Graphene/transition metal oxide composite cathode material and preparation method thereof

A transition metal and negative electrode material technology, applied in battery electrodes, structural parts, electrical components, etc., can solve the problem of poor high-rate performance of graphene/transition metal oxides, high rate, unsatisfactory long-term cycle performance, and inability to effectively provide Problems such as electron transfer channels, to achieve high long-term cycle stability, avoid volume changes and agglomeration problems, and achieve good long-term cycle stability

Inactive Publication Date: 2011-10-05
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although the results reported so far show that graphene / transition metal oxide composites have improved low-rate charge-discharge performance, their high-rate and long-cycle performance is still not ideal.
This is mainly because graphene is a two-dimensional nano-open system. If metal oxide nanoparticles cannot be tightly fixed on graphene sheets, transition metal oxide nanoparticles are easy to agglomerate during charge and discharge, and graphene cannot Efficiently provides electron transport channels, resulting in poor high-rate performance of graphene / transition metal oxides
Recently, Yang et al. prepared graphene-coated transition metal oxide nanostructures. Although the tight coating structure can effectively prevent metal oxides from agglomerating, it is not conducive to the insertion and extraction of lithium ions at high rates [Yang, S . et al, Fabrication of Graphene-Encapsulated Oxide Nanoparticles: Toward High-Performance Anode Materials for Lithium Storage. Angew. Chem. Int. Ed. 2010, 49, 8408-8411.]
In addition, the preparation process of this method is complicated, the cost is high, and it is difficult to prepare large quantities of

Method used

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  • Graphene/transition metal oxide composite cathode material and preparation method thereof
  • Graphene/transition metal oxide composite cathode material and preparation method thereof
  • Graphene/transition metal oxide composite cathode material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Weigh 16g iron nitrate (Fe(NO 3 ) 3 ·6H 2 (2) and 2g of graphene nanosheets, mixed with 40ml of absolute ethanol, ultrasonically mixed evenly, and then magnetically stirred in a water bath at 80°C until the absolute alcohol was completely volatilized. Put the dried mixture into a carbonization furnace, and raise the temperature from room temperature to 500 °C at a rate of 1.5 °C / min under a nitrogen atmosphere, keep it warm for 3 hours, and then cool it down to room temperature. That is, the graphene / iron oxide composite material is obtained. Wherein the content of iron oxide is 80wt%, the content of graphene nano sheet is 20wt%, and the size of graphene sheet is 0.5-10μm.

[0030] as attached figure 1 The iron oxide nanoparticles shown by the scanning electron microscope (SEM) are loaded on the graphene nanosheets, the iron oxide nanoparticles have a diameter ranging from 5 to 50 nm, and the graphene nanosheets have 1 to 10 layers;

[0031] as attached Figure 5 ...

Embodiment 2

[0034] Weigh 0.8 copper nitrate (Cu(NO 3 ) 2 ·3H 2 O) and 2g graphene nanosheets, mixed with 40ml acetone, ultrasonically mixed, then magnetically stirred in a water bath at 50°C until the acetone was completely volatilized. Put the dried mixture into a carbonization furnace, and raise the temperature from room temperature to 200 °C at a rate of 1.5 °C / min under a nitrogen atmosphere, keep it warm for 5 hours, and then cool it down to room temperature. That is, the graphene / copper oxide composite material is obtained. Wherein the content of copper oxide is 30wt%, the content of graphene nano sheet is 70wt%, and the size of graphene sheet is 1-15μm.

[0035]as attached figure 2 Scanning electron microscope (SEM) analysis shows that the copper oxide nanoparticles are loaded on the graphene nanosheets, and the diameter of the copper oxide nanoparticles ranges from 10 to 30 nm.

[0036] The electrochemical performance test results show that the reversible capacity of the com...

Embodiment 3

[0038] Weigh 20 cobalt nitrate (Co(NO 3 ) 2 ·3H 2 O) and 1g of graphene nanosheets, mixed with 40ml N-methylpyrrolidone, ultrasonically mixed, and then magnetically stirred in a water bath at 60°C until the N-methylpyrrolidone was completely volatilized. Put the dried mixture into a carbonization furnace, and raise the temperature from room temperature to 600 °C at a rate of 1.5 °C / min under a nitrogen atmosphere, keep it warm for 0.5 hours, and then cool to room temperature. That is, the graphene / cobalt oxide composite material is obtained. Wherein the content of cobalt oxide is 95wt%, the content of graphene nano sheet is 5wt%, and the size of graphene sheet is 2-20μrn.

[0039] as attached image 3 The cobalt oxide nanoparticles shown by the scanning electron microscope (SEM) are loaded on the graphene nanosheets, the diameter of the cobalt oxide nanoparticles ranges from 15 to 80 nm, and the graphene nanosheets have 1 to 10 layers;

[0040] The electrochemical perform...

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Abstract

The invention provides a graphene / transition metal oxide composite electrode material applicable to a high-performance lithium ion battery. The diameter range of metal oxide nano particles is 10-100 nm, and the thickness of each graphene nano sheet is 1-20 layers. Metal oxides and the graphene nano sheets are connected by covalent bonds to form a strong interface reaction. The material has good high-rate performance and long-term circulation stability when being used as the cathode material of the lithium ion battery. Meanwhile, the invention also discloses a method for preparing the composite material.

Description

technical field [0001] The invention relates to the field of negative electrode materials for lithium ion batteries, in particular to a graphene / transition metal oxide composite negative electrode material and a preparation method thereof. Background technique [0002] Due to the advantages of high energy density, high output potential and no pollution, lithium-ion secondary batteries have not only been widely used in small portable electronic devices, but will also be gradually used in large power devices such as electric bicycles and electric vehicles. Therefore, a new generation of electrode materials should have high reversible capacity, good cycle stability and long cycle life at the same time. Due to the advantages of high theoretical specific capacity, environmental friendliness, and low cost, transition metal oxides have become the research hotspots of anode materials for lithium-ion secondary batteries. However, due to the drastic volume change of transition metal ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/48H01M4/131H01M4/1391
CPCY02E60/122Y02E60/12Y02E60/10
Inventor 宋怀河周继升陈晓红
Owner BEIJING UNIV OF CHEM TECH
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