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Hollow secondary core-shell structure silicon-carbon composites and their preparation and application

A silicon-carbon composite material, core-shell structure technology, applied in structural parts, secondary batteries, electrical components, etc., can solve the problems of limiting comprehensive electrochemical performance, difficult to ensure fast transmission, increasing production costs, etc., to achieve excellent electrochemical performance. Cyclic stability, suitable for large-scale production, and the effect of reducing the capacity decay rate

Active Publication Date: 2019-06-14
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If the concentration of HF aqueous solution is too high or the corrosion time is too long, HF will corrode SiO 2 After that, the Si core may be further corroded, resulting in the loss of Si and increasing production costs
In addition, the resulting Si@void@C needs to be strictly regulated in the size of the voids, and the electrical contact between the silicon core and the carbon shell is poor, so it is difficult to ensure that Li + and e - rapid transport, thus limiting the improvement of its comprehensive electrochemical performance

Method used

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  • Hollow secondary core-shell structure silicon-carbon composites and their preparation and application
  • Hollow secondary core-shell structure silicon-carbon composites and their preparation and application
  • Hollow secondary core-shell structure silicon-carbon composites and their preparation and application

Examples

Experimental program
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Effect test

Embodiment 1

[0037] (1) Weigh 0.36g nano-silica powder (10-200nm), add 200mL tris (hydroxymethyl) aminomethane buffer solution (Tris, 0.01M, pH ~ 8.5) and 20mL absolute ethanol, add 0.36g after ultrasonication for 20min Dopamine hydrochloride, continue to sonicate for 20 minutes, stir for 24 hours, centrifuge, wash with deionized water three times, and dry at 80°C in vacuum; transfer the dried product to a tube furnace, and raise the temperature to 400°C under the protection of Ar (1°C min -1 ), then heated up to 800°C (5°C min -1 ), constant temperature for 3h; after natural cooling, the primary product of Si@C with primary core-shell structure was obtained.

[0038] (2) Disperse 0.30g Si@C in a mixture of 240mL deionized water and absolute ethanol (volume ratio 1:3), add 0.30g cetyltrimethylammonium bromide (CTAB) and 3mL Ammonia water (28wt.%), add 2.8mL tetraethyl orthosilicate drop by drop under vigorous stirring, stir for 4 hours after completion, centrifuge, wash with alcohol three...

Embodiment 2

[0045] (1) Weigh 0.50g of nano-silica powder (10-200nm), add 200mL tris (hydroxymethyl) aminomethane buffer solution (Tris, 0.01M, pH ~ 8.5) and 20mL absolute ethanol, add 0.50g after ultrasonication for 20min Dopamine hydrochloride, continue to sonicate for 20 minutes, stir for 24 hours, centrifuge, wash with deionized water three times, and dry at 80°C in vacuum; transfer the dried product to a tube furnace, and raise the temperature to 400°C under the protection of Ar (1°C min -1 ), then heated up to 800°C (5°C min -1 ), constant temperature for 3h; after natural cooling, the primary product of Si@C with primary core-shell structure was obtained.

[0046] (2) Disperse 0.30g Si@C in a mixture of 240mL deionized water and absolute ethanol (volume ratio 1:3), add 0.30g CTAB and 3mL ammonia water (28wt.%), drop by drop under vigorous stirring Add 3 mL of tetraethyl orthosilicate dropwise, stir for 4 hours after completion, centrifuge, wash with alcohol three times, and then dr...

Embodiment 3

[0051] (1) Weigh 0.36g nano-silica powder (10-200nm), add 200mL tris (hydroxymethyl) aminomethane buffer solution (Tris, 0.01M, pH ~ 8.5) and 20mL absolute ethanol, add 0.36g after ultrasonication for 10min For dopamine hydrochloride, continue to sonicate for 10 min, stir for 18 h, centrifuge, wash with deionized water three times, and vacuum-dry at 80 °C; transfer the dried product to a tube furnace, and raise the temperature to 400 °C under the protection of Ar (1 °C min -1 ), then heated up to 800°C (5°C min -1 ), constant temperature for 3h; after natural cooling, the primary product of Si@C with primary core-shell structure was obtained.

[0052] (2) Disperse 0.30g Si@C in a mixture of 240mL deionized water and absolute ethanol (volume ratio 1:3), add 0.30g CTAB and 3mL ammonia water (28wt.%), drop by drop under vigorous stirring Add 2 mL of methyl orthosilicate dropwise, stir for 5 hours after completion, centrifuge, wash with alcohol three times, and then dry to obtain...

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Abstract

The invention discloses a silicon-carbon composite material with a hollow two-stage core-shell structure as well as a preparation method and application thereof. The silicon-carbon composite material is of a two-stage core-shell structure: the first-stage core-shell structure takes silicon with the particle size of 10 to 500 nm as a core and carbon as a shell, thus forming a Si@C core-shell structure, and the second-stage core-shell structure takes the first Si@C core-shell structure as a core and carbon as a shell; a clearance is formed between the first-stage structure and the second-stage structure, but the two structures are closely connected at certain portions to form a conductive bridge; the clearance space between the two stages of carbon shells is 5 to 400 percent of the volume of the first Si@C core-shell structure. The silicon-carbon composite material can obviously improve electric contact between the silicon core and the carbon shell in the conventional hollow core-shell structure to enhance the conductivity of the whole material, and can be used for negative electrode materials of lithium ion batteries.

Description

(1) Technical field [0001] The invention belongs to the technical field of electrode materials, in particular to a hollow secondary core-shell structure silicon-carbon composite material, a preparation method thereof, and the application of the material in the field of lithium ion batteries. (2) Background technology [0002] The rapid development of electric vehicles requires high-capacity, long-life and high-safety lithium-ion batteries. Among the anode materials, silicon is rich in sources and has a high theoretical capacity (4200mAh g -1 , Li 22 Si 5 ) and high safety (the lithium intercalation potential is about 0.15V higher than that of graphite) and other advantages, it has attracted widespread attention from researchers. But its conductivity is poor (1.6×10 -3 S m -1 ), and the volume change during the cycle exceeds 300% (much higher than 10% of graphite), which can easily cause the fragmentation and pulverization of silicon particles, making them lose electrica...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/38H01M4/583H01M4/1393H01M4/1395H01M10/0525
CPCH01M4/1393H01M4/1395H01M4/362H01M4/386H01M4/583H01M10/0525Y02E60/10
Inventor 王连邦苏利伟谢剑
Owner ZHEJIANG UNIV OF TECH