A kind of silicon/silicon carbon/graphite composite negative electrode material for lithium ion battery

A technology for lithium-ion batteries and negative electrode materials, applied in battery electrodes, secondary batteries, electrode carriers/collectors, etc., can solve problems such as accelerated transmission speed, battery capacity attenuation, agglomeration, etc., achieve good electrochemical stability, reduce volume change, the effect of material structure stabilization

Active Publication Date: 2016-05-18
CHINA AUTOMOTIVE BATTERY RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] There are two main methods to improve silicon negative electrode materials: one is the nanometerization of the material size. By reducing the particle size, the tension generated by the volume expansion can be easily released, so as to prevent particle breakage and shorten the lithium ion (Li + ) transmission distance, to speed up the transmission speed; however, pure silicon nanoparticles have high surface energy and defects, their thermodynamic properties are unstable, and they are easy to agglomerate in the process of charging and discharging, resulting in rapid decay of battery capacity

Method used

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  • A kind of silicon/silicon carbon/graphite composite negative electrode material for lithium ion battery
  • A kind of silicon/silicon carbon/graphite composite negative electrode material for lithium ion battery
  • A kind of silicon/silicon carbon/graphite composite negative electrode material for lithium ion battery

Examples

Experimental program
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Effect test

Embodiment 1

[0051] Take 100g of silicon nanoparticles (particle size D50 is 100nm) and disperse in 1000g of liquid vinyl tris (2-methoxyethoxy) silane monomer compound, stir for 0.5h by a vacuum stirrer, under the condition of stirring , add 500mLpH to the above-mentioned dispersion liquid and be the ethanol-water mixed solution (ethanol / water=9 / 1, volume ratio) of 6.8, and keep stirring for 4h, add 700g conductive graphite (model is KS-6) and continue stirring for 4h, obtain Viscous mixture, the viscous mixture is extruded 4 times through a screw extruder to obtain a paste mixture.

[0052] The obtained paste mixture precursor was treated at 700°C for 1 h in a protective atmosphere to obtain a theoretical stoichiometric ratio of 0.06Si-0.012SiO 1.5 C 2.1 -C silicon / silicon carbon / graphite composite bulk material.

[0053] The obtained silicon / silicon carbon / graphite composite material was crushed by magnetic force for 1min, and processed under a planetary ball mill at 500rpm for 12h to...

Embodiment 2

[0056] The same process as in Example 1, the difference is that the number of times of screw extrusion becomes 3 times. The initial charging and discharging points of the composite materials are 746mAh / g and 614.1mAh / g respectively, the first Coulombic efficiency is 82.3%, the specific capacity after 10 cycles is 556.2mAh / g, and the capacity retention rate is 90.57%.

Embodiment 3

[0058] The same process as in Example 1, except that the number of times of screw extrusion becomes 2 times. The first reversible specific capacity of the composite material is 459.9mAh / g, the specific capacity after 5 cycles is 548.8mAh / g, the specific capacity after 10 cycles is 533.5mAh / g, and the capacity retention rate is 116%.

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Abstract

The invention relates to a silicon / silicon carbon / graphite composite negative electrode material for a lithium ion battery, which is a silicon-containing material with a uniform and firm dispersion size below 3 μm on the surface of the graphite negative electrode. The present invention also provides a preparation method for the composite negative electrode material, comprising: dispersing the silicon-containing material in a liquid organosiloxane monomer, sequentially adding an acidic solution of ethanol-water, a curing agent and graphite negative electrode material, and then performing ball milling or Mechanical stirring and kneading are mixed to obtain a paste mixture. The paste is calcined at high temperature and crushed and sieved in a protective atmosphere to obtain silicon / silicon carbon / graphite lithium ion battery negative electrode materials with various particle sizes. The silicon-containing material in the silicon / silicon carbon / graphite composite negative electrode material is firmly and evenly distributed on the surface of the graphite material. This structure can make the silicon material effectively adsorb on the surface of the graphite, avoiding the agglomeration of the silicon material itself and the interaction with the graphite. It has the characteristics of adjustable charge-discharge specific capacity and high electrochemical cycle stability.

Description

technical field [0001] The invention relates to a highly dispersed silicon / silicon carbon / graphite composite negative electrode material for lithium ion batteries and a preparation method thereof. technical background: [0002] Due to its performance advantages, lithium-ion batteries have been used in various mobile energy storage, such as laptops, mobile phones and cameras. With the development of lithium-ion batteries, high specific energy, long-life, and low-cost lithium-ion batteries that can be used in the fields of electric vehicles and energy storage power stations will become the focus of research. Currently, as one of the main factors determining battery performance, positive electrode materials, such as lithium manganese oxide (LiMn 2 o 4 ), lithium cobaltate (LiCoO 2 ), lithium iron phosphate (LiFePO 4 ) and ternary materials, a major breakthrough has been made in technology, which has laid the foundation for the research and development of high-performance li...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/38H01M4/48H01M4/66
CPCH01M4/139H01M4/38H01M4/48H01M4/66H01M10/0525Y02E60/10
Inventor 卢世刚王建涛杨娟玉李涛谭翱王耀黄斌黄倩
Owner CHINA AUTOMOTIVE BATTERY RES INST CO LTD
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