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Silicon-carbon anode material for lithium ion batteries and preparation method thereof

A lithium-ion battery and negative electrode material technology, applied in battery electrodes, nanotechnology for materials and surface science, secondary batteries, etc., can solve the problems that are difficult to meet the needs of society and life, poor conductivity, low energy density, etc. problems, to achieve the effect of improving the first efficiency, improving conductivity, and the steps are simple and easy

Inactive Publication Date: 2019-12-20
HUBEI WANRUN NEW ENERGY TECH DEV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] Lithium-ion batteries are widely used in portable electronic devices and electric vehicles because of their advantages such as high specific energy, high working voltage, low self-discharge, small size, and light weight. However, with the improvement of living standards, the original lithium-ion batteries Battery performance has been difficult to meet the needs of society and life, so higher requirements are put forward for lithium-ion batteries
At present, the commercial lithium-ion battery anode material is mainly graphite, but its theoretical specific capacity is only 372mAh / g, which is far from meeting people's needs, while silicon material has a theoretical specific capacity ten times that of graphite (4200mAh / g ), low lithiation potential, high energy density, cheap price, no pollution, etc., and become one of the best choices for a new generation of high energy density anode materials
[0003] However, due to the poor electrical conductivity of the silicon material itself and the structural damage or even pulverization caused by the large volume expansion during the charging and discharging process, it has a large capacity fading during the cycle, which limits its wider application. The material is considered to be an excellent option for silicon material compounding due to its good conductivity and low cost

Method used

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  • Silicon-carbon anode material for lithium ion batteries and preparation method thereof
  • Silicon-carbon anode material for lithium ion batteries and preparation method thereof
  • Silicon-carbon anode material for lithium ion batteries and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Step 1, wet ball milling: Weigh 30nm nano-silicon, spherical graphite and citric acid with a mass ratio of 1:7:5, disperse the nano-silicon in a certain amount of deionized water, and add 1% volume ratio of anhydrous Ethanol, ultrasonic 0.5h disperse, dissolve the coated carbon source in a small amount of water, mix the solution, pour it into a ball mill jar together with spherical graphite, and ball mill at 350r / min for 3h;

[0022] Step 2, spray drying: take out the dispersion liquid after ball milling, start spray drying, the air inlet temperature is 200°C, the outlet air temperature is 85°C, and the feed rate is 20ml / min for spray drying;

[0023] Step 3, sintering and carbonization: in the atmosphere furnace, under the protection of nitrogen atmosphere, keep the temperature at 850° C. for 3 hours, and finally obtain the desired silicon-carbon negative electrode material.

Embodiment 2

[0025] The difference from Embodiment 1 is that this embodiment includes the following steps

[0026] Step 1, wet ball milling: Weigh 30nm nano-silicon, spherical graphite and PVP with a mass ratio of 1:7:5, disperse the nano-silicon in a certain amount of deionized water, and add 1% volume ratio of absolute ethanol , disperse by ultrasonication for 0.5h, dissolve the coated carbon source in a small amount of water, mix the solution, pour it into a ball mill jar together with spherical graphite, and mill at 350r / min for 3h;

[0027] Step 3, sintering and carbonization: in an atmosphere furnace under the protection of a nitrogen atmosphere, keep the temperature at 650° C. for 3 hours, and finally obtain the required silicon-carbon negative electrode material.

[0028] Others are the same as in Example 1 and will not be repeated here.

Embodiment 3

[0030] Step 1, wet ball milling: Weigh 30nm particle size nano-silicon, spherical graphite and citric acid, the mass ratio is 1:5:5, disperse the nano-silicon in a certain amount of deionized water, add 1% volume ratio of anhydrous Ethanol, ultrasonic 0.5h disperse, dissolve the coated carbon source in a small amount of water, mix the solution, pour it into a ball mill jar together with spherical graphite, and ball mill at 350r / min for 3h;

[0031] Others are identical with embodiment 1 and are not repeated here.

[0032] Battery assembly: Mix and stir the silicon-carbon negative electrode material prepared in Examples 1-3 with conductive agent (superP), binder (CMC, SBR), and solvent to obtain electrode slurry, and then coat it on the current collector A negative electrode is obtained; the negative electrode is assembled with a counter electrode lithium sheet, a separator, and foamed nickel to obtain a half-cell to be tested.

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Abstract

The invention discloses a silicon-carbon anode material for lithium ion batteries and a preparation method thereof. The silicon-carbon anode material is a silicon-carbon composite material with core-shell structure formed by compounding spherical graphite and nano-silicon, and coating the outer layer with a carbon layer. The method firstly uniformly dispersing spherical graphite and nano-silicon by wet ball mill and generating a certain mechanical combination; then spray drying the obtained paste so as to coat the surface of the composite structure with an organic carbon layer, sintering and carbonizing the composite structure, and finally obtaining the corresponding silicon-carbon anode material. Compounding the nano-silicon with the spherical graphite reduces the capacity loss caused byvolume expansion and pulverization when the nano-silicon is lithiated. The outer layer is coated with the carbon layer so as to compensate for the shortcomings of low conductivity of the silicon and avoid the case where the direct contact of the silicon and an electrolyte forms unstable solid electrolyte interface film and thus causes a reversible capacity loss, thereby improving electrochemical performance.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a silicon-carbon negative electrode material for lithium-ion batteries and a preparation method thereof. Background technique [0002] Lithium-ion batteries are widely used in portable electronic devices and electric vehicles because of their advantages such as high specific energy, high working voltage, low self-discharge, small size, and light weight. However, with the improvement of living standards, the original lithium-ion batteries Battery performance has been difficult to meet the needs of society and life, so higher requirements are put forward for lithium-ion batteries. At present, the commercial lithium-ion battery anode material is mainly graphite, but its theoretical specific capacity is only 372mAh / g, which is far from meeting people's needs, while silicon material has a theoretical specific capacity ten times that of graphite (4200mAh / g ), low lithiat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525B82Y30/00
CPCH01M4/366H01M4/386H01M4/628H01M4/625H01M10/0525B82Y30/00Y02E60/10
Inventor 胡培刘世琦徐风叶建史德友
Owner HUBEI WANRUN NEW ENERGY TECH DEV