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Preparation method of silicon-based composite material

A technology of silicon-based composite materials and silicon powder, which is applied in the direction of active material electrodes, electrical components, electrochemical generators, etc., can solve the problems of high cost, difficulty in dispersing graphene, and poor economic efficiency, so as to improve hardness and toughness, and effectively Good for recycling and low production cost

Inactive Publication Date: 2019-11-01
SHANGHAI ELECTRICGROUP CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] For example, the published patent CN106532010A discloses a silicon-silicon nitride-carbon composite material, which uses silicon nitride nanowires to coat nano-silicon in situ, and then uses graphene to modify the surface of silicon nitride to form silicon-silicon nitride-carbon Composite materials, but it requires a high temperature of 1200-1400°C when synthesizing silicon nitride-coated nano-silicon, so it consumes a lot of energy, and the coating amount of silicon nitride>20% makes the capacity of the coated silicon drop significantly. The highest gram capacity is only 512mAh / g. In addition, graphene is difficult to disperse and the price remains high, making this method less economical
[0004] For example, the published patent CN1075079792A discloses a preparation method of a silicon-carbon negative electrode material, a silicon-carbon negative electrode material, and a lithium-ion battery. Silicon alloys are used as raw materials, and porous silicon is obtained by pickling, and the porous silicon and carbon sources are mixed and sintered. Silicon-carbon composite materials are produced, but pickling is required in the preparation process, which will generate a large amount of waste water and cause great environmental pollution. The highest capacity of the prepared silicon-based material is only 1086mAh / g, and the capacity remains after 20 cycles. Only 83.4%
[0005] Another example is the published patent CN108390049A which discloses a silicon@silicon carbide@carbon core-shell composite material and its preparation method. The innermost layer is silicon powder, the middle cladding layer is silicon carbide, and the outermost cladding layer is carbon material. , but the formation of silicon carbide requires high temperature (>1000°C) and gas phase coating, which requires high equipment and poor economic benefits, which is not conducive to large-scale commercialization
[0006] Therefore, how to simplify the production process, reduce production costs, and improve the capacity and service life of silicon-carbon composite materials has become an urgent need for those skilled in the art in view of the above-mentioned defects such as complex production process, high cost, low capacity and service life of the existing silicon-carbon composite materials. Solved technical problems

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  • Preparation method of silicon-based composite material

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Experimental program
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Effect test

Embodiment 1

[0026] (1) Put 5g of silicon powder into the atmosphere furnace and pass through the compressed air for heat treatment at 650°C for 20min, and after cooling, crush it with a grinder for 60s;

[0027] (2) Disperse the crushed silicon powder in a LiOH ethanol solution with a mass fraction of 2% and sonicate it for 10 minutes, evaporate it to dryness by spray drying, and heat-treat it at 700° C. for 5 hours under a nitrogen atmosphere;

[0028] (3) Ball milling the sintered material in an atmosphere of carbon dioxide for 2 hours to obtain a silicon-based composite material;

[0029] (4) The CR2032 button battery was prepared by using metal lithium sheet as the counter electrode, and the prepared silicon-based composite material, conductive agent Super P, and binder CMC / SBR were mixed in deionized water at a mass ratio of 65:15:10:10. Mix evenly, apply it on the surface of copper foil with a wet method film applicator, dry it in an oven at 50°C, and use a slicer to cut out an elec...

Embodiment 2

[0031] (1) Put 5g of silicon powder into the atmosphere furnace and pass through the compressed air for heat treatment at 580°C for 30min, and after cooling, crush it with a grinder for 60s;

[0032] (2) Disperse the crushed silicon powder in a LiOH ethanol solution with a mass fraction of 2% and sonicate it for 10 minutes, evaporate it to dryness by spray drying, and heat-treat it at 800° C. for 5 hours under a nitrogen atmosphere;

[0033] (3) Ball milling the sintered material in an atmosphere of carbon dioxide for 5 hours to obtain a silicon-based composite material;

[0034] (4) A CR2032 button battery was prepared with a lithium metal sheet as the counter electrode. The first reversible capacity of the material was 2297.5mAh / g, and the capacity retention rate after 100 cycles was 62.3%, as shown in Table 1.

Embodiment 3

[0036] (1) Put 5g of silicon powder into the atmosphere furnace and pass through the compressed air for heat treatment at 680°C for 15min, and after cooling, crush it with a grinder for 60s;

[0037] (2) Disperse the crushed silicon powder in a LioH ethanol solution with a mass fraction of 2% and sonicate it for 10 minutes, evaporate it to dryness by spray drying, and heat-treat it at 750° C. for 5 hours under a nitrogen atmosphere;

[0038] (3) Ball milling the sintered material in an atmosphere of carbon dioxide for 10 hours to obtain a silicon-based composite material;

[0039] (4) A CR2032 button battery was prepared with a lithium metal sheet as the counter electrode. The first reversible capacity of the material was 2012.7mAh / g, and the capacity retention rate after 100 cycles was 78.9%, as shown in Table 1.

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Abstract

The invention discloses a preparation method of a silicon-based composite material. The method comprises the steps of: (1) placing a certain amount of silicon powder into an atmosphere furnace, and introducing compressed air, performing heat treatment at a temperature of 550-700 DEG C for 15-30min, and adopting a grinder for crushing for 30-60s after cooling; (2) dispersing the crushed silicon powder in an LiOH ethanol solution for ultrasonic treatment for 5-15min, adopting spray drying to dry, and putting the dried material in a nitrogen atmosphere for high-temperature sintering; and (3) performing ball milling of the sintered material to obtain a silicon-based composite material. The preparation method is simple in process and low in production cost, and the manufactured silicon-based composite material has the high capacity, the long circulation and the like.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and relates to a lithium ion battery negative electrode material, in particular to a preparation method of a silicon-based composite material. Background technique [0002] Carbon materials, such as natural graphite, graphitized mesocarbon microspheres, etc., are widely used in lithium-ion battery anode materials. Among non-carbon anode materials, silicon has a very high theoretical specific capacity, a low lithium storage reaction voltage platform, and silicon is widely distributed in nature, and its content in the earth’s crust is second only to oxygen, so silicon-based anode materials It is a new type of high-energy material with great development prospects. [0003] For example, the published patent CN106532010A discloses a silicon-silicon nitride-carbon composite material, which uses silicon nitride nanowires to coat nano-silicon in situ, and then uses graphene to modify the s...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/62H01M10/0525H01M2004/021H01M2004/027Y02E60/10
Inventor 李旺詹吟桥闫海陈献武周兰刘佳丽
Owner SHANGHAI ELECTRICGROUP CORP