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Silicon-based composite negative electrode material and preparation method thereof and energy storage device

A technology of silicon-based materials and negative electrode materials, applied in the direction of electrical components, battery electrodes, structural parts, etc., can solve the problems of fast consumption of electrolyte, structural damage of electrode materials, pulverization, etc., and achieve improved negative electrode cycle performance and long life Safety performance, effect of preventing corrosion damage

Active Publication Date: 2019-05-07
HUAWEI TECH CO LTD
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Problems solved by technology

However, silicon-based materials will experience severe volume expansion (0-300%) and shrinkage during the lithium-deintercalation reaction, which will lead to structural damage and pulverization of the electrode material, and the silicon surface will continue to produce new SEI films with the electrolyte. , resulting in the depletion of the electrolyte and rapid decline in battery capacity
[0004] In order to solve the above problems, the industry usually adopts nanometerization to improve the volume expansion effect of silicon. However, nanometerization also brings high specific surface area, easy aggregation and difficult dispersion, large contact area with electrolyte, and fast electrolyte consumption. question
In order to further solve the above-mentioned problems caused by nanometerization, people set up coating layers (such as carbon material layers) on the surface of nano-silicon anode materials, but the strength of these coating layers is still not enough to support the multiple expansion and contraction of silicon-based materials. , the coating layer will eventually break away from the surface of the silicon material, which will intensify the consumption of electrolyte, the inactivation of silicon, and finally reflect the decline of capacity
In addition, in order to improve the cycle performance of silicon-based materials, a high content of fluoroethylene carbonate (FEC) is usually added to the electrolyte or an artificial SEI film (such as LiF, MgF, etc.) is coated on the surface of silicon-based materials. 2 etc.), however, the introduction of F will lead to the generation of HF, which will corrode the positive and negative electrode materials and current collectors, and eventually lead to high-temperature gas production, poor storage performance and safety, and rapid capacity decay

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  • Silicon-based composite negative electrode material and preparation method thereof and energy storage device
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  • Silicon-based composite negative electrode material and preparation method thereof and energy storage device

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[0041] Correspondingly, the embodiment of the present invention also provides a method for preparing a silicon-based composite negative electrode material, including the following steps:

[0042] S10, taking a silicon-based material, and forming a fast ion conductor layer on the surface of the silicon-based material;

[0043] S20, forming a fluorine-containing carbon material layer on the surface of the fast ion conductor layer to obtain a silicon-based composite negative electrode material, the silicon-based composite negative electrode material comprising a silicon-based material core and a coating formed on the surface of the silicon-based material core core layer, the cladding layer includes a fast ion conductor layer and a fluorocarbon material layer, the fluorocarbon material layer is formed on the surface of the fast ion conductor layer, and the fast ion conductor layer is formed on the silicon-based material core The surface is located between the silicon-based materia...

Embodiment 1

[0054] A method for preparing a silicon-based composite negative electrode material, comprising the steps of:

[0055] S101, Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 Fabrication of Coated Silicon (Si@LATP) Materials

[0056] Add 10 g of commercial nano-silicon (median particle size D50 is 80nm-150nm) into 100mL deionized water, ultrasonically disperse, and then sequentially add lithium acetate (Li(CH 3 COO)·2H 2 O), aluminum nitrate (Al(NO) with a final concentration of 0.6mol / L 3 )·9H 2 O) and ammonium dihydrogen phosphate (NH 4 h 2 PO 4 ), magnetically stirred at room temperature until completely dissolved. Add 5 mL of acetylacetone to the mixed salt solution, stir for 15 min, drop in stoichiometric ratio of 0.34 mol / L butyl titanate drop by drop, continue to stir for 2 h to obtain Si@LATP sol, stand and mature for 24 h, and place the gel in Vacuum dry at 100°C for 6h, then raise to 700°C at 5°C / min, and keep for 2h to obtain the silicon material Si@LATP coated with LATP o...

Embodiment 2

[0064] A method for preparing a silicon-based composite negative electrode material, comprising the steps of:

[0065] S101, Li 7 La 3 Zr 2 o 12 Preparation of Coated SiO(SiO@LLZO) Material

[0066] Take Li 2 CO 3 , La 2 o 3 and ZrO(NO 3 ) 2 ·6H 2 O, according to the molar ratio of 7.7:3:2 feeding and dissolving in the aqueous solution, adjust the pH~7 to obtain Li 7 La 3 Zr 2 o 12 Precursor solution: Disperse commercial SiO samples (median particle size D50 of 1 μm-5 μm) in LLZO precursor solution, mix well, filter, dry the obtained solid, and sinter at 850°C for 5-8h (under argon atmosphere ), get Li 7 La 3 Zr 2 o 12 Coated SiO material SiO@LLZO.

[0067] S102. Preparation of graphene-coated SiO@LLZO (SiO@LLZO@graphene) material

[0068] Disperse SiO@LLZO on the quartz substrate, transfer it to the furnace, pass in a hydrogen-argon mixture gas, raise it to 1000°C at a rate of 20°C / min, and maintain it for 20 minutes; then stop the flow of protective gas a...

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Abstract

The embodiment of the invention provides a silicon-based composite negative electrode material, which comprises a silicon-based material core and a coating layer formed on the surface of the silicon-based material core. The coating layer comprises a fast ion conductor layer and a fluorocarbon material layer. The fluorocarbon material layer is formed on the surface of the fast ion conductor layer.The fast ion conductor layer is formed on the surface of the silicon-based material core, and is located between the silicon-based material core and the fluorocarbon material layer to separate the silicon-based material core from the fluorocarbon material layer. The silicon-based composite negative electrode material has high capacity, high electrical conductivity and ionic conductivity and high structural stability, can protect itself from corrosion of the silicon-based material core by HF, can generate a LiF layer in situ during the first battery charging process, and has good cyclic stability. The embodiment of the invention also provides a preparation method of the silicon-based composite negative electrode material and an energy storage device comprising the silicon-based composite negative electrode material.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a silicon-based composite negative electrode material, a preparation method thereof, and an energy storage device. Background technique [0002] Lithium-ion batteries are widely used in portable electronic devices, electric vehicles and energy storage devices due to their advantages such as high working voltage, high energy density, long cycle life and no memory effect. However, with the increasing demand for high capacity density, long life and high safety of equipment, people put forward higher requirements for the energy density and service life of lithium-ion batteries. [0003] When the current commercial cathode material lithium cobalt oxide reaches its maximum limit (4.4V, compaction 4.2g / cm 3 ), the capacity of the negative electrode is crucial to the improvement of the energy density of the entire battery cell. However, the current commercial graphite ano...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/583H01M4/62H01M10/0525
CPCY02E60/10
Inventor 苏航李阳兴刘辰光王平华
Owner HUAWEI TECH CO LTD
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