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A carbon sheet cage-coated porous silicon material and its preparation method and application

A technology of porous silicon and cages, applied in the direction of active material electrodes, structural parts, electrical components, etc., can solve the problems of low electron ion transmission efficiency, collapse of negative electrode material structure, and influence on lithium ion transmission, so as to shorten the transmission distance and make it possible High controllability, easy insertion/extraction effect

Active Publication Date: 2021-08-24
GUANGDONG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, there are still many problems with silicon-based materials as the negative electrode of lithium-ion batteries, such as volume expansion, low first effect, repeated growth of SEI film, consumption of electrolyte, low electron ion transmission efficiency, poor conductivity, etc., and volume expansion is the main problem; Because the alloy phase Li is formed during the intercalation of lithium ions into the silicon anode 15 Si 4 etc., resulting in extremely obvious volume expansion (more than 360%), and at the same time, huge stress will be formed due to the intercalation / removal of lithium ions; due to the above-mentioned effects, the following problems will occur: the active material is peeled off from the current collector; Crushing and pulverization of materials; continuous and repeated regeneration of SEI film
At the same time, a dense carbon layer is coated on the outer layer of silicon, which will affect the transmission of lithium ions, resulting in a large interface impedance.
The above processes are likely to cause the structural collapse of the negative electrode material and the attenuation of the battery capacity.

Method used

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  • A carbon sheet cage-coated porous silicon material and its preparation method and application
  • A carbon sheet cage-coated porous silicon material and its preparation method and application
  • A carbon sheet cage-coated porous silicon material and its preparation method and application

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] 1. Add aluminum-silicon alloy (average particle size D50 is 1-5 μm, mass ratio of aluminum to silicon is 4:1) into hydrochloric acid (0.5mol / L), stir by magnetic force, filter or centrifuge to make porous silicon.

[0036] 2. Prepare the sol-gel solution: add 0.1 g of glucose and 0.2 mL of siloxane to the mixed solution of 100 ml of ethanol and water (50 ml of ethanol, 50 ml of deionized water).

[0037] 3. Slowly and evenly add 0.5g of porous silicon powder to the prepared sol-gel solution; stir for 30min; then heat at 160°C for 12h to prepare the precursor;

[0038] 4. After sintering the precursor of step 3 at 1000°C under an inert atmosphere (argon or nitrogen), the C / SiO 2 Bicontinuous coated porous silicon.

[0039] 5. Add the C / SiO from step 4 2 The bicontinuous coated porous silicon is added into 5wt% hydrofluoric acid, washed and then dried to obtain the carbon sheet cage coated porous silicon.

[0040] Mix the porous silicon coated carbon sheet cage obtaine...

Embodiment 2

[0042] 1. Add aluminum-silicon alloy powder with an average diameter of 1 μm (purchased from Jiweixin, the mass ratio of aluminum to silicon is 4:1) to 0.5mol / L HCl, stir for 12 hours by magnetic force, after passing through deionized water and absolute ethanol After washing for the first time, the obtained sample was placed in a vacuum drying oven and baked at 50° C. for 10 h to obtain porous silicon.

[0043] 2. Configure the sol-gel solution: add 0.1g sucrose (C 6 h 12 o 6 ) and 0.2 mL tetraethyl orthosilicate (28% TEOS) solution.

[0044] 3. Slowly and evenly add 0.5g of porous silicon powder to the prepared sol-gel solution; stir for 30min; then heat at 160°C for 12h to prepare the precursor;

[0045] 4. Under argon, the precursor was raised to 800°C at a rate of 5°C / min and then annealed for 2 hours, and then cooled to room temperature to obtain SiO 2 The / C bicontinuous item is coated with porous silicon.

[0046] 5. According to the chemical equation 4HF+SiO 2 = ...

Embodiment 3

[0049] 1. Add aluminum-silicon alloy powder with an average diameter of 1 μm (purchased from Jiweixin, the mass ratio of aluminum to silicon is 4:1) to 0.5mol / L HCl, stir for 12 hours by magnetic force, and wash with deionized water and absolute ethanol. After washing for the first time, the obtained sample was placed in a vacuum drying oven and baked at 50° C. for 10 h to obtain porous silicon.

[0050] 2. Configure the sol-gel solution: add 0.1g sucrose (C 6 h 12 o 6 ) and 1 mL tetraethyl orthosilicate (28% TEOS) solution.

[0051] 3. Slowly and uniformly add 0.5g of porous silicon powder into the prepared sol-gel solution; stir for 30min, and heat at 160°C for 12h to prepare the precursor.

[0052] 4. Under the protection of pure argon, the precursor was annealed at a rate of 5 °C / min to 900 °C for 2 hours, and then cooled to room temperature to obtain C / SiO 2 The bicontinuous item is coated with porous silicon.

[0053] 5. The amount of HF was calculated according to ...

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Abstract

The invention belongs to the technical field of lithium batteries, and discloses a carbon sheet cage-coated porous silicon material, a preparation method and application thereof. The carbon sheet cage-coated porous silicon material is prepared by adding aluminum-silicon alloy into an inorganic acid solution, stirring, filtering or centrifuging to prepare porous silicon, and adding porous silicon to ethanol / deionized water containing carbon source and silicon dioxide source Stir in the mixed solution and keep warm at 150-170°C to prepare the precursor; the obtained precursor is sintered at 800-1000°C under an inert atmosphere to obtain C / SiO 2 Bicontinuous coating of porous silicon, the C / SiO 2 Double continuous coated porous silicon is prepared by adding hydrofluoric acid, washing and drying. The carbon sheet cage-coated porous silicon material of the present invention has excellent high reversible capacity, cycle stability and rate performance, and can be applied in the field of lithium batteries.

Description

technical field [0001] The invention belongs to the technical field of lithium batteries, and in particular relates to a carbon sheet cage-coated porous silicon material and a preparation method and application thereof. Background technique [0002] Lithium-ion batteries have been widely used in portable consumer electronics, new energy vehicles, medical electronics and other fields due to their environmental protection and pollution-free advantages. With its wide application, consumers have a demand for the energy density of lithium batteries It is also growing. Under the condition that the positive electrode cannot effectively increase the energy density of the battery, it is imminent to increase the theoretical specific energy density of the negative electrode material. At present, the most commonly used is graphite negative electrode, whose theoretical specific capacity is only 372mAh / g, while the current theoretical lithium intercalation capacity of the new silicon car...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/583H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/583H01M4/625H01M10/0525H01M2004/027Y02E60/10
Inventor 李新喜方称辉张国庆杨晓青刘龙郑炳河
Owner GUANGDONG UNIV OF TECH