Silicon-carbon composite material with multi-layer coating structure and preparation method thereof

A silicon-carbon composite material and coating structure technology, applied in structural parts, carbon compounds, chemical instruments and methods, etc., can solve the problems of active lithium ion and electrolyte consumption, low battery coulomb efficiency, SEI film rupture, etc. Improve coulombic efficiency and cycle retention, reduce side reactions, and reduce consumption

Active Publication Date: 2020-06-30
西安英纳吉科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, silicon has a volume expansion of up to 400% when intercalating lithium, and the brittle SEI film is easily broken, causing silicon to be directly exposed to the electrolyte.
During the charge-discharge cycle, with the intercalation and extraction of lithium ions, the newly exposed silicon surface contacts and reacts with the electrolyte solution, which continuously causes the consumption of active lithium ions and electrolyte solution, which is manifested by low coulombic efficiency of the battery. and decreasing capacity

Method used

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  • Silicon-carbon composite material with multi-layer coating structure and preparation method thereof
  • Silicon-carbon composite material with multi-layer coating structure and preparation method thereof
  • Silicon-carbon composite material with multi-layer coating structure and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0043] Step 1: Weigh 1 part of nano-silicon, mix it with 8 parts of ethanol and grind it in a sand mill to obtain an ethanol dispersion of D50 silicon at 150 nm;

[0044] Step 2: Weigh 8 parts of graphite with a D50 of 5 μm, and add it into the ethanol dispersion of nano-silicon, and stir evenly to obtain the ethanol dispersion of nano-silicon and graphite;

[0045] Step 3: Add 0.4 parts of asphalt with a softening point of 160°C and a particle size of D50 of 1.8 μm into the dispersion of nano-silicon and graphite and mix evenly;

[0046] Step 4: Spray-dry the ethanol dispersion of nano-silicon, graphite and asphalt, and the spray-drying temperature is 160°C to obtain a dry powdery single-stage coated silicon-carbon material precursor;

[0047] Step 5: Weigh 0.8 parts of high-temperature asphalt (softening point is 260°C, coking value is 70%, particle size is 3 μm), and mix it with the single-stage coated silicon carbon material precursor evenly, then add it to the high-temper...

Embodiment approach 2

[0083] Step 1: Weigh 2 parts of nano-silicon, mix it with 10 parts of ethanol and grind it in a sand mill to obtain an ethanol dispersion of D50 at 200nm silicon;

[0084] Step 2: Weigh 10 parts of graphite with a D50 of 7 μm, and add it into the ethanol dispersion of nano-silicon, and stir evenly to obtain the ethanol dispersion of nano-silicon and graphite;

[0085] Step 3: Add 0.5 parts of asphalt with a softening point of 160°C and a particle size of D50 of 1.5 μm into the dispersion of nano-silicon and graphite and mix evenly;

[0086] Step 4: Spray-dry the ethanol dispersion of nano-silicon, graphite and pitch at a spray-drying temperature of 180°C to obtain a dry powder single-stage coated silicon-carbon material precursor;

[0087] Step 5: Weigh 1 part of high-temperature pitch (softening point of 250°C, coking value of 70%, particle size of 3 μm), and mix it with the single-stage coated silicon carbon material precursor evenly, then add it to the high-temperature VC m...

Embodiment approach 3

[0090] Step 1: Weigh 1 part of nano-silicon, mix it with 7 parts of methanol, and grind it in a sand mill to obtain a D50 dispersion of 150nm silicon;

[0091] Step 2: Weighing 8 parts of graphite with a D50 of 5 μm, and adding it to the nano-silicon dispersion, stirring evenly to obtain a mixed dispersion of nano-silicon and graphite;

[0092] Step 3: Add 0.4 parts of asphalt with a softening point of 160°C and a particle size of D50 of 1.3 μm into the dispersion of nano-silicon and graphite and mix evenly;

[0093] Step 4: Spray-dry the dispersion of nano-silicon, graphite and asphalt, and the spray-drying temperature is 210°C to obtain a dry powder single-stage coated silicon-carbon material precursor;

[0094] Step 5: Weigh 0.8 parts of high-temperature asphalt (softening point is 260°C, coking value is 70%, particle size is 3 μm), and mix it with the single-stage coated silicon carbon material precursor evenly, then add it to the high-temperature VC mixer, under nitrogen C...

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Abstract

The invention belongs to the technical field of silicon-carbon composite materials with multi-layer coating structures. The invention relates to a silicon-carbon composite material, in particular to asilicon-carbon composite material with a multi-layer coating structure. A preparation method is based on a cross-scale modification technology for a silicon-based negative electrode. Secondary particle self-assemblying and uniform dispersion of nano-silicon in gaps of graphite secondary granulation particles can be realized; through fine regulation and structural design of asphalt with differentsoftening points, multi-layer carbon layer coating can be realized; volume expansion of silicon is effectively buffered; the bonding of the secondary particles in the drying process is assisted; through fine screening and targeted regulation and control of asphalt with different softening points, distribution of nano-silicon in gaps of secondary granulation of the graphite matrix and coating modification of the surface of the graphite matrix are realized; the structure can effectively isolate direct contact between silicon and an electrolyte, reduce side reactions, effectively reduce consumption of active lithium ions and the electrolyte in a battery cycle process, and improve coulombic efficiency and cycle retention rate of the material.

Description

technical field [0001] The invention relates to the technical field of multi-level coating structure silicon-carbon composite materials, in particular to a multi-level coating structure silicon-carbon composite material and a preparation method thereof. Background technique [0002] In recent years, due to the dual pressure of energy crisis and environmental pollution, the importance of exploring and developing sustainable new energy has become increasingly prominent. At the same time, electrochemical energy storage devices represented by secondary batteries have also become the focus of the industry for their applications in new energy vehicles, grid energy storage, and digital products. How to further increase the energy density of lithium batteries has always been a frontier research direction in the lithium battery industry. Traditional graphite materials are currently the most widely used anode materials in lithium batteries. However, the theoretical capacity of graphi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B32/205C01B32/20C01B33/02H01M4/38H01M4/62H01M10/052
CPCC01B32/205C01B32/20C01B33/02H01M4/386H01M4/625H01M10/052Y02E60/10
Inventor 马越
Owner 西安英纳吉科技有限公司
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