Surface treatment method of solid electrolyte for sodium secondary battery

Patent metadata

Field	Value
Publication number	US-9653758-B2
Application number	US-201514827096-A
Country	US
Kind code	B2
Filing date	Aug 14, 2015
Priority date	Aug 25, 2014
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

Provided are a solid electrolyte for a sodium secondary battery, and a surface treatment method thereof, and more specifically, a solid electrolyte for a sodium secondary battery capable of having excellent electrochemical performance by improving wettability with respect to molten sodium, even under a low temperature operation environment of 250° C. or less, and a surface treatment method thereof.

First claim

What is claimed is:

1. A surface treatment method of a solid electrolyte for a sodium secondary battery, comprising:
a first step of preparing a polymer solution obtained by polymerizing a first hydrocarbon-based binder having a hydroxyl group in a molecular structure and a second, hydrocarbon-based binder having an amine group in the molecular structure, wherein the polymerizing of the first hydrocarbon-based binder and the second hydrocarbon-based binder is performed by adding an acid catalyst to a mixed solution including the first hydrocarbon-based binder, the second, hydrocarbon-based binder, and a pore-forming agent;
a second step of forming a polymer film by coating the polymer solution onto one region of a surface of a sodium ion conductive solid electrolyte; and
a third step of forming a porous carbon coating layer by carbonizing the polymer film.

2. The surface treatment method of claim 1 , wherein the sodium ion conductive solid electrolyte is beta alumina or NASICON.

3. The surface treatment method of claim 1 , wherein the carbon coating layer contacts molten sodium of the sodium secondary battery.

4. The surface treatment method of claim 1 , wherein the first hydrocarbon-based binder is represented by Chemical Formula 1 below:

in Chemical Formula 1,
R 1 to R 3 are each independently hydrogen or (C1˜C4)alkyl.

5. The surface treatment method of claim 4 , wherein the second hydrocarbon-based binder is represented by Chemical Formula 2 below:

in Chemical Formula 2,
R 4 to R 7 are each independently hydrogen or (C1˜C4)alkyl.

6. The surface treatment method of claim 5 , wherein the mixed solution of step 1 contains 20 to 35 parts by weight of the second hydrocarbon-based binder and 30 to 70 parts by weight of the pore-forming agent, in relation to 100 parts by weight of the first hydrocarbon-based binder.

7. The surface treatment method of claim 6 , wherein the acid catalyst of step 1 has a content of 0.1 to 2.0 parts by weight, in relation to 100 parts by weight of the first hydrocarbon-based binder.

8. The surface treatment method of claim 1 , wherein the polymerizing of step 1 is performed at a temperature between −20 to 110° C.

9. The surface treatment method of claim 1 , wherein the coating of step 2 is performed by coating the polymer solution having a coating amount within a range of 0.01 to 0.5 g/cm 2 .

10. The surface treatment method of claim 1 , wherein the carbonizing of step 3 is performed under an inert atmosphere within a range of 300 to 600° C.

11. A solid electrolyte surface-treated with a carbon coating layer having a porosity of 0.01 to 0.3 cm 3 /g carbon .

12. The solid electrolyte of claim 11 , wherein the carbon coating layer is an amorphous carbon, a crystalline carbon or mixtures thereof.

13. The solid electrolyte of claim 12 , wherein the solid electrolyte has permeability with respect to sodium ions, and has impermeability with respect to anions.

14. The solid electrolyte of claim 13 , wherein ionic conductivity with respect to the sodium ions of the solid electrolyte has a range of 20 to 400 mS/cm 2 at 90 to 200° C.

15. A sodium secondary battery including the solid electrolyte of claim 11 .

16. The sodium secondary battery of claim 15 , wherein the sodium secondary battery includes an anode containing sodium; a molten sodium contacting the carbon coating layer of the solid electrolyte; and a cathode.

17. The sodium secondary battery of claim 16 , wherein the cathode contains a transition metal and/or a transition metal halide.

18. The sodium secondary battery of claim 17 , wherein the cathode contains a halide in which a halide containing sodium and a halide containing aluminum, achieve a eutectic point; a sodium salt; or mixtures thereof, and the sodium salt contains a halide containing a hydroxide, a borate or a phosphate.

Assignees

• Sk Innovation Co Ltd

Inventors

• Kim Young Shol
• Chung Ku Bong
• Jo Seung Hwan
• Kim Jeong Soo

Classifications

• H01M2300/0068

  inorganic · CPC title

• H01M10/399

  Cells with molten salts · CPC title

• H01M10/3918 Primary

  characterised by the electrolyte · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title