WO2023206673A1 - 表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料及其制备方法 - Google Patents

表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料及其制备方法 Download PDF

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WO2023206673A1
WO2023206673A1 PCT/CN2022/094412 CN2022094412W WO2023206673A1 WO 2023206673 A1 WO2023206673 A1 WO 2023206673A1 CN 2022094412 W CN2022094412 W CN 2022094412W WO 2023206673 A1 WO2023206673 A1 WO 2023206673A1
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nano
aluminum metaphosphate
graphite
composite
powder
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French (fr)
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刘文平
秦海青
雷晓旭
卢安军
张振军
莫祖学
唐慧杰
蒙光海
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中国有色桂林矿产地质研究院有限公司
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Priority to US18/124,632 priority Critical patent/US20230231114A1/en
Publication of WO2023206673A1 publication Critical patent/WO2023206673A1/zh

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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention relates to the technical field of electrochemical power supplies, and specifically relates to a nano silicon-graphite composite negative electrode material with a carbon coating and an aluminum metaphosphate composite modification layer on the surface and a preparation method thereof.
  • the lithium intercalation process is accompanied by a huge volume expansion, and the delithiation and dealloying process is accompanied by a violent volume shrinkage.
  • This volume change is as high as 300%, which is very serious. It is easy to cause the silicon material to pulverize, seriously affecting the cycle stability.
  • nano-silica powder of appropriate particle size By preparing nano-silica powder of appropriate particle size, the particle pulverization of silicon materials during the electrochemical cycle can be effectively solved.
  • the huge volume change effect of nano-silicon materials after lithium embedding still exists. After repeated volume expansion and contraction of the electrode, the particles Electrical contact and pulverization will still be lost, resulting in capacity loss and cycle life degradation.
  • the expansion and contraction rates of lithium deintercalation are inconsistent, which can easily cause the nano-silicon particles to lose electrical contact, causing capacity loss.
  • the SEI film formed on the surface is unstable and continuously consumes the electrolyte, which is the lithium of the battery. Ion transport is hindered, causing the cycle life of the material to decrease.
  • the cycle life is mainly improved by nanometerizing silicon materials and compounding them with other materials.
  • the silicon material is nanometered, the specific surface area is larger, and the surface is easily eroded by the electrolyte.
  • the silicon material is nanometered, the lithium insertion expansion still exists, so further surface modification is required.
  • the present invention obtains nano silicon-graphite composite negative electrode materials with long cycle life by performing carbon coating and metaphosphoric acid composite modification on the surface of the material in a simple and easy manner.
  • the object of the present invention is to provide a nano silicon-graphite composite negative electrode material with a carbon coating and aluminum metaphosphate composite modification layer on the surface and a preparation method thereof.
  • a nano-silicon-graphite composite anode material with a carbon coating and an aluminum metaphosphate composite modification layer on the surface is mainly prepared from the following components in mass percentage:
  • Another technical object of the present invention is to provide a method for preparing the above-mentioned nano silicon-graphite composite negative electrode material with a carbon coating and aluminum metaphosphate composite modification layer on the surface, including a surface carbon coating and an aluminum metaphosphate composite modification layer, nano silicon- Preparation of graphite composite materials and methods and steps for using them as silicon-carbon composite materials for lithium-ion batteries; wherein, the preparation method involved in the present invention is as follows:
  • nano-silica powder to deionized water for ultrasonic dispersion to obtain a uniform dispersion, then add graphite powder and mix ultrasonically evenly, then add water-based asphalt, stir and mix evenly, spray dry, and combine the dried powder with metaphosphate.
  • Mechanical fusion is carried out, and finally transferred to high-temperature carbonization in a vacuum furnace to obtain a nano-silicon-graphite composite negative electrode material with carbon coating and aluminum metaphosphate composite modification layer on the surface.
  • step 2) Stir the suspension in step 1) at high speed, first add graphite powder according to the formula ratio, stir and mix for a certain period of time, then add water-based asphalt, stir evenly at high speed, and add deionized water at the same time to control the solid content of the suspension at 10 to 15 wt.%. In the range;
  • step 2) Spray dry the suspension in step 2) with a spray dryer, control the spray inlet temperature at 200-220°C, and the feed amount at 20-30kg/h to obtain dry powder;
  • step 3 Weigh the aluminum metaphosphate powder according to the formula proportion, add it to the dry powder in step 3), mix evenly, and add it to a mechanical fusion machine for fusion to obtain a precursor with a surface coated with a layer of asphalt and aluminum metaphosphate modification;
  • step 5) Transfer the precursor in step 4) into a vacuum furnace and carbonize at high temperature of 800-1200°C for 3-6 hours, then take it out and crush it through a sieve to obtain nano-silicon with a carbon coating and aluminum metaphosphate composite modification layer on the surface.
  • Graphite composite anode material
  • the present invention can improve the bonding strength of nano-silicon and graphite by modifying the carbon coating layer on the surface of the nano-silicon-graphite composite negative electrode material, and improve the conductivity of the silicon material.
  • modifying the surface with aluminum metaphosphate It can well alleviate volume expansion and stabilize the SEI film formed on the surface of the material.
  • the present invention enhances the conductivity of nano-silicon particles through surface carbon coating and aluminum metaphosphate composite modification layers, stabilizes the SEI film, and alleviates material volume changes. To obtain composite anode materials with higher cycle life.
  • the present invention discloses a nano silicon-graphite composite negative electrode material with a carbon coating and aluminum metaphosphate composite modification layer on the surface and a preparation method thereof, which has the following beneficial effects:
  • the composite modification layer not only has the effect of traditional carbon coating, such as improving the conductivity of silicon materials, isolating the erosion of silicon materials by electrolyte, mitigating volume expansion, etc., but at the same time, aluminum metaphosphate is dispersed in the coating layer to enhance the The peel strength of the coating can better adapt to the volume changes of the material.
  • Figure 1 is an energy spectrum analysis of the nano silicon-graphite composite negative electrode material with aluminum metaphosphate modification on the surface prepared by the present invention.
  • Figure 2 is a graph of the capacity retention rate tested after the silicon-carbon composite material prepared in Example 1 and Comparative Example 1 of the present invention was made into a negative electrode sheet and then assembled into a 2032 button cell.
  • the invention discloses a method for preparing a nano silicon-graphite composite negative electrode material with a carbon coating and an aluminum metaphosphate composite modification layer on the surface.
  • a method for preparing a nano silicon-graphite composite anode material with a carbon coating and an aluminum metaphosphate composite modification layer on the surface specifically including the following steps:
  • step 2) Stir the suspension in step 1) at high speed, add 1950g graphite powder at the same time, stir thoroughly and mix evenly, then add 1200g water-based asphalt (solid content 50wt.%, vacuum carbonization residual carbon content 50wt.%), and mix evenly to obtain Uniform slurry with solid content of about 10wt.%;
  • step 3 Spray dry the uniform slurry obtained in step 2) while ultrasonic stirring, control the inlet temperature of the sprayer at 220°C, and the feed amount at 30kg/h to obtain dry powder;
  • step 4) Weigh 300g of aluminum metaphosphate powder and add the dry powder obtained in step 3) into a mechanical fusion machine, squeeze and fuse at high speed for 20 minutes to obtain a precursor with a surface coated with a layer of asphalt and aluminum metaphosphate modification;
  • step 5) Transfer the precursor in step 4) to a vacuum furnace and carbonize it under vacuum conditions at 800°C for 3 hours to carbonize the pitch at high temperature to obtain about 10 wt.% pitch cracked carbon and 10 wt.% aluminum metaphosphate on the surface.
  • the nano-silicon-graphite composite negative electrode material prepared in this example was prepared into a negative electrode sheet, and assembled into a 2032 button battery to test the cycle life.
  • the material performance data are shown in Table 1, and the cycle life curve is shown in Figure 2.
  • the battery cycle performance test method is: first discharge to 0.01v with a current density of 100mA/g, then discharge to 0.005v with a current of 10mA/g, let it stand for 3 minutes, and then charge to 1.5 with a current density of 100mA/g v, use this as a loop to test loop performance.
  • a method for preparing a nano silicon-graphite composite anode material with a carbon coating and an aluminum metaphosphate composite modification layer on the surface specifically including the following steps:
  • step 2) Stir the suspension in step 1) at high speed, add 2130g graphite powder at the same time, stir thoroughly and mix evenly, then add 1200g water-based asphalt (solid content 50wt.%, vacuum carbonization residual carbon content 50wt.%), and mix evenly to obtain Uniform slurry with solid content of about 10wt.%;
  • step 3 Spray dry the uniform slurry obtained in step 2) while ultrasonic stirring, control the inlet temperature of the sprayer at 200°C, and the feed amount at 30kg/h to obtain dry powder;
  • step 4) Weigh 120g of aluminum metaphosphate powder and add the dry powder obtained in step 3) into a mechanical fusion machine, extrusion and fusion at high speed for 20 minutes to obtain a precursor coated with a layer of asphalt and modified with aluminum metaphosphate on the surface;
  • step 5) Transfer the precursor in step 4) to a vacuum furnace and carbonize it under vacuum conditions at 800°C for 6 hours to carbonize the pitch at high temperature to obtain about 10 wt.% pitch cracked carbon and 4 wt.% aluminum metaphosphate on the surface.
  • a method for preparing a nano silicon-graphite composite anode material with a carbon coating and an aluminum metaphosphate composite modification layer on the surface specifically including the following steps:
  • step 2) Stir the suspension in step 1) at high speed, add 1950g graphite powder at the same time, stir thoroughly and mix evenly, then add 1200g water-based asphalt (solid content 50wt.%, vacuum carbonization residual carbon content 50wt.%), and mix evenly to obtain Uniform slurry with solid content of about 15wt.%;
  • step 3 Spray dry the uniform slurry obtained in step 2) while ultrasonic stirring, control the inlet temperature of the sprayer at 200°C, and the feed amount at 30kg/h to obtain dry powder;
  • step 4) Weigh 300g of aluminum metaphosphate powder and add the dry powder obtained in step 3) into a mechanical fusion machine, squeeze and fuse at high speed for 20 minutes to obtain a precursor with a surface coated with a layer of asphalt and aluminum metaphosphate modification;
  • step 5) Transfer the precursor in step 4) to a vacuum furnace and carbonize it under vacuum conditions at 1000°C for 6 hours to carbonize the pitch at high temperature to obtain about 10 wt.% pitch cracked carbon and 10 wt.% aluminum metaphosphate on the surface.
  • a method for preparing a nano silicon-graphite composite anode material with a carbon coating and an aluminum metaphosphate composite modification layer on the surface specifically including the following steps:
  • step 2) Stir the suspension in step 1) at high speed, add 2010g graphite powder at the same time, stir thoroughly and mix evenly, then add 1200g water-based asphalt (solid content 50wt.%, vacuum carbonization residual carbon content 50wt.%), and mix evenly to obtain Uniform slurry with solid content of about 12.2wt.%;
  • step 2) Spray dry the uniform slurry obtained in step 2) while ultrasonic stirring, control the inlet temperature of the sprayer at 210°C, and the feed amount at 30kg/h to obtain dry powder;
  • step 4 Weigh 240g of aluminum metaphosphate powder and add it to the mechanical fusion machine together with the dry powder obtained in step 3), and squeeze and fuse at high speed for 20 minutes to obtain a precursor with a surface coated with a layer of asphalt and aluminum metaphosphate modification;
  • step 5) Transfer the precursor in step 4) to a vacuum furnace and carbonize it under vacuum conditions at 1200°C for 3 hours to carbonize the pitch at high temperature to obtain about 10 wt.% pitch cracked carbon and 8 wt.% aluminum metaphosphate on the surface.
  • a method for preparing a nano silicon-graphite composite anode material with a carbon coating and an aluminum metaphosphate composite modification layer on the surface specifically including the following steps:
  • step 2) Stir the suspension in step 1) at high speed, add 2070g graphite powder at the same time, stir thoroughly and mix evenly, then add 1200g water-based asphalt (solid content 50wt.%, vacuum carbonization residual carbon content 50wt.%), and mix evenly to obtain Uniform slurry with solid content of about 10.4wt.%;
  • step 3 Spray dry the uniform slurry obtained in step 2) while ultrasonic stirring, control the inlet temperature of the sprayer at 220°C, and the feed amount at 30kg/h to obtain dry powder;
  • step 4) Weigh 180g of aluminum metaphosphate powder and the dry powder obtained in step 3) and add it to a mechanical fusion machine, extrusion and fusion at high speed for 20 minutes to obtain a precursor coated with a layer of asphalt and modified with aluminum metaphosphate on the surface;
  • step 5) Transfer the precursor in step 4) to a vacuum furnace and carbonize it under vacuum conditions at 1100°C for 4 hours to carbonize the pitch at high temperature to obtain about 10 wt.% pitch cracked carbon and 6 wt.% aluminum metaphosphate on the surface.
  • step 2) Stir the suspension in step 1) at high speed, add 1950g graphite powder at the same time, stir thoroughly and mix evenly, then add 1200g water-based asphalt (solid content 50wt.%, vacuum carbonization residual carbon content 50wt.%), and mix evenly to obtain Uniform slurry with solid content of about 10wt.%;
  • step 3 Spray dry the uniform slurry obtained in step 2) while ultrasonic stirring, control the inlet temperature of the sprayer at 220°C, and the feed amount at 30kg/h to obtain dry powder;
  • step 4) Transfer the precursor in step 3) to a vacuum furnace and carbonize it under vacuum conditions at 800°C for 3 hours to carbonize the pitch at high temperature to obtain nano silicon-graphite with only a carbon coating layer on the surface and no aluminum metaphosphate modification.
  • Composite negative electrode materials
  • the nano-silicon-graphite composite negative electrode material without surface modification in Comparative Example 1 was assembled into a 2032 button battery to test the cycle life.
  • the material performance data are shown in Table 1, and the cycle life curve is shown in Figure 2.
  • step 2) Stir the suspension in step 1) at high speed, add 1950g graphite powder at the same time, stir thoroughly and mix evenly, then add 1200g water-based asphalt (solid content 50wt.%, vacuum carbonization residual carbon content 50wt.%), and mix evenly to obtain Uniform slurry with solid content of about 10wt.%;
  • step 3 Spray dry the uniform slurry obtained in step 2) while ultrasonic stirring, control the inlet temperature of the sprayer at 220°C, and the feed amount at 30kg/h to obtain dry powder;
  • step 4) Transfer the precursor in step 3) to a vacuum furnace and carbonize it under vacuum conditions at 800°C for 3 hours to carbonize the pitch at high temperature to obtain nano-silicon-graphite with no carbon coating layer on the surface and only aluminum metaphosphate modification.
  • Composite negative electrode materials
  • the nano-silicon-graphite composite negative electrode material without surface modification in Comparative Example 2 was assembled into a 2032 button battery to test the cycle life.
  • the material performance data are shown in Table 1.
  • step 2) Stir the suspension in step 1) at high speed, add 1950g graphite powder at the same time, stir thoroughly and mix evenly to obtain a uniform slurry with a solid content of about 10wt.%;
  • step 3 Spray dry the uniform slurry obtained in step 2) while ultrasonic stirring, control the inlet temperature of the sprayer at 220°C, and the feed amount at 30kg/h to obtain dry powder;
  • step 4) Transfer the precursor in step 3) into a vacuum furnace and carbonize it under vacuum conditions at 800°C for 3 hours to obtain a nanometer silicon-graphite composite anode material with neither carbon coating nor aluminum metaphosphate modification on the surface;
  • the nano-silicon-graphite composite negative electrode material without surface modification in Comparative Example 3 was assembled into a 2032 button battery to test the cycle life.
  • the material performance data are shown in Table 1.
  • Comparative Example 3 without surface modification only has a capacity retention rate of 28.4% after 300 cycles
  • Comparative Example 1 with only carbon coating modification has a capacity retention of 70.7% after 300 cycles. rate
  • Comparative Example 2 with only aluminum metaphosphate modification has a capacity retention rate of 46.2% after 300 cycles
  • the capacity retention rates were 103.7%, 87.8%, 104.3%, 102.8% and 104.4% respectively.

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Abstract

本发明涉及一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料及其制备方法，主要由以下组份按照质量百分比制备而成：4～10wt.％的偏磷酸铝、10wt.％的沥青裂解碳、15wt.％的球形纳米硅粉和71-65wt.％的石墨粉；通过将纳米硅粉加入去离子水中超声分散，随后加入石墨粉超声搅拌均匀，然后加入水性沥青，搅拌混合均匀以后，进行喷雾干燥，将干燥以后的粉末与偏磷酸盐复合进行机械融合，最后转入真空炉中高温碳化，即得。本发明公开了一种具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料，表面存在的复合修饰层可以很好的抑制电解液对纳米硅材料的腐蚀，缓解体积膨胀，提升导电性，增加循环寿命。

Description

表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料及其制备方法 技术领域
本发明涉及电化学电源技术领域，具体涉及一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料及其制备方法。
背景技术
硅通过与锂形成锂硅合金的方式来嵌锂，在嵌锂过程中伴随有巨大的体积膨胀，脱锂去合金化过程中又伴随着剧烈的体积收缩，这种体积变化高达300％，极易造成硅材料粉化，严重影响循环稳定性。通过制备合适粒度的纳米硅粉，可以有效解决硅材料在电化学循环过程中的颗粒粉化，但是纳米硅材料嵌锂以后巨大的体积变化效应仍然存在，电极经过反复的体积膨胀和收缩，颗粒仍然会失去电接触和粉化，造成容量损失，引起循环寿命衰减。以现有的成熟的商业化石墨类负极材料为基础骨架复合纳米硅材料，来弥补硅基材料的固有缺点，获得比容量和循环寿命满足锂离子电池负极材料需求的新型复合负极材料，不失为一种有效可行的低成本化方法。
但是纳米硅跟石墨复合以后，两者的脱嵌锂膨胀收缩率不一致，容易导致纳米硅颗粒失去电接触，造成容量损失，同时表面形成的SEI膜不稳定，不断消耗电解液，是电池的锂离子传输受阻，从而引起材料循环寿命下降。再者，现阶段主要通过将硅材料纳米化，并和其他材料复合来提升循环寿命。但是硅材料纳米化以后比表面积大，表面容易受到电解液的侵蚀，且虽然硅材料纳米化以后嵌锂膨胀仍然存在，因此需要进一步进行表面修饰。本发明通过简单易行的方式在材料表面进行碳包覆和偏磷酸复合修饰来获得长循环寿命的纳米硅-石墨复合负极材料。
发明内容
有鉴于此，本发明的目的是提供一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料及其制备方法。
为了实现上述目的，本发明采用如下技术方案：
一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料，所述负极材料主要由以下组份按照质量百分比制备而成：
偏磷酸铝4～10wt.％、沥青裂解碳10wt.％、球形纳米硅粉15wt.％和石墨粉71-65wt.％。
本发明另一项技术目的是提供上述表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法，包括表面碳包覆和偏磷酸铝复合修饰层、纳米硅-石墨复合材料的制备和其作为锂离子电池用的硅碳复合材料使用的方法及步骤；其中，本发明中所涉及的制备方法如下：
首先将纳米硅粉加入去离子水中超声分散，得到均匀的分散液，再加入石墨粉超声搅拌均匀，然后加入水性沥青，搅拌混合均匀以后，进行喷雾干燥，将干燥以后的粉末与偏磷酸盐复合进行机械融合，最后转入真空炉中高温碳化，得到表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料。
具体包括以下步骤：
1)按配方称纳米硅粉加入到去离子水中并超声搅拌分散，得到纳米硅粉分散液；
2)将步骤1)的悬浮液高速搅拌，先根据配方比例加入石墨粉，搅拌混合一定时间后加入水性沥青，高速搅拌均匀，同时加入去离子水控制悬浮液的固含量在10～15wt.％的范围内；
3)将步骤2)的悬浮液再用喷雾干燥机进行喷雾干燥，控制喷雾进口温度在200-220℃，进料量在20-30kg/h，得到干燥粉末；
4)按配方比例称偏磷酸铝粉末，加入到步骤3)的干燥粉末中，混合均匀后，加入到机械融合机中进行融合，得到表面包覆一层沥青和偏磷酸铝修饰的前驱体；
5)将步骤4)中的前驱体转入至真空炉中在800-1200℃高温碳化3-6h，然后取出破碎过筛，得到表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料。
值得说明的是，本发明通过纳米硅-石墨复合负极材料表面碳包覆层修饰，可以很好的提升纳米硅和石墨的结合强度，并改善硅材料的导电性，通过表面偏磷酸铝修饰可以很好的缓解体积膨胀，稳定材料表面形成的SEI膜。本发明在纳米硅跟石墨复合制备纳米硅-石墨复合负极材料的基础上，通过表面碳包覆和偏磷酸铝复合修饰层来增强纳米硅颗粒的导电性，并稳定SEI膜，缓解材料体积变化来获得更高循环寿命的复合负极材料。
与现有技术相比，本发明公开了一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料及其制备方法，具有如下有益效果：
1)复合修饰层的存在不仅具有传统碳包覆的效果，如提高硅材料的导电性，隔绝电解液对硅材料的侵蚀，缓解体积膨胀等，同时偏磷酸铝弥散在包覆层中增强了包覆层的剥离强度，能够更好的适应材料的体积变化。
2)偏磷酸铝的存在可以有助于在材料表面形成稳定的SEI膜，减少电解液的消耗，获得更高的循环寿命。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据提供的附图获得其他的附图。
图1为本发明制备的表面具有偏磷酸铝修饰的纳米硅-石墨复合负极材料的能谱分析。
图2为将本发明实施例1、对比例1制得的硅碳复合材料制成负极片，再组装成2032扣式电池后测试得到的容量保持率曲线图。
具体实施方式
下面将结合说明书附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明公开保护一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法。
下面结合具体实施例进一步阐述本发明的技术方案，但本发明的内容不仅仅局限于下面的实施例。
实施例1：
一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法，具体包括以下步骤：
1)称取450g纳米硅粉加入27kg去离子水中并超声搅拌分散，得到纳米硅粉的悬浮液；
2)将步骤1)的悬浮液高速搅拌，同时加入1950g石墨粉，充分搅拌混合均匀，再加入1200g水性沥青(固含量50wt.％，真空碳化残碳量50wt.％)，并混合均匀，得到固含量10wt.％左右的均匀浆料；
3)将步骤2)得到的均匀浆料边超声搅拌边喷雾干燥，控制喷雾机进口温度在220℃，进料量在30kg/h，得到干燥粉末；
4)称取300g偏磷酸铝粉末和步骤3)得到的干燥粉末一起加入到机械融合机中，高速挤压融合20min，得到表面包覆一层沥青和偏磷酸铝修饰的前驱体；
5)将步骤4)中的前驱体转入至真空炉中在800℃的真空条件下碳化处理3h，使沥青高温碳化，得到表面具有10wt.％左右的沥青裂解碳和10wt.％偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料；
将本实施例制得的纳米硅-石墨复合负极材料制备成负极片，组装成2032扣式电池测试循环寿命，材料性能数据如表1所示，循环寿命曲线如图2所示。
其中，电池循环性能的测试方法为：先以100mA/g的电流密度放电至0.01v，再以10mA/g的电流放至0.005v，静置3min，然后以100mA/g的电流密度充电至1.5v，以此为一个循环测试循环性能。
此外，对本发明制备的表面具有偏磷酸铝修饰的纳米硅-石墨复合负极材料进行能谱分析，具体如附图1。从能谱图中可以看出，纳米硅颗粒分散在复合材料中的石墨颗粒表面，通过表面的碳包覆和偏磷酸铝修饰层将颗粒结合成一个整体。
实施例2
一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法，具体包括以下步骤：
1)称取450g纳米硅粉加入27kg去离子水中并超声搅拌分散，得到纳米硅粉的悬浮液；
2)将步骤1)的悬浮液高速搅拌，同时加入2130g石墨粉，充分搅拌混合均匀，再加入1200g水性沥青(固含量50wt.％，真空碳化残碳量50wt.％)，并混合均匀，得到固含量10wt.％左右的均匀浆料；
3)将步骤2)得到的均匀浆料边超声搅拌边喷雾干燥，控制喷雾机进口温度在200℃，进料量在30kg/h，得到干燥粉末；
4)称取120g偏磷酸铝粉末和步骤3)得到的干燥粉末一起加入到机械融合机中，高速挤压融合20min，得到表面包覆一层沥青和偏磷酸铝修饰的前驱体；
5)将步骤4)中的前驱体转入至真空炉中在800℃的真空条件下碳化处理6h，使沥青高温碳化，得到表面具有10wt.％左右的沥青裂解碳和4wt.％偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料；
实施例3
一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法，具体包括以下步骤：
1)称取450g纳米硅粉加入17kg去离子水中并超声搅拌分散，得到纳米硅粉的悬浮液；
2)将步骤1)的悬浮液高速搅拌，同时加入1950g石墨粉，充分搅拌混合均匀，再加入1200g水性沥青(固含量50wt.％，真空碳化残碳量50wt.％)，并混合均匀，得到固含量15wt.％左右的均匀浆料；
3)将步骤2)得到的均匀浆料边超声搅拌边喷雾干燥，控制喷雾机进口温度在200℃，进料量在30kg/h，得到干燥粉末；
4)称取300g偏磷酸铝粉末和步骤3)得到的干燥粉末一起加入到机械融合机中，高速挤压融合20min，得到表面包覆一层沥青和偏磷酸铝修饰的前驱体；
5)将步骤4)中的前驱体转入至真空炉中在1000℃的真空条件下碳化处理6h，使沥青高温碳化，得到表面具有10wt.％左右的沥青裂解碳和10wt.％偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料；
实施例4
一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法，具体包括以下步骤：
1)称取450g纳米硅粉加入22kg去离子水中并超声搅拌分散，得到纳米硅粉的悬浮液；
2)将步骤1)的悬浮液高速搅拌，同时加入2010g石墨粉，充分搅拌混合均匀，再加入1200g水性沥青(固含量50wt.％，真空碳化残碳量50wt.％)，并混合均匀，得到固含量12.2wt.％左右的均匀浆料；
3)将步骤2)得到的均匀浆料边超声搅拌边喷雾干燥，控制喷雾机进口温度在210℃，进料量在30kg/h，得到干燥粉末；
4)称取240g偏磷酸铝粉末和步骤3)得到的干燥粉末一起加入到机械融合机中，高速挤压融合20min，得到表面包覆一层沥青和偏磷酸铝修饰的前驱体；
5)将步骤4)中的前驱体转入至真空炉中在1200℃的真空条件下碳化处理3h，使沥青高温碳化，得到表面具有10wt.％左右的沥青裂解碳和8wt.％偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料；
实施例5
一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法，具体包括以下步骤：
1)称取450g纳米硅粉加入27kg去离子水中并超声搅拌分散，得到纳米硅粉的悬浮液；
2)将步骤1)的悬浮液高速搅拌，同时加入2070g石墨粉，充分搅拌混合均匀，再加入1200g水性沥青(固含量50wt.％，真空碳化残碳量50wt.％)，并混合均匀，得到固含量10.4wt.％左右的均匀浆料；
3)将步骤2)得到的均匀浆料边超声搅拌边喷雾干燥，控制喷雾机进口温度在220℃，进料量在30kg/h，得到干燥粉末；
4)称取180g偏磷酸铝粉末和步骤3)得到的干燥粉末一起加入到机械融合机中，高速挤压融合20min，得到表面包覆一层沥青和偏磷酸铝修饰的前驱体；
5)将步骤4)中的前驱体转入至真空炉中在1100℃的真空条件下碳化处理4h，使沥青高温碳化，得到表面具有10wt.％左右的沥青裂解碳和6wt.％偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料。
下面为进一步验证本发明申请相较现有技术存在的优异效果，发明人还进行了如下对比实验及性能测试，具体内容如下：
对比例1
1)称取450g纳米硅粉加入27kg去离子水中并超声搅拌分散，得到纳米硅粉的悬浮液；
2)将步骤1)的悬浮液高速搅拌，同时加入1950g石墨粉，充分搅拌混合均匀，再加入1200g水性沥青(固含量50wt.％，真空碳化残碳量50wt.％)，并混合均匀，得到固含量10wt.％左右的均匀浆料；
3)将步骤2)得到的均匀浆料边超声搅拌边喷雾干燥，控制喷雾机进口温度在220℃，进料量在30kg/h，得到干燥粉末；
4)将步骤3)中的前驱体转入至真空炉中在800℃的真空条件下碳化处理3h，使沥青高温碳化，得到表面只有碳包覆层，没有偏磷酸铝修饰的纳米硅-石墨复合负极材料；
取对比例1中没有表面修饰的纳米硅-石墨复合负极材料组装成2032扣式电池测试循环寿命，材料性能数据如表1所示，循环寿命曲线如图2所示。
对比例2
1)称取450g纳米硅粉加入27kg去离子水中并超声搅拌分散，得到纳米硅粉的悬浮液；
2)将步骤1)的悬浮液高速搅拌，同时加入1950g石墨粉，充分搅拌混合均匀，再加入1200g水性沥青(固含量50wt.％，真空碳化残碳量50wt.％)，并混合均匀，得到固含量10wt.％左右的均匀浆料；
3)将步骤2)得到的均匀浆料边超声搅拌边喷雾干燥，控制喷雾机进口温度在220℃，进料量在30kg/h，得到干燥粉末；
4)将步骤3)中的前驱体转入至真空炉中在800℃的真空条件下碳化处理3h，使沥青高温碳化，得到表面没有碳包覆层，只有偏磷酸铝修饰的纳米硅-石墨复合负极材料；
取对比例2中没有表面修饰的纳米硅-石墨复合负极材料组装成2032扣式电池测试循环寿命，材料性能数据如表1所示。
对比例3
1)称取450g纳米硅粉加入27kg去离子水中并超声搅拌分散，得到纳米硅粉的悬浮液；
2)将步骤1)的悬浮液高速搅拌，同时加入1950g石墨粉，充分搅拌混合均匀，得到固含量10wt.％左右的均匀浆料；
3)将步骤2)得到的均匀浆料边超声搅拌边喷雾干燥，控制喷雾机进口温度在220℃，进料量在30kg/h，得到干燥粉末；
4)将步骤3)中的前驱体转入至真空炉中在800℃的真空条件下碳化处理3h，得到表面既没有碳包覆和也没有偏磷酸铝修饰的纳米硅-石墨复合负极材料；
取对比例3中没有表面修饰的纳米硅-石墨复合负极材料组装成2032扣式电池测试循环寿命，材料性能数据如表1所示。
从表1中可以看出，未做表面修饰的对比例3经过300个循环以后只有28.4％的容量保持率，只有碳包覆层修饰的对比例1经过300个循环以后具有70.7％的容量保持率，仅有偏磷酸铝修饰的对比例2经过300个循环以后容量保持率为46.2％，而经过碳包覆和偏磷酸铝复合修饰以后，材料的循环寿命显著提升，实施例1至实施例5的样品经过300个循环以后，容量保持率分别为103.7％、87.8％、104.3％、102.8％和104.4％。通过对比分析可以发现本发明设计的碳包覆和偏磷酸铝复合修饰层可以大大的提升纳米硅-石墨复合负极材料的循环寿命。
表1
Figure PCTCN2022094412-appb-000001
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。

Claims (4)

  1. 一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料，其特征在于，所述负极材料主要由以下组份按照质量百分比制备而成：
    偏磷酸铝4～10wt.％、沥青裂解碳10wt.％、球形纳米硅粉15wt.％和石墨粉71-65wt.％。
  2. 一种如权利要求1所述的表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法，其特征在于，包括以下步骤：
    1)按配方称纳米硅粉加入到去离子水中并超声搅拌分散，得到纳米硅粉分散液；
    2)将步骤1)的悬浮液高速搅拌，先根据配方比例加入石墨粉，搅拌混合一定时间后加入水性沥青，高速搅拌均匀，同时加入去离子水控制悬浮液的固含量在10～15wt.％的范围内；
    3)将步骤2)的悬浮液再用喷雾干燥机进行喷雾干燥，得到干燥粉末；
    4)按配方比例称偏磷酸铝粉末，加入到步骤3)的干燥粉末中，混合均匀后，加入到机械融合机中进行融合，得到表面包覆一层沥青和偏磷酸铝修饰的前驱体；
    5)将步骤4)中的前驱体转入至真空炉中高温碳化，然后取出破碎过筛，得到表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料。
  3. 根据权利要求2所述的一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法，其特征在于，步骤3)中，喷雾进口温度为200-220℃，进料量在20-30kg/h。
  4. 根据权利要求2所述的一种表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料的制备方法，其特征在于，步骤5)中，高温碳化温度为800-1200℃，碳化时间为3-6h。
PCT/CN2022/094412 2022-04-29 2022-05-23 表面具有碳包覆和偏磷酸铝复合修饰层的纳米硅-石墨复合负极材料及其制备方法 WO2023206673A1 (zh)

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