Surface-treated active materials and surface treatment method thereof

1. A surface treatment method of an active material, the surface treatment method comprising:

a) preparing a precursor solution comprising a first precursor used to generate a first metal oxide containing lithium, wherein the first metal oxide is represented by the following Chemical Formula 1:

LixM y O z   [Chemical Formula 1]

wherein M comprises at least two selected from the group consisting of P, V, S, and W, and x, y and z are 1 to 8; and

a second precursor used to generate a second metal oxide, wherein the second metal oxide comprises at least one selected from the group consisting of P, S, W and V, and wherein the second precursor comprises at least one selected from the group consisting of an ammonium salt, an aniline salt, a pyridinium salt, a methylammonium salt and an ammonium carbonate salt that are used to generate an anion; and

b) coating the active material with a precursor solution comprising the first precursor and the second precursor by mixing the active material with the precursor solution to generate a coating layer on said active material, wherein said coating layer comprises a mixture of said first metal oxide containing lithium and said second metal oxide; and

heat-treating the active material comprising said coating layer at a temperature of 300° C. to 1000° C. for 30 minutes to 5 hours,

wherein the anion comprises at least one of (XO 4 ) n− wherein X is P, S, W or V, and n is 1 to 4.

2. The surface treatment method of claim 1 , wherein a mass ratio of the first precursor:the second precursor ranges from 1:1 to 1:100.

3. The surface treatment method of claim 1 , wherein the first precursor comprises at least one selected from the group consisting of a nitride of a metal, a chloride of a metal, a sulfide of a metal, an acetate of a metal, and a carbonate of a metal.