WO2022134562A1 - 二次造粒的硅碳基材电池负极材料及其制备方法 - Google Patents

二次造粒的硅碳基材电池负极材料及其制备方法 Download PDF

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WO2022134562A1
WO2022134562A1 PCT/CN2021/107632 CN2021107632W WO2022134562A1 WO 2022134562 A1 WO2022134562 A1 WO 2022134562A1 CN 2021107632 W CN2021107632 W CN 2021107632W WO 2022134562 A1 WO2022134562 A1 WO 2022134562A1
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silicon
nano
carbon substrate
carbon
negative electrode
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PCT/CN2021/107632
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English (en)
French (fr)
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周宪聪
吴玉祥
胡旭添
陈伯坤
汤昊
刘烈凯
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荣炭科技股份有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes

Definitions

  • the present invention relates to a carbon-based battery negative electrode material, in particular to a secondary granulated silicon carbon-based battery negative electrode material and a preparation method thereof.
  • the common negative electrode granulation process in the prior art is to mix coke and pitch by high-temperature melting, and then proceed through carbonization, graphitization and other procedures in sequence.
  • FIG. 1 is a schematic diagram of a carbon-based battery negative electrode material in the prior art.
  • the added silicon oxide 140 may adhere to the surface of the graphite 120 by means of the pitch 160 , as shown in FIG. 1 .
  • the silicon oxide 140 falls off from the graphite 120 during battery slurrying, which will affect the uniformity of battery slurrying in subsequent applications.
  • the volume change of the silicon oxide 140 will also cause the silicon oxide 140 to fall off from the surface of the graphite 120, thereby affecting the cycle stability of the battery.
  • the above phenomena will make the battery using the negative electrode material of the prior art unable to exert its due performance.
  • the present invention provides a secondary granulated silicon carbon substrate battery negative electrode material and a preparation method thereof, the above secondary granulated silicon carbon substrate battery negative electrode material and The preparation method is not only simple in the process, but also has the advantages of greatly improving the uniformity of the battery during slurry mixing and the liquid permeability of the negative electrode material. More preferably, the above-mentioned secondary granulated silicon carbon substrate battery negative electrode material and preparation method thereof It can effectively improve the cycle stability of the battery, and then can effectively improve the effect of industrial competitiveness.
  • One object of the present invention is to provide a secondary granulated silicon-carbon substrate battery negative electrode material and a preparation method thereof. By embedding nano-silicon in the pores on the surface of the carbon substrate, it is possible to reduce the reduction of battery adjustment due to the peeling of nano-silicon. Homogeneity of pulp.
  • Another object of the present invention is to provide a secondary granulated silicon carbon substrate battery negative electrode material and a preparation method thereof. of exudation.
  • Another object of the present invention is to provide a secondary granulated silicon carbon substrate battery negative electrode material and a preparation method thereof.
  • a modified layer to coat the carbon substrate with nano-silicon embedded in the surface pores, so that the above-mentioned two
  • the secondary granulated silicon carbon substrate battery anode material can further prevent the nano-silicon from falling off the carbon substrate, thereby reducing the uniformity of the battery during slurry mixing and improving the liquid permeability during battery application due to the falling off of the nano-silicon.
  • Another object of the present invention is to provide a secondary granulated silicon carbon substrate battery negative electrode material and a preparation method thereof.
  • a modified layer to coat the carbon substrate with nano-silicon embedded in the surface pores the above secondary granulation can be achieved.
  • the granulated silicon carbon-based battery negative electrode material can provide sufficient buffer capacity during battery application to respond to the volume change of nano-silicon due to charging and discharging, thereby achieving the effect of improving the cycle stability of the battery.
  • Another object of the present invention is to provide a method for preparing a secondary granulated silicon carbon base battery negative electrode material, by using a temperature-changeable rotary kiln to make the above secondary granulated silicon carbon base battery negative electrode material
  • the preparation method can complete the secondary granulation in the rotary kiln, thereby achieving the effect of simplifying the process.
  • the present invention discloses a secondary granulated silicon carbon substrate battery negative electrode material and a preparation method thereof.
  • the above-mentioned secondary granulated silicon carbon base battery negative electrode material includes a carbon base material, a plurality of nano-silicon, and a modified layer.
  • the above-mentioned plurality of nano-silicons can be respectively embedded in the surface pores of the above-mentioned carbon substrate, so as to form a carbon substrate with nano-silicon embedded in the surface pores.
  • the plurality of nano-silicons can be respectively extruded and embedded in the surface pores of the carbon substrate to form a carbon substrate with nano-silicon embedded in the surface pores.
  • the above-mentioned modification layer may be coated on the above-mentioned carbon substrate with surface pores embedded with nano-silicon.
  • the preparation method of the secondary granulated silicon carbon substrate battery negative electrode material includes the steps of mixing nano-silicon and carbon substrate, adding a binder, granulating and carbonizing, disintegrating, and sieving.
  • the above-mentioned step of mixing the nano-silicon and the carbon substrate may further include the step of extruding the nano-silicon into the carbon substrate.
  • the above-mentioned granulation and carbonization steps may be performed in a rotary kiln.
  • the use of nano-silicon and the modified layer can not only greatly improve the uniformity of the battery during slurry mixing and the liquid permeability of the negative electrode material, but also better, the above-mentioned secondary granulated silicon carbon-based
  • the material battery anode material and its preparation method can effectively improve the cycle stability of the battery, and then can effectively improve the effect of industrial competitiveness.
  • FIG. 1 is a schematic diagram of a negative electrode material of a silicon carbon substrate battery in the prior art.
  • FIG. 2A is a schematic diagram of a secondary granulated silicon carbon based battery negative electrode material according to an example of the present specification.
  • FIG. 2B is a schematic diagram of a secondary granulated silicon carbon based battery negative electrode material according to another example of the present specification.
  • FIG. 3 is a flow chart of a method for preparing a secondary granulated silicon carbon substrate battery negative electrode material according to the present specification.
  • Figure 4 is a comparison diagram of coin cells made of different anode materials for 50 battery cycle tests.
  • Figure 5 is a comparison diagram of 1000 battery cycle tests performed on pouch cells made of different anode materials.
  • the direction discussed in the present invention is a secondary granulated silicon carbon base battery negative electrode material and a preparation method thereof.
  • detailed process steps or compositional structures will be set forth in the following description. Obviously, the practice of the present invention is not limited to the specific details familiar to those skilled in the art. In other instances, well-known compositions or process steps have not been described in detail so as not to unnecessarily limit the invention.
  • the preferred system of the present invention will be described in detail as follows, but in addition to these detailed descriptions, the present invention can also be widely implemented in other systems, and the scope of the present invention is not limited, and the scope to be protected by its patent shall prevail .
  • An embodiment of the present invention discloses a secondary granulated silicon carbon substrate battery negative electrode material.
  • the above-mentioned secondary granulated silicon carbon base battery negative electrode material includes a carbon base material, a plurality of nano-silicon, and a modified layer.
  • the above-mentioned plurality of nano-silicons can be respectively embedded in the surface pores of the above-mentioned carbon substrate, so as to form a carbon substrate with nano-silicon embedded in the surface pores.
  • the above-mentioned plurality of nano-silicons can be squeezed and embedded in the surface pores of each carbon substrate by an external force, so as to form a nano-silicon embedded in the surface pores.
  • the modification layer can be coated on the carbon substrate with nano-silicon embedded in the surface pores to form a carbon substrate with nano-silicon embedded in the surface pores coated with the modification layer.
  • a plurality of the carbon substrates coated with the modification layer and the surface pores of which are embedded with nano-silicon can be stacked to form a set of carbon substrates.
  • FIG. 2A is a schematic diagram of a secondary granulated silicon carbon based battery negative electrode material according to a preferred example of the present embodiment.
  • the secondary granulated silicon carbon base battery negative electrode material 200 includes a carbon base material 220 , a plurality of nano-silicon 240 , and a modification layer 260 .
  • the carbon substrate 220 may be selected from one or a combination of the following groups: natural graphite, artificial graphite, graphene, carbon nanotubes (CNTs), and vapor growth Carbon fiber (VGCF), mesophase carbon microsphere material (MCMB).
  • the particle size of the carbon substrate 220 is about 5-20 ⁇ m. In another preferred embodiment according to this example, the particle size of the carbon substrate 220 is about 15 ⁇ m.
  • a plurality of nano-silicons 240 may be respectively embedded in the surface pores of the carbon substrate 220 to form a carbon substrate with nano-silicon embedded in the surface pores.
  • the above-mentioned plurality of nano-silicon 240 can be squeezed and embedded in the surface pores of each carbon substrate 220 by an external force, so that the nano-silicon 240 It can be extruded deeper into the surface of the carbon substrate 220 to form a carbon substrate with surface pores embedded with nano-silicon.
  • the particle size of the nano-silicon 240 is about 100-900 nm.
  • the particle size of the nano-silicon 240 is about 200 nm.
  • the modification layer 260 is coated on the carbon substrate with the nano-silicon embedded in the surface pores, so as to form the carbon substrate coated with the modification layer and the surface pores embedded with the nano-silicon.
  • the thickness of the modification layer 260 is about 15-1000 nm. In another preferred embodiment according to this example, the thickness of the modification layer 260 is about 100 nm.
  • the composition of the above-mentioned modification layer 260 may include an adhesive.
  • the above-mentioned binder can be selected from one of the following groups or a combination thereof: asphalt, phenolic resin, carboxymethyl cellulose (CMC for short), malt Dextrin, styrene-butadiene rubber (Styrene-Butadiene Rubber, referred to as SBR).
  • FIG. 2B is a schematic diagram of a secondary granulated silicon carbon based battery negative electrode material according to another preferred example of the present embodiment.
  • the secondary granulated silicon carbon substrate battery negative electrode material 200' includes a plurality of carbon substrates 220', a plurality of nano-silicon 240', and a modification layer 260'.
  • the above-mentioned plurality of nano-silicon 240' are respectively embedded in the surface pores of each carbon substrate 220' to form a carbon substrate with nano-silicon embedded in the surface pores.
  • the above-mentioned plurality of nano-silicon 240 ′ can be squeezed and embedded in the surface pores of each carbon substrate 220 ′ by extruding by an external force, so as to form surface pore embedding Carbon substrate with nano-silicon.
  • the carbon substrate 220 ′ can be selected from one or a combination of the following groups: natural graphite, artificial graphite, graphene, carbon nanotube (CNT), and gas phase Growing carbon fiber (VGCF), mesophase carbon microsphere material (MCMB).
  • the particle size of the carbon substrate 220' is about 5-20 ⁇ m. In another preferred embodiment according to this example, the particle size of the carbon substrate 220' is about 15 ⁇ m. In a preferred embodiment according to this example, the particle size of the nano-silicon 240' is about 100-900 nm. In another preferred embodiment according to this example, the particle size of the nano-silicon 240' is about 200 nm.
  • the above-mentioned modification layer 260' may be coated on the above-mentioned carbon substrate whose surface pores are embedded with nano-silicon, as shown in FIG. 2B .
  • a plurality of carbon substrates coated with modified layers and embedded with nano-silicon in surface pores can be stacked to form a set of carbon substrates, as shown in FIG. 2B .
  • the thickness of the modification layer 260' is about 15-30 nm. In another preferred embodiment according to this example, the thickness of the modification layer 260' is about 20 nm.
  • the trim layer 260' described above contains an adhesive.
  • the above-mentioned binder can be selected from one of the following groups or a combination thereof: asphalt, phenolic resin, carboxymethyl cellulose (CMC for short), malt Dextrin, styrene-butadiene rubber (Styrene-Butadiene Rubber, referred to as SBR).
  • FIG. 3 is a schematic diagram of a method for preparing a secondary granulated silicon carbon substrate battery negative electrode material according to the present embodiment.
  • the above-mentioned preparation method of the secondary granulated silicon carbon substrate battery negative electrode material includes the steps of mixing nano-silicon and carbon substrate, adding a binder, granulating and carbonizing, disintegrating, and sieving.
  • the carbon substrate and nano-silicon are first mixed, so that the nano-silicon is respectively embedded in the surface voids of the carbon substrate, so as to form surface void embedding A carbon substrate with nano-silicon, as shown in step 310 .
  • the above-mentioned step 310 may further include a step of extruding the nano-silicon into the carbon substrate.
  • the above-mentioned plurality of nano-silicons are respectively extruded and embedded into the surface of the carbon substrate by an external force, so as to form a carbon substrate with surface pores embedded with nano-silicon.
  • the carbon substrate may be selected from one or a combination of the following: natural graphite, artificial graphite, graphene, carbon nanotubes (CNTs), and vapor grown carbon fibers (VGCFs). ), mesophase carbon microsphere material (MCMB).
  • the proportion of the above-mentioned nano-silicon is about 0.1-20 wt % of the carbon substrate. In a preferred example according to this embodiment, the proportion of the above-mentioned nano-silicon is about 3-15 wt % of the carbon substrate.
  • the above-mentioned step of mixing the carbon substrate and the nano-silicon can be completed at room temperature (about 10-40° C.).
  • the particle size of the carbon substrate is about 5-20 ⁇ m. In another preferred embodiment according to this example, the particle size of the carbon substrate is about 15 ⁇ m.
  • the particle size of the above-mentioned nano-silicon is about 100-900 nm. In another preferred embodiment according to this example, the particle size of the above-mentioned nano-silicon is about 200 nm.
  • the above-mentioned step of mixing the carbon substrate and the nano-silicon can be completed in a mixer with extrusion force.
  • a binder is added to the aforementioned carbon substrate with nano-silicon embedded in the surface pores, as shown in step 320 .
  • the temperature can be started to enter the granulation and carbonization steps, as shown in step 330 .
  • the above-mentioned binder may be selected from one of the following groups or a combination thereof: asphalt, phenolic resin, carboxymethyl cellulose (CMC for short), malt Dextrin, styrene-butadiene rubber (Styrene-Butadiene Rubber, referred to as SBR).
  • step 320 may be performed at room temperature (about 10-40° C.).
  • the weight ratio of the above-mentioned binder is about 5-15 wt% of the carbon substrate whose surface pores are embedded with nano-silicon.
  • the weight ratio of the above-mentioned binder is about 5-10 wt% of the carbon substrate whose surface pores are embedded with nano-silicon.
  • the step 320 may further include adding a solvent to the carbon substrate with nano-silicon embedded in the surface pores, wherein the solvent in the solution can be used in the subsequent granulation and carbonization steps volatilized.
  • the above-mentioned solvent may be selected from one or a combination of the following: water, alcohol.
  • the adhesive will be melted and coated on the carbon substrate with the nano-silicon embedded in the surface pores to form the surface pores embedded with the nano-silicon coated with the modification layer.
  • carbon substrate depending on the adhesive used, the formation temperature of the carbon substrate with nano-silicon embedded in the surface pores covered with the modification layer can be raised to about 20 Completed at -350°C.
  • a plurality of the carbon substrates with nano-silicon embedded in the surface pores coated with the modification layer can be stacked to form a set of carbon substrates.
  • the thickness of the modification layer is about 15-1000 nm. In another preferred embodiment according to this example, the thickness of the modification layer is about 100 nm.
  • the carbonization temperature is about 900-1100°C.
  • the granulation and carbonization process of step 330 can be completed in a rotary furnace, a tube furnace, a push-plate furnace, a rolling furnace, or a static heating furnace.
  • step 340 may disintegrate the above-mentioned carbon substrate coated with the modification layer and embedded with nano-silicon into the surface pores into a plurality of small particles.
  • a filtering step 350 may be performed on the disintegrated small particles.
  • the above step 350 can screen out particles with a D50 of about 10-30 ⁇ m.
  • the above step 350 can screen out particles with a D50 of about 17-23 ⁇ m.
  • Nano silicon powder (D50 about 300nm), artificial graphite (D50 about 14-17 ⁇ m), and pitch (D50 about 2-5 ⁇ m) were mixed uniformly in a V-type mixer, and then transferred to a tube furnace.
  • the addition amount of the above-mentioned nano-silicon powder is about 3wt% of the total weight of the artificial graphite and the nano-silicon powder.
  • the addition amount of the above-mentioned pitch is about 7 wt % of the total weight of artificial graphite and nano-silicon powder.
  • Carbonization was performed by heating to 1000°C in a tube furnace. Under an inert atmosphere, the tube furnace was heated from room temperature to 1000°C at a heating rate of 5°C/min, and held for 3 hours. Then, the temperature in the tube furnace is returned to room temperature to obtain the silicon-carbon composite material.
  • nano silicon powder (D50 about 300nm) and artificial graphite (D50 about 14-17 ⁇ m) are mixed uniformly in a V-type mixer.
  • the addition amount of the above-mentioned nano-silicon powder is about 3wt% of the total weight of the artificial graphite and the nano-silicon powder.
  • pitch (D50 about 2-5 ⁇ m) was added to the above-mentioned V-type mixer, and the pitch, the above-mentioned nano-silica powder and artificial graphite were uniformly mixed, and then transferred to a tube furnace.
  • the addition amount of the above-mentioned pitch is about 7 wt % of the total weight of artificial graphite and nano-silicon powder.
  • the tube furnace was heated from room temperature to 1000°C at a heating rate of 5°C/min, and held for 3 hours. Then, the temperature in the tube furnace is returned to room temperature to obtain the silicon-carbon composite material.
  • nano silicon powder (D50 about 300nm) and artificial graphite (D50 about 14-17 ⁇ m) are mixed uniformly in a V-type mixer.
  • the addition amount of the above-mentioned nano-silicon powder is about 3wt% of the total weight of the artificial graphite and the nano-silicon powder.
  • pitch (D50 about 2-5 ⁇ m) was added to the above-mentioned V-type mixer, and the pitch, the above-mentioned nano-silica powder and artificial graphite were uniformly mixed, and then transferred to a rotary kiln.
  • the addition amount of the above-mentioned pitch is about 7 wt % of the total weight of artificial graphite and nano-silicon powder.
  • the rotary furnace Under an inert atmosphere, the rotary furnace was heated from room temperature to 1000°C at a heating rate of 5°C/min, and kept for 3 hours. After that, the temperature in the rotary furnace is returned to room temperature to obtain the silicon-carbon composite material.
  • nano silicon powder (D50 about 300 nm) and artificial graphite (D50 about 14-17 ⁇ m) are mixed uniformly in a mixer with extrusion force, so that the nano silicon powder is embedded in the artificial graphite.
  • the addition amount of the above-mentioned nano-silicon powder is about 3wt% of the total weight of the artificial graphite and the nano-silicon powder.
  • pitch (D50 about 2-5 ⁇ m) was added to the above-mentioned V-type mixer, and the pitch, the above-mentioned nano-silica powder and artificial graphite were uniformly mixed, and then transferred to a rotary kiln.
  • the addition amount of the above-mentioned pitch is about 7 wt % of the total weight of artificial graphite and nano-silicon powder.
  • the rotary furnace Under an inert atmosphere, the rotary furnace was heated from room temperature to 1000°C at a heating rate of 5°C/min, and kept for 3 hours. After that, the temperature in the rotary furnace is returned to room temperature to obtain the silicon-carbon composite material.
  • the silicon-carbon composite material obtained in Example 1 because the nano-silicon powder is extruded and embedded on the surface of the artificial graphite, and a modified layer (pitch) is added to coat the artificial graphite with the nano-silicon powder embedded in the surface pores. Therefore, the silicon-carbon composite material obtained in Example 1 will not find nano-silicon powder falling off from the artificial graphite.
  • the coating of the modification layer after the above-mentioned silicon-carbon composite material is applied to the battery, it will not be easy to crack due to expansion or escape of nano-silicon powder during the charging and discharging process.
  • the silicon-carbon composite materials obtained in the above Comparative Examples 1-3 and Example 1 were used as negative electrode materials, and were assembled into coin-type batteries respectively to conduct CR2032 coin-type semi-electric tests.
  • the assembly method of the above button battery and the CR2032 button half-electric test process are briefly described as follows.
  • the silicon-carbon composites, conductive agents, base binders, dispersants and solvents obtained in Comparative Examples 1-3 and Example 1 were stirred in a planetary mixer for 3 hours to obtain a well-mixed slurry.
  • the above slurry was uniformly coated on the copper foil current collector with an automatic film coating machine, and the coating thickness was about 200 ⁇ m. After drying by blowing at 60° C. for 30 minutes, it was placed in a vacuum drying oven and vacuum-dried at 120° C. for 12 hours to obtain a negative electrode piece.
  • the above-mentioned base binder is styrene-butadiene rubber (SBR), the dispersant is sodium carboxymethyl cellulose (CMC), and the conductive agent is super carbon black (SP).
  • the electrolyte used in the button battery is 1M LiPF 6 [in EC:DMC:EMC(1:1:1vol.%)with 3wt.%FEC], the metal lithium sheet is used as the counter electrode, and the separator is made of polypropylene (PP) microfiber. Pore membrane.
  • the finally obtained negative electrode sheet was cut with a punching machine to obtain an electrode sheet with a diameter of 12 mm.
  • the electrode sheets were then transferred into an argon-filled super-purified glove box for the assembly of CR2032 coin-type half-cells.
  • the general operation flow of the CR2032 coin-type half-cell assembly is as follows.
  • the electrode sheet is placed in the center of the positive electrode case, and the electrolyte is dropped on it to completely soak the electrode sheet.
  • a lithium sheet was placed on the separator as a counter electrode. Place the above-mentioned gaskets and shrapnel on the lithium sheet in order so that they are in the center of the battery, and then buckle the negative electrode shell. Then use a packaging machine to carry out pressure packaging to obtain a CR2032 coin-type half-cell.
  • the CR2032 coin-type half-cell that has been encapsulated above can be put on hold for 12 hours before the test can be started.
  • the above-mentioned CR2032 coin-type half-cell battery can be tested for constant current charge-discharge cycle at a current density of 0.1C under a voltage range of 0.005-2.0V using a blue battery test system.
  • Figure 4 shows the results of the 50-time charge-discharge cycle test.
  • FIG. 4 is a comparison diagram of battery cycle tests performed 50 times of charge-discharge cycle tests according to this example using the silicon-carbon composite materials obtained in Comparative Examples 1-3 and Example 1 as negative electrode materials.
  • the X-axis is the number of cycles of the cycle test;
  • the Y-axis is the specific capacity, in mAh/g.
  • Example 1 the test results of Example 1 are far superior to those of Comparative Examples 1-3. That is, when mixing nano-silicon powder and artificial graphite, if an external force is applied to extrude, the nano-silicon powder is extruded and embedded on the surface of artificial graphite, and the obtained silicon-carbon composite material can be further improved when applied to the negative electrode of battery. Cycling performance of the battery.
  • the silicon-carbon composite materials obtained in the above comparative examples and examples were used as negative electrode materials, and were respectively assembled with 523-type positive ternary materials to form soft-pack batteries for full battery testing.
  • the assembly method and full battery testing process of the above-mentioned soft pack battery are briefly described as follows.
  • PVDF Polyvinylidene fluoride
  • NMP N-methyl-2-pyrrolidone
  • SP super carbon black
  • the positive electrode active material 523 type ternary material was added to the above conductive glue solution, and stirred in a planetary mixer for 4 hours to make it evenly mixed to prepare a positive electrode slurry.
  • the viscosity of the positive electrode slurry was adjusted to 8000 ⁇ 2000 cp with NMP to obtain a positive electrode slurry with good fluidity.
  • the positive electrode slurry with good fluidity is uniformly coated on both sides of the aluminum foil, and the positive electrode sheet can be obtained after drying, rolling, slitting, die-cutting and other processes. Finally, the above-mentioned positive electrode sheet is put into an oven, and vacuum-dried for later use.
  • the above-mentioned negative electrode sheet is put into an oven, and vacuum-dried for later use.
  • the aforementioned negative electrode sheet, separator (polypropylene microporous membrane), and positive electrode sheet are loaded into a lamination machine for lamination to obtain a bare cell.
  • the above bare cells are packaged with aluminum-plastic film, and then go through the steps of vacuum baking, liquid injection [1M LiPF 6 in EC:DMC:EMC(1:1:1vol.%)with 3wt.%FEC], packaging, and standing. After that, a lithium ion secondary battery can be obtained.
  • the above secondary battery can be charged at 0.5C/discharged at 1C, with a voltage range of 3.0V-4.2V, for energy density tests at room temperature, and for loop stability tests at room temperature or 45°C.
  • FIG. 5 is a comparison diagram of a battery cycle test performed according to this example using the silicon carbon composite materials obtained in Comparative Examples 1-3 and Example 1 as negative electrode materials to perform a 1000-cycle charge-discharge cycle test.
  • the X-axis is the number of cyclic test cycles; the Y-axis is the retention rate.
  • Example 1 It can be seen from FIG. 5 that the test results of Example 1 are far superior to the coin cells made by using the silicon-carbon composite materials obtained in Comparative Examples 1-3. After 1000 cycles of charge and discharge, the retention rates of Comparative Examples 1-2 all dropped significantly, while the retention rate of Comparative Example 3 was about 70%. Even better, after 1000 charge-discharge cycles, the retention rate of Example 1 can still be maintained at about 80%.
  • the above-mentioned secondary granulated silicon carbon base battery negative electrode material includes a carbon base material, a plurality of nano-silicon, and a modified layer.
  • the above-mentioned plurality of nano-silicons can be respectively embedded in the surface pores of the above-mentioned carbon substrate, so as to form a carbon substrate with nano-silicon embedded in the surface pores.
  • the plurality of nano-silicons can be respectively extruded and embedded in the surface pores of the carbon substrate to form a carbon substrate with nano-silicon embedded in the surface pores.
  • the above-mentioned modified layer can be coated on the above-mentioned carbon substrate with surface pores embedded with nano-silicon.
  • a plurality of carbon substrates with surface pores coated with a modification layer and embedded with nano-silicon can be stacked to form a set of carbon substrates.
  • the preparation method of the secondary granulated silicon carbon substrate battery negative electrode structure includes the steps of mixing nano-silicon and carbon substrate, adding a binder, granulating and carbonizing, disintegrating, and sieving.
  • the step of mixing the carbon substrate and the nano-silicon further includes the step of extruding the nano-silicon into the carbon substrate to form a carbon substrate with surface pores embedded with the nano-silicon.
  • the use of nano-silicon and the modified layer can not only greatly improve the uniformity of the battery and the liquid permeability of the negative electrode material during slurry mixing, but also better, the above-mentioned secondary granulated silicon carbon-based Compared with the existing negative electrode materials of silicon carbon substrate batteries, the material battery negative electrode material and its preparation method can effectively improve the cycle performance and stability of the battery, and then can effectively improve the effect of industrial competitiveness.

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Abstract

一种二次造粒的硅碳基材电池负极材料（200，200'）及其制备方法。上述二次造粒的硅碳基材电池负极材料（200，200'）包含碳基材（220，220'）、多个纳米硅（240，240'）、以及修饰层（260，260'）。上述二次造粒的硅碳基材电池负极材料（200，200'）的制备方法借由将纳米硅（240，240'）嵌入碳基材（220，220'）的表面孔隙、与修饰层（260，260'）的包覆，可提升电池调浆时的均匀性与负极材料（200，200'）的渗液性，进而可达到有效提升电池的循环性能与稳定性的效果。

Description

二次造粒的硅碳基材电池负极材料及其制备方法 技术领域
本发明是关于一种碳基材电池负极材料，特别是关于一种二次造粒的硅碳基材电池负极材料及其制备方法。
背景技术
新能源电池的发展在很大的程度上取决于高性能正、负极材料的开发与应用。以负极材料为例，现有习知技艺者已经发现，使用经过造粒制程来形成的电池负极材料可大幅提升电池寿命，增加产品的充放电次数。现有习知技艺中使用天然或人造石墨来作为电极材料时，为了降低初期的不可逆电容量与提升电池的循环寿命，通常需要先以沥青类芳烃化合物材料来进行表面改质。
现有习知技艺中常见的负极造粒制程，是先以高温熔融方式来混合焦碳与沥青，然后再依序经过碳化、石墨化等程序来完成。
为了进一步提升负极材料的性能，现有习知技艺中常会在上述制程的一开始即添加氧化硅于石墨。图1是现有习知技艺的碳基材电池负极材料示意图。在碳基材负极材料100中，所添加的氧化硅140可以是借由沥青160来沾附于石墨120的表面上，如图1所示。然而，在添加氧化硅140之后，因为氧化硅140与石墨120间的结合力不足，在电池调浆时，氧化硅140自石墨120脱落，将影响后续应用时电池调浆的均匀性。另一方面，在电池充放电时，氧化硅140的体积变化，也会造成氧化硅140从石墨120的表面脱落，进而影响电池的回圈稳定性。上述现象都会使得使用现有习知技艺的负极材料的电池无法发挥其应有的效能。
有鉴于此，开发可在有效地提升电池负极材料的性能时，同时兼顾负极材料的渗液性、电池调浆的均匀性、与提升电池回圈的稳定性的碳基材 电池负极材料及其制备方法，是一项相当值得产业重视且可有效提升产业竞争力的课题。
发明内容
鉴于上述的发明背景中，为了符合产业上的要求，本发明提供一种二次造粒的硅碳基材电池负极材料及其制备方法，上述二次造粒的硅碳基材电池负极材料及其制备方法，不仅制程简易，更具有可大幅提升电池调浆时的均匀性与负极材料的渗液性，更好的是，上述二次造粒的硅碳基材电池负极材料及其制备方法可有效提升电池的回圈稳定性，进而可有效提升产业竞争力的效果。
本发明的一目的在于提供一种二次造粒的硅碳基材电池负极材料及其制备方法，借由将纳米硅嵌入于碳基材表面的孔隙，以降低因为纳米硅脱落而降低电池调浆时的均匀性。
本发明的另一目的在于提供一种二次造粒的硅碳基材电池负极材料及其制备方法，借由使用表面孔隙嵌有纳米硅的碳基材来进行造粒，以提升电池应用时的渗液性。
本发明的再一目的在于提供一种二次造粒的硅碳基材电池负极材料及其制备方法，借由使用修饰层来包覆表面孔隙嵌有纳米硅的碳基材，使得在上述二次造粒的硅碳基材电池负极材料可进一步预防纳米硅从碳基材脱落，进而降低因为纳米硅脱落而降低电池调浆时的均匀性与提升电池应用时的渗液性。
本发明的又一目的在于提供一种二次造粒的硅碳基材电池负极材料及其制备方法，借由使用修饰层来包覆表面孔隙嵌有纳米硅的碳基材，使得上述二次造粒的硅碳基材电池负极材料可在电池应用时提供充分缓冲能力来因应纳米硅因充放电而产生的体积变化，进而达到提升电池的回圈稳定性的效果。
本发明的又一目的在于提供一种二次造粒的硅碳基材电池负极材料的 制备方法，借由使用可改变温度的回转炉，使得上述二次造粒的硅碳基材电池负极材料的制备方法可在回转炉中完成二次造粒，进而达到简化制程的效果。
根据以上所述的目的，本发明揭示了一种二次造粒的硅碳基材电池负极材料及其制备方法。上述二次造粒的硅碳基材电池负极材料包含碳基材、多个纳米硅、以及修饰层。上述的多个纳米硅可以是分别嵌入于上述碳基材的表面孔隙，以形成表面孔隙嵌有纳米硅的碳基材。在根据本说明书的一较佳范例中，上述的多个纳米硅可以是分别挤压嵌入于上述碳基材的表面孔隙，以形成表面孔隙嵌有纳米硅的碳基材。上述的修饰层可以是包覆于上述表面孔隙嵌有纳米硅的碳基材之上。
上述二次造粒的硅碳基材电池负极材料的制备方法包含混合纳米硅与碳基材、添加粘合剂、造粒与碳化、解碎、以及过筛等步骤。在根据本说明书的一较佳范例中，上述混合纳米硅与碳基材的步骤可以更包含将纳米硅挤压嵌入碳基材的步骤。在根据本说明书的一较佳范例中，上述的造粒与碳化步骤可以是在一回转炉中完成。根据本说明书的技术方案，借由纳米硅与修饰层的使用，不仅可大幅提升电池调浆时的均匀性与负极材料的渗液性，更好的是，上述二次造粒的硅碳基材电池负极材料及其制备方法可有效提升电池的回圈稳定性，进而可有效提升产业竞争力的效果。
附图说明
图1是现有习知技艺的硅碳基材电池负极材料的示意图。
图2A是根据本说明书的一范例的二次造粒的硅碳基材电池负极材料的示意图。
图2B是根据本说明书的另一范例的二次造粒的硅碳基材电池负极材料的示意图。
图3是根据本说明书的二次造粒的硅碳基材电池负极材料的制备方法的流程图。
图4是不同负极材料制成的扣式电池进行50次电池循环测试的比较图。
图5是不同负极材料制成的软包电池进行的1000次电池循环测试的比较图。
[主要元件符号说明]
100：现有习知技艺的碳基材电池负极材料
120：焦碳
140：氧化硅
160：沥青
200：二次造粒的硅碳基材电池负极材料
220：碳基材
240：纳米硅
260：修饰层
200’：二次造粒的硅碳基材电池负极材料
220’：碳基材
240’：纳米硅
260’：修饰层
300：二次造粒的硅碳基材电池负极材料的制备方法
310：混合纳米硅与碳基材的步骤
320：添加粘合剂的步骤
330：造粒与碳化步骤
340：解碎步骤
350：过筛步骤
具体实施方式
本发明在此所探讨的方向为一种二次造粒的硅碳基材电池负极材料及其制备方法。为了能彻底地了解本发明，将在下列的描述中提出详尽的制 程步骤或组成结构。显然地，本发明的施行并未限定于该领域的技艺者所熟习的特殊细节。另一方面，众所周知的组成或制程步骤并未描述于细节中，以避免造成本发明不必要的限制。本发明的较佳体系会详细描述如下，然而除了这些详细描述的外，本发明还可以广泛地施行在其他的体系中，且本发明的范围不受限定，以其专利所要保护的范围为准。
本发明的一实施例揭露一种二次造粒的硅碳基材电池负极材料。上述二次造粒的硅碳基材电池负极材料包含碳基材、多个纳米硅、以及修饰层。上述的多个纳米硅可以是分别嵌入于上述碳基材的表面孔隙，以形成表面孔隙嵌有纳米硅的碳基材。在根据本实施例的一较佳范例中，可借由一外力挤压，使得上述的多个纳米硅分别挤压嵌入于每一碳基材的表面孔隙，以形成表面孔隙嵌有纳米硅的碳基材。上述的修饰层可以是包覆于上述表面孔隙嵌有纳米硅的碳基材之上，以形成包覆有修饰层的表面孔隙嵌有纳米硅的碳基材。
在根据本实施例的一较佳范例中，多个上述包覆有修饰层的表面孔隙嵌有纳米硅的碳基材可堆叠成一碳基材集合。
图2A是一根据本实施例的一较佳范例的二次造粒的硅碳基材电池负极材料的示意图。如图2A所示，上述二次造粒的硅碳基材电池负极材料200包含碳基材220、多个纳米硅240、以及修饰层260。在根据本范例的一较佳实施方式中，上述碳基材220可以是选自下列群组之一者或其组合：天然石墨、人造石墨、石墨烯、纳米碳管(CNT)、以及气相成长碳纤维(VGCF)、中间相碳微球材料(MCMB)。在根据本范例的一较佳实施方式中，上述碳基材220的粒径约5–20μm。在根据本范例的另一较佳实施方式中，上述碳基材220的粒径约15μm。
参见图2A，多个纳米硅240可以是分别嵌入于碳基材220的表面孔隙，以形成表面孔隙嵌有纳米硅的碳基材。在根据本实施例的一较佳范例中，可借由一外力挤压，使得上述的多个纳米硅240分别挤压嵌入于每一碳基材220的表面孔隙，如此一来，纳米硅240可挤压嵌入至碳基材220表面 的更深处，以形成表面孔隙嵌有纳米硅的碳基材。在根据本范例的一较佳实施方式中，上述纳米硅240的粒径约100–900nm。在根据本范例的另一较佳实施方式中，上述纳米硅240的粒径约200nm。修饰层260包覆于上述表面孔隙嵌有纳米硅的碳基材之上，以形成包覆有修饰层的表面孔隙嵌有纳米硅的碳基材。在根据本范例的一较佳实施方式中，上述修饰层260的厚度约15–1000nm。在根据本范例的另一较佳实施方式中，上述修饰层260的厚度约100nm。上述修饰层260的组成可以是包含粘合剂。在根据本范例的一较佳实施方式中，上述粘合剂可以是选自下列群组之一者或其组合：沥青、酚醛树酯、羧甲基纤维素(Carboxymethyl Cellulose，简称CMC)、麦芽糊精、丁苯橡胶(Styrene-Butadiene Rubber，简称SBR)。
图2B是一根据本实施例的另一较佳范例的二次造粒的硅碳基材电池负极材料的示意图。如图2B所示，上述二次造粒的硅碳基材电池负极材料200＇包含多个碳基材220’、多个纳米硅240’、以及修饰层260’。
根据本范例，上述的多个纳米硅240’分别嵌入于每一碳基材220’的表面孔隙，以形成表面孔隙嵌有纳米硅的碳基材。在根据本实施例的一较佳范例中，可借由一外力挤压，使得上述的多个纳米硅240’分别挤压嵌入于每一碳基材220’的表面孔隙，以形成表面孔隙嵌有纳米硅的碳基材。
在根据本范例的一较佳实施方式中，上述碳基材220’可以是选自下列群组之一者或其组合：天然石墨、人造石墨、石墨烯、纳米碳管(CNT)、以及气相成长碳纤维(VGCF)、中间相碳微球材料(MCMB)。在根据本范例的一较佳实施方式中，上述碳基材220’的粒径约5–20μm。在根据本范例的另一较佳实施方式中，上述碳基材220’的粒径约15μm。在根据本范例的一较佳实施方式中，上述纳米硅240’的粒径约100–900nm。在根据本范例的另一较佳实施方式中，上述纳米硅240’的粒径约200nm。
上述修饰层260’可以是包覆于上述表面孔隙嵌有纳米硅的碳基材之上，如图2B所示。在根据本范例的一较佳实施方式中，多个包覆有修饰层 的表面孔隙嵌有纳米硅的碳基材可堆叠成一碳基材集合，如图2B所示。在根据本范例的一较佳实施方式中，上述修饰层260’的厚度约15–30nm。在根据本范例的另一较佳实施方式中，上述修饰层260’的厚度约20nm。上述修饰层260’包含粘合剂。在根据本范例的一较佳实施方式中，上述粘合剂可以是选自下列群组之一者或其组合：沥青、酚醛树酯、羧甲基纤维素(Carboxymethyl Cellulose，简称CMC)、麦芽糊精、丁苯橡胶(Styrene-Butadiene Rubber，简称SBR)。
本发明的另一实施例揭露一种二次造粒的硅碳基材电池负极材料的制备方法。图3是一根据本实施例的二次造粒的硅碳基材电池负极材料的制备方法的示意图。如图3所示，上述二次造粒的硅碳基材电池负极材料的制备方法包含混合纳米硅与碳基材、添加粘合剂、造粒与碳化、解碎、以及过筛等步骤。
根据本实施例的二次造粒的硅碳基材电池负极材料的制备方法，先将碳基材与纳米硅予以混合，使纳米硅分别嵌入于碳基材的表面空隙，以形成表面孔隙嵌有纳米硅的碳基材，如步骤310所示。在根据本实施例的一较佳范例中，上述步骤310可更包含将纳米硅挤压嵌入碳基材的步骤。根据本范例，借由一外力挤压，使得上述的多个纳米硅分别挤压嵌入至碳基材表面的更深处，以形成表面孔隙嵌有纳米硅的碳基材。在根据本实施例的一较佳范例中，上述碳基材可以是选自下列之一者或其组合：天然石墨、人造石墨、石墨烯、纳米碳管(CNT)、以及气相成长碳纤维(VGCF)、中间相碳微球材料(MCMB)。在根据本实施例的一较佳范例中，上述纳米硅的占比约为0.1-20wt％的碳基材。在根据本实施例的一较佳范例中，上述纳米硅的占比约为3-15wt％的碳基材。在根据本实施例的一较佳范例中，上述混合碳基材与纳米硅的步骤可以在室温(约10-40℃)完成。在根据本范例的一较佳实施方式中，上述碳基材的粒径约5–20μm。在根据本范例的另一较佳实施方式中，上述碳基材的粒径约15μm。在根据本范例的一较佳实施方式中，上述纳米硅的粒径约100–900nm。在根据本范例的另一较佳 实施方式中，上述纳米硅的粒径约200nm。
在根据本实施例的一较佳范例中，上述混合碳基材与纳米硅的步骤可以在一带有挤压力的混合机中完成。
接下来，将粘合剂添加至上述表面孔隙嵌有纳米硅的碳基材，如步骤320所示。在粘合剂与上述表面孔隙嵌有纳米硅的碳基材充分混合后，即可开始升温，进入造粒与碳化步骤，如步骤330所示。
在根据本实施例的一较佳范例中，上述粘合剂可以是选自下列群组之一者或其组合：沥青、酚醛树酯、羧甲基纤维素(Carboxymethyl Cellulose，简称CMC)、麦芽糊精、丁苯橡胶(Styrene-Butadiene Rubber，简称SBR)。在根据本实施例的一较佳范例中，步骤320可以是在室温(约为10-40℃)完成。在根据本实施例的一较佳范例中，上述粘合剂的重量比约为表面孔隙嵌有纳米硅的碳基材的5-15wt％。在根据本实施例的一较佳范例中，上述粘合剂的重量比约为表面孔隙嵌有纳米硅的碳基材的5-10wt％。
在根据本实施例的一较佳范例中，上述步骤320可以更包含添加一溶剂至上述表面孔隙嵌有纳米硅的碳基材，其中，上述溶液中的溶剂可在后续的造粒与碳化步骤中挥发。上述溶剂可以是选自下列一者或其组合：水、酒精。
在造粒与碳化步骤330的升温过程中，粘合剂将发生熔融，并包覆于上述表面孔隙嵌有纳米硅的碳基材上，以形成包覆有修饰层的表面孔隙嵌有纳米硅的碳基材。在根据本实施例的一较佳范例中，随着所使用的粘合剂不同，上述包覆有修饰层的表面孔隙嵌有纳米硅的碳基材的形成温度可以是在升温至约为20-350℃时完成。在根据本范例的一较佳实施方式中，多个上述包覆有修饰层的表面孔隙嵌有纳米硅的碳基材可堆叠成一碳基材集合。在根据本范例的一较佳实施方式中，上述修饰层的厚度约15–1000nm。在根据本范例的另一较佳实施方式中，上述修饰层的厚度约100nm。
在根据本实施例的一较佳范例中，上述碳化的温度约为900-1100℃。在根据本实施例的一较佳范例中，步骤330的造粒与碳化过程可以在回转 炉、管式炉、推板炉、滚道炉、或静态加热炉中完成。
经过造粒与碳化步骤后，可将上述碳化后的包覆有修饰层的表面孔隙嵌有纳米硅的碳基材进行解碎，如步骤340所示。在根据本实施例的一较佳范例中，步骤340可将上述包覆有修饰层的表面孔隙嵌有纳米硅的碳基材解碎成多个小颗粒。根据本实施例，在解碎步骤340之后，可对解碎后的小颗粒进行一过滤的步骤350。在根据本实施例的一较佳范例中，上述步骤350的可筛选出D50约为10-30μm的颗粒。在根据本实施例的一较佳范例中，上述步骤350的可筛选出D50约为17-23μm的颗粒。
以下将叙明根据本说明书的二次造粒的硅碳基材电池负极材料及其制备方法的较佳范例。
比较例1：
将纳米硅粉(D50约300nm)、人造石墨(D50约14-17μm)、以及沥青(D50约2-5μm)在V型混合机内一次混合均匀后，转移到管式炉中。上述纳米硅粉的添加量约为人造石墨与纳米硅粉总重量的3wt％。上述沥青的添加量约为人造石墨与纳米硅粉总重量的7wt％。
以管式炉加热至1000℃进行碳化。在惰性气氛下，将管式炉从室温以5℃/min的升温速率升温到1000℃，并保温3小时。之后将管式炉内降温回室温，以得到硅碳复合材料。
比较例2：
首先将纳米硅粉(D50约300nm)、与人造石墨(D50约14-17μm)在V型混合机内混合均匀。上述纳米硅粉的添加量约为人造石墨与纳米硅粉总重量的3wt％。
随后将沥青(D50约2-5μm)添加至上述V型混合机中，使沥青与上述纳米硅粉与人造石墨混合均匀后，转移到管式炉中。上述沥青的添加量约为人造石墨与纳米硅粉总重量的7wt％。
在惰性气氛下，将管式炉从室温以5℃/min的升温速率升温到1000℃，并保温3小时。之后将管式炉内降温回室温，以得到硅碳复合材料。
比较例3：
首先将纳米硅粉(D50约300nm)、与人造石墨(D50约14-17μm)在V型混合机内混合均匀。上述纳米硅粉的添加量约为人造石墨与纳米硅粉总重量的3wt％。
随后将沥青(D50约2-5μm)添加至上述V型混合机中，使沥青与上述纳米硅粉与人造石墨混合均匀后，转移到回转炉中。上述沥青的添加量约为人造石墨与纳米硅粉总重量的7wt％。
在惰性气氛下，将回转炉从室温以5℃/min的升温速率升温到1000℃，并保温3小时。之后将回转炉内降温回室温，以得到硅碳复合材料。
范例1：
首先将纳米硅粉(D50约300nm)、与人造石墨(D50约14-17μm)在带有挤压力的混合机内混合均匀，使上述纳米硅粉嵌入上述人造石墨。上述纳米硅粉的添加量约为人造石墨与纳米硅粉总重量的3wt％。
随后将沥青(D50约2-5μm)添加至上述V型混合机中，使沥青与上述纳米硅粉与人造石墨混合均匀后，转移到回转炉中。上述沥青的添加量约为人造石墨与纳米硅粉总重量的7wt％。
在惰性气氛下，将回转炉从室温以5℃/min的升温速率升温到1000℃，并保温3小时。之后将回转炉内降温回室温，以得到硅碳复合材料。
范例1所得到的硅碳复合材料，由于纳米硅粉挤压嵌入于人造石墨的表面，加上有修饰层(沥青)包覆于表面孔隙嵌有纳米硅粉的人造石墨上。所以，在范例1所得到的硅碳复合材料将不会发现从人造石墨脱落下来的纳米硅粉。另一方面，由于有了修饰层的包覆，上述硅碳复合材料应用于电池之后，在充放电的过程中，也将不易因为膨胀而出现破裂或纳米硅粉逸出的现象。
上述比较例1-3与范例1所制得的硅碳复合材料的性质可整理如下表一。
表一
Figure PCTCN2021107632-appb-000001
由表一可看出，虽然比较例1-3与范例1所得到的硅碳复合材料经解碎过筛后，所得到材料粒径相似，但范例1所得到硅碳复合材料具有最低的比表面积。说明根据范例1的作法，沥青又对硅碳复合材料发挥最佳的包覆效果，从而减少了表面孔隙。再者，由表一也可发现，范例1所得到的硅碳复合材料中，由硅材料氧化残留即灰分值较高。上述灰分值说明挤压入石墨后，硅粉可以更稳固存在于石墨表面。
范例2：扣式电池测试
将上述比较例1-3与范例1所得的硅碳复合材料用作负极材料，并分别组装成扣式电池，以进行CR2032扣式半电测试。上述扣式电池的组装方式与CR2032扣式半电测试过程简述如下。
将比较例1-3和范例1中所得的硅碳复合材料、导电剂、基底粘结剂、分散剂和溶剂在行星搅拌机中搅拌3小时，以得到混合均匀的浆料。以自动涂膜机将上述浆料均匀涂布到铜箔集流体上，涂布厚度约为200μm。在60℃下鼓风干燥30分钟后，放置于真空干燥箱中，使其在120℃真空干燥12小时，以得到负极极片。上述基底粘结剂为丁苯橡胶(SBR)，分散剂为羧甲基纤维素钠(CMC)，导电剂超级碳黑(SP)。上述负极材料、SP、CMC、与SBR的重量比约为负极材料:SP:CMC:SBR＝94.5:2:1.5:2。扣式电池采用的电解液为1M的LiPF 6[in EC:DMC:EMC(1:1:1vol.％)with 3wt.％FEC]，金属锂片为对电极，隔膜采用聚丙烯(PP)微孔膜。
将最终得到的负极片用冲孔机进行裁片，以得到直径为12mm的电极片。然后将电极片转移到充满氩气的超级净化手套箱中，进行CR2032扣式半电池的组装。
CR2032扣式半电池的组装的大致操作流程如后。将电极片放置于正极壳的中央，在上面滴加电解液，使电极片完全浸润。将隔膜平整地放置在极片上，再滴加电解液，使隔膜完全浸润。将锂片作为对电极放置在隔膜上。将上述垫片、弹片依序放置在锂片上，使其处于电池的中心位置，再将负极壳扣上。再使用封装机进行加压封装，以得到CR2032扣式半电池。
将上述封装完成的CR2032扣式半电池搁置12小时后即可开始进行测试。上述CR2032扣式半电池可使用蓝电电池测试***在0.005-2.0V的电压范围下以0.1C的电流密度对电池进行恒电流充放电回圈测试。50次的充放电回圈测试结果如图4所示。图4是将上述比较例1-3与范例1所得的硅碳复合材料用作负极材料依据本范例进行50次的充放电回圈测试的电池循环测试的比较图。其中，X轴为循环测试圈数；Y轴为比容量，单位为mAh/g。
由图4可看出，比较例2的测试结果相较于比较例1更好。上述比较说明了，先将纳米硅粉与人造石墨混合的操作方式，可让纳米硅粉均匀沾附于人造石墨表面。先混合纳米硅粉与人造石墨之后再添加沥青，再经过加热碳化所得到的硅碳复合材料可发挥出较佳性能。同时由图4也可发现，虽然比较例3前十次回圈测试结果较差，但整体回圈保持率优于比较例2。这是因为仅以普通混合方式，硅粉不能稳固存在于石墨表面。在动态的回转炉进行碳化过程虽然可得到较佳的沥青包覆与造粒效果，但是因为部分硅粉已经由石墨上脱落并团聚，而脱落并团聚的硅粉造成测试中的回圈性能衰减迅速。另一方面，由图4也可发现，范例1的测试结果又远比使用比较例1-3更优越。亦即，在混合纳米硅粉与人造石墨时，如加上外力挤压，使纳米硅粉挤压嵌入至人造石墨的表面，所得到的硅碳复合材料应用于电池负极时，更可进一步提升电池的循环性能。
上述比较例1-3与范例1所制得的硅碳复合材料依据本范例进行电池 循环测试的结果可整理如下表二。
表二
  克容量(mAh/g) 库伦效率(％)
比较例1 430.1 93.51
比较例2 430.5 93.72
比较例3 429.5 94.11
范例1 430.2 94.35
由表二可看出，由于添加了纳米硅粉，比较例1-3与范例1的克容量均比石墨大幅提升(石墨的克容量理论值是372mAh/g)。更好的是，范例1的库伦效率又优于比较例1-3。
范例3：全电池测试的电池性能比较
将上述比较例与范例所得的硅碳复合材料用作负极材料，并分别和523型正极三元材料组装成软包电池，以进行全电池测试。上述软包电池的组装方式与全电池测试过程简述如下。
将聚偏氟乙烯(PVDF)与N-甲基-2-吡咯烷酮(NMP)在行星搅拌机中混合均匀以制成胶液。然后，在上述胶液中加入超级碳黑(SP)并混合均匀以制成导电胶液。在上述导电胶液里加入正极活性物质523型三元材料，并在行星搅拌机中搅拌4小时，使其混合均匀以制得正极浆料。再以NMP将上述正极浆料的粘度调节至8000±2000cp，以得到流动性良好的正极浆料。之后，将上述流动性良好的正极浆液均匀涂布在铝箔的两面再经过干燥、辊压、分切、模切等工艺后，可得到正极片。最后，将上述正极片放入烘箱，进行真空干燥后待用。其中，上述523型三元材料、导电剂、以及粘结剂的重量比约为，523型三元材料:导电剂:粘结剂＝95:2:3。
将CMC与蒸馏水在行星搅拌机上混合均匀制成胶液。然后，在上述胶 液中加入SP，并均匀混合，以制成导电胶液。将比较例1-3和范例1中所得负极材料(硅碳复合材料)分别加入到上述的导电胶液中，并予以均匀混合，以制得负极浆料。最后，使用蒸馏水将上述负极浆料的粘度调节至2000±500cp，以得到流动性良好的负极浆料。将上述流动性良好的负极浆液均匀涂布在铜箔的两面，并经过干燥、辊压、分切、模切等工艺后，即可得到负极片。最后，将上述负极片放入烘箱，并进行真空干燥后待用。其中，上述负极材料、SP、CMC、与SBR的重量比约为，负极材料:SP:CMC:SBR＝94.5:2:1.5:2。
将前述的负极片、隔膜(聚丙烯微孔膜)、正极片装入叠片机中进行叠片，以得到裸电芯。上述裸电芯经铝塑膜封装，再经过真空烘烤、注液[1M LiPF 6in EC:DMC:EMC(1:1:1vol.％)with 3wt.％FEC]、封装、静置等步骤后，即可得到锂离子二次电池。上述二次电池可在0.5C充电/1C放电，电压范围3.0V-4.2V，室温条件下进行能量密度测试，以及在室温或45℃条件下进行回圈稳定性测试。全电池1000次循环充放电回圈测试的结果如图5所示。图5是将上述比较例1-3与范例1所得的硅碳复合材料用作负极材料依据本范例进行1000次循环充放电回圈测试的电池循环测试的比较图。其中，X轴为循环测试圈数；Y轴为保持率。
由图5可看出，范例1的测试结果又远比使用比较例1-3所得到的硅碳复合材料所制成的扣式电池更优越。在经过1000次循环充放电之后，比较例1-2的保持率皆大幅下降，而比较例3的保持率约70％。更好的是，经过1000次循环充放电之后，范例1的保持率仍可维持约80％。
综上所述，本说明书揭露一种二次造粒的硅碳基材电池负极材料及其制备方法。上述二次造粒的硅碳基材电池负极材料包含碳基材、多个纳米硅、以及修饰层。上述的多个纳米硅可以是分别嵌入于上述碳基材的表面孔隙，以形成表面孔隙嵌有纳米硅的碳基材。在根据本说明书的一较佳范例中，上述的多个纳米硅可以是分别挤压嵌入于上述碳基材的表面孔隙，以形成表面孔隙嵌有纳米硅的碳基材。上述的修饰层可以是包覆于上述表 面孔隙嵌有纳米硅的碳基材之上。在根据本说明书的一较佳范例中，多个包覆有修饰层的表面孔隙嵌有纳米硅的碳基材可堆叠成一碳基材集合。上述二次造粒的硅碳基材电池负极结构的制备方法包含混合纳米硅与碳基材、添加粘合剂、造粒与碳化、解碎、以及过筛等步骤。在根据本说明书的一较佳范例中，上述混合碳基材与纳米硅的步骤更包含将纳米硅挤压嵌入碳基材的步骤，以形成表面孔隙嵌有纳米硅的碳基材。根据本说明书的技术方案，借由纳米硅与修饰层的使用，不仅可大幅提升电池调浆时的均匀性与负极材料的渗液性，更好的是，上述二次造粒的硅碳基材电池负极材料及其制备方法相较于现有硅碳基材电池负极材料可有效提升电池的循环性能、以及稳定性，进而可有效提升产业竞争力的效果。
以上所述，仅是本发明的较佳实施例而已，并非对本发明做任何形式上的限制，虽然本发明已以较佳实施例揭露如上，然而并非用以限定本发明，任何熟悉本专业的技术人员，在不脱离本发明技术方案范围内，当可利用上述揭示的技术内容做出些许更动或修饰为等同变化的等效实施例，但凡是未脱离本发明技术方案的内容，依据本发明的技术实质对以上实施例所做的任何简单修改、等同变化与修饰，均仍属于本发明技术方案的范围内。

Claims (10)

  1. 一种二次造粒的硅碳基材电池负极材料，其特征在于，包含：
    碳基材；
    多个纳米硅，上述纳米硅分别嵌入于上述碳基材的表面孔隙，形成表面孔隙嵌有纳米硅的碳基材；以及
    修饰层，上述修饰层包覆于上述碳基材与上述纳米硅之上，上述修饰层包覆于上述表面孔隙嵌有纳米硅的碳基材之上。
  2. 根据权利要求1所述的二次造粒的硅碳基材电池负极材料，其特征在于，所述纳米硅是挤压嵌入于上述碳基材的表面孔隙。
  3. 根据权利要求1所述的二次造粒的硅碳基材电池负极材料，其特征在于，上述碳基材是选自下列群组之一者或其组合：天然石墨、人造石墨、石墨烯、纳米碳管(CNT)、以及气相成长碳纤维(VGCF)、中间相碳微球材料(MCMB)。
  4. 根据权利要求1所述的二次造粒的硅碳基材电池负极材料，其特征在于，上述修饰层包含粘合剂，其中上述粘合剂是选自下列群组之一者或其组合：沥青、酚醛树酯。
  5. 根据权利要求1所述的二次造粒的硅碳基材电池负极材料，其特征在于，多个上述包覆有修饰层的表面孔隙嵌有纳米硅的碳基材能堆叠成一碳基材集合。
  6. 一种二次造粒的硅碳基材电池负极材料的制备方法，其特征在于，包含：
    混合碳基材与纳米硅，以形成表面孔隙嵌有纳米硅的碳基材；
    将粘合剂添加至上述表面孔隙嵌有纳米硅的碳基材，以得到表面孔隙嵌有纳米硅的碳基材与粘合剂的混合物；
    对上述混合物进行造粒与碳化，其中上述混合物在升温过程中形成多个包覆有修饰层的表面孔隙嵌有纳米硅的碳基材，并在造粒与碳化步骤中形成碳化后的包覆有修饰层的表面孔隙嵌有纳米硅的碳基材；
    对碳化后的包覆有修饰层的表面孔隙嵌有纳米硅的碳基材进行解碎；以及
    对解碎后的包覆有修饰层的表面孔隙嵌有纳米硅的碳基材进行过筛。
  7. 根据权利要求6所述的二次造粒的硅碳基材电池负极材料的制备方法，其特征在于，上述混合碳基材与纳米硅的步骤更包含将纳米硅挤压嵌入碳基材的步骤，以形成表面孔隙嵌有纳米硅的碳基材。
  8. 根据权利要求6所述的二次造粒的硅碳基材电池负极材料的制备方法，其特征在于，上述纳米硅的占比为0.1-20wt％的碳基材。
  9. 根据权利要求6所述的二次造粒的硅碳基材电池负极材料的制备方法，其特征在于，上述粘合剂的重量比为表面孔隙嵌有纳米硅的碳基材的5-15wt％。
  10. 根据权利要求6所述的二次造粒的硅碳基材电池负极材料的制备方法，其特征在于，造粒与碳化步骤是在回转炉中完成。
PCT/CN2021/107632 2020-12-21 2021-07-21 二次造粒的硅碳基材电池负极材料及其制备方法 WO2022134562A1 (zh)

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