Porous electrode active material and secondary battery including the same
Provided are an electrode active material having a plurality of pores and a secondary battery including the same, and more particularly, a porous electrode active material including silicon-based oxide expressed by SiO x (0.5≦x≦1.2) and having a Brunauer, Emmett, and Teller (BET) specific surface area ranging from 2 m 2 /g to 100 m 2 /g, and a secondary battery including a cathode including a cathode active material, a separator, an anode including an anode active material, and an electrolyte, in which the anode active material includes a porous electrode active material including silicon-based oxide expressed by SiO x (0.5≦x≦1.2) and having a BET specific surface area ranging from 2 m 2 /g to 100 m 2 /g.
1. A method of preparing a porous electrode active material comprising silicon-based oxide expressed by SiO x (0.5≦x≦1.2) and having a Brunauer, Emmett, and Teller (BET) specific surface area ranging from 42.8 m 2 /g to 100 m 2 /g, wherein porosity is in a range of from 38% to 90%, and wherein pores in a honeycomb shape are included at least on a surface of the porous electrode active material, the method comprising:
electrodepositing metal particles on surfaces of the SiO x (0.5≦x≦1.2) particles in a mixed solution of a fluorine-based solution and a metal precursor solution, wherein an amount of the SiO x particles is present in a range of 0.001 to 50 parts by weight based on 100 parts by weight of the mixed solution;
etching the surface of the SiO x particles under the metal particles electrodeposited thereon in an etching solution for a period ranging from 2 hours to 5 hours, wherein the etching solution includes hydrogen fluoride (HF) and hydrogen peroxide (H 2 O 2 ) mixed at a volume ratio ranging from 10:90 to 90:10; and
removing the metal particles from the etched SiO x particles in a metal removing solution.
2. The method of claim 1 , wherein the fluorine-based solution includes one or more selected from the group consisting of hydrogen fluoride (HF), silicon fluoride (H 2 SiF 6 ), and ammonium fluoride (NH 4 F).
3. The method of claim 1 , wherein the metal precursor solution comprises one or more selected from the group consisting of silver (Ag), gold (Au), platinum (Pt), and copper (Cu).
4. The method of claim 1 , wherein the fluorine-based solution and the metal precursor solution are present in the mixed solution at a volume ratio ranging from 10:90 to 90:10.
5. The method of claim 1 , wherein the metal removing solution is one or more selected from the group consisting of nitric acid (HNO 3 ), sulfuric acid (H 2 SO 4 ), and hydrochloric acid (HCl).