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Nitrogen-doped nanocarbon coated/oxidized modified graphite composite material and preparation method thereof

A nitrogen-doped nano-carbon, oxidation modification technology, applied in electrical components, battery electrodes, circuits, etc., can solve problems such as battery safety hazards and environmental pollution, and achieve high current performance improvement, good conductivity, and high current performance. obvious effect

Inactive Publication Date: 2015-03-25
SHANGHAI SECOND POLYTECHNIC UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the battery will produce strong acidic HF during charging and discharging, which poses a safety hazard to the battery.
Chinese patent CN 102231434 A discloses a natural graphite negative electrode material for a lithium-ion battery and a preparation method thereof. The natural graphite is coated with a boron-containing hard carbon layer, and the boron-containing hard carbon layer is coated with a soft carbon layer to reduce the Reduce the production cost and increase the specific capacity of the material, but produce organic solvents containing a large amount of acetone and toluene, which will pollute the environment

Method used

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  • Nitrogen-doped nanocarbon coated/oxidized modified graphite composite material and preparation method thereof
  • Nitrogen-doped nanocarbon coated/oxidized modified graphite composite material and preparation method thereof
  • Nitrogen-doped nanocarbon coated/oxidized modified graphite composite material and preparation method thereof

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Experimental program
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Effect test

Embodiment 1

[0037] 24g graphite raw material (particle size D 50 = 16.1 μm) (Shanghai Shanshan Technology Co., Ltd., natural graphite) was placed in the reactor, 9.6 g of hydrogen peroxide with a concentration of 30 wt% was added, and 20 ml of glacial acetic acid was added (hydrogen peroxide was used as an oxidant, and glacial acetic acid was conducive to the increase of the graphite layer spacing. ), mixed and stirred evenly, reacted in an oven at 95 °C for 12 h, taken out and cooled naturally, and dried the sample in an oven at 105 °C. The dried sample was put into a quartz tube furnace with nitrogen gas, and 30 ml of diethylamine was introduced at the same time, and the temperature was raised to 1000 °C at 20 °C / min, kept for 2 hours, and naturally cooled to obtain a modified natural graphite sample.

[0038] The prepared modified sample was taken out and used as the negative electrode material. Lithium sheet was used as the positive electrode material, and 1 mol / L LiPFB was used. 6B ...

Embodiment 2

[0043] In the present embodiment, the amount of hydrogen peroxide added is 14.4g, except that, other processes and conditions are consistent with embodiment 1. The average particle diameter D of the modified graphite obtained in the present embodiment 50 It is basically the same as Example 1 (16.2 μm). At 0.1C, its first charge capacity is 383.1mAh / g, the first discharge capacity is 462.2mAh / g, and the first Coulombic efficiency is 89.9%. Under the current density of 3C, the chargeable gram capacity is 336.3mAh / g, and the capacity retention rate is 87.8%. At a current density of 1C, after 20 charge-discharge cycles, the charging capacity is 303.9mAh / g, and the capacity retention rate is 84.2%.

Embodiment 3

[0045] In this embodiment, the added oxidizing agent is concentrated phosphoric acid, and the added amount is 2.4 g. Other than that, other processes and conditions were consistent with Example 1. The average particle diameter D of the modified graphite obtained in the present embodiment 50 It is 17.3 μm, larger than the particle size of the sample in Example 1. At 0.1C, its initial charge capacity is 350mAh / g, its initial discharge capacity is 395.9mAh / g, and its initial Coulombic efficiency is 88.4%. Under the current density of 3C, the chargeable gram capacity is 341.0mAh / g, and the capacity retention rate is 97.4%. At a current density of 1C, after 20 charge-discharge cycles, the charging capacity is 291.4mAh / g, and the capacity retention rate is 83.3%.

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Abstract

The invention discloses a nitrogen-doped nanocarbon coated / oxidized modified graphite composite material and a preparation method thereof. The preparation method of the composite material comprises the following steps: fully mixing graphite with oxidizing agents; putting into a hydrothermal reaction kettle between 95 and 220 DEG C to react for 0.5-24 hours to obtain graphite oxide; drying the material and carbonizing at a high temperature; introducing organic amine along with inert gas; and forming a nitrogen-doped carbon CNx coating layer on the surface of the graphite material to obtain a modified graphite composite material. The modified graphite composite material is high in conductivity, the first charging / discharging efficiency is 89.8 percent, the reversible capacity can reach 383.2 mAh / g, the large current performance is obviously increased, and the capacity retention ratio of IC current circulation for 20 times can reach 84.6 percent. The preparation method is simple, the process is easy to control, the condition is mild, and the cost is low.

Description

technical field [0001] The invention belongs to the technical field of energy materials and electrochemistry, and in particular relates to a preparation method of a nitrogen-doped nano-carbon coated / oxidized modified graphite composite material. Background technique [0002] As a lithium battery anode material, natural graphite has the advantages of high specific capacity, large tap density, and stable charge and discharge platform. It has always been a good material for lithium ion anode materials, but it also exists with organic solvents (especially PC-based electrolytes). Poor compatibility, co-intercalation of solvated lithium easily occurs, causing exfoliation of the graphite layer, which eventually leads to large irreversible capacity, poor cycle life, and safety issues. [0003] In order to overcome the defects of natural graphite, improve the electrochemical performance of carbon anode materials, and reduce the production cost, the modification method of natural grap...

Claims

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Application Information

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IPC IPC(8): H01M4/587H01M4/62
CPCH01M4/48H01M4/587H01M4/625Y02E60/10
Inventor 王利军刘华靖
Owner SHANGHAI SECOND POLYTECHNIC UNIVERSITY
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