Preparation method of nitrogen-doped graphene for cathode of lithium ion battery

A technology of nitrogen-doped graphene and lithium-ion batteries, which is applied in the field of preparation of nitrogen-doped graphene, can solve the problems of being unsuitable for large-scale production, graphene difficulties, and high temperature requirements, and achieves easy operation of preparation equipment, low price, and low energy consumption. short-term effect

Inactive Publication Date: 2015-04-01
百顺松涛(天津)动力电池科技发展有限公司
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Problems solved by technology

This method is difficult to prepare large-area graphene with a single thickness, and requires a temp...

Method used

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  • Preparation method of nitrogen-doped graphene for cathode of lithium ion battery
  • Preparation method of nitrogen-doped graphene for cathode of lithium ion battery
  • Preparation method of nitrogen-doped graphene for cathode of lithium ion battery

Examples

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Embodiment 1

[0039] A method for preparing nitrogen-doped graphene for negative electrodes of lithium-ion batteries, comprising three processes: preparation of graphene oxide, reduction of graphene oxide, and preparation of nitrogen-doped graphene:

[0040] 1. The preparation process of graphene oxide

[0041] 1), 0.5 g of graphite powder and 1.5 g of potassium permanganate were added to 20 mL of concentrated sulfuric acid with a mass concentration of 98%, and uniformly stirred at 25° C., and then the entire reaction system was stirred at 60° C. for 2.5 hours;

[0042] 2), pour the mixture obtained after the reaction in step 1) into 200 mL of deionized water, continue to stir for 15 min, and then add 15 mL of hydrogen peroxide with a mass fraction of 30%;

[0043] 3), carry out suction filtration, wash away metal ions with the dilute hydrochloric acid that mass fraction is 15%, remove acid again with deionized water;

[0044] 4), adding the solid obtained in step 3) into 200mL deionized w...

Embodiment 2

[0051] A method for preparing nitrogen-doped graphene for negative electrodes of lithium-ion batteries, comprising three processes of preparation of graphene oxide, reduction of graphene oxide and preparation of nitrogen-doped graphene, wherein the first two processes are the same as in Example 1, During the preparation of nitrogen-doped graphene, the graphene prepared by reducing graphene oxide is placed in a vacuum tube furnace and annealed at a high temperature under an ammonia atmosphere at 500 °C. The amount of nitrogen doped in the prepared nitrogen-doped graphene is 4.98at%, and the low current (45mA / g) reversible specific capacity is 827mAh / g.

Embodiment 3

[0053] A method for preparing nitrogen-doped graphene for negative electrodes of lithium-ion batteries, comprising three processes of preparation of graphene oxide, reduction of graphene oxide and preparation of nitrogen-doped graphene, wherein the first two processes are the same as in Example 1, During the preparation of nitrogen-doped graphene, the graphene prepared by reducing graphene oxide is placed in a vacuum tube furnace and annealed at a high temperature under an ammonia atmosphere at 700 °C. The amount of nitrogen doped in the prepared nitrogen-doped graphene is 4.77at%, and the low current (45mA / g) reversible specific capacity is 790mAh / g.

[0054] The above three examples illustrate that the temperature of 500°C is not enough for nitrogen ions and graphene decomposed from ammonia to completely generate carbon-nitrogen bonds; and the reason for the low amount of nitrogen doping at 700°C is that nitrogen doping is more likely to occur in defects or graphene Edge...

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Abstract

The invention provides a preparation method of nitrogen-doped graphene for a cathode of a lithium ion battery. The method comprises three processes: preparing graphene oxide, restoring graphene oxide, and preparing the nitrogen-doped graphene. The nitrogen-doped graphene is prepared by the following steps: restoring the graphene oxide into prepared graphene; putting into a vacuum tube furnace; and carrying out high-temperature annealing in an ammonia gas at 500-700 DEG C. The prepared nitrogen-doped graphene is annealed in a high-temperature environment until the nitrogen doping amount reaches the maximal value, thus the electronic structure of the graphene is changed; the density of a free carrier of the graphene is improved; and the conductive property, the stability, the first charge-discharge efficiency and the reversible capacity of the graphene are further improved.

Description

technical field [0001] The invention relates to the technical field of graphene preparation, in particular to a method for preparing nitrogen-doped graphene used for lithium-ion battery negative electrodes. Background technique [0002] The research on lithium-ion battery anode materials mainly focuses on carbonaceous materials, alloy materials and composite materials. Carbonaceous materials are the earliest materials studied by people and applied to the commercialization of lithium-ion batteries, and they are still one of the focuses of everyone's attention and research. Carbonaceous materials can be divided into graphitizable carbon (soft carbon), amorphous carbon (hard carbon) and graphite according to their structural characteristics. At present, the research on carbon negative electrode mainly uses various methods to modify its surface, but the surface treatment of artificial graphite will further increase the manufacturing cost, so the focus of future research will st...

Claims

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Application Information

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IPC IPC(8): C01B31/04
Inventor 王卿
Owner 百顺松涛(天津)动力电池科技发展有限公司
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