Silicon/carbon composite material and preparation method thereof and application of silicon/carbon composite material

A technology of carbon composite materials and composites, which is applied in the field of lithium-ion batteries, can solve problems such as unfavorable nanosheet layered structure, unstable sheet structure, and increased silicon layer thickness, so as to improve cycle performance, improve electrochemical performance, The effect of increasing the gap

Active Publication Date: 2019-12-03
TONGJI UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, if it is directly reduced, it will easily lead to instability of its sheet structure. During the reduction process, the inter-diffusion of silicon between the sheets will increase the thickness of the silicon layer, which is not conducive to the formation of a nanosheet layered structure.

Method used

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  • Silicon/carbon composite material and preparation method thereof and application of silicon/carbon composite material
  • Silicon/carbon composite material and preparation method thereof and application of silicon/carbon composite material
  • Silicon/carbon composite material and preparation method thereof and application of silicon/carbon composite material

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preparation example Construction

[0044]

[0045] The preparation method of silicon / carbon composite material of the present invention comprises the steps:

[0046] (1) Place the silicate with water-containing layered structure in a preheated tube furnace with an inert protective gas for rapid heating to obtain a layered silicate material, and then place the organic carbon source under the inert protection The gas is carried into the tube furnace, and after high temperature pyrolysis, a layer of carbon material is uniformly coated on the surface of the layered silicate material to obtain a carbon-coated material;

[0047] (2) After cooling the carbon-coated material to room temperature, add dilute hydrochloric acid to remove the metal oxide in the layered silicate material to obtain a silicon oxide / carbon compound;

[0048] (3) After mixing the oxide / carbon compound of silicon, the reducing agent and the chloride, heat treatment is carried out in an inert gas, and then the excess impurities are removed with ...

Embodiment 1

[0073] Such as figure 1 As shown, the preparation method of the silicon / carbon composite material of the present embodiment includes the following steps:

[0074] (1), put 2g of vermiculite material into the corundum porcelain boat, then put the porcelain boat into a tube furnace heated to 700°C with argon shielding gas for rapid heat treatment for 10s, and then add toluene (as organic Carbon source) is passed into a tube furnace under the argon protective gas, and pyrolyzed at 700°C for 20 minutes to obtain a carbon-coated material;

[0075] (2), after cooling the carbon-coated material to room temperature, put it into dilute hydrochloric acid and stir for 12 hours, remove the residual metal oxide in the material, and obtain a silicon oxide / carbon composite;

[0076] (3), the compound of silicon oxide / carbon, aluminum powder, AlCl 3 , NaCl were mixed evenly, transferred to a stainless steel reaction kettle in a glove box, and protected in an argon atmosphere. Then transfer...

Embodiment 2

[0082] The preparation method of the silicon / carbon composite material of the present embodiment comprises the following steps:

[0083] (1), put 5g of halloysite into a corundum porcelain boat, then put the porcelain boat into a tube furnace heated to 1000°C with an argon shielding gas for rapid heat treatment for 5s, and then add ethanol (as organic Carbon source) is passed into a tube furnace under the argon protective gas, and pyrolyzed at 700°C for 10 minutes to obtain a carbon-coated material;

[0084] (2) After cooling the carbon-coated material to room temperature, put it into dilute sulfuric acid and stir for 14 hours to remove the residual metal oxide in the material to obtain a silicon oxide / carbon compound;

[0085] (3), the compound of silicon oxide / carbon, magnesium powder, AlCl 3 , NaCl were mixed evenly, transferred to a stainless steel reaction kettle in a glove box, and protected in an argon atmosphere. Then transfer the reactor to a tube furnace, heat it t...

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Abstract

The invention provides a silicon/carbon composite material and a preparation method thereof and application of a silicon/carbon composite material. The preparation method comprises the following stepsof: taking silicate with an aquifer-shaped structure as a silicon source; performing rapid heating treatment on the mixture in an inert atmosphere; uniformly coating a layer of nanocarbon on the surface of a silicon/carbon composite material by adopting a chemical vapor deposition method, reducing silicon oxide by a molten salt system after acid pickling and impurity removal, removing impuritiesby acid pickling, performing etching by hydrofluoric acid to remove molten salt and other oxides, and performing treating to obtain the silicon/carbon composite material. According to the composite material disclosed by the invention, holes between the layers and the internal portion of the composite material inhibit the volume expansion of silicon in a charging and discharging process and stabilizes the solid electrolyte interface film formed in the charging and discharging process, so that the rate capability and the cycle performance of the lithium ion battery are improved, the coating of the carbon layer is beneficial to improving the conductivity of the material, improving the charge transfer rate at the interface of the material and the electrolyte, inhibiting the polarization phenomenon in the cycle process and improving the electrochemical performance.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a silicon / carbon composite material and a preparation method and application thereof. Background technique [0002] With the rapid development of electric vehicles, the demand for energy density of batteries is increasing day by day. Due to its low specific capacity (372mAh / g), the existing graphite anode is difficult to meet the needs of future long-range electric vehicles. Silicon material is due to its higher theoretical specific capacity (4200mAh / g) and lower lithium potential (0.1V vs Li / Li + ), making it show a high application prospect in the field of lithium-ion battery anode. [0003] However, due to the low conductivity of the silicon material itself and the irreversible huge volume change during the intercalation and extraction of lithium ions, the material is pulverized and the structure collapses. Compared with the graphite negative electr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/625H01M10/0525Y02E60/10
Inventor 包志豪黄曦柳盼盼李敏
Owner TONGJI UNIV
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