阅读说明：本技术 一种高分散性硅碳负极锂离子电池电极材料的制备方法及应用 (Preparation method and application of high-dispersity silicon-carbon negative electrode lithium ion battery electrode material ) 是由 孙林 刘宴秀 吴俊� 张磊 姜瑞雨 于 2021-06-22 设计创作，主要内容包括：本发明公开了一种高分散性硅碳负极锂离子电池电极材料的制备方法及应用,按质量份数配比1:1-1:5的Zintl相化合物和特定的有机物至于反应瓶中,利用双排管操作线将反应瓶中置换成惰性气氛；保持温度在50-200℃反应10-48小时；待温度降到室温后,将得到的产物用N,N二甲基甲酰胺和二氯甲烷分别洗涤数次,真空60℃烘干；将烘干后的产物置于水平放置的管式炉中,通入氩气气氛,于500-1000℃热处理0.5-10小时,冷却至室温后即得高分散性硅碳复合材料；高分散性硅碳复合材料与导电石墨、CMC粘合剂按质量份数配比8:1:1混合调成浆料,然后均匀涂覆在铜箔集流体上,真空干燥后切成直径13-15毫米的圆片制得高分散性硅碳负极锂离子电池电极材料。(The invention discloses a preparation method and application of a high-dispersity silicon-carbon negative electrode lithium ion battery electrode material, wherein a Zintl phase compound and a specific organic matter are placed in a reaction bottle according to the mass part ratio of 1:1-1:5, and the reaction bottle is replaced by an inert atmosphere by using a double-row pipe operating line; keeping the temperature at 50-200 ℃ and reacting for 10-48 hours; after the temperature is reduced to room temperature, the obtained product is respectively washed for a plurality of times by N, N-dimethylformamide and dichloromethane, and is dried at the temperature of 60 ℃ in vacuum; placing the dried product in a horizontally placed tube furnace, introducing argon atmosphere, carrying out heat treatment at 500-1000 ℃ for 0.5-10 hours, and cooling to room temperature to obtain the high-dispersity silicon-carbon composite material; the high-dispersity silicon-carbon composite material, conductive graphite and a CMC binder are mixed and prepared into slurry according to the mass ratio of 8:1:1, then the slurry is uniformly coated on a copper foil current collector, and the copper foil current collector is dried in vacuum and then cut into wafers with the diameter of 13-15 mm to prepare the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material.)

1. A preparation method of a high-dispersity silicon-carbon negative electrode lithium ion battery electrode material is characterized by comprising the following steps:

the first step is as follows: placing Zintl phase compounds and organic matters in a reaction bottle according to the mass part ratio of 1:1-1:5, and replacing the reaction bottle with inert atmosphere by using a double-row pipe operating line; keeping the temperature at 50-200 ℃ and reacting for 10-48 hours;

the second step is that: after the temperature is reduced to room temperature, washing the obtained product with N, N-dimethylformamide for 3-5 times, then washing with dichloromethane for 1-2 times, and transferring the product to a vacuum drying oven for vacuum drying at 60 ℃;

the third step: placing the dried product in a horizontally placed tube furnace, introducing argon atmosphere, carrying out heat treatment at 500-1000 ℃ for 0.5-10 hours, and cooling to room temperature to obtain the high-dispersity silicon-carbon composite material;

the fourth step: the high-dispersity silicon-carbon composite material, conductive graphite and a CMC binder are mixed according to the mass ratio of 8:1:1, are prepared into slurry, are uniformly coated on a copper foil current collector, and are cut into round pieces with the diameter of 13-15 mm after being dried in vacuum, so that the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material is prepared.

2. The preparation method of the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material according to claim 1 is characterized by comprising the following steps of: in the first step, the Zintl compound is one or more of calcium silicide, magnesium silicide, sodium silicide, potassium silicide and potassium silicide.

3. The preparation method of the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material according to claim 1 is characterized by comprising the following steps of: in the first step, the organic matter is one or more of benzylamine, bromobenzyl, p-bromotoluene, p-nitrobenzyl bromide and benzyl chloride.

4. The preparation method of the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material according to claim 1 is characterized by comprising the following steps of: in the first step, the dosage of the Zintl compound and the organic matter is 1-3 parts of the Zintl compound and 1-10 parts of the organic matter according to the mass part ratio.

5. The preparation method of the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material according to claim 1 is characterized by comprising the following steps of: in the second step, the N, N-dimethylformamide and the dichloromethane are respectively washed for 3-5 times by using the N, N-dimethylformamide and then washed for 1-2 times by using the dichloromethane.

6. The application of the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material prepared by the preparation method of claim 1 in a lithium battery.

7. The application of the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material in a lithium battery as claimed in claim 6 is characterized by comprising the following steps:

the first step is as follows: with metal Li as a counter electrode, 1M concentration LiPF₆The mixed solvent (EC: DMC =1:1 volume ratio) of the (C) is electrolyte, the diaphragm is a polypropylene microporous membrane, and the button simulated battery (CR 2025) is assembled in an argon-protected glove box with water and oxygen content lower than 1 ppm;

the second step is that: the assembled simulated battery is subjected to constant-current charge and discharge test on a Xinwei tester, the charge and discharge voltage window is 0.01-3V, and the charge and discharge current densityIs 0.1A g^-1The first discharge specific capacity is more than 2000 mA h g^-1The first charging specific capacity is more than 1800 mA h g^-1。

Technical Field

The invention relates to the technical field of energy material synthesis, in particular to a preparation method and application of a high-dispersity silicon-carbon negative electrode lithium ion battery electrode material.

Background

Nano-silicon (Si) materials are considered to be the most promising lithium ion battery negative electrode materials to replace current commercial graphite electrodes. The theoretical capacity of Si can reach 4200 mA h g^-1Is far larger than that of a commercial graphite cathode (theoretical capacity-370 mA h g)^-1). However, in the process of lithium intercalation and deintercalation, the volume change of the Si material reaches 300-400%, which easily causes pulverization of the active material, electrode disconnection and formation of an unstable Solid Electrolyte Interface (SEI) film, thereby greatly shortening the service life of the battery. In addition, the poor conductivity of the silicon material further limits the performance enhancement. Therefore, a single Si material cannot satisfy the use requirements of a high-capacity negative electrode. At present, an important idea is to compound the nano-Si material with other conductive matrixes so as to improve the electrochemical performance of the silicon material. Among them, the carbon material is the first choice to be compounded with the Si material due to advantages of good conductivity, ductility, low price, strong workability, and the like. However, in the current research, the compounding of carbon is usually realized by chemical coating or physical mixing, and the carbon is difficult to realize complete uniform distribution in the composite material, so that the cycle stability is reduced in the charging and discharging process, and therefore, how to construct uniform coating of the carbon material with low dimensionality is one of the key scientific problems which are not solved at present. Using easily activatable Zintl compounds, e.g. CaSi₂、Mg₂Si and the like are effective as raw materials for preparing the low-dimensional silicon-carbon composite material. Although there are some reports on the synthesis of highly dispersed silicon-carbon composite materials (such as Au precursor, a highly dispersed silicon-carbon solid solution, its preparation method and application, application No. 201910645744.1, using silicon nano material as dispersoid, carbon as dispersion medium, and silicon coatingA continuous carbon layer is coated or embedded in a continuous carbon phase. A silicon-carbon solid solution is formed by a high-temperature anodic polarization method, and the electrochemical performance is excellent).

Chinese patent CN201910645744.1 discloses a highly dispersed silicon-carbon solid solution, its preparation method and application, using silicon as dispersoid, carbon as dispersion medium, silicon being coated or buried in continuous carbon phase by continuous carbon layer, the size of silicon at least in a certain dimension being less than 80 nm, the mass percentage of silicon in the highly dispersed silicon-carbon solid solution being 5% -90%. However, the prior art is slightly deficient in consideration of the requirement of harsh reaction conditions, such as the involvement of molten salt electrolyte and high-temperature anodic oxidation, which limits the industrialization of the method.

Disclosure of Invention

Solves the technical problem

The invention discloses a preparation method and application of a high-dispersity silicon-carbon cathode lithium ion battery electrode material, which are beneficial to solving the problems that harsh reaction conditions are usually involved, multi-step reactions are mostly involved, the yield is low and the like in the prior art. Provides a convenient method for preparing high-dispersity silicon-carbon composite material by only using Zintl compound which is easy to activate, such as CaSi₂、Mg₂Si, NaSi and the like and specific organic matters are heated at a certain temperature in a sealed environment, and organic modification groups can be grafted on the surface of Si in a form of forming Si-C bonds. And further carrying out pyrolysis in an inert atmosphere to obtain the high-dispersity silicon-carbon composite material. The composite material is used as a lithium battery cathode, shows excellent electrochemical performance, and has a first-circle specific discharge capacity of more than 2000 mA h g^-1. The method has the advantages of easy amplification and convenient operation, and is expected to be used for industrially preparing the high-performance silicon-carbon cathode material.

Technical scheme

The invention provides a preparation method of a high-dispersity silicon-carbon negative electrode lithium ion battery electrode material, which specifically comprises the following steps:

the first step is as follows: placing Zintl phase compounds and organic matters in a reaction bottle according to the mass part ratio of 1:1-1:5, and replacing the reaction bottle with inert atmosphere by using a double-row pipe operating line; keeping the temperature of the reaction flask at 50-200 ℃ to react for 10-48 hours;

the second step is that: after the temperature is reduced to room temperature, washing the obtained product with N, N-dimethylformamide for 3-5 times, then washing with dichloromethane for 1-2 times, transferring the collected sample to a vacuum drying oven, and drying at 60 ℃ in vacuum;

the third step: placing the dried product in a horizontally placed tube furnace, introducing argon atmosphere, carrying out heat treatment at 500-1000 ℃ for 0.5-10 hours, and cooling to room temperature to obtain the high-dispersity silicon-carbon composite material;

the fourth step: the high-dispersity silicon-carbon composite material, conductive graphite and a CMC binder are mixed and prepared into slurry according to the mass ratio of 8:1:1, then the slurry is uniformly coated on a copper foil current collector, and the copper foil current collector is dried in vacuum and then cut into wafers with the diameter of 13-15 mm to prepare the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material.

Preferably, the Zintl compound in the first step is one or more of calcium silicide, magnesium silicide, sodium silicide, potassium silicide and potassium silicide.

Preferably, the organic matter in the first step is one or more of benzylamine, bromobenzyl, p-bromotoluene, p-nitrobenzyl bromide and benzyl chloride.

Preferably, the amount of the Zintl compound and the organic matter in the first step is 1 part by weight of the Zintl compound and 1 part by weight of the organic matter.

Preferably, the specific steps of the N, N-dimethylformamide and the dichloromethane in the second step are that the N, N-dimethylformamide is firstly used for washing 3 times, and then the dichloromethane is used for washing 2 times.

The application also discloses an application of the high-dispersity silicon-carbon negative lithium ion battery electrode material prepared by the preparation method of the high-dispersity silicon-carbon negative lithium ion battery electrode material in a lithium battery.

Preferably, the application of the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material in a lithium battery comprises the following steps:

the first step is as follows: with metal Li as a counter electrode, 1M concentration LiPF₆Mixed solvent of (2)The button simulation battery is assembled in an argon-protected glove box with water and oxygen contents lower than 1ppm by taking DMC =1:1 as electrolyte and a polypropylene microporous membrane as a diaphragm; firstly, mixing a silicon-carbon active material and a sodium carboxymethylcellulose (CMC) adhesive in water to prepare slurry with certain viscosity, then hanging the slurry on a copper foil current collector by coating, and drying the copper foil current collector in a vacuum drying oven. Then cutting the substrate into a wafer with the diameter of 13-15 mm for assembling the simulation battery;

the second step is that: the assembled simulated battery is subjected to constant-current charge and discharge test on a Xinwei tester, the charge and discharge voltage window is 0.01-3V, and the charge and discharge current density is 0.1A g^-1The obtained first-circle specific discharge capacity is more than 2000 mA h g^-1The charging specific capacity of the first loop is more than 1800 mA h g^-1。

Has the advantages that:

compared with the prior art, the preparation method and the application of the high-dispersity silicon-carbon negative electrode lithium ion battery electrode material provided by the invention have the following advantages:

1. provides a convenient method for preparing high-dispersity silicon-carbon composite material by only using Zintl compound which is easy to activate, such as CaSi₂、Mg₂Si, NaSi and the like and specific organic matters are heated at a certain temperature in a sealed environment, and organic modification groups can be grafted on the surface of Si in a form of forming Si-C bonds; further carrying out pyrolysis in an inert atmosphere to obtain the high-dispersity silicon-carbon composite material;

2. the composite material is used as a lithium battery cathode, shows excellent electrochemical performance, and has a first-circle specific discharge capacity of more than 2000 mA h g^-1；

3. The method has the advantages of easy amplification and convenient operation, and is expected to be used for industrial preparation of high-performance silicon-carbon cathode materials;

4. the assembled simulated battery is subjected to constant-current charge and discharge test on a Xinwei tester, the charge and discharge voltage window is 0.01-3V, and the charge and discharge current density is 0.1A g^-1The obtained first charge-discharge curve is shown in figure 1;

5. the discharge capacity of the first ring reaches 2200 mA h g^-1First turn charge capacity up to1820 mA h g^-1The first turn coulomb efficiency reaches 83%;

drawings

Fig. 1 is a graph of capacity-voltage curves of the first cycle of charge and discharge of the high-dispersibility silicon-carbon electrode of the present application.

FIG. 2 is an infrared spectrogram of a butyl-modified Si nanosheet, and the butyl-modified Si nanosheet shows strong fluorescence under the irradiation of ultraviolet light with a wavelength of 365 nm.

In FIG. 3, (a), (b), and (c) are CaSi₂The optical photo of the benzyl modified two-dimensional nano Si sheet and the thermally treated high-dispersity Si/C composite material shows that the volume of a sample in a graph b is obviously larger than that in a graph a, which shows that the reaction can react with CaSi₂The sheets of (a) are opened.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The features and properties of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

Example 1

The embodiment provides a preparation method and application of a high-dispersity silicon-carbon negative electrode lithium ion battery electrode material, which comprises the following specific steps:

the first step is as follows: placing calcium silicide and benzylamine with the mass fraction ratio of 1:1 into a reaction bottle, replacing the reaction bottle with inert atmosphere by using a double-row pipe operating line, and keeping the temperature of the reaction bottle at 120 ℃ for reaction for 24 hours;

the second step is that: after the temperature is reduced to room temperature, washing the obtained product with N, N-dimethylformamide for 3 times, then washing with dichloromethane for 2 times, transferring the washed sample into a vacuum drying oven, and drying at 60 ℃ in vacuum;

the third step: placing the dried product in a horizontally placed tubular furnace, introducing argon atmosphere, carrying out heat treatment at 700 ℃ for 5 hours, and cooling to room temperature to obtain the high-dispersity silicon-carbon composite material;

the fourth step: the obtained material is mixed with conductive graphite and a CMC adhesive (the mass ratio is 8:1: 1) to prepare slurry with certain viscosity, then the slurry is uniformly coated on a copper foil current collector, and the copper foil current collector is cut into a wafer with the diameter of 14 mm after vacuum drying;

the fifth step: the CR2025 button battery case was used as a simulated battery. With metal Li as a counter electrode, 1M concentration LiPF₆The mixed solvent (EC: DMC =1:1 volume ratio) of the battery is electrolyte, the diaphragm is a polypropylene microporous membrane, and the battery is assembled into a simulation battery in an argon-protected glove box with water and oxygen content lower than 1 ppm;

and a sixth step: the assembled simulated battery is subjected to constant-current charge and discharge test on a Xinwei tester, the charge and discharge voltage window is 0.01-3V, and the charge and discharge current density is 0.1A g^-1；

The seventh step: the first circle discharge specific capacity of the battery is not lower than 2000 mA h g^-1。

Example 2

The embodiment provides a preparation method and application of a high-dispersity silicon-carbon negative electrode lithium ion battery electrode material, which comprises the following specific steps:

the first step is as follows: putting Zintl compound magnesium silicide and benzylamine with the mass fraction ratio of 1:1 into a reaction bottle, and replacing the reaction bottle with inert atmosphere by using a double-row pipe operating line. Keeping the temperature of the reaction flask at 120 ℃ for reaction for 24 hours; (step two, after the temperature is reduced to room temperature, step two, the obtained product is washed by N, N dimethylformamide for 3 times and then by dichloromethane for 2 times, and the washed sample is transferred to a vacuum drying oven and dried at the temperature of 60 ℃ in vacuum;

the third step: placing the dried product in a horizontally placed tubular furnace, introducing argon atmosphere, carrying out heat treatment at 700 ℃ for 5 hours, and cooling to room temperature to obtain the high-dispersity silicon-carbon composite material;

the fourth step: the obtained material is mixed with conductive graphite and a CMC adhesive (the mass ratio is 8:1: 1) to prepare slurry with certain viscosity, then the slurry is uniformly coated on a copper foil current collector, and the copper foil current collector is cut into a wafer with the diameter of 14 mm after vacuum drying;

the fifth step: the CR2025 button battery case was used as a simulated battery. With metal Li as a counter electrode, 1M concentration LiPF₆The mixed solvent (EC: DMC =1:1 volume ratio) of the battery is electrolyte, the diaphragm is a polypropylene microporous membrane, and the battery is assembled into a simulation battery in an argon-protected glove box with water and oxygen content lower than 1 ppm;

and a sixth step: the assembled simulated battery is subjected to constant-current charge and discharge test on a Xinwei tester, the charge and discharge voltage window is 0.01-3V, and the charge and discharge current density is 0.1A g^-1；

The seventh step: the first circle discharge specific capacity of the battery is not lower than 2000 mA h g^-1。

Example 3

The embodiment provides a preparation method and application of a high-dispersity silicon-carbon negative electrode lithium ion battery electrode material, which comprises the following specific steps:

the first step is as follows: putting calcium silicide and benzyl chloride organic matters with the mass fraction ratio of 1:1 into a reaction bottle, replacing the reaction bottle with inert atmosphere by using a double-row pipe operating line, and keeping the temperature of the reaction bottle at 120 ℃ for reacting for 24 hours;

the second step is that: after the temperature is reduced to room temperature, washing the obtained product with N, N-dimethylformamide for 3 times, then washing with dichloromethane for 2 times, transferring the washed sample into a vacuum drying oven, and drying at 60 ℃ in vacuum;

the third step: placing the dried product in a horizontally placed tubular furnace, introducing argon atmosphere, carrying out heat treatment at 700 ℃ for 5 hours, and cooling to room temperature to obtain the high-dispersity silicon-carbon composite material;

the fourth step: the obtained material is mixed with conductive graphite and a CMC adhesive (the mass ratio is 8:1: 1) to prepare slurry with certain viscosity, then the slurry is uniformly coated on a copper foil current collector, and the copper foil current collector is cut into a wafer with the diameter of 14 mm after vacuum drying;

the fifth step: the CR2025 button battery case was used as a simulated battery. With metal Li as a counter electrode, 1M concentration LiPF₆The mixed solvent (EC: DMC =1:1 volume ratio) of (A) is an electrolyte, and a separatorThe battery is a polypropylene microporous membrane, and is assembled into a simulated battery in an argon-protected glove box with water and oxygen content lower than 1 ppm;

and a sixth step: the assembled simulated battery is subjected to constant-current charge and discharge test on a Xinwei tester, the charge and discharge voltage window is 0.01-3V, and the charge and discharge current density is 0.1A g^-1；

The seventh step: the first circle discharge specific capacity of the battery is not lower than 2000 mA h g^-1。

Example 4

The embodiment provides a preparation method and application of a high-dispersity silicon-carbon negative electrode lithium ion battery electrode material, which comprises the following specific steps:

the first step is as follows: putting calcium silicide and benzyl chloride organic matters with the mass fraction ratio of 1:3 into a reaction bottle, replacing the reaction bottle with inert atmosphere by using a double-row pipe operating line, and keeping the temperature of the reaction bottle at 150 ℃ for reacting for 24 hours;

the second step is that: after the temperature is reduced to room temperature, washing the obtained product with N, N-dimethylformamide for 3 times, then washing with dichloromethane for 2 times, transferring the washed sample into a vacuum drying oven, and drying at 60 ℃ in vacuum;

the third step: placing the dried product in a horizontally placed tubular furnace, introducing argon atmosphere, carrying out heat treatment at 700 ℃ for 5 hours, and cooling to room temperature to obtain the high-dispersity silicon-carbon composite material;

the fourth step: the obtained material is mixed with conductive graphite and a CMC adhesive (the mass ratio is 8:1: 1) to prepare slurry with certain viscosity, then the slurry is uniformly coated on a copper foil current collector, and the copper foil current collector is cut into a wafer with the diameter of 14 mm after vacuum drying;

the fifth step: the CR2025 button battery case was used as a simulated battery. With metal Li as a counter electrode, 1M concentration LiPF₆The mixed solvent (EC: DMC =1:1 volume ratio) of the battery is electrolyte, the diaphragm is a polypropylene microporous membrane, and the battery is assembled into a simulation battery in an argon-protected glove box with water and oxygen content lower than 1 ppm;

and a sixth step: the assembled simulated battery is subjected to constant-current charge and discharge test on a Xinwei tester, the charge and discharge voltage window is 0.01-3V, and the charge and discharge current densityIs 0.1A g^-1；

The seventh step: the first circle discharge specific capacity of the battery is not lower than 2000 mA h g^-1The charging specific capacity of the first circle is not less than 1800 mA h g^-1。

The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.