Electron emission element and method for manufacturing the same

1. An electron emission device, comprising:

a substrate comprising a metal tip;

carbon nano tubes that are positioned on the metal tip; and

a lithium layer that is positioned on the carbon nano tubes.

2. The electron emission device of claim 1 , wherein the lithium layer has an average thickness of 4 nm to 5 nm.

3. The electron emission device of claim 2 , wherein a value of a thickness of the lithium layer at a to end portion of the metal tip is less than values of thicknesses of the lithium layer at other portions of the metal tip.

4. The electron emission device of claim 3 , wherein a thickness of the lithium layer at a base end portion of the metal tip is greater than the thickness of the lithium layer at the top end portion of the metal tip.

5. The electron emission device of claim 1 , wherein the lithium layer has an average thickness of 4.6 nm to 4.7 nm.

6. The electron emission device of claim 1 , wherein the carbon nano tubes have a diameter of 10 nm to 15 nm, when the carbon nano tubes are a multi-walled carbon nano tube.

7. The electron emission device of claim 1 , wherein the carbon nano tubes have a diameter of 1 nm to 2 nm, when the carbon nano tubes are a single wall carbon nano tube.

8. The electron emission device of claim 1 , wherein the metal tip has an average diameter of 400 nm to 600 nm.

9. A method of manufacturing an electron emission device, the method comprising:

providing a substrate comprising a metal tip;

electrochemically etching the substrate;

providing carbon nano tubes on the substrate using electrophoretic deposition (EPD); and

plating the carbon nano tubes with lithium.

10. The method of claim 9 , wherein the plating of the carbon nano tubes with lithium comprises:

providing a plating solution comprising ethylene carbonate (EC), diethyl carbonate (DEC), and lithium hexafluorophosphate (LiPF 6 );

dipping a substrate in which the carbon nano tubes are provided in the plating solution and providing the substrate as a negative electrode;

dipping a positive electrode comprising lithium in the plating solution; and

applying a voltage to the positive electrode and the substrate and plating the substrate with lithium.

11. The method of claim 10 , wherein at the plating of the substrate with lithium, a distance between the positive electrode and the substrate is 10 mm to 30 mm, and the voltage is 3V to 5V.

12. The method of claim 11 , wherein a thickness of a lithium layer that is formed by plating with the lithium is proportional to the voltage applied time.

13. The method of claim 12 , wherein the voltage applied time is 3 seconds or less.

14. The method of claim 13 , wherein the voltage applied time is 2 seconds or less.

15. The method of claim 12 , wherein an increase rate of a thickness of the lithium layer is 3 nm/s to 6 nm/s.