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A kind of silicon-based Si-C negative electrode material and its electrochemical synthesis method and application

A technology of negative electrode material and synthesis method, which is applied in the field of silicon-based Si-C negative electrode material and its electrochemical synthesis, and can solve problems such as complex process, ohmic polarization, and uneven distribution of silicon and carbon

Active Publication Date: 2020-10-27
NORTHEASTERN UNIV LIAONING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The amorphous carbon formed after calcination isolates the contact between silicon and electrolyte and improves the stability of the material, but there are still problems such as uneven distribution of silicon and carbon, easy agglomeration of silicon particles, insufficient conductivity, and easy ohmic polarization.
At the same time, the preparation process of the above-mentioned silicon-carbon composite materials is complicated and the production cost is high.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] An electrochemical synthesis method of a silicon-based Si-C negative electrode material is carried out according to the following steps;

[0061] (1) CaCl 2 , CaO, NaCl, cut metallurgical-grade silicon wafers, and graphite rods were placed in a high-temperature vacuum drying furnace at a temperature of 400°C and a pressure of -0.1MPa, and dried for 12 hours to remove adsorbed water and part of the crystallized water.

[0062] (2) Connect iron-chromium-aluminum wire and graphite rod to form an anode, and pass through the reactor cover; use molybdenum wire to connect the cut silicon raw material sheet with the metal collector rod of the agitation device connected to the reactor cover constitute the cathode.

[0063] (3) Weigh 500±0.1gCaCl in an argon gas environment 2 , 50±0.1gCaO, 100±0.1gNaCl, after mixing, pour it into the nickel crucible embedded in the reactor placed in the resistance wire furnace, and seal the reactor with the reactor cover.

[0064] (4) Place th...

Embodiment 1

[0072] According to the mass ratio, the ratio of silicon-based Si-C negative electrode material: conductive agent acetylene black: binder PVDF=6:2:2, the silicon-based Si-C with a particle size of 30-300 nanometers prepared in Example 1 The negative electrode material is evenly mixed with the conductive agent acetylene black and the binder PVDF, and the solvent N-methylpyrrolidone is added to prepare a slurry, and the slurry is coated on the copper foil current collector to obtain an electrode sheet.

[0073] Place the electrode sheet in a vacuum dryer and dry it at 80°C for 12 hours. After the electrode sheet is completely dry, punch the electrode sheet into a circular electrode sheet with a diameter of 12mm.

[0074] The obtained disc electrode sheet was used as the negative electrode, the metal lithium sheet was used as the positive electrode, Celgard2400 was used as the separator, and EC / DMC (1:1)-LiPF6 (1M) was used as the electrolyte, and the battery was assembled in a gl...

Embodiment 2

[0077] A kind of electrochemical synthesis method of silicon-based Si-C negative electrode material, with embodiment 1, difference is:

[0078] (1) In step (3), 100g sodium chloride is replaced with 100g potassium chloride;

[0079] (2) In step (5), the synthesis temperature is 760°C;

[0080] Other methods are the same.

[0081] Prepare a silicon-based Si-C negative electrode material with a particle size of 50-280 nanometers, and prepare a lithium-ion battery with the silicon-based Si-C negative electrode material in the manner of Application Example 1. The first discharge specific capacity of the prepared lithium-ion battery is 2908.4 mAh·g -1 , with a Coulombic efficiency of 76%, at 0.1A g -1 After 500 cycles of current density, the reversible cycle specific capacity of the battery is 1400.5mAh g -1 , the Coulombic efficiency was maintained at 99%.

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Abstract

A silicon-based Si-C negative electrode material and its electrochemical synthesis method and application belong to the field of battery negative electrode material preparation. This electrochemical method uses metallurgical silicon and carbon dioxide as raw materials, in CaCl 2 -In CaO-based salts, static metallurgical silicon or dynamically rotating metallurgical silicon is used as the cathode, graphite rods or inert materials are used as the anode, and a voltage higher than the decomposition of calcium oxide and lower than the decomposition of molten salt is applied between the cathode and the anode, electrolysis Afterwards, introduce CO 2 , left to stand, and after post-processing, the silicon-based Si-C anode material is obtained. This method controls the silicon and carbon in the silicon-based Si-C anode material through the salt composition, synthesis temperature, synthesis time, decomposition voltage and cathode rotation rate. Distribution, control product morphology and particle size. This method achieves low-cost, controlled preparation of silicon-based Si-C anode materials, and the operation process is simple. The prepared lithium-ion battery has good specific capacity and cycle performance.

Description

technical field [0001] The invention relates to the field of battery negative electrode material preparation, in particular to a silicon-based Si-C negative electrode material and an electrochemical synthesis method and application thereof. Background technique [0002] With the increasing use of portable electronic devices and electric vehicles, the development of lithium-ion batteries with high energy density has become an urgent need. Graphite is the current commercial lithium-ion battery anode material, and its theoretical capacity is 372mAh / g, which cannot meet the high-capacity demand of the next-generation lithium-ion battery. Therefore, it is urgent to develop a high-capacity, high-power-density anode material to replace graphite. As the anode material of lithium-ion batteries, silicon has attracted much attention because of its theoretical capacity as high as 4200mAh / g, abundant reserves, low price, and low intercalation / delithiation potential. However, the volume...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525C25B1/00
CPCC25B1/00C25B1/33H01M4/362H01M4/386H01M4/625H01M4/628H01M10/0525H01M2004/021H01M2004/027Y02E60/10
Inventor 谢宏伟徐亚男王锦霞尹华意宋秋实宁志强
Owner NORTHEASTERN UNIV LIAONING