Nitrogen-doped carbon-coated silicon composite material and preparation method thereof

A composite material and silicon-coated technology, which is used in electrical components, electrochemical generators, battery electrodes, etc., can solve the problems of electrical conductivity limiting the charge and discharge performance of composite materials, affecting the cycle performance of composite materials, and unfavorable large-scale preparation. Achieve good high-current charge-discharge characteristics, excellent electrochemical performance, and good cycle stability.

Inactive Publication Date: 2015-11-11
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Nanoization mainly includes methods such as preparing nano-silicon powder (such as Chinese patent CN104332613A), silicon nanowires (such as Chinese patent CN103515604A) and silicon thin films (such as Chinese patent CN102637852A). Attenuation problem, but the synthesis process it adopts is complex, time-consuming and labor-intensive, which is not conducive to large-scale preparation
Silicon compounding is mainly to prepare silicon-carbon composite materials, s

Method used

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  • Nitrogen-doped carbon-coated silicon composite material and preparation method thereof
  • Nitrogen-doped carbon-coated silicon composite material and preparation method thereof
  • Nitrogen-doped carbon-coated silicon composite material and preparation method thereof

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preparation example Construction

[0028] The preparation method of nitrogen-doped carbon-coated silicon composite material of the present invention comprises the following steps:

[0029] (1) Metal magnesium is mixed with silicon dioxide, and the silicon dioxide is converted into a silicon material with lithium storage activity by a metal magnesium thermal reduction method;

[0030] (2) adding the ionic liquid to the silicon material obtained in step (1), and mixing to obtain the precursor of the composite material;

[0031] (3) Heat-treating the composite material precursor obtained in step (2) under a protective atmosphere to obtain a nitrogen-doped carbon-coated silicon composite material.

[0032] In step (1), metallic magnesium refers to one or both of magnesium particles and magnesium powder.

[0033] In step (2), the ionic liquid refers to monoethyltrimethylimidazolium tricyanomethyl salt (EMIM-TCCN).

[0034] In step (2), the mass ratio of the silicon material to the ionic liquid is (2:9)-(4:1), and ...

Embodiment 1

[0039] Weigh 1g of silica pellet powder and 1g of magnesium powder, mix evenly, spread it on an alumina porcelain boat, place it in the heating zone of a tube furnace, and heat it at a rate of 2°C / min under the protection of an argon atmosphere. Raise the temperature to 680°C, keep it warm for 6 hours, and cool down to room temperature with the furnace, then place the magnesium heat product in 50mL of hydrochloric acid with a concentration of 1mol / L, stir for 5 hours, centrifuge, wash with distilled water three times, and place the obtained solid in In 50 mL of hydrochloric acid with a concentration of 1 mol / L, stir for 5 hours, centrifuge, wash with distilled water three times, wash with absolute ethanol twice, and finally vacuum-dry at 60°C for 24 hours to obtain nano silicon powder.

[0040] Mix 150mg of the above-mentioned nano-silicon powder with 150mg of the ionic liquid and grind them evenly to obtain the precursor of the composite material.

[0041] The precursor of th...

Embodiment 2

[0045] According to the method for preparing nano-silicon powder in Example 1, prepare nano-silicon powder.

[0046] Mix 100mg of the above-mentioned nano-silicon powder with 150mg of ionic liquid and grind them evenly to obtain the precursor of the composite material.

[0047] The precursor of the above-mentioned composite material was transferred to a tube furnace for heat treatment. Under an argon atmosphere, the temperature was raised to 200 °C at a rate of 2 °C / min, kept for 2 hours, and then the temperature was raised to 650 °C at a rate of 2 °C / min. ℃, keep it warm for 5 hours, and cool with the furnace to get the nitrogen-doped carbon-coated silicon composite material. The content of silicon in the composite material is 65.6%wt.

[0048] According to the method for preparing a button battery in Example 1, use the nitrogen-doped carbon-coated silicon composite material prepared in this example to make a button battery, and perform the charge-discharge cycle performance...

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Abstract

The invention discloses a nitrogen-doped carbon-coated silicon composite material and a preparation method thereof, and belongs to the field of lithium ion batteries. The nitrogen-doped carbon-coated silicon composite material comprises a silicon lithium-storage material which exists in the composite material as a main active substance, and organic pyrolytic nitrogen-doped carbon with certain lithium storage capacity and good electrical conductivity as a coating layer, wherein the content of silicon in the composite material is 30%-90%; and the preparation method comprises preparation and carbon-coating technologies of a composite material precursor. In addition, with cheap silicon dioxide as a silicon source, and the silicon dioxide is transformed into a silicon material with the lithium storage activity through a metal magnesiothermic reduction process. Compared with the prior art, the preparation method of the nitrogen-doped carbon-coated silicon composite material is short in flow, easy to operate and simple in synthetic process; large-scale production is easy to realize; and the prepared nitrogen-doped carbon-coated silicon composite material has excellent electrochemical property when taken as a lithium ion battery anode material, and has a potential application prospect in the fields of portable mobile devices and electric cars.

Description

Technical field: [0001] The invention relates to the field of negative electrode materials for lithium ion batteries, in particular to a nitrogen-doped carbon-coated silicon composite material and a preparation method thereof. Background technique: [0002] At present, the negative electrodes of commercial lithium-ion batteries mainly use graphite-like carbon materials as active materials, but their theoretical capacity is low, only 372mAh / g, and it is gradually difficult to meet people's needs for lithium-ion batteries with high capacity and high energy density. . [0003] In recent years, various high-capacity negative electrode materials for lithium-ion batteries have been gradually developed, among which silicon negative electrode materials are due to their very high theoretical capacity (4200mAh / g, Li 22 Si 5 ) has become a hot spot for researchers. However, the silicon negative electrode is accompanied by a huge volume change (about 300%) during the charge-discharge...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M10/0525
CPCH01M4/366H01M4/386H01M4/587H01M10/0525Y02E60/10
Inventor 张校刚郑浩方姗童震坤
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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