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Carbon cladding layer expansion graphite composite material used for lithium ion batteries and preparation method thereof

A technology for lithium ion batteries and composite materials, applied in the field of graphite-based composite materials and preparation, can solve the problems of unfavorable industrial application of modified expanded graphite negative electrode materials for lithium ion batteries, unfavorable electrochemical stability of materials, and serious damage of nearly spherical graphite. and other problems, to achieve the effect of improving high power performance, increasing reversible specific capacity, and improving electrochemical performance

Inactive Publication Date: 2010-09-22
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Furthermore, due to the introduction of H during the preparation process 2 SO 4 , the sulfur component in the obtained powder material is difficult to remove, and the existence of residual sulfur is not conducive to the electrochemical stability of the material
In addition, in the literature reports, the treatment method of expansion first and then coating is adopted. This process has extremely severe heat treatment, serious damage to near-spherical graphite, high energy consumption, cumbersome process, and long preparation cycle. Conducive to the industrial application of modified expanded graphite anode materials for lithium-ion batteries

Method used

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  • Carbon cladding layer expansion graphite composite material used for lithium ion batteries and preparation method thereof
  • Carbon cladding layer expansion graphite composite material used for lithium ion batteries and preparation method thereof
  • Carbon cladding layer expansion graphite composite material used for lithium ion batteries and preparation method thereof

Examples

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Effect test

Embodiment 1

[0023] The carbon-coated expanded graphite composite negative electrode material for lithium ion batteries has a "shell-core" structure, the inner core is expanded graphite doped with phosphorus, the outer shell is the pyrolysis product of phenolic resin, and the graphite layer spacing is 0.3387nm.

[0024] The preparation method of the above-mentioned carbon-coated expanded graphite composite negative electrode material is as follows:

[0025] Step 1: In N 2 Under the protection of the atmosphere, the microcrystalline graphite raw material was heated to 1000° C., heat-treated at a constant temperature for 0.5 h, and the pretreated microcrystalline graphite raw material was obtained after cooling.

[0026] The second step: at the temperature of -10 ° C, 10 g of the pretreated microcrystalline graphite raw material, 10 g of NaNO 3 and 20g of oxalic acid were added to 20.0ml of 85% concentrated H 3 PO 4 solution, after stirring evenly, let stand for 12h, graphite: H 3 PO 4 ...

Embodiment 2

[0029] The carbon-coated expanded graphite composite negative electrode material for lithium ion batteries has a "shell-core" structure, the inner core is expanded graphite doped with phosphorus, the outer shell is the pyrolysis product of phenolic resin, and the graphite layer spacing is 0.3383nm.

[0030] The preparation method of the above-mentioned carbon-coated expanded graphite composite negative electrode material is as follows:

[0031] Step 1: In N 2 Under the protection of the atmosphere, the microcrystalline is heated to 1000°C, heat-treated at a constant temperature for 2 hours, and the pretreated microcrystalline graphite raw material is obtained after cooling.

[0032] The second step: at a temperature of 20 ° C, 10 g of pretreated microcrystalline graphite raw materials, 15 g of NaNO 3 and 50g of acetic acid were sequentially added to 80.0ml of NH with a concentration of 300g / l 4 h 2 PO 4 solution, after stirring evenly, let stand for 10h, graphite: NH 4 h 2...

Embodiment 3

[0035] The above-mentioned carbon-coated expanded graphite composite negative electrode material fine powder was made into an electrode; as a comparison, the microcrystalline graphite was ground, and then passed through a 325-mesh sieve, and the resulting -325-mesh graphite powder was made into an electrode. This is Comparative Example 1. Other test conditions are the same, the test results are as follows:

[0036]

[0037] The comparison results show that the interlayer spacing of the carbon-coated expanded graphite composite negative electrode material of the present invention is slightly larger than that of the microcrystalline graphite material, and the reversible specific capacity and cycle life of the lithium ion battery negative electrode made with it under the charging and discharging conditions of 0.15C and 10C The electrochemical performance has been greatly improved.

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Abstract

The invention provides a carbon cladding layer expansion graphite composite material used for lithium ion batteries and a preparation method thereof. The carbon cladding layer expansion graphite composite material has a shell-kernel structure, wherein, the inner kernel is phosphorus-doped layer expansion graphite, and the layer spacing is 0.3360-0.3390nm; the outer shell is a pyrolysis product of phenolic resin; the carbon cladding layer expansion graphite composite material is prepared by the processes of raw material pretreatment, oxidized intercalation, cladding and layer removing; phosphoric acid dissolved with organic acid or a phosphate-nitrate system is adopted as oxidized intercalator. Lithium ion battery cathode prepared by the carbon cladding layer expansion graphite composite material of the invention has the characteristics of high capacity, high power and long service life. The preparation method of the invention has the characteristics of simple and easily operated process, and moderate and practical conditions and the like.

Description

technical field [0001] The invention relates to a graphite-based composite material and a preparation method thereof, in particular to a carbon-coated expanded layer graphite composite negative electrode material for lithium ion batteries and a preparation method thereof. Background technique [0002] At present, most commercial lithium-ion batteries use graphite-based negative electrode materials. Although this type of traditional graphite negative electrode material has a low and stable potential platform and good cycle performance, due to its low lithium insertion and extraction capacity (372mAh / g), And the diffusion coefficient of lithium ions between graphite layers is small (1×10 -12 cm / s), which seriously restricts the improvement of specific power and specific capacity of lithium-ion batteries. [0003] Reasonably increasing the interlayer spacing of graphite materials is expected to fundamentally improve the specific capacity and rate performance of graphite-based ...

Claims

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Application Information

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IPC IPC(8): H01M4/133H01M4/1393
Inventor 刘洪波石磊何月德简志敏
Owner HUNAN UNIV
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