Secondary battery, graphene oxide, and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-11437622-B2
Application number	US-202117184074-A
Country	US
Kind code	B2
Filing date	Feb 24, 2021
Priority date	Dec 24, 2015
Publication date	Sep 6, 2022
Grant date	Sep 6, 2022

Abstract

To provide a manufacturing method of graphene oxide that allows mass production through a relatively simple process, at low costs, and with safety and efficiency. A hydrogen peroxide solution, sulfuric acid, and flake graphite are put in a reaction container, and the mixture is stirred to obtain expansion graphite. The synthesized expansion graphite is washed not with pure water but with a saturated aqueous solution of magnesium sulfate (MgSO4) or an organic solvent, whereby a large amount of sulfuric acid is contained between graphite layers. The expansion graphite is subjected to heat treatment or microwave irradiation to form expanded graphite, and a graphite layer is peeled by ultrasonic treatment and then oxidized to form a graphene compound.

First claim

What is claimed is:

1. A method for manufacturing a graphene compound, comprising steps of:
adding graphite into solution including sulfuric acid;
washing the graphite with an aqueous solution containing sulfate or an organic solvent after adding;
forming expanded graphite from the graphite after washing; and
performing ultrasonic treatment on the expanded graphite.

2. The method for manufacturing a graphene compound according to claim 1 , wherein, in the step of the ultrasonic treatment, the expanded graphite is dispersed in a dispersed medium.

3. The method for manufacturing a graphene compound according to claim 2 , wherein the dispersed medium is ethanol.

4. The method for manufacturing a graphene compound according to claim 1 , wherein the expanded graphite is formed by heat treatment or microwave irradiation.

5. The method for manufacturing a graphene compound according to claim 1 , wherein the graphite is flake graphite.

6. The method for manufacturing a graphene compound according to claim 1 , wherein the sulfate is magnesium sulfate, potassium sulfate, or titanium sulfate.

7. The method for manufacturing a graphene compound according to claim 1 , wherein the aqueous solution containing sulfate is a saturated aqueous solution of magnesium sulfate, a saturated aqueous solution of potassium sulfate, or a saturated aqueous solution of titanium sulfate.

8. The method for manufacturing a graphene compound according to claim 1 , wherein the organic solvent is γ-butyrolactone.

9. A method for manufacturing a secondary battery, comprising the steps of:
adding graphite into solution including sulfuric acid;
washing the graphite with an aqueous solution containing sulfate or an organic solvent after adding;
forming expanded graphite from the graphite after washing;
performing ultrasonic treatment on the expanded graphite to form graphene oxide;
mixing the graphene oxide with an active material to form a paste;
applying the paste on a current collector to form a first electrode; and
overlapping the first electrode and a second electrode with a separator positioned therebetween.

10. The method for manufacturing a secondary battery according to claim 9 , wherein, in the step of the ultrasonic treatment, the expanded graphite is dispersed in a dispersed medium.

11. The method for manufacturing a secondary battery according to claim 10 , wherein the dispersed medium is ethanol.

12. The method for manufacturing a secondary battery according to claim 9 , wherein the expanded graphite is formed by heat treatment or microwave irradiation.

13. The method for manufacturing a secondary battery according to claim 9 , wherein the graphite is flake graphite.

14. The method for manufacturing a secondary battery according to claim 9 , wherein the sulfate is magnesium sulfate, potassium sulfate, or titanium sulfate.

15. The method for manufacturing a secondary battery according to claim 9 , wherein the aqueous solution containing sulfate is a saturated aqueous solution of magnesium sulfate, a saturated aqueous solution of potassium sulfate, or a saturated aqueous solution of titanium sulfate.

16. The method for manufacturing a secondary battery according to claim 9 , wherein the organic solvent is γ-butyrolactone.

Assignees

• Semiconductor Energy Lab

Inventors

• Yoneda Yumiko
• Oguni Teppei
• Miwa Takuya
• Yamakaji Masaki
• TSURUTA Ayae

Classifications

• H01M50/429

  Natural polymers · CPC title

• H01M50/417

  Polyolefins · CPC title

• H01M4/587 Primary

  for inserting or intercalating light metals · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/625

  Carbon or graphite · CPC title