阅读说明：本技术 一种锂电池硅基负极材料的制备方法、负极材料和锂电池 (Preparation method of silicon-based negative electrode materials of lithium battery, negative electrode materials and lithium battery ) 是由 周勇岐 顾华清 袁树兵 毕文君 冯苏宁 刘芳 李辉 卢勇 于 2019-10-25 设计创作，主要内容包括：本发明实施例涉及一种锂电池硅基负极材料的制备方法、负极材料和锂电池,所述方法包括：将石墨烯粉末加入有机溶剂中,超声分散后形成第一分散液；向第一分散液中加入二氧化硅颗粒,再加入金属粉末材料,形成悬浊液；常温下对悬浊液进行超声分散和机械搅拌得到石墨烯/二氧化硅/金属粉末材料的第二分散液；将第二分散液在惰性气氛条件下进行喷雾干燥,得到石墨烯/二氧化硅/金属粉末材料的粉体；在粉体中加入沥青粉末并均匀分散,烧结得到锂电池硅基负极材料；所得材料具有由二氧化硅与金属粉末材料反应得到的纳米硅和金属硅酸盐形成的缓冲层结构,石墨烯均匀分散在缓冲层结构中形成的导电网络,以及沥青在烧结过程中碳化形成的碳包覆层。(The embodiment of the invention relates to a preparation method of lithium battery silicon-based negative electrode materials, a negative electrode material and a lithium battery, and the method comprises the steps of adding graphene powder into an organic solvent, performing ultrasonic dispersion to form th dispersion liquid, adding silica particles into th dispersion liquid, adding a metal powder material to form suspension liquid, performing ultrasonic dispersion and mechanical stirring on the suspension liquid at normal temperature to obtain second dispersion liquid of the graphene/silica/metal powder material, performing spray drying on the second dispersion liquid under the condition of inert atmosphere to obtain powder of the graphene/silica/metal powder material, adding asphalt powder into the powder, uniformly dispersing and sintering to obtain the lithium battery silicon-based negative electrode material, wherein the obtained material has a buffer layer structure formed by nano silicon and metal silicate obtained by reaction of silica and the metal powder material, the graphene is uniformly dispersed in the buffer layer structure to form a conductive network, and a carbon coating layer formed by carbonization of the asphalt in the sintering process.)

1, A preparation method of silicon-based negative electrode material of lithium battery, characterized in that, the preparation method comprises:

adding quantitative graphene powder into an organic solvent, and performing ultrasonic dispersion to form th dispersion liquid with the dispersion concentration of 0.5-3 g/L;

adding quantitative silicon dioxide particles into th dispersion liquid, wherein the dispersion concentration is 5g/L-25g/L, and then adding quantitative metal powder material, and the dispersion concentration is 1g/L-10g/L to form suspension;

performing ultrasonic dispersion on the suspension at normal temperature, and then mechanically stirring to obtain a second dispersion liquid of the graphene/silicon dioxide/metal powder material; in the second dispersion liquid, silicon dioxide and metal powder materials are uniformly dispersed with graphene powder in a physical adsorption mode; wherein the graphene/silicon dioxide/metal powder material is a mixture of graphene, silicon dioxide and metal powder material;

performing spray drying on the second dispersion liquid under the inert atmosphere condition to obtain powder of the graphene/silicon dioxide/metal powder material;

adding 3-10% of asphalt powder into the powder, uniformly dispersing, and sintering at 700-1300 ℃ for 5-24 hours under the inert atmosphere condition to obtain solid powder, namely the silicon-based negative electrode material of the lithium battery;

wherein, the silicon-based negative electrode material of the lithium battery comprises: the buffer layer structure is formed by nanometer silicon and metal silicate obtained by the reaction of the silicon dioxide and the metal powder material, the graphene is uniformly dispersed in a conductive network formed in the buffer layer structure, and the asphalt is carbonized in the sintering process to form a carbon coating layer.

2. The method for preparing the silicon-based negative electrode material of the lithium battery as claimed in claim 1, wherein the organic solvent comprises or more of methanol, ethanol, toluene, ethylbenzene, acetone, tetrahydrofuran, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

3. The method for preparing the silicon-based negative electrode material of the lithium battery as claimed in claim 1, wherein the graphene powder comprises or more of single-layer graphene, double-layer graphene, few-layer graphene and multi-layer graphene.

4. The method for preparing silicon-based negative electrode material for lithium battery as claimed in claim 1, wherein the silicon dioxide particles have an average particle size of 0.1 μm to 3 μm and a specific surface area of 0.5m²/g-30m²/g。

5. The method for preparing the silicon-based negative electrode material of the lithium battery as claimed in claim 1, wherein the metal powder material comprises or more of lithium powder, lithium oxide, lithium carbonate, magnesium powder, magnesium oxide, magnesium carbonate, sodium powder, sodium oxide or sodium carbonate;

the average particle size of the metal powder particles is 0.1-1 μm, and the material purity is more than or equal to 99.9%.

6. The method for preparing silicon-based negative electrode material for lithium battery as claimed in claim 1,

the ultrasonic frequency of the ultrasonic dispersion is 10-40kHz, and the ultrasonic dispersion time is 10-60 min;

the mechanical stirring speed is 400-1600rmp, and the stirring time is 1-12 hours.

7. The method for preparing the silicon-based negative electrode material of the lithium battery as claimed in claim 1, wherein the average particle diameter of the powder of the graphene/silicon dioxide/metal powder material is 3 μm to 20 μm, and the specific surface area is 1m²/g-50m²/g。

8. The method for preparing the silicon-based anode material for the lithium battery as recited in claim 1, wherein the inert atmosphere comprises or more of nitrogen atmosphere, argon atmosphere and helium atmosphere.

9, silicon-based negative electrode material for lithium battery prepared by the method of any of the claims 1-8 and .

10, a lithium battery comprising the silicon-based negative electrode material for a lithium battery as claimed in claim 9.

Technical Field

The invention relates to the technical field of battery materials, in particular to a preparation method of silicon-based negative electrode materials of a lithium battery, the negative electrode materials and the lithium battery.

Background

Graphite is a mainstream lithium battery negative electrode material at present, but with the gradual increase of the requirements of energy density and power density of a lithium battery, the specific capacity (theoretical capacity 372mAh/g) of graphite is gradually difficult to meet the market demand, and silicon has the advantages of high specific capacity (theoretical capacity 4200mAh/g), low charge and discharge platform, abundant resources, good safety and the like, so that the graphite becomes a research hotspot at present, and is also considered to be the most possible to replace graphite to become a new -generation lithium battery negative electrode material.

The problems of volume expansion and poor conductivity of the silicon material cause pulverization phenomenon in the material circulation process, and the characteristics of short service life and poor cyclicity in the lithium battery circulation process. In order to solve the problems of volume expansion and poor conductivity of the material, a buffer substance is usually added and the surface of the material is coated with a conductive substance.

Aiming at market demands, the modification preparation method of the silicon-based negative electrode material is gradually diversified, but the high-capacity silicon-based negative electrode material with excellent cycle performance, high first-time efficiency, low volume expansion and simple process preparation is still deeply researched for a while.

Disclosure of Invention

The invention aims to provide lithium battery silicon-based negative electrode materials, a negative electrode material and a lithium battery, wherein silicon dioxide is reduced by adopting metal powder to prepare the silicon-based negative electrode materials, the defects of the silicon-based negative electrode materials are improved by virtue of excellent mechanical and electrical properties of graphene, and the application of the silicon-based negative electrode materials in the lithium battery is improved.

In order to achieve the above object, in , the invention provides a preparation method of silicon-based negative electrode materials for lithium batteries, the preparation method comprising:

adding quantitative graphene powder into an organic solvent, and performing ultrasonic dispersion to form th dispersion liquid with the dispersion concentration of 0.5-3 g/L;

adding quantitative silicon dioxide particles into th dispersion liquid, wherein the dispersion concentration is 5g/L-25g/L, and then adding quantitative metal powder material, and the dispersion concentration is 1g/L-10g/L to form suspension;

performing ultrasonic dispersion on the suspension at normal temperature, and then mechanically stirring to obtain a second dispersion liquid of the graphene/silicon dioxide/metal powder material; in the second dispersion liquid, silicon dioxide and metal powder materials are uniformly dispersed with graphene powder in a physical adsorption mode; wherein the graphene/silicon dioxide/metal powder material is a mixture of graphene, silicon dioxide and metal powder material;

performing spray drying on the second dispersion liquid under the inert atmosphere condition to obtain powder of the graphene/silicon dioxide/metal powder material;

adding 3-10% of asphalt powder into the powder, uniformly dispersing, and sintering at 700-1300 ℃ for 5-24 hours under the inert atmosphere condition to obtain solid powder, namely the silicon-based negative electrode material of the lithium battery;

wherein, the silicon-based negative electrode material of the lithium battery comprises: the buffer layer structure is formed by nanometer silicon and metal silicate obtained by the reaction of the silicon dioxide and the metal powder material, the graphene is uniformly dispersed in a conductive network formed in the buffer layer structure, and the asphalt is carbonized in the sintering process to form a carbon coating layer.

Preferably, the organic solvent comprises or more of methanol, ethanol, toluene, ethylbenzene, acetone, tetrahydrofuran, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

Preferably, the graphene powder comprises or more of single-layer graphene, double-layer graphene, few-layer graphene and multi-layer graphene.

Preferably, the silica particles have an average particle diameter of 0.1 to 3 μm and a specific surface area of 0.5m²/g-30m²/g。

Preferably, the metal powder material comprises or more of lithium powder, lithium oxide, lithium carbonate, magnesium powder, magnesium oxide, magnesium carbonate, sodium powder, sodium oxide or sodium carbonate;

the average particle size of the metal powder particles is 0.1-1 μm, and the material purity is more than or equal to 99.9%.

Preferably, the ultrasonic frequency of the ultrasonic dispersion is 10-40kHz, and the ultrasonic dispersion time is 10-60 min;

the mechanical stirring speed is 400-1600rmp, and the stirring time is 1-12 hours.

Preferably, the average particle diameter of the powder of the graphene/silicon dioxide/metal powder material is 3-20 μm, and the specific surface area is 1m²/g-50m²/g。

Preferably, the inert atmosphere comprises or more of nitrogen atmosphere, argon atmosphere and helium atmosphere.

In a second aspect, the embodiment of the present invention provides silicon-based negative electrode materials for lithium batteries, which are prepared by the method described in the above .

In a third aspect, the embodiment of the present invention provides lithium batteries including the silicon-based negative electrode material for lithium batteries described in the second aspect.

According to the preparation method of the silicon-based negative electrode material of the lithium battery, provided by the embodiment of the invention, the silicon dioxide material is reduced by metal at a high temperature to form metal silicate and simple substance silicon, the volume expansion of the simple substance silicon in the circulation process is controlled by the metal silicate, the conductive network is constructed by the graphene, the conductive performance of the silicon-based material in the early and later cycle pulverization is improved, the specific surface area of the material is reduced by the carbon layer coated on the surface, and the first cycle efficiency and the cycle performance of the material are improved.

Drawings

Fig. 1 is a flowchart of a method for preparing a silicon-based negative electrode material for a lithium battery according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the internal structure of a material before high-temperature sintering according to an embodiment of the present invention;

fig. 3 is a test curve of electrochemical performance of a half cell made of the silicon-based negative electrode material provided in example 1 of the present invention.

Detailed Description

The technical solution of the present invention is further described in steps by the accompanying drawings and examples.

The lithium battery silicon-based negative electrode material preparation methods provided by the embodiments are used for lithium battery negative electrode material preparation, fig. 1 is a flow chart of the lithium battery silicon-based negative electrode material preparation method provided by the embodiments of the present invention, and the following description is made on the preparation method embodiments of the present invention according to fig. 1, and the preparation method mainly includes the following steps:

step 110, adding quantitative graphene powder into an organic solvent, and performing ultrasonic dispersion to form th dispersion liquid with the dispersion concentration of 0.5-3 g/L;

specifically, the graphene powder comprises or more of single-layer graphene, double-layer graphene, few-layer graphene and multi-layer graphene.

The organic solvent comprises or more of methanol, ethanol, toluene, ethylbenzene, acetone, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

Step 120, adding quantitative silicon dioxide particles into th dispersion liquid, wherein the dispersion concentration is 5g/L-25g/L, and then adding quantitative metal powder materials, wherein the dispersion concentration is 1g/L-10g/L, so as to form suspension;

specifically, silica particlesThe particles have an average particle diameter of 0.1-3 μm and a specific surface area of 0.5m²/g-30m²Per gram of particles.

The metal powder material comprises or more of lithium powder, lithium oxide, lithium carbonate, magnesium powder, magnesium oxide, magnesium carbonate, sodium powder, sodium oxide or sodium carbonate, the average particle diameter of the metal powder is 0.1-1 μm, and the material purity is more than or equal to 99.9%.

It should be noted that in the specific operation of adding the metal powder, because the properties of different materials are different, the specific treatment operation is performed on the materials with specific properties according to the safety regulations and requirements.

For example, when lithium powder is added, it is necessary to perform operations in a dry room to avoid danger, the surface of the selected lithium powder is passivated to reduce the reactivity, and the reaction is also performed in an atmosphere of argon or helium.

Step 130, performing ultrasonic dispersion on the suspension at normal temperature, and then mechanically stirring to obtain a second dispersion liquid of the graphene/silicon dioxide/metal powder material;

the graphene/silicon dioxide/metal powder material is a mixture of graphene, silicon dioxide and metal powder material; the ultrasonic frequency of ultrasonic dispersion is 10-40kHz, and the ultrasonic dispersion time is 10-60 min; the mechanical stirring speed is 400-1600rmp, and the stirring time is 1-12 hours.

In the formed second dispersion liquid, the silicon dioxide and the metal powder material are uniformly dispersed with the graphene powder in a physical adsorption manner.

140, performing spray drying on the second dispersion liquid under the inert atmosphere condition to obtain powder of the graphene/silicon dioxide/metal powder material;

the average particle diameter of the powder of the graphene/silicon dioxide/metal powder material is 3-20 mu m, and the specific surface area is 1m²/g-50m²/g。

Step 150, adding 3-10% of asphalt powder into the powder, uniformly dispersing, and sintering at 700-1300 ℃ for 5-24 hours under the inert atmosphere condition to obtain solid powder, namely the silicon-based negative electrode material of the lithium battery;

specifically, a schematic diagram of an internal structure of the material before high-temperature sintering is shown in fig. 2, graphene is uniformly distributed as a conductive network, and in the high-temperature sintering process, a metal reduces a silicon dioxide material to form metal silicate and elemental silicon, that is, after high-temperature sintering, the silicon dioxide material and the metal become Si and silicate crystal phases which are uniformly distributed in particles, and the outside is carbonized by asphalt in the high-temperature process to form a coating layer which is uniformly coated on the surface of the material.

Therefore, the obtained silicon-based negative electrode material for the lithium battery has the following characteristics: the buffer layer structure is formed by nanometer silicon and metal silicate obtained by reaction of silicon dioxide and metal powder materials, the conductive network formed by graphene uniformly dispersed in the buffer layer structure, and the carbon coating layer formed by carbonization of asphalt in the sintering process. In addition, the silicon-based negative electrode material of the lithium battery may have residual SiO₂The specific residual amount of the material is different according to different material proportions and different reaction temperature and time.

According to the preparation method of the silicon-based negative electrode material of the lithium battery, provided by the embodiment of the invention, the silicon dioxide material is reduced by metal at a high temperature to form metal silicate and simple substance silicon, the volume expansion of the simple substance silicon in the circulation process is controlled by the metal silicate, the conductive network is constructed by the graphene, the conductive performance of the silicon-based material in the early and later cycle pulverization is improved, the specific surface area of the material is reduced by the carbon layer coated on the surface, and the material is used as the negative electrode material of the lithium battery in the lithium battery, so that the first cycle efficiency and the cycle performance of the battery can be effectively improved.

The preparation process and performance of the silicon-based negative electrode material for lithium battery of the present invention are illustrated by specific examples.