Multi-core core-shell-structure silicon carbon composite negative pole material and preparation method thereof

A technology of negative electrode material and core-shell structure, which is applied in the field of lithium-ion battery composite negative electrode materials and its preparation, can solve the problems of electrode cycle performance degradation, limited commercial application, and material structure damage, and solve the problem of poor silicon conductivity and improve Capacity utilization rate and effect of improving tap density

Active Publication Date: 2013-05-08

CENT SOUTH UNIV

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AI-Extracted Technical Summary

Problems solved by technology

Due to the severe volume expansion and contraction of silicon materials during the lithium ion intercalation and deintercalation cycle, resulting in the d...

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Abstract

The invention relates to a multi-core core-shell-structure silicon carbon composite negative pole material and a preparation method thereof. The preparation method comprises the following steps: 1. preparation method of high-dispersivity multi-core porous spheres; 2. preparation of high-dispersivity asphalt suspension; and 3. preparation of multi-core core-shell-structure silicon carbon composite negative pole material: adding the porous spheres prepared in the step 1 into the high-dispersivity asphalt suspension prepared in the step 2, carrying out ultrasonic dispersion, heating and drying by distillation while intensely stirring to remove the solvent, transferring the powder particles into a protective atmosphere, and holding at low temperature so that the asphalt liquid enters the inside of the porous spheres to enhance the binding strength between the silicon source and the conducting carbon mesh, carry out secondary coating on the silicon source, overcome the defects in the coating in the step 1 and enhance the capacity performance of the silicon; and carrying out high-heat treatment. The invention is simple and easy to implement, and has the advantage of high practicality. The prepared silicon carbon composite material has the advantages of high reversible capacity, designable capacity, favorable cycle performance, favorable heavy-current discharge capacity, high tap density and the like.

Application Domain

Cell electrodes

Technology Topic

SolventCarbon composites +10

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Examples

Experimental program(6)

Example Embodiment

[0032] Example 1

[0033] (1) High-dispersion multi-nuclear porous ball: add thermosetting phenolic resin (added according to the pyrolytic carbon content of the spherical core material after sintering is 5wt%) into an appropriate amount of detetrahydrofuran, magnetically stir to form a solution with a certain viscosity, and then Add silicon powder (based on the silicon/carbon mass ratio of the sintered spherical core material at 1:19) and natural graphite (based on 80% of the total mass of the sintered spherical composite material), then add 10wt% polyethylene glycol dispersant, ball mill 5h, ultrasonic and mechanical stirring and dispersion for 1h, after spray drying the uniformly dispersed suspension at 120~200℃, it is the precursor of polynuclear porous sphere. The obtained powder is transferred to a protective atmosphere at 500°C for 2 hours and cooled with the furnace to form a multi-nuclear porous ball.

[0034] (2) Preparation of high-dispersion pitch suspension: pre-crush the coal tar pitch, take a certain amount of pre-crushed material and place it in the grinding tank, add stainless steel balls according to the abrasive ratio of 8:1, and add a certain amount of ethanol , Ball mill at 150 rpm for 20 hours, prepare the slurry obtained by ball milling into an ethanol suspension, and ultrasonically disperse for 120 min to obtain a highly dispersible asphalt suspension.

[0035] (3) Preparation of multi-core core-shell structure silicon-carbon composite negative electrode material: add the highly dispersive multi-core porous sphere prepared in step (1) to the highly dispersed pitch suspension prepared in step (2) ( The solid content is 1g/100mL, and the pitch pyrolysis carbon content in the spherical core material after sintering is added as 10wt.%), ultrasonically dispersed for 1h, and then heated under strong agitation to evaporate the solvent. The resulting powder particles are transferred to a protective atmosphere. Constant temperature at ℃ for 20h, and continue heating to 1000℃ for 1h to obtain high-dispersion multi-nuclear carbon-silicon composite material

[0036] The composition and content of the sintered silicon-carbon composite are shown in Table 1, and the electrochemical properties of the silicon-carbon composite are shown in Table 2.

Example Embodiment

[0037] Example 2

[0038] (1) High-dispersion multi-nuclear porous ball: Add polyvinyl alcohol-124 (added according to 15wt.% of pyrolysis carbon content in the sintered composite material) into an appropriate amount of deionized water, and magnetically stir to form a solution with a certain viscosity , And then add nano silicon powder (Nano-Si, according to the mass ratio of silicon/carbon in the spherical core material after sintering 1:10) and natural graphite (according to 50wt.% of the total mass of the spherical composite material after sintering, and then add 10wt.% Propylene glycol dispersant, ultrasonic and mechanical stirring and dispersion for 1 hour. After spray-drying the uniformly dispersed suspension at 170~200℃, it is the precursor of polynuclear porous spheres. The resulting powder is transferred to a protective atmosphere at 1000℃ for 2h, and the furnace Cooling, that is, multi-core porous ball.

[0039] (2) Preparation of high-dispersion asphalt suspension: pre-crush the petroleum asphalt, take a certain amount of pre-crushed material and place it in a stainless steel ball mill tank, add stainless steel balls according to the abrasive ratio of 15:1, and add a certain amount of Ethanol, ball milled at 250 rpm for 1 hour, the slurry obtained by ball milling was prepared into an ethanol suspension, and ultrasonically dispersed for 30 min to obtain a highly dispersible pitch suspension.

[0040] (3) Preparation of multi-core core-shell structure silicon-carbon composite negative electrode material: add the highly dispersive multi-core porous sphere prepared in step (1) to the highly dispersed pitch suspension prepared in step (2) ( The solid content is 20g/100mL, and the pitch pyrolysis carbon content in the spherical core material after sintering is added as 25wt.%), ultrasonically dispersed for 5h, and then heated under strong stirring to evaporate the solvent, the resulting powder particles are transferred to a protective atmosphere 300 Keep the temperature at a constant temperature of 1h, and continue to heat up to a constant temperature of 800°C for 2h to obtain a high-dispersion multi-nuclear carbon-silicon composite material.

[0041] The composition and content of the sintered spherical core material and silicon-carbon composite material are shown in Table 1, and the electrochemical properties of the silicon-carbon composite material are shown in Table 2.

Example Embodiment

[0042] Example 3

[0043] (1) High-dispersion multi-nuclear porous ball: Add urea-formaldehyde resin (added according to the pyrolysis carbon content of the spherical core material after sintering is 10wt.%) into an appropriate amount of deionized water, magnetically stir to form a solution with a certain viscosity, and then Add nano silicon powder and silicon oxide (Si:SiO=1:1, according to the mass ratio of silicon/carbon in the spherical core material after sintering 2:5) and natural graphite (according to 40wt.% of the total mass of the spherical composite material after sintering), Then add 1wt.% of polyvinyl acetate dispersant, ball mill for 1h, ultrasonic and mechanical stirring and dispersion for 1h, and spray-dry the uniformly dispersed suspension at 170~200℃ to form a polynuclear porous ball precursor. The obtained powder is transferred to a protective atmosphere at 500°C for 5 hours and cooled with the furnace to form a multi-nuclear porous ball.

[0044] (2) Preparation of high-dispersion pitch suspension: pre-crush the coal pitch, take a certain amount of pre-crushed material and place it in a stainless steel ball mill tank, add stainless steel balls according to the abrasive ratio of 30:1, and add a certain amount of Ethanol, ball milled at 500 rpm for 1 h, the slurry obtained by ball milling was prepared into an ethanol suspension, and ultrasonically dispersed for 30 min to obtain a highly dispersible pitch suspension.

[0045] (3) Preparation of multi-core core-shell structure silicon-carbon composite negative electrode material: add the highly dispersive multi-core porous sphere prepared in step (1) to the highly dispersed pitch suspension prepared in step (2) ( The solid content of 10g/100mL is added according to the pitch pyrolysis carbon content of the sintered spherical core material as 10wt.%), ultrasonically dispersed for 2h, and then heated under strong stirring to evaporate the solvent, the resulting powder particles are transferred to a protective atmosphere at 200°C Constant temperature for 5 hours, continue to heat up to 1000 ℃ constant temperature for 2 hours to obtain high-dispersion multi-nuclear carbon silicon composite material.

[0046] The composition and content of the sintered spherical core material and silicon-carbon composite material are shown in Table 1, and the electrochemical properties of the silicon-carbon composite material are shown in Table 2.

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PUM

Property	Measurement	Unit
Particle size	1.5 ~ 50.0	µm
Granularity	0.05 ~ 5.0	µm
Solid content	1.0 ~ 20.0
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

High bond strength
High bonding strength

Multi-core core-shell-structure silicon carbon composite negative pole material and preparation method thereof

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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