Nano-silicon amorphous carbon composition lithium ion battery cathode material and preparation method therefor

A technology of lithium-ion batteries and negative electrode materials, which is applied in the field of electrochemical power sources, can solve problems such as slow structure destruction, and achieve the effects of long cycle life and large capacity

Inactive Publication Date: 2009-09-09
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, it is difficult for existing methods to make silicon evenly and tightly coated or distributed in carbon, and the slow destruction of silicon structure during reversible charge and discharge cannot be completely avoided.

Method used

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  • Nano-silicon amorphous carbon composition lithium ion battery cathode material and preparation method therefor
  • Nano-silicon amorphous carbon composition lithium ion battery cathode material and preparation method therefor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] a) In a water bath at 90°C, 15g of pure polyvinyl alcohol (molecular weight: 80,000) and 135g of deionized water solvent were mixed by strong mechanical stirring for 12 hours until uniform white and transparent;

[0029] b) 1g of nano silicon powder with a particle size of 40nm, 0.5g of surfactant sodium phenylmethylsulfonate and 10g of deionized water were mixed and magnetically stirred for 1 hour, ultrasonicated for 1 hour, and finally stirred for 2 hours;

[0030] c) After mixing the solutions of steps a and b, use strong mechanical stirring for 12 hours, then mix the deionized water solvent, nano silicon powder and polyvinyl alcohol evenly;

[0031] d) Inject the suspension obtained in step c into a syringe, and use a pulse electrostatic generator to generate 25KV high voltage for electrospinning; the tip of the needle is ground flat, with an inner diameter of 1mm, and the flow rate is controlled by a syringe pump at a flow rate of 1ml / h. Collect the grounded alumin...

Embodiment 2

[0035] a) In a water bath at 50°C, 5g of polyacrylonitrile (molecular weight: 90,000) and 45g of solvent dimethylformamide were subjected to strong magnetic stirring for 12 hours until uniform yellow and transparent;

[0036]b) Mix 0.4g of nano silicon powder with a particle size of 40nm, 0.2g of surfactant sodium phenylmethylsulfonate and 10g of dimethylformamide with magnetic stirring for 1 hour, ultrasonication for 1 hour, and finally magnetic stirring for 2 hours ;

[0037] c) After mixing the solutions of steps a and b, use strong magnetic force to stir for 12 hours, and mix the dimethylformamide solvent, nano silicon powder and polyacrylonitrile evenly;

[0038] d) Inject the suspension obtained in step c into a syringe, and use a pulse-type electrostatic generator to generate 20KV high voltage for electrospinning; the tip of the needle is ground flat, with an inner diameter of 1mm, and the flow rate is controlled by a syringe pump at a flow rate of 1ml / h. Collect the g...

Embodiment 3

[0042] a) In a water bath at 40°C, 4g of polymethyl methacrylate (molecular weight: 30,000) and 40g of solvent dimethylformamide were subjected to strong magnetic stirring for 3 hours until uniform and transparent;

[0043] b) 1 g of nano silicon powder with a particle size of 40 nm, 0.5 g of surfactant sodium phenylmethylsulfonate and 8 g of dimethylformamide were mixed magnetically for 1 hour, ultrasonically for 1 hour, and finally magnetically stirred for 2 h;

[0044] d) After mixing the solutions of steps a and b, use strong magnetic force to stir for 12 hours, and mix the dimethylformamide solvent, nano silicon powder and polymethyl methacrylate evenly;

[0045] d) Inject the suspension obtained in step c into a syringe, and use a pulse-type electrostatic generator to generate 18KV high voltage for electrospinning; the tip of the needle is ground flat, with an inner diameter of 1mm, and the flow rate is controlled by a syringe pump at a flow rate of 1ml / h. Collect the gr...

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Abstract

The invention relates to a nano-silicon amorphous carbon composition lithium ion battery cathode material and a preparation method therefore, belonging to the field of electrochemistry power supply. The cathode material consists of a substrate and granules distributed evenly thereon, wherein, cores of the nano-granules are nano-silicon while shells thereof are amorphous carbon obtained by pyrogenation of organic substance; and the substrate thereof is obtained by pyrogenation and carbonization of organic electrospun fibre; wherein, content range of monomer silicon is 10%-50% and content range of amorphous carbon is 90%-50%. The preparation method comprises that nano-silicon granules and electrospun-available organic substances are uniformly stirred and mixed in solvent; high-voltage static electrospun is carried out to obtain fibrous composition; temperature is maintained at 80-200 DEG C, so as to volatilize the solvent completely; and carbonization is then carried out at 400-1000 DEG C. The silicon/carbon composition cathode material prepared by the method can effectively control volume change of silicon electrode material in charging and discharging process. Therefore, the electrode structure is maintained integral; the volume is released gradually. And the silicon/carbon composition cathode material has large circular volume, long circular service life and excellent electrochemical performance.

Description

technical field [0001] The invention relates to a lithium-ion battery silicon / carbon composite negative electrode material with a structure of nano core-shell particles embedded in a carbon matrix and a preparation method thereof, belonging to the field of electrochemical power sources. Background technique [0002] Due to the rapid development and wide application of various portable electronic devices and electric vehicles, there is an urgent need for lithium-ion batteries with high energy and long cycle life. At present, graphite, the main negative electrode material of commercial lithium-ion batteries, has low theoretical capacity (372mAh / g) and poor high-rate charge and discharge performance, which limits the further improvement of lithium-ion battery energy. [0003] So far, silicon has the highest theoretical capacity among anode materials, and Li and Si form an alloy Li x Si (0<x≤4.4), when forming Li 4.4 The theoretical capacity of Si compound is as high as 420...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/04
CPCY02E60/12Y02E60/10
Inventor 郑永平樊星邹麟沈万慈康飞宇黄正宏刘璇
Owner TSINGHUA UNIV
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