SUPERCRITICAL CONTINUOUS HYDROTHERMAL SYNTHESIS OF LITHIUM TITANATE ANODE MATERIALS FOR LITHIUM-ION BATTERIES

• US 20140105811A1
• Filed: 08/16/2013
• Published: 04/17/2014
• Est. Priority Date: 10/12/2012
• Status: Active Grant

• Current Assignee: Hefei Guoxuan High-Tech Power Energy Company Limited (Gotion High-tech Co., Ltd)
• Original Assignee: Hefei Guoxuan High-Tech Power Energy Company Limited (Gotion High-tech Co., Ltd)
• Inventors: Yang, Maoping, Yang, Xulai, Xu, Xiaoming, Xie, Jia, Zhu, Wenting, Li, Zhen
• Granted Patent: US 9,711,789 B2
• Time in Patent Office: Days
• US Class Current: 423/598
• CPC Class Codes: C01D 15/02 Oxides; Hydroxides
• CPC Class Codes: C01G 23/005 Alkali titanates
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 4/485 of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy H01M4/505, H01M4/525 take precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 20/54 using solvents, e.g. supercritical solvents or ionic liquids

Abstract

A method for synthesizing lithium titanate includes preparing a supercritical fluid from water; reacting a solution containing lithium and titanium with the supercritical fluid under a condition that maintains the supercritical fluid in its supercritical state to produce a reaction mixture comprising the lithium titanate; and collecting the lithium titanate. The supercritical fluid is prepared at a temperature of 375-500° C. and a pressure of 22-35 MPa. The solution containing lithium and titanium is prepared by mixing a solution containing lithium, prepared by dissolving a lithium source in a selected solvent, and a solution containing titanium, prepared by dissolving a titanium source in the selected solvent, wherein a molar ratio of lithium:titanium is between 4.0:5.0 and 4.5:5.0. The lithium source is lithium hydroxide, lithium carbonate, lithium acetate, lithium oxalate, lithium nitrate, or lithium oxide, and the titanium source is tetrabutyl titanate.

Claims

1. A method for synthesizing lithium titanate, comprising:

preparing a supercritical fluid from water;

reacting a solution comprising lithium and titanium in the supercritical fluid under a condition that maintains the supercritical fluid in its supercritical state to produce a reaction mixture comprising the lithium titanate; and

collecting the lithium titanate.

2. The method of claim 1, wherein the solution comprising lithium and titanium is prepared by mixing a solution comprising lithium and a solution comprising titanium.

3. The method of claim 2, wherein the solution comprising lithium is prepared by dissolving a lithium source in a selected solvent, and the solution comprising titanium is prepared by dissolving a titanium source in the selected solvent.

4. The method of claim 3, wherein the selected solvent is an alcohol.

5. The method of claim 3, wherein the lithium source is selected from lithium hydroxide, lithium carbonate, lithium acetate, lithium oxalate, lithium nitrate, lithium oxide, or a combination thereof, and the titanium source is tetrabutyl titanate.

6. The method of claim 3, wherein the solution comprising lithium and the solution comprising titanium are bubbled with an inert gas to remove a dissolved gas.

7. The method of claim 6, wherein the inert gas is nitrogen.

8. The method of claim 1, wherein the water is bubbled with an inert gas to remove a dissolved gas prior to the preparing the supercritical fluid.

9. The method of claim 8, wherein the inert gas is nitrogen.

10. The method of claim 1, further comprising cooling the reaction mixture or allowing the reaction mixture to cool prior to the collecting the lithium titanate.

11. The method of claim 1, wherein the collecting the lithium titanate is by filtration or centrifugation.

12. The method of claim 1, wherein the supercritical fluid is prepared at a temperature in a range of about 375-500°

C. and a pressure in a range of about 22-35 MPa.

13. The method of claim 1, wherein the supercritical fluid is prepared at a temperature of about 400°

C. and a pressure of about 25 MPa.

14. The method of claim 1, wherein a molar ratio of lithium:

titanium in the solution is between about 4.0;

5.0 and about 4.5;

5.0.

15. The method of claim 1, wherein a molar ratio of lithium:

titanium in the solution is between about 4.0;

5.0 and about 4.2;

5.0.

16. The method of claim 1, wherein a molar ratio of lithium:

titanium in the solution is about 4.2;

5.0.

17. The method of claim 1, further comprising purifying the collected lithium titanate by:

suspending the collected lithium titanate in water to produce a suspension;

sonicating the suspension; and

centrifuging the suspension to collect purified lithium titanate.

18. The method of claim 1, wherein the supercritical fluid is pumped into a reactor at a rate of from 9 g/min to 18 g/min, and the solution comprising lithium and titanium source is pumped into the reactor at a rate of 1.7˜

3.0 g/min.

19. A lithium titanate prepared by the method of claim 1.

20. A lithium-ion battery comprising an anode made of the lithium titanate of claim 19.