, the adhesive is an organic powder, composed of any one or any two or more of the following: thermoplastic phenolic resin, polyethylene (PE), polystyrene (PS), polypropylene (PP), polyacrylonitrile (PAN), polyaniline (PANI), polyurethane (PU), polyvinylpyrrolidone (PVP), nylon (PA), ABS, PET, asphalt, gelatin, and gum arabic, in any proportion.

[0015] More preferably, the D50 particle size of the adhesive powder is in the range of 0.1 μm to 200 μm.

[0016] The present invention also provides a method for preparing the above-mentioned composite material, the specific preparation steps of which are as follows:

[0017] Step 1: After removing water from the silicon powder, add a coating agent until the silicon powder is completely wetted by the coating agent and forms a slurry, to obtain a silicon powder slurry. Then, disperse the silicon powder slurry at high speed to prepare slurry A.

[0018] Step 2: Add graphene powder to pure solvent a and disperse at high speed until the graphene becomes a uniformly dispersed paste B.

[0019] Step 3: Add the carbon fiber powder to pure solvent b and disperse at high speed until the carbon fiber powder becomes a uniformly dispersed and paste-like slurry C.

[0020] Step 4: Slowly stir the slurry A mentioned in Step 1 and slowly add the slurry B obtained in Step 2, stirring at high speed until a uniform and paste-like slurry D is formed.

[0021] Step 5: After slowly stirring the slurry D mentioned in Step 4, add 50% of the formula amount of adhesive. After the addition is complete, continue stirring until the adhesive and slurry D are evenly mixed and do not separate into layers. Continue to slowly stir the treated mixed slurry D and slowly add slurry C. Stir at high speed until it is evenly mixed and forms a paste. Then, slowly stir and add the remaining 50% of the formula amount of adhesive. After the addition is complete, stir until the adhesive and slurry C are evenly mixed and do not separate into layers to obtain the mixed slurry E.

[0022] Step 6: After allowing the mixed slurry E described in Step 5 to stand, add filler material and mix evenly to obtain mixed slurry F;

[0023] Step 7: Defoam, dry, compact, and degas the mixed slurry F described in Step 6 to obtain solid material G;

[0024] Step 8: Sinter, crush, and sieve the solid material G mentioned in Step 7 to obtain the powder product H of the concrete structure composite material. The D50 particle size range of the powder product H is 0.5μm~15μm.

[0025] Furthermore, the preparation method also includes the following steps:

[0026] Step 9: Add the powder product H described in Step 8 to the resin and pure solvent c, stir and disperse until the powder becomes a uniformly dispersed and paste-like slurry I; dry the slurry I and then perform high-temperature carbonization treatment to obtain the optimized concrete structure composite material powder product J.

[0027] More optimally, the pure solvent a in step two is any one or any two or more of deionized water, N-methylpyrrolidone, N-ethylpyrrolidone, ethanol, propanol, isopropanol, butanol, ethylene glycol, pentane, hexane, and octane; the mass ratio of graphene powder to pure solvent a is in the range of 1:50~2000.

[0028] More optimally, the pure solvent b in step three is any one or any two or more of deionized water, ethanol, propanol, butanol, and ethylene glycol; the mass ratio of the carbon fiber to the pure solvent b is in the range of 1:20~10000.

[0029] More optimally, the resin in step nine is any one or any two or more of phenolic resin, ion exchange resin, polyimide resin, epoxy resin, and polyetheretherketone resin; the pure solvent c is any one or any two or more of alcohol, ester, or ketone solvents; the mass ratio of the powder product H: resin: pure solvent c is in the range of 1:0.001~0.15:2.5~20; the resin can also be replaced by glucose, sucrose, dextrin, or asphalt.

[0030] The present invention also proposes specific applications of the above-mentioned composite material, as follows:

[0031] The above composite material was mixed with carbon black, sodium carboxymethyl cellulose, styrene-butadiene rubber latex, and carbon fiber tubes in a mass percentage ratio of 93%:2.96%:2%:2%:0.04% and added to deionized water. The mixture was stirred to obtain a uniformly mixed negative electrode slurry, which was then used to make a soft-pack lithium-ion battery.

[0032] This invention, by adding aggregates, dopants, and gelling agents to silicon materials, enables the composite material to possess the bonding properties, strength, and elasticity of concrete structures. This improves the density, tensile strength, and crack resistance of the composite material, effectively buffering the volume change effect of silicon materials during charging and discharging, and slowing down the continuous formation of new SEI films in silicon materials that lead to lithium ion consumption, thereby improving the stability of the composite material. At the same time, by using an adhesive to tightly bond the surface of the silicon material with conductive agents such as carbon fiber tubes, the conductivity of the composite material is improved. The lithium-ion battery prepared using the composite material of this invention has excellent cycle performance. Attached Figure Description

[0033] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0034] in:

[0035] Figure 1 is a cross-sectional electron microscope image of the composite material of the present invention;

[0036] Figure 2 is a cross-sectional electron microscope image of the composite material of the present invention; Detailed Implementation

[0037] To make the technical problems, technical solutions, and beneficial effects of this invention clearer and more understandable, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0038] An embodiment of the present invention provides a composite material for a concrete structure, wherein the composite material is composed of any two or more components selected from silica powder, encapsulating agent, graphene, carbon fiber, binder, filler, and additives; wherein the mass ratio of silica powder: encapsulating agent: graphene: carbon fiber: binder: filler: additive is 1:0.05~10:0.0001~0.02:0.0001~0.02:0.15~1:0.01~0.5:0.001~0.1. The final product of the concrete structure composite material is irregular particles with an internal structure similar to that of concrete; wherein silica powder and filler serve as aggregates in the composite material; graphene and carbon fiber serve as dopants; binder serves as a cementing material; encapsulating agent serves as a protective agent for silica particles; and additives are used to facilitate the smooth formation of the concrete structure.

[0039] The silicon powder is made of nanoscale or micrometer-scale materials. The silicon powder composition is any one or more of pure silicon (Si), silicon-silica composite (SiOx), and silicon alloys. The D50 particle size range of the silicon powder is 1 nm to 500 nm or 0.02 μm to 6 μm. The shape of the silicon powder is flake-shaped, spherical, or irregular.

[0040] The components other than silicon powder are micron-sized materials, including:

[0041] The encapsulating agent is any one or a mixture of two or more solvents selected from alcohols, ketones, esters, and organic acids, and the purity of the encapsulating agent is analytical grade or higher. Preferably, the encapsulating agent is ethanol, propanol, isopropanol, butanol, ethylene glycol, acetone, toluene, xylene, ethyl acetate, butyl acetate, acetic acid, or propionic acid.

[0042] The graphene powder is made of single-layer graphene, multi-layer graphene, or carbon black, and the number of layers in the multi-layer graphene does not exceed 100.

[0043] The carbon nanotubes mentioned are one of single-walled carbon nanotubes, multi-walled carbon nanotubes, and vapor-grown carbon fibers, or other carbon fibers may be used instead.

[0044] The filler material is composed of any one or any two or more of the following in any proportion: amorphous hard carbon, flake graphite, spherical graphite, microcrystalline graphite, mesophase carbon microspheres (MCMB), carbon fiber, thermosetting phenolic resin, thermosetting polyurethane, epoxy resin, and polyimide resin. The D50 particle size of the filler material is in the range of 1µm to 8µm.

[0045] The adhesive is an organic powder composed of any one or any two or more of the following: thermoplastic phenolic resin, polyethylene (PE), polystyrene (PS), polypropylene (PP), polyacrylonitrile (PAN), polyaniline (PANI), polyurethane (PU), polyvinylpyrrolidone (PVP), nylon (PA), ABS, PET, asphalt, gelatin, and gum arabic, in any proportion. The D50 particle size of the adhesive powder ranges from 0.1 μm to 200 μm.

[0046] The composite material proposed in this invention possesses the bonding properties, strength, and elasticity of concrete structures. The material cross-section reveals that aggregates, admixtures, and cementitious materials are tightly bonded in a disordered manner (see Figures 1 and 2), with no gaps or only occasional pores. When the composite material is crushed to a D50 particle size range of 3μm~10μm, the tapped density can reach 0.8~2g / cm3. Furthermore, the performance of the composite material can be further optimized through re-carbon coating.

[0047] This invention also proposes a method for preparing the above-mentioned composite material, the specific preparation steps of which are as follows:

[0048] Step 1: First, place silicon powder with a D50 particle size range of 1nm~500nm in a vacuum drying oven and heat it under vacuum to remove moisture. Depending on the moisture content of the silicon powder, the heating temperature is 60℃~200℃, and the treatment time is 0.5~24 hours. The lower the heating temperature, the longer the treatment time, and vice versa. Then, add the coating agent to the dehydrated silicon powder until the silicon powder is completely impregnated with the coating agent to form a slurry. Depending on the different concentration requirements, the amount of coating agent added is 5%~1000% of the silicon powder. Within this range, the coating agent... The more additives, the thinner the slurry, but this does not affect the performance of subsequent products. The silicon powder slurry with added encapsulating agent is placed in a high-speed dispersion device for high-speed dispersion to prepare slurry A. The dispersion speed is 1500 rpm to 30000 rpm or the dispersion linear velocity is 5 m / s to 100 m / s, and the stirring time is 1 minute to 240 minutes. The faster the stirring speed, the shorter the stirring time. At this time, a dense silanol group or silanol carboxyl group and its bonded functional groups are initially formed on the surface of the silicon powder, protecting the silicon powder from oxidation during subsequent processing.

[0049] Step 2: Add graphene powder to pure solvent a for high-shear dispersion. The ratio of graphene powder to pure solvent a is 1:50~2000, until the mixture of graphene powder and pure solvent a becomes a uniformly dispersed paste B. The dispersion speed is 5000rpm~30000rpm or the linear velocity is 10m / s~100m / s, and the stirring time is 5 minutes~120 minutes. The faster the stirring speed, the shorter the stirring time. Pure solvent a is any one or a mixture of two or more solvents, including deionized water, ketone solvents such as N-methylpyrrolidone (NMP) and N-ethylpyrrolidone (NEP), alcohol solvents such as ethanol, propanol, isopropanol, butanol, and ethylene glycol, pentane, hexane, and octane.

[0050] Step 3: Add the carbon fiber powder to pure solvent b and disperse it by high-speed stirring until the mixture of carbon fiber powder and pure solvent b becomes a uniformly dispersed paste slurry C. Use a stirring paddle with a speed of 5000 rpm to 30000 rpm or a stirring paddle linear velocity of 12 m / s to 30 m / s, and a stirring time of 30 minutes to 120 minutes. The faster the stirring speed, the shorter the stirring time. The pure solvent b is any one or any two or more solvents such as deionized water, ethanol, propanol, butanol, and ethylene glycol. The ratio of carbon fiber powder to pure solvent b is in the range of 1:20 to 10000.

[0051] Step 4: Place the slurry A mentioned in Step 1 into a mixing container and stir slowly. Set the stirring speed of the mixing paddle in the mixing container to 20 rpm to 50 rpm. Then slowly add the slurry B mentioned in Step 2. After adding the slurry, continue stirring for 10 to 30 minutes. Then increase the stirring speed to 5000 rpm to 30000 rpm and stir at high speed for 30 to 120 minutes until a uniform paste-like slurry D is formed.

[0052] Step 5: Slowly stir the slurry D mentioned in Step 4. Set the stirring paddle speed of the stirring container to 20 rpm to 50 rpm. Then add 50% of the formula amount of binder. After adding, continue stirring for 10 to 30 minutes. Then increase the stirring speed to 5000 rpm to 30000 rpm and stir at high speed for 30 to 120 minutes until the binder and slurry D are evenly mixed and do not separate. Then continue slow stirring, setting the stirring paddle speed to 20 rpm to 50 rpm. Slowly add slurry C and continue stirring for 10 to 30 minutes after addition. Then increase the stirring speed to 5000 rpm to 30000 rpm and stir at high speed for 30 to 120 minutes until a uniform paste slurry E is formed. Continue slow stirring of paste slurry E, setting the stirring paddle speed to 20 rpm to 50 rpm. Then add the remaining 50% of the binder in the formula and continue stirring for 10 to 30 minutes after addition. Then increase the stirring speed to 5000 rpm to 30000 rpm and stir at high speed for 30 to 120 minutes until the mixture is uniform and does not separate into layers, resulting in the mixed slurry E.

[0053] Step 6: Let the mixed slurry E from Step 5 stand for 30 minutes, then pour it into the mixing device. Add filler material to the mixing device and mix slurry E with filler material for 30 to 120 minutes to ensure uniform mixing and obtain mixed slurry F. The mixing device is a vertical or horizontal mixing device with a rake-tooth mixing paddle.

[0054] Step 7: The mixed slurry F described in Step 6 is subjected to vacuum treatment using a vibration device, ultrasonic device, or by pouring it into a vacuum container to remove air bubbles from the mixed slurry F. The defoamed mixed slurry F is then dried using a closed-loop spray dryer or a vacuum distillation device to obtain dried powder F. The evaporated solvent during the drying process is recovered using a recovery device. The dried powder F is then compacted into blocks, granules, strips, or flakes using a compaction device to remove air from the powder, thereby obtaining solid material G and preventing oxidation of solid material G during subsequent processing. Alternatively, the defoamed mixed slurry F can be dried directly using vacuum distillation to obtain block-shaped solid material G. The compaction device includes tablet presses, extruders, kneaders, and other equipment with extrusion or mixing functions.

[0055] Step 8: Place the solid material G from Step 7 into a high-temperature furnace, introduce inert gas, and then heat to 550℃~1100℃ for sintering treatment for 1 hour to 30 hours to solidify the material. The high-temperature furnace can be a tube furnace, box furnace, pit furnace, rotary furnace, or other kiln capable of heating to above 550℃; the inert gas can be nitrogen, argon, or an argon-hydrogen mixture. Crush the solid material G using a crushing device, and then sieve the crushed material using a screening device to finally obtain a concrete structure composite material powder product H with a D50 particle size range of 0.5μm~10μm. The crushing device can be a combination of 2-3 types of equipment, such as a crusher, pulverizer, air jet mill, air jet mill, vibrating mill, ball mill, roller press, or grinding mill. The screening device can be a combination of one or more types of equipment, such as a manual sieve, vibrating screen, or air classifier.

[0056] To further optimize the product, a carbon coating step is added to the composite material. The specific steps are as follows:

[0057] Steps one through eight are the same as described above;

[0058] Step Nine: Place the concrete structure composite material powder product H obtained in Step Eight into a mixing container, add resin and pure solvent c, and perform high-speed stirring and dispersion until the mixture of powder product H and pure solvent c becomes a uniformly dispersed paste slurry I. The stirring speed is 3000 rpm to 30000 rpm or the stirring blade linear velocity is 9 m / s to 30 m / s, and the stirring time is 30 minutes to 240 minutes. The faster the stirring speed, the shorter the stirring time. The pure solvent c is any one or any two or more solvents of alcohol, ester, or ketone, preferably one or more of ethanol, propanol, butanol, pentanol, ethyl acetate, butyl acetate, dimethyl carbonate, and acetone. The mass mixing ratio of powder product H: resin: pure solvent c is in the range of 1:0.001 to 0.15:2.5 to 20. The resin can be replaced with glucose, sucrose, dextrin, or asphalt. The paste-like slurry I is dried using a spray dryer to obtain a dried powder I with a particle size of 1µm to 25µm. The dried powder I is then placed in a high-temperature furnace, inert gas is introduced, and the temperature is raised to 550℃ to 1200℃ for carbonization treatment for 2 to 8 hours. This process allows resin carbonization to coat the surface of the powder product, resulting in an optimized concrete structural composite material powder product J. The high-temperature furnace can be a tube furnace, box furnace, pit furnace, rotary furnace, or other kiln capable of heating to above 550℃. The inert gas can be nitrogen, argon, or an argon-hydrogen mixture.

[0059] The advantages of the product optimized in step nine are that after the surface of powder product H is re-carbon coated, the specific surface area of ​​the powder particles can be reduced, the surface defects of the particles can be improved, and the stability can be better. When used as a negative electrode material in batteries, it can effectively slow down the internal penetration of electrolyte into the negative electrode material and extend the battery cycle life. Example

[0060] (1.1) First, place 500g of pure silicon powder with a particle size D50≈150nm in a vacuum drying oven and heat it at 100℃ for 6 hours to remove moisture; then add 2000g of butanol and stir to prepare a slurry; then place it in a high-speed mixer and disperse it at 5000rpm for 30 minutes to obtain slurry A.

[0061] (1.2) Add 0.3g of graphene powder to 300g of butanol and disperse it in a high-speed mixer at 15000rpm for 30 minutes to prepare slurry B;

[0062] (1.3) Add 2g of multi-walled carbon nanotube powder (MWCNTs) to 300g of butanol and disperse it in a high-speed mixer at 15000rpm for 30 minutes to prepare slurry C;

[0063] (1.4) Place slurry A in a mixer and mix slowly at 35 rpm. Slowly add slurry B to the mixer. After adding the slurry B, continue mixing for 10 minutes. Then increase the mixing speed to 9000 rpm and mix at high speed for 50 minutes to obtain slurry D.

[0064] (1.5) Stir slurry D at 30 rpm, then add 50 g of polypropylene (PP) powder with a particle size of D50≈10 μm, 300 g of asphalt powder with a particle size of D50≈5 μm, and 20 g of polyvinylpyrrolidone (PVP). After adding, continue stirring for 10 minutes, then increase the stirring speed to 5000 rpm and stir at high speed for 40 minutes. Then reduce the stirring speed to 50 rpm and stir slowly. Slowly add slurry C. After adding, continue stirring for 10 minutes, then increase the stirring speed to 15000 rpm and stir for 50 minutes. Then reduce the stirring speed to 30 rpm and stir slowly. Continue adding 50 g of polypropylene (PP) powder with a particle size of D50≈10 μm and 300 g of asphalt powder with a particle size of D50≈5 μm. After adding, continue stirring for 10 minutes, then increase the stirring speed to 5000 rpm and stir at high speed for 40 minutes to obtain slurry E.

[0065] (1.6) After the slurry has been left to stand for 30 minutes, it is poured into a vertical mixer with a rake-tooth mixing paddle. 100g of microcrystalline graphite with a particle size of D50≈1um and 5g of carbon fiber with a particle size of D50≈2um are added to the mixer and mixed for 60 minutes to obtain mixed slurry F.

[0066] (1.7) Put the slurry into a vacuum degasser and let it stand for 15 minutes to remove the air bubbles in the slurry. Then dry it with a vacuum distillation apparatus to obtain solid material G in block form.

[0067] (1.8) Place solid material G in a box furnace, introduce high-purity nitrogen gas, and wait until the oxygen content in the box furnace drops below 1%. Then raise the temperature to 1000℃ for sintering and hold for 2 hours. Crush the sintered solid material G into small pieces using a double-roll crusher, then pulverize it again using a pulverizer, and finally sieve the pulverized material using a 325-mesh sieve to obtain concrete structure composite material powder product H with D50≈15um. Example

[0068] (2.1) First, place 100g of pure silicon powder with a particle size D50≈30nm in a vacuum drying oven and heat it at 80℃ for 24 hours to remove moisture; then add 700g of ethanol and stir to prepare a slurry; place the slurry in a high-speed mixer and stir at 6000rpm for 30 minutes to obtain slurry A.

[0069] (2.2) Add 0.15g of graphene powder to 200g of ethanol and disperse it in a high-speed mixer at 10000rpm for 50 minutes to prepare slurry B;

[0070] (2.3) Add 0.1g of single-walled carbon nanotube (SWCNT) powder to 200g of ethanol and disperse it at a high speed of 30m / s linear velocity for 30 minutes using a high-speed disperser to prepare slurry C;

[0071] (2.4) Place slurry A in a mixer and mix slowly at 30 rpm. Slowly add slurry B to the mixer. After adding the slurry B, continue mixing for 15 minutes. Then increase the mixing speed to 8000 rpm and mix at high speed for 60 minutes to obtain slurry D.

[0072] (2.5) Stir slurry D slowly at 30 rpm, then add 10g of polypropylene (PP) powder with a particle size of D50≈5um, 100g of asphalt powder with a particle size of D50≈5um, and 5g of polystyrene (PS) powder with a particle size of D50≈10um. After adding, continue stirring for 15 minutes, then increase the stirring speed to 5000 rpm and stir at high speed for 40 minutes. Then reduce the stirring speed to 50 rpm and stir slowly, slowly adding slurry C. Continue stirring for 10 minutes, then increase the stirring speed to 20,000 rpm and stir for 30 minutes. Then reduce the stirring speed to 30 rpm and stir slowly. Continue to add 20g of polypropylene (PP) powder with a particle size of D50≈5um, 100g of asphalt powder with a particle size of D50≈5um, and 5g of polystyrene (PS) powder with a particle size of D50≈10um. After adding all the powder, continue stirring for 15 minutes, then increase the stirring speed to 5,000 rpm and stir at high speed for 40 minutes to obtain slurry E.

[0073] (2.6) After letting slurry E stand for 30 minutes, pour it into a vertical mixer with a rake-tooth mixing paddle. Add 10g of flake graphite with a particle size of D50≈3um and 5g of amorphous carbon with a particle size of D50≈1um to the mixer and mix for 60 minutes to obtain mixed slurry F.

[0074] (2.7) Put the slurry F into a vacuum degasser and let it stand for 15 minutes. Then pour out the slurry and dry it with a closed-loop spray dryer to obtain dried powder F. Press the dried powder F into tablets with a tablet press to obtain solid material G.

[0075] (2.8) Place solid material G in a box furnace, introduce high-purity nitrogen gas, and wait until the oxygen content in the box furnace drops below 50 ppm. Then, raise the temperature to 950℃ for sintering and hold for 2 hours. Crush the sintered solid material G into granules using a double-roll crusher, then further crush it using an air jet mill, and finally screen the crushed material using a 400-mesh vibrating screen to obtain concrete structure composite material powder product H with D50≈10um. Example

[0076] (3.1) 100g of pure silicon powder with a particle size of D50≈30nm and 100g of silicon-silica composite (SiOx) powder with a particle size of D50≈1μm were placed in a beaker and heated at 90℃ for 20 hours in a vacuum drying oven; then 1500g of isopropanol was added and stirred to prepare a slurry, and then placed in a high-speed dispersion device and dispersed at a speed of 5000rpm for 40 minutes to obtain slurry A;

[0077] (3.2) Add 0.2g of graphene powder to 500g of isopropanol and disperse it in a high-speed mixer at 15000rpm for 50 minutes to prepare slurry B;

[0078] (3.3) Add 0.2g of single-walled carbon nanotube powder (SWCNTs) to 500g of isopropanol and disperse it under high shear at 15000rpm for 50 minutes using a high-speed mixer to prepare slurry C;

[0079] (3.4) Place slurry A in a mixer and mix slowly at 30 rpm. Slowly add slurry B to the mixer. After adding the slurry B, continue mixing for 15 minutes. Then increase the mixing speed to 9000 rpm and mix at high speed for 30 minutes to obtain slurry D.

[0080] (3.5) Stir slurry D slowly at 30 rpm, then add 30g of thermoplastic phenolic resin, 8g of polyacrylonitrile (PANI) with a particle size of D50≈3um, 150g of asphalt powder with a particle size of D50≈5um, and 10g of polyethylene (PE) with a particle size of D50≈10um. After adding all the ingredients, continue stirring for 15 minutes. Then increase the stirring speed to 5000 rpm and stir at high speed for 40 minutes. Then reduce the stirring speed to 50 rpm and stir slowly. Slowly add slurry C. After adding all the ingredients... Continue stirring for 10 minutes, then increase the stirring speed to 20,000 rpm and stir for 30 minutes. Then reduce the stirring speed to 30 rpm and stir slowly. Continue to add 30g of thermoplastic phenolic resin, 8g of polyacrylonitrile (PANI) with a particle size of D50≈3um, 150g of asphalt powder with a particle size of D50≈5um, and 10g of polyethylene (PE) with a particle size of D50≈10um. After adding all the ingredients, continue stirring for 15 minutes, then increase the stirring speed to 7,000 rpm and stir at high speed for 30 minutes to obtain slurry E.

[0081] (3.6) After letting slurry E stand for 30 minutes, pour it into a vertical mixer with a rake-tooth mixing paddle. Add 10g of mesophase carbon microspheres (MCMB) with a particle size of D50≈3um, 10g of amorphous carbon with a particle size of D50≈1um, and 15g of thermosetting phenolic resin with a particle size of D50≈2um to the mixer. Mix for 60 minutes to obtain mixed slurry F.

[0082] (3.7) Put the slurry F into a vacuum degasser and let it stand for 15 minutes. Then pour out the slurry and dry it with a closed-loop spray dryer to obtain dried powder E. Extrude the powder E with a screw extruder to obtain solid material G.

[0083] (3.7) Place solid material G in a box furnace, introduce high-purity nitrogen gas, and wait until the oxygen content in the box furnace drops below 50 ppm. Then, raise the temperature to 900℃ for sintering and hold for 2 hours. Crush the sintered solid material G into granules using a double-roll crusher, then further crush it using an air jet mill, and finally screen the crushed material using a 400-mesh vibrating screen to obtain concrete structure composite material powder product H with D50≈12um. Example

[0084] (4.1) Place 200g of pure silicon powder with a particle size D50≈100nm in a vacuum drying oven and bake at 150℃ for 5 hours; then add 1000g of ethanol and 500g of butanol and stir to prepare a slurry, and then place it in a high-speed dispersion device and disperse at 5000rpm for 40 minutes to obtain slurry A;

[0085] (4.1) Add 0.3g of graphene powder to 500g of ethanol and disperse it in a high-speed mixer at 15000rpm for 50 minutes to prepare slurry B;

[0086] (4.3) Add 0.2g of single-walled carbon nanotube powder (SWCNTs) to 500g of ethanol and disperse it under high shear at 15000rpm for 50 minutes using a high-speed mixer to prepare slurry C;

[0087] (4.4) Place slurry A in a mixer and mix slowly at 30 rpm. Slowly add slurry B to the mixer. After adding the slurry B, continue mixing for 15 minutes. Then increase the mixing speed to 9000 rpm and mix at high speed for 30 minutes to obtain slurry D.

[0088] (4.5) Stir slurry D slowly at 30 rpm, then add 100g of thermoplastic phenolic resin, 150g of asphalt powder with a particle size of D50≈5um, and 10g of polyethylene (PE) with a particle size of D50≈10um. After adding, continue stirring for 15 minutes, then increase the stirring speed to 5000 rpm and stir at high speed for 40 minutes, then reduce the stirring speed to 50 rpm and stir slowly. Slowly add slurry C, and after adding, continue stirring for 10 minutes, then increase the stirring speed to 20000 rpm and stir for 30 minutes, then reduce the stirring speed to 30 rpm and stir slowly. Continue adding 100g of thermoplastic phenolic resin, 150g of asphalt powder with a particle size of D50≈5um, and 10g of polyethylene (PE) with a particle size of D50≈10um. After adding, continue stirring for 15 minutes, then increase the stirring speed to 7000 rpm and stir at high speed for 30 minutes to obtain slurry E.

[0089] (4.6) After letting slurry E stand for 30 minutes, pour it into a vertical mixer with a rake-tooth mixing paddle. Add 10g of mesophase carbon microspheres (MCMB) with a particle size of D50≈3um, 10g of amorphous carbon with a particle size of D50≈1um, and 15g of thermosetting phenolic resin with a particle size of D50≈2um to the mixer. Mix for 60 minutes to obtain mixed slurry F.

[0090] (4.7) Put the slurry F into a vacuum degasser and let it stand for 15 minutes. Then pour out the slurry and dry it with a closed-loop spray dryer to obtain dried powder F. Knead the powder F with a kneader to obtain solid material G.

[0091] (4.8) Place solid material G in a box furnace, introduce high-purity nitrogen gas, and wait until the oxygen content in the box furnace drops below 50 ppm. Then, raise the temperature to 1100℃ for sintering and hold for 2 hours. Crush the sintered solid material G into granules using a double-roll crusher, then further crush it using an air jet mill, and finally screen the crushed material using a 400-mesh vibrating screen to obtain concrete structure composite material powder product H with D50≈15um. Example

[0092] 100g of the concrete structure composite material powder product H obtained in Example 4 was placed in a stainless steel mixing container, 10g of phenolic resin and 1000g of ethanol were added, and the mixture was placed in a mixer and slowly stirred at 30 rpm for 10 minutes. After the powder was completely wetted, the stirring speed was increased to 5000 rpm and stirred at high speed for 120 minutes to obtain a paste slurry I. The paste slurry I was dried using a closed spray dryer to obtain a dry powder I with D50≈16um. The dry powder I was placed in a box furnace and high-purity argon gas was introduced. After the oxygen content in the box furnace dropped to below 50ppm, the temperature was raised to 1000℃ for sintering and held for 3 hours to obtain the optimized concrete structure composite material powder product J.

[0093] The present invention also proposes specific applications of the above-mentioned composite materials:

[0094] The composite material proposed in this invention was added to deionized water in a mass percentage ratio of 93%:2.96%:2%:2%:0.04% with carbon black, sodium carboxymethyl cellulose, styrene-butadiene rubber latex, and carbon nanotubes. The mixture was stirred for 0.5 to 2 hours to obtain a uniformly mixed negative electrode slurry. The negative electrode slurry was then uniformly coated onto an 8 μm thick copper foil. The copper foil coated with the negative electrode slurry was then dried in an oven and cut into negative electrode sheets. A 200mAh capacity soft-pack lithium-ion battery was then manufactured using conventional battery manufacturing methods. The reversible capacity at 0.1C current density and the charge / discharge cycle life at 0.5C / 1C rate were tested.

[0095] Electrical performance comparison table:

[0096]

[0097] In summary, the existing technical solution is as follows:

[0098] 1. Silicon material is prepared into nano-scale powder or micro-nano-scale powder. After carbon coating of the powder with carbon source, it is applied to the negative electrode of battery. During the charging and discharging process of battery, silicon particles will gradually expand, pulverize and eventually fail, resulting in battery life reduction.

[0099] 2. Silicon material is prepared into silicon suboxide (SiOx). After the powder is simply coated with carbon using a carbon source, it is applied to the negative electrode of the battery. During the charging and discharging process of the battery, the silicon suboxide (SiOx) particles will react with lithium ions to generate irreversible lithium compounds, resulting in a low initial coulombic efficiency of the battery. In addition, silicon suboxide has poor conductivity and will still expand significantly during the charging and discharging process, leading to gradual battery degradation and failure.

[0100] The present invention combines silicon material with aggregates, dopants, and gel materials to form a concrete-structured composite negative electrode material, giving it the bonding properties, strength, and elasticity of concrete. This improves the material's density, tensile strength, and crack resistance, effectively buffering the volume change effect of silicon particles during charging and discharging, and slowing down the continuous formation of new SEI films by silicon particles, which leads to the consumption of lithium ions, thereby improving the material's stability. As a result, lithium-ion batteries prepared using this composite material have excellent cycle performance.

[0101] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A composite material for concrete structures, characterized in that, The composite material is composed of any two or more of the following components: silicon powder, encapsulating agent, graphene, carbon fiber tube, adhesive, filler, and additives. The mass ratio of silicon powder: encapsulating agent: graphene: carbon fiber tube: adhesive: filler: additive is 1:0.05~10:0.0001~0.02:0.0001~0.02:0.15~1:0.01~0.5:0.001~0.

1.

2. The composite material for a concrete structure according to claim 1, characterized in that, The silicon powder is made of nanoscale or microscale materials, and the other components are microscale materials.

3. The composite material for a concrete structure according to claim 1, characterized in that, The silicon powder is composed of any one or more of pure silicon (Si), silicon-silica composite (SiOx), and silicon alloy, and the D50 particle size of the silicon powder is in the range of 1nm~500nm or 0.02μm~6μm.

4. The composite material for a concrete structure according to claim 1, characterized in that, The encapsulating agent is any one or a mixture of two or more of alcohols, ketones, esters and organic acid solvents, and the purity of the encapsulating agent used is analytical grade or higher.

5. The composite material for a concrete structure according to claim 1, characterized in that, The graphene powder is made of single-layer graphene, multi-layer graphene, or carbon black, wherein the number of layers in the multi-layer graphene does not exceed 100. The carbon nanotubes are made of any one of single-walled carbon nanotubes, multi-walled carbon nanotubes, or vapor-grown carbon fibers. The filler material is composed of any one or any two or more of amorphous hard carbon, flake graphite, spherical graphite, microcrystalline graphite, mesophase carbon microspheres (MCMB), or carbon fibers in any proportion, and the D50 particle size of the filler material ranges from 1 μm to 8 μm. The binder is an organic powder composed of any one or any two or more of thermoplastic phenolic resin, polyethylene (PE), polystyrene (PS), polypropylene (PP), polyacrylonitrile (PAN), polyaniline (PANI), polyurethane (PU), polyvinylpyrrolidone (PVP), nylon (PA), ABS, PET, asphalt, gelatin, or gum arabic in any proportion, and the D50 particle size of the binder powder ranges from 0.1 μm to 200 μm.

6. The composite material for a concrete structure according to claim 1, characterized in that, The finished product of the composite material is irregular particles with an internal structure similar to that of concrete.

7. A method for preparing a composite material for a concrete structure, characterized in that, The specific preparation steps for the composite material used to prepare the concrete structure according to any one of claims 1-6 are as follows: Step 1: After removing water from the silicon powder, add a coating agent until the silicon powder is completely wetted by the coating agent and forms a slurry, to obtain a silicon powder slurry. Then, disperse the silicon powder slurry at high speed to prepare slurry A. Step 2: Add graphene powder to pure solvent a and disperse at high speed until the graphene becomes a uniformly dispersed paste B. Step 3: Add the carbon fiber powder to pure solvent b and disperse at high speed until the carbon fiber powder becomes a uniformly dispersed and paste-like slurry C. Step 4: Slowly stir the slurry A mentioned in Step 1 and slowly add the slurry B prepared in Step 2, stirring at high speed until a uniform and paste-like slurry D is formed. Step 5: After slowly stirring the slurry D mentioned in Step 4, add 50% of the formula amount of adhesive. After the addition is complete, continue stirring until the adhesive and slurry D are evenly mixed and do not separate into layers. Continue to slowly stir the treated mixed slurry D and slowly add slurry C. Stir at high speed until it is evenly mixed and forms a paste. Then, slowly stir and add the remaining 50% of the formula amount of adhesive. After the addition is complete, stir until the adhesive and slurry C are evenly mixed and do not separate into layers to obtain the mixed slurry E. Step 6: After allowing the mixed slurry E described in Step 5 to stand, add filler material and mix evenly to obtain mixed slurry F; Step 7: Defoam, dry, compact, and degas the mixed slurry F described in Step 6 to obtain solid material G; Step 8: Sinter, crush, and sieve the solid material G obtained in Step 7 to obtain the powder product H of concrete structure composite material. The D50 particle size range of the powder product H is 0.5μm~15μm.

8. The method for preparing a composite material for a concrete structure according to claim 6, characterized in that, It also includes the following steps: Step 9: Add the powder product H described in Step 8 to the resin and pure solvent c, stir and disperse until the powder becomes a uniformly dispersed and paste-like slurry I; dry the slurry I and then perform high-temperature carbonization treatment to obtain the optimized concrete structure composite material powder product J.

9. The method for preparing a composite material for a concrete structure according to claim 6, characterized in that, In step two, the pure solvent a is any one or more of deionized water, N-methylpyrrolidone, N-ethylpyrrolidone, ethanol, propanol, isopropanol, butanol, ethylene glycol, pentane, hexane, and octane; the mass ratio of graphene powder to pure solvent a is in the range of 1:50~2000. In step three, the pure solvent b is any one or more of deionized water, ethanol, propanol, butanol, and ethylene glycol; the mass ratio of the carbon fiber to pure solvent b is in the range of... The ratio is 1:20~10000; the resin in step nine is any one or any two or more of phenolic resin, ion exchange resin, polyimide resin, epoxy resin, and polyetheretherketone resin; the pure solvent c is any one or any two or more of alcohol, ester, or ketone solvents; the mass ratio of powder product H: resin: pure solvent c is in the range of 1:0.001~0.15:2.5~20; the resin can be replaced by glucose, sucrose, dextrin, or asphalt.

10. The application of the composite material in a concrete structure according to claim 1, characterized in that, The composite material prepared by the method for preparing the composite material of the concrete structure according to any one of claims 7-9, together with carbon black, sodium carboxymethyl cellulose, styrene-butadiene rubber latex, and carbon fiber tubes, is added to deionized water in a mass percentage ratio of 93%:2.96%:2%:2%:0.04% and stirred to obtain a uniformly mixed negative electrode slurry. The negative electrode slurry is then used to make a soft-pack lithium-ion battery.

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