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A preparation method of graphene-coated nitrogen-doped lithium titanate micro-nanospheres

A graphene-coated, heterolithic lithium titanate technology, which is applied in the manufacture of hybrid/electric double layer capacitors, hybrid capacitor electrodes, etc., can solve the problems of limited application, low specific capacity, poor electrical conductivity, etc., to improve electrochemical performance, Conductive network integrity, the effect of inhibiting secondary growth

Active Publication Date: 2019-07-16
SOUTH CHINA NORMAL UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, due to its poor conductivity, the conductivity is only 10 -13 ~10 -19 S / cm, the discharge specific capacity is low at high rates, so it limits its wide range of applications in the energy field
[0004] Graphene oxide has been widely used because it contains many oxygen-containing functional groups on its surface. Although its electrical conductivity is poor, it has a large specific surface area and good electrical conductivity after being reduced to reduced graphene oxide. Electrochemical properties have very important uses. However, the biggest disadvantage of reduced graphene oxide is that it is prone to irreversible agglomeration and curling. Once serious agglomeration occurs, its excellent performance will be greatly reduced. In order to improve the poor conductivity of lithium titanate The disadvantage is that it is an excellent solution to combine reduced graphene oxide with lithium titanate, but considering that if you directly combine reduced graphene oxide with lithium titanate, since both are easy to agglomerate, the best composite effect cannot be achieved

Method used

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  • A preparation method of graphene-coated nitrogen-doped lithium titanate micro-nanospheres
  • A preparation method of graphene-coated nitrogen-doped lithium titanate micro-nanospheres
  • A preparation method of graphene-coated nitrogen-doped lithium titanate micro-nanospheres

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] (1) Disperse 4.2mL of tetrabutyl titanate in 30mL of ethanol, and gradually add it into a mixed system containing 30mL of ethanol and 2mL of deionized water at a rate of 0.2mL / s for hydrolysis for 1 hour to obtain Sol A.

[0038] (2) Dissolve 0.2g of dopamine hydrochloride in 100mL with a pH of 8.5 and a concentration of 1×10 -2 mol / L tris hydrochloric acid buffer solution, stirring and dissolving for 30s, to obtain solution B.

[0039] (3) 0.2 g of graphene oxide was ultrasonically dispersed in 200 mL of deionized water, and ultrasonically dispersed for 4 hours to obtain 1 g / L graphene oxide dispersion C.

[0040] (4) Add solution B to sol A at a rate of 100 mL / s, stir and react at 25° C. for 12 h to obtain sol D.

[0041] (5) Add dispersion C to sol D at a rate of 0.2mL / s. After stirring for 4 hours, add 0.4406g LiOH·H 2 O in 30mL lithium hydroxide solution, mix well and freeze-dry. Finally, the dried powder was calcined in a nitrogen atmosphere at 800 °C for 12 h,...

Embodiment 2

[0043] (1) Disperse 4.2mL of tetrabutyl titanate in 30mL of ethanol, and gradually add it into a mixed system containing 30mL of ethanol and 2mL of deionized water at a rate of 0.5mL / s for hydrolysis for 2 hours to obtain Sol A.

[0044] (2) Dissolve 0.2g of dopamine hydrochloride in 100mL with a pH of 6.5 and a concentration of 1×10 -2 mol / L Tris hydrochloric acid buffer solution, stirring and dissolving for 2 minutes to obtain solution B.

[0045] (3) 0.4 g of graphene oxide was ultrasonically dispersed in 200 mL of deionized water, and ultrasonically dispersed for 1 h to obtain 2 g / L graphene oxide dispersion C.

[0046] (4) Add solution B to sol A at a rate of 10 mL / s, stir and react at 25° C. for 24 hours to obtain sol D.

[0047] (5) Add dispersion C to sol D at a rate of 0.2mL / s. After stirring for 4 hours, add 0.4364g LiOH·H 2 O in 30mL lithium hydroxide solution, mix well and freeze-dry. Finally, the dried powder was calcined in a nitrogen atmosphere at 700° C. for...

Embodiment 3

[0049] (1) Disperse 4.2mL of tetrabutyl titanate in 30mL of ethanol, and gradually add it into a mixed system containing 30mL of ethanol and 4mL of deionized water at a rate of 0.2mL / s for hydrolysis for 2 hours to obtain Sol A.

[0050] (2) Dissolve 0.2g of dobutamine hydrochloride in 100mL with a pH of 6.5 and a concentration of 1×10 -2 mol / L tris hydrochloric acid buffer solution, stirring and dissolving for 30s, to obtain solution B.

[0051] (3) 0.2 g of graphene oxide was ultrasonically dispersed in 200 mL of deionized water, and ultrasonically dispersed for 1 hour to obtain 1 g / L graphene oxide dispersion C.

[0052] (4) Add solution B to sol A at a rate of 10 mL / s, stir and react at 25° C. for 12 h to obtain sol D.

[0053] (5) Add dispersion C to sol D at a rate of 1mL / s. After stirring for 4 hours, add 0.4406g LiOH·H 2 O in 30mL lithium hydroxide solution, mix well and freeze-dry. Finally, the dried powder was calcined in a nitrogen atmosphere at 800° C. for 20 h ...

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Abstract

The invention discloses a preparation method for a graphene-coated nitrogen-doped lithium titanate micro nanosphere. The preparation method comprises the following steps of preparing titanium hydroxide sol from a titanium source, and sequentially adding a nitrogen-containing crosslinking agent and a graphene oxide dispersion liquid, wherein a supermolecule sol system can be formed between the titanium hydroxide sol and graphene oxide due to an effect of the crosslinking agent, a graphene oxide sheet is coated on a surface of the titanium hydroxide sol; performing freezing and drying after thedissolved lithium source is added, wherein the structure which the graphene oxide sheet is coated on the surface of the titanium hydroxide sol can be reserved; and obtaining the graphene-coated nitrogen-doped lithium titanate micro nanosphere after calcination. The capacity retention rate (111.5mAh / g) still can be maintained at 97% after circulation of charging and discharging for 300 times under20C, and the graphene-coated nitrogen-doped lithium titanate micro nanosphere can be used as a negative electrode of a lithium ion capacitor.

Description

technical field [0001] The invention relates to the technical field of electrochemical battery materials, in particular to a method for preparing graphene-coated nitrogen-doped lithium titanate micro-nanospheres. Background technique [0002] Lithium-ion batteries have been used in all aspects of life due to their high energy density, fast charge and discharge, wide operating temperature range, and relatively friendly to the environment. Supercapacitor is a new type of energy storage device whose performance is between that of batteries and traditional capacitors. It has the advantages of high power density, fast charge and discharge speed, and long service life. It has broad application prospects. As a derivative of lithium-ion batteries and supercapacitors, lithium-ion capacitors have higher energy density than supercapacitors and higher power density than lithium-ion batteries, so they have superior performance, long cycle life, and high charge and discharge efficiency. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01G11/50H01G11/46H01G11/32H01G11/86
CPCY02E60/13
Inventor 易芬云张凡舒东高爱梅孟涛程红红李康万
Owner SOUTH CHINA NORMAL UNIVERSITY
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