Method of manufacturing composite positive active material, composite positive active material manufactured thereby, and positive electrode and lithium battery including the composite positive active material
Provided are a method of manufacturing a composite positive active material, a composite positive active material manufactured by the method, and a positive electrode and a lithium battery including the composite positive active material. The method may include acid-treating an overlithiated lithium transition metal oxide; and applying fluorine onto the acid-treated overlithiated lithium transition metal oxide using a fluorine compound.
1. A method of manufacturing a composite positive active material, the method comprising:
acid-treating an overlithiated lithium transition metal oxide represented by Formula 1 or Formula 2;
applying fluorine onto the acid-treated overlithiated lithium transition metal oxide; and
drying the acid-treated overlithiated lithium transition metal oxide at a temperature in a range of 100° C. to about 200° C. after the acid-treating of the overlithiated lithium transition metal oxide and before the applying of the fluorine onto the acid-treated overlithiated lithium transition metal oxide:
x Li 2 MO 3 -(1− x )LiM′O 2 Formula 1
wherein M has an average oxidation number +4 and is at least one transition metal selected from a Group 4 transition metal and a Group 5 transition metal of the Periodic Table,
M′ has an average oxidation number +3 and is selected from a Group 4 transition metal and a Group 5 transition metal of the Periodic Table, and
0 <x< 1
x Li 2 MO 3 - x ′LiM′O 2 - x ″Li 1+d M″ 2-d O 4 Formula 2
wherein M has an average oxidation number +4 and is at least one transition metal selected from a Group 4 transition metal and a Group 5 transition metal of the Periodic Table,
M′ has an average oxidation number +3 and is at least one transition metal selected from a Group 4 transition metal and a Group 5 transition metal of the Periodic Table,
M″ has mixed average oxidation numbers +3 and +4 and is at least one transition metal selected from a Group 4 transition metal and a Group 5 transition metal of the Periodic Table, and
x+x′+x″= 1; 0< x< 1, 0< x′< 1, 0< x″< 1; and 0< d< 0.33.
2. The method of claim 1 , wherein M is at least one metal selected from manganese (Mn), titanium (Ti), zirconium (Zr), tin (Sn), and molybdenum (Mo).
3. The method of claim 1 , wherein M′ at least one metal selected from nickel (Ni), cobalt (Co), manganese (Mn), iron (Fe), aluminum (Al), magnesium (Mg), zinc (Zn), copper (Cu), chromium (Cr), vanadium (V), and niobium (Nb).
4. The method of claim 1 , wherein the overlithiated lithium transition metal oxide is represented by Formula 3:
x Li 2 MnO 3 -(1− x )LiNi a Co b Mn c O 2 Formula 3
wherein 0<x<1, 0<a<1, 0<b<1, 0<c<1, and a+b+c=1.
5. The method of claim 1 , wherein an average particle diameter of the overlithiated lithium transition metal oxide is in a range of about 10 nm to about 500 μm.
6. The method of claim 1 , wherein the acid-treating of the overlithiated lithium transition metal oxide is performed by using an acidic solution containing at least one acid selected from nitric acid, sulfuric acid, hydrochloric acid, citric acid, fumaric acid, maleic acid, boric acid (H 3 BO 3 ), and phosphoric acid.
7. The method of claim 1 , wherein the applying of the fluorine on the acid-treated overlithiated lithium transition metal oxide is performed by using a doping solution containing at least one fluorine compound selected from lithium fluoride (LiF), magnesium fluoride (MgF 2 ), strontium fluoride (SrF 2 ), beryllium fluoride (BeF 2 ), calcium fluoride (CaF 2 ), ammonium fluoride (NH 4 F), ammonium bifluoride (NH 4 HF 2 ), and ammonium hexafluoroaluminate ((NH 4 ) 3 AlF 6 ).
8. The method of claim 7 , wherein an amount of the fluorine compound is in a range of about 0.01 wt % to about 10 wt % based on a total amount of the doping solution.
9. The method of claim 1 , further comprising heat-treating the fluorine-doped overlithiated lithium transition metal oxide at a temperature in a range of about 200° C. to about 500° C. in air.
10. A composite positive active material manufactured by the method of claim 1 .
11. A lithium battery comprising:
a positive electrode comprising the composite positive active material of claim 10 ;
a negative electrode disposed opposite to the positive electrode; and
an electrolyte disposed between the positive electrode and the negative electrode.
12. The lithium battery of claim 11 , wherein M is at least one metal selected from manganese (Mn), titanium (Ti), zirconium (Zr), tin (Sn), and molybdenum (Mo).
13. The lithium battery of claim 11 , wherein M′ at least one metal selected from nickel (Ni), cobalt (Co), manganese (Mn), iron (Fe), aluminum (Al), magnesium (Mg), zinc (Zn), copper (Cu), chromium (Cr), vanadium (V), and niobium (Nb).
14. The lithium battery of claim 11 , wherein the overlithiated lithium transition metal oxide is represented by Formula 3:
x Li 2 MnO 3 -(1− x )LiNi a Co b Mn c O 2 Formula 3
wherein 0<x<1, 0<a<1, 0<b<1, 0<c<1, and a+b+c=1.
15. The lithium battery of claim 11 , wherein an average particle diameter of the overlithiated lithium transition metal oxide is in a range of about 10 nm to about 500 μm.
16. The lithium battery of claim 11 , wherein the acid-treating of the overlithiated lithium transition metal oxide is performed by using an acidic solution containing at least one acid selected from nitric acid, sulfuric acid, hydrochloric acid, citric acid, fumaric acid, maleic acid, boric acid (H 3 BO 3 ), and phosphoric acid.
17. The lithium battery of claim 11 , wherein the acid-treating of the overlithiated lithium transition metal oxide is performed by using an acidic solution containing nitric acid.
18. The lithium battery of claim 11 , wherein the applying of the fluorine on the acid-treated overlithiated lithium transition metal oxide is performed by using a doping solution containing at least one fluorine compound selected from lithium fluoride (LiF), magnesium fluoride (MgF 2 ), strontium fluoride (SrF 2 ), beryllium fluoride (BeF 2 ), calcium fluoride (CaF 2 ), ammonium fluoride (NH 4 F), ammonium bifluoride (NH 4 HF 2 ), and ammonium hexafluoroaluminate ((NH 4 ) 3 AlF 6 ).
19. The lithium battery of claim 11 , wherein the applying of the fluorine on the acid-treated overlithiated lithium transition metal oxide is performed by using a doping solution containing at lithium fluoride (LiF) or ammonium fluoride (NH 4 F).