WO2021077884A1

WO2021077884A1 - Composite material, preparation method therefor and use thereof as electrode material

Info

Publication number: WO2021077884A1
Application number: PCT/CN2020/110557
Authority: WO
Inventors: 赵娟; 杨耐德
Original assignee: 广东海洋大学
Priority date: 2019-10-23
Filing date: 2020-08-21
Publication date: 2021-04-29
Also published as: CN110752364A; ZA202105317B; CN110752364B

Abstract

Disclosed are a composite material, a preparation method therefor and an application thereof. The preparation method for the composite material comprises the following steps: mixing MXene and a transition metal salt solution, and then sequentially performing filtering and drying treatment to obtain transition metal salt loaded MXene; performing high-temperature chemical vapor deposition on the transition metal salt loaded MXene and a carbon source to obtain a first product; performing acid treatment on the first product; performing high-temperature chemical vapor deposition on the first product subjected to the acid treatment and a silicon source to obtain a second product; and performing high-temperature chemical vapor deposition on the second product and the carbon source to obtain the composite material. According to the preparation method, the MXene, the carbon source and the silicon source can be effectively combined, so that the capacity, rate capability and cycling stability of a lithium-ion battery can be greatly improved.

Description

Composite material and its preparation method and use as electrode material

Technical field

The invention relates to the technical field of battery materials, in particular to a composite material and a preparation method, application, electrode, and lithium ion battery.

Background technique

Lithium-ion batteries have a series of advantages such as high specific capacity, stable working voltage, good safety, and no memory effect. Therefore, they are widely used in many portable electronic equipment such as notebook computers, mobile phones, instruments and meters. With the rapid development of various electronic devices and electric vehicles, people have higher and higher requirements for the energy and cycle life of lithium-ion batteries. The negative electrode material is an important part of the battery. Together with the positive electrode material, it determines the cycle life, capacity and safety of lithium-ion batteries and other key properties, and has become the focus of research in various countries. The current commercial graphite-based anode materials have a low specific capacity of only 372mAh/g, which limits the increase in the overall capacity of lithium-ion batteries and can no longer meet the needs of the market. According to reports, the theoretical lithium storage capacity of silicon is as high as 4200mAh/g, and the lithium-insertion platform is slightly higher than that of graphite, and the potential safety hazard is small; however, silicon exhibits a volume change of up to 300% during charge and discharge, so it is easy to cause silicon particles to become pulverized , The internal conductive network of the electrode is destroyed, and the conductivity is not good.

In recent years, two-dimensional materials have shown great advantages in the field of energy storage due to their large specific surface area and short ion transmission path. MXene is a type of two-dimensional transition metal carbide with a graphene-like structure with high specific surface area, Good electrical conductivity and hydrophilicity are expected to be used as an ideal matrix material for constructing nanocomposite structures and improve the electrical conductivity of composite materials. Although in the prior art, a composite material formed by combining MXene and nano-silicon can alleviate the volume effect of silicon material and improve the cycle performance of the material; however, the lithium ion battery made by using the composite material has the problem of poor rate performance.

Summary of the invention

The purpose of the present invention is to provide a method for preparing composite materials to solve the above-mentioned problems.

In order to achieve the above objectives, the present invention provides the following technical solutions:

A method for preparing a composite material includes the following steps:

(1) Under vacuum conditions, mix MXene with the transition metal salt solution, and then sequentially perform filtration and drying treatments to obtain MXene loaded with the transition metal salt;

(2) Under a protective atmosphere, subject the MXene loaded with the transition metal salt obtained in step (1) to high-temperature chemical vapor deposition with a carbon source to obtain a first product deposited with carbon nanotubes;

(3) Treat the first product with acid;

(4) Under a protective atmosphere, subject the acid-treated first product and the silicon source to high-temperature chemical vapor deposition to obtain a second product deposited with nano-silicon;

(5) Under a protective atmosphere, the second product and the carbon source are subjected to high-temperature chemical vapor deposition to form a carbon coating layer to obtain the composite material.

In the present invention, the MXene is a kind of metal carbide material with a two-dimensional layered structure.

Preferably, the molecular formula of the MXene is Ma ₊₁ X _a ; wherein the M atomic layer is hexagonally close-packed, X atoms are filled in the octahedral vacancies to form an MX layer, and M is Ti, Zr, Cr, Mo, V, Ta One or more of; X is C or N.

Preferably, MXene is one of Ti ₃ C ₂ , Ti ₂ C and Ti ₄ C ₃ .

Preferably, the transition metal salt solution is one or more of a nitrate solution, a chloride salt solution, a sulfate solution and an oxalate solution of a transition metal; the transition metal is preferably iron or cobalt , One or more of nickel and chromium.

Preferably, the concentration of the transition metal salt solution is 0.1-10 mol/L.

Preferably, the MXene particles loaded with transition metal salt are obtained in the step (1);

Preferably, in the steps (2) and (5), the carbon sources are each independently one or more of acetylene, ethylene, methane, ethane, propane and n-butane.

Preferably, in the steps (2), (4) and (5), the temperature of the high-temperature chemical vapor deposition is independently 500-1000°C.

Preferably, in the steps (2), (4) and (5), the protective atmosphere is independently nitrogen and/or argon atmosphere.

Preferably, in the step (3), the acid treatment method is: after the first product is soaked in the acid for 0.5-6 hours, washing, dehydration and drying are performed in sequence; the acid is preferably The inorganic acid is, for example, one or more of nitric acid, hydrochloric acid, and sulfuric acid. The first product is treated with acid to remove the transition metal salt.

Preferably, in the step (4), the silicon source is monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, monomethyltrichlorosilane, dimethyltrichlorosilane and trimethylmonochlorosilane. One or more of silanes.

Preferably, the step (5) specifically includes the following steps:

Under a protective atmosphere, the second product and the carbon source are subjected to high-temperature chemical vapor deposition to obtain a third product deposited with a carbon coating layer;

The third product is mixed with a carbon material to obtain the composite material; the carbon material is one or more of natural graphite, artificial graphite, mesophase carbon microspheres, soft carbon and hard carbon; The particle size of the carbon material is 1-60 μm, and the mass of the carbon material is 0-90% of the mass of the entire composite material, for example, 1-90%, 2-80%.

Another object of the present invention is to provide a composite material prepared by the above preparation method; the mass ratio of nano silicon, MXene and carbon nanotubes in the composite material is (5～80):(1～40):(1) ~10).

Another object of the present invention is to provide an application of the above-mentioned composite material as a battery material.

Another object of the present invention is to provide an electrode, part or all of which is coated with the above-mentioned composite material.

Preferably, the preparation method of the electrode includes the following steps:

1) The composite material is mixed with polyvinylidene fluoride and conductive graphite to obtain an active slurry; the mass ratio of the composite material, polyvinylidene fluoride and conductive graphite is preferably (90～95): (4～ 6): (1～4);

2) Coating the active slurry on the metal foil to obtain the electrode.

Another object of the present invention is to provide a lithium ion battery, the lithium ion battery includes the above-mentioned electrode, and the electrode serves as the negative electrode of the lithium ion battery.

Compared with the prior art, the beneficial effects of the present invention are:

The invention provides a method for preparing a composite material. By introducing elastic characteristic carbon nanotubes between the MXene sheet framework, the MXene forms a three-dimensional composite network structure to support high-capacity nano-silicon, which can buffer the volume expansion of the nano-silicon, It is beneficial to keep the structure of the negative electrode material intact; at the same time, the silicon nanoparticles are located inside and on the surface of the three-dimensional conductive network structure constructed by multilayer MXene and carbon nanotubes, which greatly improves the conductivity of the silicon nanoparticles. Therefore, the effective combination of MXene, carbon nanotubes and silicon materials can greatly improve the capacity, rate performance and cycle stability of lithium-ion batteries.

Specifically, the present invention uses MXene with better hydrophilicity as the substrate. Because MXene can easily combine with the transition metal ions Fe ²⁺ , Co ²⁺ , Ni ^2+, etc. in the transition metal salt solution, These ions can be uniformly dispersed in the nano- and sub-micron voids between the MXene sheets, which act as a catalyst for the chemical vapor deposition reaction to form carbon nanotubes between the MXene sheets, and then deposit nano-silicon on the three-dimensional structure obtained above. On the MXene. Inserting carbon nanotubes between MXene sheets can significantly increase the interlayer spacing and surface area of MXene sheets, and can also provide free space for nano-silicon to buffer its volume expansion during energy storage. In addition, the carbon coating layer formed by the preparation method can prevent the direct contact between the electrolyte and the silicon, which is beneficial to keep the structure of the negative electrode material intact, thereby improving the capacity, cycle performance and service life of the battery. At the same time, the conductive network formed by carbon nanotubes connects MXene and nano-silicon, which greatly improves the conductivity of silicon. This conductive network ^{provides a channel for the transmission of Li +} during the charging and discharging process of the battery, which is beneficial to shorten the electrons. The transmission path, thereby improving the battery's charge and discharge rate and rate performance.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

Example 1 Preparation of composite material

(1) Put 10g of MXene into the reaction vessel, start the vacuum pump to make the vacuum degree of the reaction vessel reach 0.06MPa, then turn off the vacuum pump; then add 1L ferric nitrate solution with a molar concentration of 1mol/L to the reaction vessel at a rate of 40mL/min After stirring for 30 minutes at a rotation speed of 100 r/min in the reaction vessel, it was then placed at a temperature of 80° C. for drying for 6 hours to obtain MXene particles loaded with transition metal salts.

(2) Put the above-mentioned MXene particles loaded with transition metal salts in a rotary kiln, and in a nitrogen atmosphere with a flow rate of 100L/min and an environment of 800°C, pass ethane at a flow rate of 1L/min for 1h , To generate carbon nanotubes, and then switch to nitrogen gas, and naturally cool to room temperature, to obtain the first product deposited with carbon nanotubes.

(3) After immersing the first product in the mixed solution of nitric acid and hydrochloric acid for 4 hours, the washing, dehydrating and drying treatments can be carried out in sequence.

(4) Put the first product after the acid passivation treatment into a rotary furnace, and pass tetrachlorosilane at a flow rate of 6L/min under a nitrogen atmosphere with a flow of 120L/min and an environment of 500°C for 1.5 h, then switch to nitrogen gas and naturally cool to room temperature to obtain a second product deposited with nano-silicon.

(5) Put the second product into the rotary kiln, and in a nitrogen atmosphere with a flow rate of 50L/min and an environment of 700℃, pass acetylene at a flow rate of 1L/min for 0.5h, and then switch to nitrogen gas. , And naturally cooled to room temperature, followed by grading and sieving, the composite material with a particle size of 1-60μm can be obtained.

Example 2 Preparation of composite material

(1) Put 10g _{of MXene with a molecular formula of Ti 2} C into the reaction vessel, start the vacuum pump to make the vacuum of the reaction vessel reach 0.05MPa, and then turn off the vacuum pump; then add 1L of ferric nitrate solution with a molar concentration of 3mol/L to 30mL/L Min. speed was added to the reaction vessel, and after stirring at a rotation speed of 200r/min for 60 minutes, and then placed at a temperature of 120 ℃ for drying for 4 hours, to obtain MXene particles loaded with transition metal salts.

(2) Put the above-mentioned MXene particles loaded with transition metal salts in a rotary kiln, and pass methane at a flow rate of 5L/min under an argon atmosphere with a flow rate of 100L/min and an environment of 800°C for 1h , To generate carbon nanotubes, and then switch to argon gas, and naturally cool to room temperature, to obtain the first product deposited with carbon nanotubes.

(3) After immersing the first product in nitric acid for 6 hours, the washing, dehydrating and drying treatments can be carried out in sequence.

(4) Put the first product after the acid passivation treatment into the rotary kiln, and inject monomethyl trichloride at a flow rate of 1L/min under an argon atmosphere with a flow rate of 200L/min and an environment of 800°C Silane lasted for 4 hours, and then switched to argon gas, and naturally cooled to room temperature, to obtain a second product deposited with nano-silicon.

(5) Put the second product into the rotary kiln, and in an argon atmosphere with a flow rate of 100L/min and an environment of 800℃, pour methane at a flow rate of 1L/min for 2h, then switch to argon Then, the composite material with a particle size of 1-60μm can be obtained by performing classification and sieving treatments in sequence after natural cooling to room temperature.

Example 3 Preparation of composite material

(1) Put 10g _{of MXene with a molecular formula of Ti 4} C ₃ into the reaction vessel, start the vacuum pump to make the vacuum of the reaction vessel reach 0.06MPa, and then turn off the vacuum pump; then add 1L of nickel nitrate solution with a molar concentration of 2mol/L to 25mL It was added to the reaction vessel at a speed of 100 r/min, stirred at a rotation speed of 100 r/min for 60 min, and then dried at 100° C. for 4 h to obtain MXene particles loaded with transition metal salts.

(2) Put the above-mentioned MXene particles loaded with transition metal salts in a rotary kiln, and in a nitrogen atmosphere with a flow rate of 50L/min and an environment of 600°C, pass ethane at a flow rate of 1L/min for 2h , To generate carbon nanotubes, and then switch to nitrogen gas, and naturally cool to room temperature, to obtain the first product deposited with carbon nanotubes.

(4) Put the first product after the acid passivation treatment into a rotary furnace, and pass tetrachlorosilane at a flow rate of 3L/min under a nitrogen atmosphere with a flow rate of 150L/min and an environment of 600°C for 2h , And then switched to nitrogen gas, and naturally cooled to room temperature, to obtain the second product deposited with nano-silicon.

(5) Put the second product into the rotary kiln, and in a nitrogen atmosphere with a flow rate of 50L/min and an environment of 700℃, pass ethane at a flow rate of 0.5L/min for 0.5h, and then switch to pass Enter nitrogen gas, cool to room temperature naturally, and sequentially perform classification and sieving treatments to obtain a third product with a particle size of 1-60 μm and a carbon coating layer deposited.

(6) Mixing 10 g of the third product and 10 g of carbon material with a particle size of 1-60 μm to obtain the composite material; wherein the carbon material is artificial graphite.

Example 4 Preparation of composite material

(1) Put 10g _{of MXene with a molecular formula of Ti 4} C ₃ into the reaction vessel, start the vacuum pump to make the vacuum of the reaction vessel reach 0.06MPa, then close the vacuum pump; then add 1L of ferric nitrate solution with a molar concentration of 0.5mol/L according to 40mL/min was added to the reaction vessel and stirred at a rotation speed of 80r/min for 30min, and then placed at 80°C for drying for 6h to obtain MXene particles loaded with transition metal salts.

(2) Place the above-mentioned MXene particles loaded with transition metal salts in a rotary kiln, and pass them in at a flow rate of 10L/min under a mixed atmosphere of argon and nitrogen at a flow rate of 100L/min and an environment of 800°C Ethane was used for 3 hours to generate carbon nanotubes, and then switched to argon and nitrogen gas, and naturally cooled to room temperature to obtain the first product deposited with carbon nanotubes.

(3) After immersing the first product in nitric acid for 4 hours, the washing, dehydrating and drying treatments can be carried out in sequence.

(4) Put the first product after the acid passivation treatment into a rotary kiln, and in a mixed atmosphere of argon and nitrogen at a flow rate of 200L/min and an environment of 500°C, pass it through at a flow rate of 2L/min. Chlorosilane lasted for 3.5 hours, then switched to argon and nitrogen gas, and naturally cooled to room temperature to obtain a second product deposited with nano-silicon.

(5) Put the second product into the rotary kiln, and in a mixed atmosphere of argon and nitrogen with a flow of 100L/min and an environment of 800℃, pour methane at a flow of 1L/min for 0.5h, then Switching to argon and nitrogen gas, and natural cooling to room temperature, followed by classification and sieving treatment, to obtain a third product with a particle size of 1-60 μm and a carbon coating layer deposited.

(6) Mixing 10 g of the third product and 6 g of carbon material with a particle size of 1-60 μm to obtain the composite material; wherein the carbon material is artificial graphite.

Example 5 Preparation of composite material

(1) Put 10g _{of MXene with a molecular formula of Ti 4} C ₃ into the reaction vessel, start the vacuum pump to make the vacuum of the reaction vessel reach 0.06MPa, and then close the vacuum pump; then add 1L of iron nitrate solution with a molar concentration of 4mol/L to 10mL It was added to the reaction vessel at a speed of 200 r/min and stirred for 60 min at a rotation speed of 200 r/min, and then dried at a temperature of 100° C. for 8 h to obtain MXene particles loaded with transition metal salts.

(2) Place the above-mentioned MXene particles loaded with transition metal salts in a rotary furnace, and pass ethane at a flow rate of 1L/min under a nitrogen atmosphere with a flow rate of 200L/min and an environment of 800°C for 1h , To generate carbon nanotubes, and then switch to nitrogen gas, and naturally cool to room temperature, to obtain the first product deposited with carbon nanotubes.

(3) After the first product is soaked in sulfuric acid for 8 hours, washing, dehydrating and drying are carried out in sequence.

(4) Put the first product after the acid passivation treatment into a rotary furnace, and pass tetrachlorosilane at a flow rate of 2L/min under a nitrogen atmosphere with a flow of 200L/min and an environment of 600°C for 1h , And then switched to nitrogen gas, and naturally cooled to room temperature, to obtain the second product deposited with nano-silicon.

(5) Put the second product into the rotary kiln, and in a nitrogen atmosphere with a flow rate of 100L/min and an environment of 700°C, ethane is introduced at a flow rate of 1L/min for 0.5h, and then switched to Nitrogen gas, and natural cooling to room temperature, followed by classification and sieving treatment, to obtain a third product with a particle size of 1-60 μm and a carbon coating layer deposited.

(6) Mixing 10 g of the third product and 50 g of a carbon material with a particle size of 1-60 μm to obtain the composite material; wherein the carbon material is natural graphite.

Example 6 Preparation of composite material

The preparation method of the composite material of this embodiment is basically the same as the preparation method provided in Example 5, except that: in step (1), cobalt chloride solution is used instead of ferric nitrate solution; in step (2), a mixture of ethylene and propane is used Instead of ethane; in step (4), use a mixture of monochlorosilane and dichlorosilane to replace tetrachlorosilane; in step (5), use a mixture of propane and n-butane instead of ethane; in step (6), use mesophase carbon A mixture of microspheres and soft carbon replaces natural graphite.

Example 7 Preparation of composite material

The preparation method of the composite material in this embodiment is basically the same as the preparation method provided in Example 5, except that: in step (1), a mixed solution of chromium sulfate, ferric nitrate and ferric oxalate is used instead of ferric nitrate solution; step (2) In step (4), use a mixture of trichlorosilane, tetrachlorosilane and monomethyltrichlorosilane to replace tetrachlorosilane; in step (5), use ethane, A mixture of propane and n-butane replaces ethane; in step (6), a mixture of mesophase carbon microspheres, soft carbon and hard carbon is used to replace natural graphite.

Example 8 Preparation of composite material

The preparation method of the composite material of this embodiment is basically the same as the preparation method provided in Example 5, except that: in step (1), a mixed solution of ferric nitrate and ferric oxalate is used instead of ferric nitrate solution; in step (2), A mixture of acetylene and ethylene is used instead of ethane; in step (4), a mixture of dimethyltrichlorosilane and trimethylmonochlorosilane is used instead of tetrachlorosilane; in step (5), a mixture of methane and ethane is used instead Ethane; In step (6), mesophase carbon microspheres are used to replace natural graphite.

Example 9 Preparation of electrode

(1) Place the composite material provided in Example 1 with polyvinylidene fluoride and conductive graphite in a high-speed disperser for stirring and mixing to obtain an active slurry; wherein the mass ratio of the composite material, polyvinylidene fluoride and conductive graphite is 90:6:4.

(2) The above-mentioned active slurry is coated on the aluminum foil to obtain the electrode. The electrode can be used as the negative electrode of a lithium ion battery.

Example 10 Preparation of electrode

(1) Place the composite material provided in Example 2 with polyvinylidene fluoride and conductive graphite in a high-speed disperser for stirring and mixing to obtain an active slurry; wherein the mass ratio of the composite material, polyvinylidene fluoride and conductive graphite is 95:4:1.

Example 11 Preparation of electrode

(1) Place the composite material provided in Example 3 with polyvinylidene fluoride and conductive graphite in a high-speed disperser for stirring and mixing to obtain an active slurry; wherein the mass ratio of the composite material, polyvinylidene fluoride and conductive graphite is 93:5:2.

Example 12 Preparation of electrodes

(1) The composite material provided in Example 4, polyvinylidene fluoride and conductive graphite are placed in a high-speed disperser for stirring and mixing to obtain an active slurry; wherein the mass ratio of the composite material, polyvinylidene fluoride and conductive graphite is 93:5:2.

Example 13 Preparation of electrode

(1) Place the composite material provided in Example 5 with polyvinylidene fluoride and conductive graphite in a high-speed disperser for stirring and mixing to obtain an active slurry; wherein the mass ratio of the composite material, polyvinylidene fluoride and conductive graphite is 93:5:2.

The electrodes prepared in the foregoing Examples 9-13 were used as negative electrodes and assembled with lithium positive electrodes to form 5 sets of lithium ion batteries; the first discharge capacity, first coulomb efficiency and cycle of the 5 sets of lithium ion batteries at different rates Performance such as capacity retention rate was tested, and the test results are shown in Table 1.

Table 1

It can be seen from Table 1 above that the use of the composite material prepared by the present invention as the negative electrode material of a lithium ion battery can improve the charge and discharge rate, rate performance and cycle life of the battery.

Those skilled in the art understand that the protection scope of the present invention is not limited to the above embodiments. Based on the disclosure of the present invention, those skilled in the art will recognize that many changes and modifications to the above-mentioned embodiments without departing from the technical features and scope of the technical solutions of the present invention belong to the present invention. protected range.

Claims

A method for preparing a composite material is characterized in that it comprises the following steps:

(1) Under vacuum conditions, mix MXene with the transition metal salt solution, and then sequentially perform filtration and drying treatments to obtain MXene loaded with the transition metal salt;

(2) Under a protective atmosphere, high-temperature chemical vapor deposition of MXene loaded with transition metal salts and a carbon source is carried out to obtain the first product deposited with carbon nanotubes;

(3) Treat the first product with acid;

(4) Under a protective atmosphere, subject the acid-treated first product and the silicon source to high-temperature chemical vapor deposition to obtain a second product deposited with nano-silicon;

(5) Under a protective atmosphere, the second product and the carbon source are subjected to high-temperature chemical vapor deposition to form a carbon coating layer to obtain the composite material.
The method for preparing a composite material according to claim 1, wherein the transition metal salt solution is a nitrate solution, a chloride solution, a sulfate solution, and an oxalate solution of transition metals. One or more; the transition metal is one or more of iron, cobalt, nickel and chromium.
The method for preparing a composite material according to claim 1, wherein the molecular formula of the MXene is Ma +1 X a ; wherein M is one of Ti, Zr, Cr, Mo, V, and Ta One or more; X is C or N.
The method for preparing a composite material according to claim 1, wherein MXene is one of Ti 3 C 2 , Ti 2 C and Ti 4 C 3 .
The method for preparing a composite material according to claim 1, wherein in the steps (2) and (5), the carbon sources are each independently acetylene, ethylene, methane, ethane, propane and n-butane. One or more of.
The method for preparing a composite material according to claim 1, wherein in the step (4), the silicon source is monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, monomethyl One or more of trichlorosilane, dimethyltrichlorosilane and trimethylmonochlorosilane.
The method for preparing a composite material according to claim 1, characterized in that, in the step (3), the method of treating with acid is: soaking the first product in acid, and then sequentially cleaning , Dehydration and drying treatment; the acid is an inorganic acid.
The method for preparing a composite material according to claim 1, wherein the step (5) comprises the following steps:

Under a protective atmosphere, subjecting the second product and the carbon source to high-temperature chemical vapor deposition to obtain a third product with a carbon coating layer;

The third product is mixed with a carbon material to obtain the composite material; the carbon material is one or more of natural graphite, artificial graphite, mesophase carbon microspheres, soft carbon and hard carbon, and The particle size of the carbon material is preferably 1 to 60 μm, and the mass of the carbon material is preferably 1 to 90% of the mass of the entire composite material.
A composite material prepared by the preparation method according to any one of claims 1-8.
An electrode comprising the composite material according to claim 9.