阅读说明：本技术 纳米非晶C-Si-C复合材料及其制造方法和制造装置 (Nano amorphous C-Si-C composite material and manufacturing method and manufacturing device thereof ) 是由 喻维杰 张锡强 赵常 杜玮 于 2019-10-17 设计创作，主要内容包括：本发明公开了纳米非晶C-Si-C复合材料及其制造方法和制造装置,制造方法包括以下步骤：利用载带气将有机炔类气体带入第一裂解区,在催化剂作用下低温裂解得到纳米非晶炭黑后进入第二裂解区；利用载带气将硅烷气体带入第二裂解区,低温裂解得到以纳米非晶炭黑为晶核的纳米非晶硅颗粒后进入第三裂解区；利用载带气将有机炔类气体带入第三裂解区,在催化剂作用下低温裂解得到炭黑并包覆在硅颗粒的表面,气固分离后得到纳米非晶C-Si-C复合材料。纳米非晶C-Si-C复合材料采用上述制造方法制得。纳米非晶C-Si-C复合材料的制造装置包括气相裂解单元、气固分离单元和尾气处理单元,本发明能够连续化生产并且可作为锂离子电池的理想负极材料。(The invention discloses a nano amorphous C-Si-C composite material and a manufacturing method and a manufacturing device thereof, wherein the manufacturing method comprises the following steps: carrying organic acetylene gas into a first cracking zone by utilizing carrier gas, cracking at low temperature under the action of a catalyst to obtain nano amorphous carbon black, and then entering a second cracking zone; carrying silane gas into a second cracking zone by utilizing carrier gas, cracking at low temperature to obtain nano amorphous silicon particles taking nano amorphous carbon black as crystal nucleus, and then entering a third cracking zone; carrying organic acetylene gas into a third cracking zone by utilizing carrier gas, cracking at low temperature under the action of a catalyst to obtain carbon black, coating the carbon black on the surface of silicon particles, and carrying out gas-solid separation to obtain the nano amorphous C-Si-C composite material. The nano amorphous C-Si-C composite material is prepared by the preparation method. The device for manufacturing the nano amorphous C-Si-C composite material comprises a gas phase cracking unit, a gas-solid separation unit and a tail gas treatment unit, can be continuously produced, and can be used as an ideal cathode material of a lithium ion battery.)

1. A method for manufacturing a nano amorphous C-Si-C composite material, characterized in that the method adopts a gas phase cracking method and comprises the following steps:

A. carrying organic acetylene gas into a first cracking zone by utilizing carrier gas, cracking at low temperature under the action of a catalyst to obtain nano amorphous carbon black, and then entering a second cracking zone;

B. carrying silane gas into a second cracking zone by utilizing carrier gas, cracking at low temperature to obtain nano amorphous silicon particles taking the nano amorphous carbon black as crystal nucleus, and then entering a third cracking zone;

C. carrying organic acetylene gas into a third cracking zone by utilizing carrier gas, cracking at low temperature under the action of a catalyst to obtain carbon black, coating the carbon black on the surface of the nano amorphous silicon particles to form nano amorphous C-Si-C composite particles, and then carrying out gas-solid separation to obtain the nano amorphous C-Si-C composite material;

wherein the first cracking zone, the second cracking zone and the third cracking zone are arranged in sequence along the material flowing direction.

2. The method for producing a nano amorphous C-Si-C composite material according to claim 1, wherein the cracking temperature of the first cracking zone and the third cracking zone is 400 to 750 ℃, and the cracking temperature of the second cracking zone is 480 to 600 ℃.

3. The method for producing a nano amorphous C-Si-C composite material according to claim 1, wherein the organic acetylene-based gas is one or more of acetylene, propyne, butyne-1 and butyne-2.

4. The method of manufacturing a nano amorphous C-Si-C composite material according to claim 1, wherein the silane gas is one or more of silane, silane or propane.

5. The method of claim 1, wherein the catalyst is a composite catalyst of metal and oxide, and is one or more of Cu, Co, Ni, Mo, Ir, Pt and Pd and Al₂O₃、MgO、TiO₂One or more of the above.

6. The method of manufacturing a nano-amorphous C-Si-C composite according to claim 1, wherein the carrier gas is high purity nitrogen or argon having a purity of more than 99.999%.

7. A nano amorphous C-Si-C composite material, characterized by being produced by the method for producing a nano amorphous C-Si-C composite material according to any one of claims 1 to 6.

8. The nano-amorphous C-Si-C composite according to claim 7, wherein the ratio of Si: the molar ratio of C is 5: 95-96: 4, the microscopic particle size of the nano amorphous silicon particles is 5-25 nm, the microscopic particle size of the nano amorphous carbon black inside is 6-30 nm, the thickness of the carbon layer coated outside is 50-150 nm, and the particle size of the nano amorphous C-Si-C composite particles is 2-15 um.

9. The apparatus for manufacturing nano amorphous C-Si-C composite material according to claim 7, wherein the apparatus comprises a gas phase cracking unit, a gas-solid separation unit and a tail gas treatment unit, wherein the gas phase cracking unit has a first material inlet at the bottom and a material outlet at the top and comprises a first cracking zone, a second cracking zone and a third cracking zone which are sequentially arranged and communicated along the material flow direction, the second material inlet and the third material inlet are further arranged at the bottom of the second cracking zone and the third cracking zone, and a multi-layer composite catalyst net perpendicular to the material flow direction is arranged in the first cracking zone and the third cracking zone.

Technical Field

The invention belongs to the technical field of lithium batteries, and particularly relates to a nano amorphous C-Si-C composite negative electrode material, and a manufacturing method and a manufacturing device thereof.

Background

According to the current technology, in order to achieve the aim of 300Wh/kg of cell energy density, a battery positive electrode material needs to adopt a high-capacity nickel-cobalt-manganese NCM811 or nickel-cobalt-aluminum NCA positive electrode material, and a negative electrode material needs to adopt a high-capacity silicon-carbon negative electrode, which is a successful technical route of Tesla company in America of the global benchmarking enterprise of the electric automobile at present.

The silicon negative electrode material has ultrahigh theoretical capacity up to 4200mAh/g, the silicon is particularly abundant in natural reserves, low in price, low in potential to metal lithium and low in possibility of surface lithium precipitation when used as a negative electrode, so that the safety performance of the battery is superior to that of a lithium battery with a graphite negative electrode when used as the negative electrode material. Based on the above advantages, silicon is recognized as the most promising negative electrode material for new high-capacity lithium ion batteries. In the last decade, materials scientists in various countries have made intensive research on silicon negative electrode materials.

As a negative electrode material, after crystalline silicon is inserted with lithium, the volume of the crystalline silicon expands by 4 times, and after lithium is removed, the volume of the crystalline silicon contracts violently, so that after the battery is cycled, the silicon particles are pulverized seriously, a new interface is generated, and an SEI film is broken continuously to regenerate and quickly consume lithium in an electrolyte. This results in a rapid decay of the battery capacity. In addition, the conductivity of the silicon material is only 6.7 multiplied by 10^-4S/cm, the conductivity is poor, which also severely affects the electrochemical performance of the cell. The practical application of the silicon negative electrode material in the field of lithium ion batteries is greatly hindered by the defects. The present practiceThe silicon is in the form of silicon monoxide, the capacity of the SiO is about 1500mAh/g, the capacity of the SiO is lower after the SiO is compounded with carbon, and the first coulombic efficiency of the SiO/C composite negative electrode material is lower. Therefore, the development of the silicon-based negative electrode material with higher capacity, better cycle performance and electrochemical performance has important practical significance and market value.

When silicon is amorphous, its amorphous disordered structure may partially counteract or buffer its volume expansion after intercalation of lithium due to its long-range disordered structure. In addition, when the grain diameter of the silicon particles is less than the critical dimension of 150nm, the complete spherical morphology can still be kept after the volume expansion of the lithium intercalation, and the particles cannot be crushed and pulverized. Therefore, the method for preparing the nano amorphous silicon powder with the grain diameter less than 150nm has important market value.

However, when the negative electrode plate is manufactured by using the nano silicon negative electrode material, the negative electrode plate can be seriously cracked after being coated and dried, and the nano silicon particles are required to be dispersed and pinned in the micron-sized Si/C composite particles mainly because the nano silicon particles can be seriously agglomerated when the negative electrode plate is dried.

The existing method for manufacturing the nano silicon powder, such as plasma evaporation, laser evaporation, SiHCl₃The Siemens method and the melt-spun quenching method actually obtain polycrystalline silicon.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provide a nano amorphous C-Si-C composite material which can be continuously produced and can be used as an ideal cathode material of a lithium ion battery.

One aspect of the present invention provides a method for manufacturing a nano amorphous C-Si-C composite material, the method using a vapor phase pyrolysis method and comprising the steps of:

A. carrying organic acetylene gas into a first cracking zone by utilizing carrier gas, cracking at low temperature under the action of a catalyst to obtain nano amorphous carbon black, and then entering a second cracking zone;

B. carrying silane gas into a second cracking zone by utilizing carrier gas, cracking at low temperature to obtain nano amorphous silicon particles taking the nano amorphous carbon black as a crystal nucleus, and then entering a third cracking zone;

C. carrying organic acetylene gas into a third cracking zone by utilizing carrier gas, cracking at low temperature under the action of a catalyst to obtain carbon black, coating the carbon black on the surface of the nano amorphous silicon particles to form nano amorphous C-Si-C composite particles, and then carrying out gas-solid separation to obtain the nano amorphous C-Si-C composite material;

wherein the first cracking zone, the second cracking zone and the third cracking zone are arranged in sequence along the material flowing direction.

According to one embodiment of the method for manufacturing the nano amorphous C-Si-C composite material, the cracking temperature of the first cracking zone and the third cracking zone is 400-750 ℃, and the cracking temperature of the second cracking zone is 480-600 ℃.

According to one embodiment of the method for manufacturing a nano amorphous C-Si-C composite material of the present invention, the organic alkyne-based gas is one or more of acetylene, propyne, butyne-1 and butyne-2.

According to one embodiment of the method for manufacturing a nano-amorphous C-Si-C composite material according to the present invention, the silane gas is one or more of silane, silane or silane.

According to one embodiment of the method for manufacturing the nano amorphous C-Si-C composite material, the catalyst is a composite catalyst formed by metal and oxide and is formed by one or more of Cu, Co, Ni, Mo, Ir, Pt and Pd and Al₂O₃、MgO、TiO₂One or more of the above.

According to one embodiment of the method for manufacturing a nano-amorphous C-Si-C composite material according to the present invention, the carrier gas is high purity nitrogen or argon having a purity of more than 99.999%.

The invention also provides a nano amorphous C-Si-C composite material which is prepared by the manufacturing method of the nano amorphous C-Si-C composite material.

According to one embodiment of the nano-amorphous C-Si-C composite material according to the present invention, the Si: the molar ratio of C is 5: 95-96: 4, the microscopic particle size of the nano amorphous silicon particles is 5-25 nm, the microscopic particle size of the nano amorphous carbon black inside is 6-30 nm, the thickness of the carbon layer coated outside is 50-150 nm, and the particle size of the nano amorphous C-Si-C composite particles is 2-15 um.

The invention provides a device for manufacturing a nano amorphous C-Si-C composite material, which comprises a gas phase cracking unit, a gas-solid separation unit and a tail gas treatment unit, wherein the gas phase cracking unit is provided with a first material inlet at the bottom and a material outlet at the top and comprises a first cracking zone, a second cracking zone and a third cracking zone which are sequentially arranged and communicated along the material flowing direction, the bottoms of the second cracking zone and the third cracking zone are also provided with a second material inlet and a third material inlet, and a plurality of layers of composite catalyst nets vertical to the material flowing direction are arranged in the first cracking zone and the third cracking zone.

According to the invention, the nano amorphous silicon particles grown by taking nano amorphous carbon as the core are coated with the nano carbon on the surface to form a C-Si-C composite material, the Si content is controllable, the material has higher capacity, and the silicon particles are not pulverized and cracked due to the particle size of the nano particles being less than 150nm during the charge-discharge cycle of the battery; in addition, the nano silicon in the C-Si-C composite material is coated and pinned by the nano carbon, so that the phenomenon of serious cracking of a pole piece caused by the agglomeration of nano silicon particles can not occur when the pole piece is dried when the pole piece is made into a negative electrode material. Due to the compounding/coating of carbon, the carbon composite material has good conductivity and can be used as an ideal negative electrode material of a lithium ion battery.

Drawings

Fig. 1 shows a schematic view of a nano-amorphous C-Si-C composite particle structure according to an exemplary embodiment of the present invention.

Fig. 2 shows a schematic structural view of a manufacturing apparatus of a nano amorphous C-Si-C composite material according to an exemplary embodiment of the present invention.

Fig. 3 is a scanning electron microscope photograph of a nano amorphous C-Si-C composite material prepared in exemplary embodiment 1 of the present invention.

Description of the drawings:

1-a gas phase cracking unit, 11-a first cracking zone, 12-a second cracking zone, 13-a third cracking zone, 2-a gas-solid separation unit and 3-a tail gas treatment unit.

Detailed Description

All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations where mutually exclusive features and/or steps are present.

Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.

The method for producing the nano amorphous C-Si-C composite material of the present invention will be described in detail.

According to an exemplary embodiment of the present invention, the method of manufacturing the nano amorphous C-Si-C composite material employs a vapor phase pyrolysis method and includes the following steps.

Step A:

organic acetylene gas is carried into the first cracking zone by carrier gas, and the organic acetylene gas is cracked at low temperature under the action of a catalyst to obtain nano amorphous carbon black and then enters the second cracking zone.

The carrier gas in the invention can be high-purity nitrogen or argon with the purity of more than 99.999 percent, and the organic acetylene gas can be one or more of acetylene, propyne, butyne-1 and butyne-2.

The organic acetylene gas enters a first cracking area under the carrying effect of carrying gas, is cracked into nano amorphous carbon black at low temperature under the catalytic effect of a catalyst, and then enters a second cracking area through the carrying gas.

Wherein the cracking temperature of the first cracking zone is controlled to be 400-750 ℃.

The catalyst arranged in the first cracking zone can lower the cracking temperature of acetylenes, and acetylenes can be cracked into nano amorphous carbon black at lower temperature when passing through the multilayer catalyst.

The catalyst adopted in the invention can be a composite catalyst formed by metal and oxide, and is prepared by Al and one or more of Cu, Co, Ni, Mo, Ir, Pt and Pd₂O₃、MgO、TiO₂One or more of the above. And can beOne or more layers of catalyst are provided as desired. For example, Cu/Co/Ni/MgO/TiO, such as an inexpensive composite network structure, can be used₂A composite catalyst. A catalyst mesh layer is arranged in the vertical direction of material flow.

And B:

and carrying silane gas into the second cracking zone by utilizing carrier gas, cracking at low temperature to obtain nano amorphous silicon particles taking nano amorphous carbon black as crystal nucleus, and then entering a third cracking zone.

The carrier gas can be the same carrier gas as in step A, and the silane gas is one or more of silane, silane or silicon propane. Silane gas enters a second cracking area under the carrying effect of carrying gas, silane in a gas phase is cracked and nano amorphous carbon black is used as crystals to generate nano amorphous silicon particles, and then the nano amorphous silicon particles enter a third cracking area under the carrying effect of the carrying gas.

The cracking temperature of the second cracking zone is preferably controlled to be 480-600 ℃, and the nano amorphous silicon can be generated. And the introduced silane is subjected to gas phase cracking at a certain temperature, and the silicon generated by taking the amorphous disordered carbon black as a core is also of a disordered amorphous structure, so that the silicon particles enter a third cracking area after the residence time in the second cracking area is short, and the silicon particles are not long enough to grow in the second cracking area.

And C:

and carrying the organic acetylene gas into a third cracking zone by utilizing carrier gas, cracking at low temperature under the action of a catalyst to obtain carbon black, coating the carbon black on the surface of the silicon particles to form nano amorphous C-Si-C composite particles, and then carrying out gas-solid separation to obtain the nano amorphous C-Si-C composite material.

Similar to the step A, carrying the same carrier gas into the organic acetylene gas again, cracking the organic acetylene gas at the cracking temperature of 400-750 ℃ and under the catalytic action of a catalyst to obtain carbon black, wherein the carbon black can completely coat silicon particles, and the nano amorphous silicon particles can not be agglomerated or grown due to the steric hindrance and pinning effect of the carbon black, so that the nano amorphous C-Si-C composite particles are formed.

Similarly, the catalyst used in this step may be the same as that used in step AThe composite catalyst is formed by metal and oxide, and is prepared from one or more of Cu, Co, Ni, Mo, Ir, Pt and Pd and Al₂O₃、 MgO、TiO₂One or more layers may be provided as required.

In the preparation process, the controllable C/Si ratio can be realized by adjusting the flow of the three paths of gases. Wherein, in the nano amorphous C-Si-C composite material, Si: the molar ratio of C is preferably 5: 95-96: 4.

fig. 1 shows a schematic structural view of nano-amorphous C-Si-C composite particles according to an exemplary embodiment of the present invention.

As shown in FIG. 1, the nano amorphous C-Si-C composite material of the present invention is prepared by the above method for preparing a nano amorphous C-Si-C composite material, and has a microstructure form as shown in FIG. 1.

Specifically, the microscopic particle size of the nano amorphous silicon particles prepared by the method is 5-25 nm, the microscopic particle size of the nano amorphous carbon black inside the nano amorphous silicon particles is 6-30 nm, the thickness of the carbon layer coated outside the nano amorphous silicon particles is 50-150 nm, and the nano amorphous C-Si-C composite particles are nearly spherical and have the particle size of 2-15 um.

The invention also provides a manufacturing device of the nano amorphous C-Si-C composite material.

Fig. 2 shows a schematic structural view of a manufacturing apparatus of a nano amorphous C-Si-C composite material according to an exemplary embodiment of the present invention.

As shown in fig. 2, according to an exemplary embodiment of the present invention, the manufacturing apparatus includes a gas phase cracking unit 1, a gas-solid separation unit 2, and a tail gas treatment unit 3, wherein the gas phase cracking unit 1 is configured to implement a continuous production reaction, the gas-solid separation unit 2 is configured to separate a reaction product from a carrier gas and the like and obtain a product, and the tail gas treatment unit 3 performs post-treatment on the separated gas and then discharges the post-treatment. Wherein, the gas-solid separation unit and the tail gas treatment unit can be assembled by selecting proper equipment according to the requirement.

The gas phase cracking unit 1 of the present invention has a first material inlet at the bottom and a material outlet at the top, and comprises a first cracking zone 11, a second cracking zone 12 and a third cracking zone 13 which are sequentially arranged and communicated along the material flow direction, wherein the second material inlet and the third material inlet are further arranged at the bottom of the second cracking zone 12 and the third cracking zone 13.

More specifically, the gas phase cracking unit 1 of the present invention is a cracking furnace with a cracking tube, the cracking tube is vertically or horizontally arranged and is respectively provided with a first cracking area 11, a second cracking area 12 and a third cracking area 13 along the material flow direction, the organic acetylenic gas and the carrier gas enter the first cracking area to be cracked to obtain the nano amorphous carbon black and then enter the second cracking area, the silane gas and the carrier gas enter the second cracking area to be cracked and form the nano amorphous silicon particles by using the product from the first cracking area as a crystal nucleus, and the organic acetylenic gas and the carrier gas enter the third cracking area to be cracked and coated on the surface of the product from the second cracking area to form the nano amorphous C-Si-C composite particles. Wherein, a plurality of layers of composite catalyst nets vertical to the material flowing direction are arranged in the first cracking zone and the third cracking zone.

The present invention will be further described with reference to specific examples, but the scope of the present invention is not limited to the examples of the present invention.

Example 1:

a304 stainless steel pipe with the inner diameter of 60mm is used as a cracking pipe of the gas phase cracking unit, a heating belt is wound outside the cracking pipe, and temperature is programmed and controlled. Because the cracking of the acetylenes and the silane is exothermic reaction, in order to effectively control the temperature of a cracking area, the periphery of the cracking pipe can be not provided with a heat preservation sleeve, and air cooling can be added if necessary.

The cracking tube is vertically arranged and is respectively a first cracking area, a second cracking area and a third cracking area from bottom to top. The height of the first cracking zone is 2 meters, the height of the second cracking zone is 2.5 meters and the height of the third cracking zone is 1.5 meters. The three air inlets are arranged at the bottom sides of the three areas and are horn-shaped air outlets. An upper layer and a lower layer of Cu/Co/Ni/MgO/TiO are horizontally arranged in the first cracking zone and the third cracking zone at equal intervals₂The mesh of the composite catalyst mesh layer is 10mm, and the diameter of the used mesh wire is 0.5 mm.

The temperature of the first cracking zone is controlled at 550 ℃, the first path inlet gas flow: 100L/h of acetylene gas and 1000L/h of high-purity (99.999 percent, 5N) nitrogen gas. The temperature of the second cracking zone is controlled at 500 ℃, and the flow rate of the second path of inlet gas: 500L/h of silicomethane and 200L/h of high-purity (99.999%) nitrogen. The temperature of the third cracking zone is controlled at 550 ℃, and the third inlet flow: acetylene gas 200L/h, high purity (5N) nitrogen 500L/h.

After the reaction, gas-solid separation is carried out through a precision filter, and tail gas is introduced into water for washing and then is exhausted. The embodiment can realize continuous production, and the adjustment of the Si/C ratio in the product can be realized by adjusting the flow of three paths of gases.

Fig. 3 shows a scanning electron micrograph of a nano amorphous C-Si-C composite prepared according to exemplary embodiment 1 of the present invention.

As shown in FIG. 3, the present example produced nano amorphous silicon particles grown with nano amorphous carbon as the core, and the surface of the nano amorphous silicon particles was coated with nano carbon to form a C-Si-C composite material.

Example 2:

a304 stainless steel pipe with the inner diameter of 100mm is used as a cracking pipe of a gas phase cracking unit, a heating belt is wound outside the cracking pipe, and temperature is programmed and controlled. Because acetylene and silane cracking are exothermic reactions, in order to effectively control the temperature of a cracking zone, the periphery of the cracking tube can be not provided with a heat-insulating sleeve, and air cooling can be added if necessary.

The cracking tube is horizontally arranged and is respectively a cracking area I, a cracking area II and a cracking area III from left to right. The length of the first cracking zone is 2.5 meters, the length of the second cracking zone is 3 meters and the length of the third cracking zone is 2 meters. The first path of air inlet is arranged on the left side of the first cracking area, the second path of air inlet is arranged on the lower left side of the second cracking area, and the third path of air inlet is arranged on the lower left side of the third cracking area and is provided with a horn-shaped air outlet. A left layer and a right layer of Cu/Co/Pt/MgO/Al are arranged in the first cracking zone and the third cracking zone at equal intervals₂O₃The mesh of the composite catalyst mesh layer is 10mm, and the diameter of the used mesh is 0.5 mm.

The temperature of the first cracking zone is controlled at 600 ℃, the first path inlet gas flow: 150L/h of propyne gas and 1000L/h of high-purity (5N) nitrogen gas. The temperature of the second cracking zone was controlled at 500 ℃, the second path inlet flow: 500L/h of silicon ethane and 200L/h of high-purity (5N) nitrogen. The temperature of the third cracking zone was controlled at 550 ℃, third path inlet flow: acetylene gas 300L/h, high purity (5N) nitrogen 500L/h.

After the reaction, gas-solid separation was carried out by a precision filter. And introducing the tail gas into water for washing, and then exhausting. The embodiment can realize continuous production, and the Si/C ratio in the product can be realized by adjusting the flow of three paths of gases.

The product micro-topography obtained in example 2 was similar to that of example 1.

The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.