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Silicon-carbon composite material and preparation method thereof, and lithium ion battery

A technology of silicon-carbon composite materials and lithium-ion batteries, which is applied in battery electrodes, secondary batteries, circuits, etc., can solve the problems of volume effect, capacity attenuation, and pulverization of silicon-based negative electrode materials that have not been fundamentally solved, and achieve improvement Rate capability, enhanced conductivity, effect of enhanced conductivity and rate capability

Active Publication Date: 2013-10-02
CHERY AUTOMOBILE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the silicon / carbon / graphite composite negative electrode material or silicon-carbon composite material prepared by the above method has improved the cycle stability of lithium-ion batteries to a certain extent, there are still pulverization and shedding phenomena.
Lithium-ion batteries using the above materials as anode materials begin to rapidly decay in capacity after multiple charge-discharge cycles, and have not fundamentally solved the volume effect of silicon-based anode materials during charge-discharge.

Method used

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  • Silicon-carbon composite material and preparation method thereof, and lithium ion battery
  • Silicon-carbon composite material and preparation method thereof, and lithium ion battery
  • Silicon-carbon composite material and preparation method thereof, and lithium ion battery

Examples

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Embodiment 1

[0035] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0036] (1) setting a transition layer on the silicon-based material to obtain the silicon-based material covered by the transition layer;

[0037] (2) Coating carbon on the silicon-based material covered by the transition layer to obtain a carbon-transition layer-silicon-based composite material;

[0038] (3) The transition layer is removed to obtain a silicon-carbon composite material.

[0039] In the above preparation method, a transition layer is provided outside the silicon-based material, carbon is coated on the outside of the transition layer, and the transition layer between the silicon-based material and carbon is removed to obtain a silicon-carbon composite material with a certain distance between the silicon base and the carbon. of pores. Setting the thickness of the transition layer according to the theoretical microscopic volume expansion ...

Embodiment 2

[0043] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0044] (1) Prepare an aqueous solution of calcium chloride, then add silicon powder, and stir to make the silicon powder evenly dispersed in the aqueous solution of calcium chloride. Under stirring state, in above-mentioned mixture, add the aqueous solution of sodium carbonate dropwise, calcium carbonate is precipitated on silicon powder, and the aqueous solution of sodium carbonate added is excessive 2% to guarantee the calcium ion precipitation in the aqueous solution completely, after standing for 2 hours, Suction filtration or centrifugation, washing 3 times, and drying to obtain a silicon-based material coated with calcium carbonate, wherein the mass ratio of the silicon-based material to calcium carbonate is 1:3.34.

[0045] (2) Add the calcium carbonate-coated silicon-based material and sucrose into a planetary ball mill, and ball mill at a speed...

Embodiment 3

[0056] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0057] (1) Prepare an aqueous solution of barium nitrate, then add silicon monoxide (the theoretical specific capacity of silicon silicide is about 1200mAh / g), and stir to make silicon monoxide evenly dispersed in the aqueous solution of barium nitrate. In the stirring state, add the aqueous solution of sodium carbonate dropwise to the above mixture, precipitate barium carbonate on the silicon monoxide, and add the aqueous solution of sodium carbonate in excess of 2% to ensure that the barium ion in the aqueous solution is completely precipitated, after standing for 2 hours , filtered or centrifuged, washed three times, and dried to obtain a silicon monoxide material coated with barium carbonate, wherein the mass ratio of silicon monoxide to barium carbonate is 1:6.5.

[0058] (2) After the barium carbonate-coated silicon monoxide material and the polya...

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Abstract

The invention discloses a silicon-carbon composite material and a preparation method thereof, and a lithium ion battery. The preparation method comprises following steps: (1) coating a silica-based material with a transition layer to obtain the transition layer-coated silica-based material; (2) coating the transition layer-coated silica-based material with carbon to obtain a carbon-transition layer-silicon based composite material; and (3) removing the transition layer to obtain the silicon-carbon composite material. The silicon-based material is coated with the transition layer, the transition layer is coated with the carbon, and the transition layer between the silicon-based material and the carbon is removed, so that a plurality of pores are formed between the silicon-based material and the carbon of the silicon-carbon composite material. The size of the pores between the silicon-based material and the carbon can be controlled precisely by setting the thickness of the transition layer according to micro-volume expansion theoretical value of the silicon-based material when lithium is embedded, so that volume effect of the silicon-carbon composite material is reduced effectively, and cycling performance of the lithium ion battery is further enhanced. The carbon of the silicon-carbon composite material is capable of increasing conductivity and rate capability of the composite material.

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, a preparation method thereof, and a lithium ion battery. Background technique [0002] At present, graphite or modified graphite is widely used as the negative electrode material in lithium-ion batteries for commercial applications. During the charging and discharging process of lithium-ion batteries, the volume expansion of the above-mentioned negative electrode materials is small when lithium is intercalated (lithium intercalation volume expansion coefficient<9%), showing high Coulombic efficiency and good cycle stability, but its maximum theoretical The specific capacity is only 372mAh / g, thus limiting the further improvement of the specific energy of lithium-ion batteries. [0003] The anode material of lithium-ion battery with high specific capacity has become the key to improve battery performance. Since sil...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/38H01M10/0525
CPCY02E60/10
Inventor 刘三兵翟丽娟
Owner CHERY AUTOMOBILE CO LTD
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