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Silicon-based negative electrode material and preparation method thereof

A silicon-based negative electrode material, carbon matrix technology, applied in negative electrodes, carbon preparation/purification, chemical instruments and methods, etc., can solve the problems of electrode cracking, peeling, difficult preparation technology, electrode capacity attenuation, etc. Machinability and conductivity, improvement of machinability and conductivity, effect of improving swelling problems

Active Publication Date: 2020-12-25
SHAANXI COAL & CHEM TECH INST
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Silicon-based materials will produce about 300% volume change during charge and discharge, which will cause electrode cracking, peeling and pulverization, and eventually cause electrode capacity attenuation or even complete failure. In order to improve the cycle stability of silicon-based negative electrode materials, silicon materials are usually Nanoization, the main research directions are: silicon nanoparticles, silicon nanowires, silicon films and 3D porous silicon, etc., but the preparation technology of complex structure nanoparticles and one-dimensional nanowires is difficult, the process is complicated, and the cost is high

Method used

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  • Silicon-based negative electrode material and preparation method thereof

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Effect test

Embodiment 1

[0026] (1) Diatomite pretreatment: keep the diatomite at 400°C for 4 hours to remove organic matter; then crush, pickle and wash the heat-treated diatomite, wherein the pickling adopts mass fraction>70% sulfuric acid at 70°C for 2 hours at a liquid-to-solid ratio of 5:1, and alternate pickling and water washing until the pH of the washing solution is between 6 and 8; then the diatomite after pickling and water washing is baked Drying, pulverization, and finally purified porous SiO 2 powder.

[0027] (2)SiOx / Si / Li 2 Preparation of SiOy composite: lithium powder and porous SiO with a mass ratio of 1:0.5 2 The powders are mixed evenly and heat-treated at 750°C under a nitrogen atmosphere to obtain porous SiOx / Si / Li 2 SiOy composite, due to the incomplete reaction of lithium powder and porous SiO2 powder, the obtained SiOx / Si / Li 2 In the SiOy composite, 1≤x≤2, 3≤y≤5.

[0028] (3) Precursor slurry preparation: Add porous SiOx / Si / Li2SiOy composite, flake graphite, and dispersan...

Embodiment 2

[0031] (1) Diatomite pretreatment: heat diatomite at 750°C for 1 hour to remove organic matter; Pickling at a solid ratio of 2:1 for 1 h, acid washing and water washing alternately until the pH of the washing solution is between 6-8; drying and pulverizing the diatomite after pickling and water washing to obtain purified porous SiO 2 powder.

[0032] (2)SiOx / Si / Li 2 Preparation of SiOy composite: lithium powder and porous SiO with a mass ratio of 1:3 2 The powders are evenly mixed, and heat-treated in an argon atmosphere at 600°C to obtain porous SiOx / Si / Li 2 SiOy composite.

[0033] (3) Precursor slurry preparation: the porous SiOx / Si / Li 2 The SiOy composite, the composite of flake graphite and soft carbon, and the dispersant were added to ethanol and acetone, respectively, and wet-milled for 12 hours to obtain a uniformly dispersed precursor slurry, in which the porous SiOx / Si / Li2SiOy composite was combined with flake graphite and soft carbon The mass ratio of the carbo...

Embodiment 3

[0036] (1) Diatomite pretreatment: heat-treat diatomite at 600°C and keep it warm for 2 hours to remove the organic matter in the diatomite; Sulfuric acid with a mass fraction > 70% was used to pickle for 4 hours at 85°C and a liquid-to-solid ratio of 3:1, alternately pickling and washing with water until the pH of the washing solution was between 6-8; Dry and pulverize algae to obtain purified porous SiO 2 powder.

[0037] (2)SiOx / Si / Li 2 Preparation of SiOy composite: Lithium powder and porous SiO with a mass ratio of 1:1 2 Mix the powders evenly, and heat-treat at 900°C under a helium atmosphere to obtain porous SiOx / Si / Li 2 SiOy composite.

[0038] (3) Precursor slurry preparation: the porous SiOx / Si / Li 2 The SiOy composite, the composite of hard carbon and artificial graphite, and the dispersant were added to ethanol, and wet-milled for 1 hour to obtain a uniformly dispersed precursor slurry, in which the mass ratio of porous SiOx / Si / Li2SiOy composite to hard carbon wa...

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Abstract

The invention discloses a silicon-based negative electrode material and a preparation method thereof. The silicon-based negative electrode material comprises an inner core, a porous intermediate layerand a shell. The inner core is a carbon matrix material, the porous intermediate layer is a SiOx / Si / Li2Oy compound, the shell is a carbon coating layer, and the porous intermediate layer takes diatomite as a silicon source, wherein x is greater than or equal to 1 and less than or equal to 2, and y is greater than or equal to 3 and less than or equal to 5. The invention aims to solve the problem of expansion of the silicon-based negative electrode material, improve the initial coulombic effect of the material on the basis of not reducing the conductivity, and reduce the preparation cost of thematerial by taking diatomite as a silicon source, thereby being beneficial to industrial production of the silicon-based negative electrode material.

Description

technical field [0001] The invention belongs to the technical field of negative electrode materials for lithium ion batteries, and in particular relates to a silicon-based negative electrode material. Background technique [0002] The improvement of energy density has always been the main theme of the development of lithium-ion battery technology. One is to optimize the battery structure, such as Ningde era CPT technology, BYD "blade battery" and other ideas; the other is to focus on breaking through the technical barriers of high-capacity materials. It is also the mainstream method adopted by battery manufacturers at present. Positive and negative electrode materials are the key to improving the energy density of lithium-ion batteries. Although the positive electrode material occupies the core position in the battery, the theoretical gram capacity of the graphite-based negative electrode material is 372mAh / g, which becomes the limiting condition for further energy improveme...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/48H01M4/62H01M10/0525C01B32/05C01B33/023C01B33/18
CPCH01M4/366H01M4/386H01M4/483H01M4/625H01M4/628H01M10/0525C01B33/18C01B32/05C01B33/023H01M2004/021H01M2004/027C01P2004/80C01P2006/40Y02E60/10
Inventor 王夏阳曹新龙田占元张长安曹国林白杨芝薛孟尧胥鑫霍林智
Owner SHAANXI COAL & CHEM TECH INST
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