Method for manufacturing secondary battery

A method for manufacturing a secondary battery comprising a positive electrode comprising a positive electrode active material, a negative electrode, and an electrolyte, the method comprising:

• mixing a composite oxide comprising lithium, cobalt, and oxygen, magnesium fluoride, nickel fluoride, and lithium fluoride to form a mixture;
• and
• heating the mixture, and
• wherein magnesium, nickel, and fluorine are segregated on a surface portion of the composite oxide heating the mixture.

A method for manufacturing a secondary battery comprising a positive electrode comprising a positive electrode active material, a negative electrode, and an electrolyte, the method comprising:

• mixing a first composite oxide, a magnesium source, and a nickel source to form a first mixture;
• performing first heating on the first mixture to form a second composite oxide;
• mixing the second composite oxide and an aluminum source to form a second mixture;
• and
• performing second heating on the second mixture,
• wherein the first composite oxide comprises lithium, cobalt, and oxygen,
• wherein the nickel source is nickel fluoride, and
• wherein magnesium, nickel, and fluorine are segregated on a surface portion of the second composite oxide by the first heating.

A method for manufacturing a secondary battery comprising a positive electrode comprising a positive electrode active material, a negative electrode, and an electrolyte, the method comprising:

• mixing a first composite oxide, a first nickel source, and lithium fluoride to form a first mixture;
• performing first heating on the first mixture to form a second composite oxide;
• and
• mixing the second composite oxide and a second nickel source to form a second mixture;
• and
• performing second heating on the second mixture, and
• wherein the first composite oxide comprises lithium and cobalt.

A method for manufacturing a secondary battery comprising a positive electrode comprising a positive electrode active material, a negative electrode, and an electrolyte, the method comprising:

• mixing a first composite oxide and a first nickel source to form a first mixture;
• performing first heating on the first mixture to form a second composite oxide;
• mixing the second composite oxide, a second nickel source, and lithium fluoride to form a second mixture;
• and
• performing second heating on the second mixture, and
• wherein the first composite oxide comprises lithium and cobalt.