Electrode including coating layer for preventing reaction with electrolyte solution

1. An electrode for secondary batteries, wherein an electrode mix layer comprising an electrode active material is coated on an electrode collector and a coating layer comprising aluminum (Al) metal and alumina (Al 2 O 3 ) is formed on the electrode mix layer.

2. The electrode according to claim 1 , wherein the coating layer is formed to a thickness of 0.5 nm to 100 nm.

3. The electrode according to claim 1 , wherein the aluminum metal and the alumina in the coating layer form a concentration gradient with respect to a thickness direction.

4. The electrode according to claim 3 , wherein, in the coating layer, an amount of aluminum metal decreases and an amount of alumina increases, toward a surface portion of the electrode from a side contacting the electrode mix layer.

5. The electrode according to claim 3 , wherein, in the coating layer, an amount of aluminum metal decreases and an amount of alumina increases, toward a side contacting the electrode mix layer and a surface portion of the electrode from the center of the coating layer.

6. The electrode according to claim 1 , wherein the coating layer is uniformly formed through electrolytic decomposition.

7. The electrode according to claim 6 , wherein, in the electrolytic decomposition, an aluminum precursor is ionized in a solution for electrolytic decomposition and is reduced to the aluminum metal in an electrolytic electrode.

8. The electrode according to claim 7 , wherein the aluminum precursor is AlCl 3 .

9. The electrode according to claim 7 , wherein the electrolytic decomposition is performed through a catalyst.

10. The electrode according to claim 9 , wherein the catalyst is at least one catalyst selected from the group consisting of ZnCl 2 , CoCl 2 , MnCl 2 , NiCl 2 , and SnCl 2 -based catalysts.

11. The electrode according to claim 1 , wherein the coating layer is partially or entirely formed on a surface of the electrode mix layer.

12. The electrode according to claim 1 , wherein the electrode active material comprises a lithium transition metal oxide represented by Formula 1 or 2 below:

Li x M y Mn 2−y O 4−z A z   (1),

wherein M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, Ti and Bi;

A is at least one monovalent or divalent anion; and

0.9 <x<1.2, 0<y<2, and 0<z<0.2,

(1−x)LiM′O 2−y A y −xLi 2 MnO 3−y′ ,A y′ ,  (2),

wherein M′ is Mn a M b ;

M b is at least one selected from the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and Period II transition metals;

A is at least one selected from the group consisting of anions such as PO 4 , BO 3 , CO 3 , F and NO 3 ; and

0<x<1, 0<y≦0.02, 0<y′≦0.02, 0.3≦a≦1.0, 0≦b≦0.7, and a+b=1.

13. The electrode according to claim 1 , wherein the electrode is a positive electrode.

14. A method of manufacturing an electrode according to claim 1 , the method comprising:

coating an electrode mix comprising an electrode active material on a collector;

preparing a solution comprising an aluminum precursor; and

coating aluminum (Al) metal and alumina (Al 2 O 3 ) on an electrode mix layer of the coating through electrolytic decomposition using the solution of the preparing.

15. The method according to claim 14 , wherein, in the electrolytic decomposition of the coating, an aluminum precursor is ionized in a solution for electrolytic decomposition and is reduced to the aluminum metal in a working electrode.

16. The method according to claim 14 , wherein the aluminum precursor is AlCl 3 .

17. A secondary battery comprising the electrode according to claim 1 .

18. The secondary battery according to claim 17 , wherein the secondary battery is a lithium ion battery, a lithium ion polymer battery or a lithium polymer battery.

19. A battery module comprising the secondary battery according to claim 17 as a unit cell.

20. A battery pack comprising the battery module according to claim 19 .

21. A device comprising the battery pack according to claim 20 as a power source.

22. The device according to claim 21 , wherein the device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or a system for storing power.