Binder, method of preparing the binder, and anode and lithium battery including the binder

A method of preparing a binder, the method comprising

• preparing a third composition by mixing together a first composition comprising a non-aqueous solvent and a first polymer and a second composition comprising a second polymer and water,
• wherein the first polymer comprises a first functional group and is selected from at least one of a polyamic acid and a polyimide, and
• the second polymer comprises a second functional group and is water-soluble;
• and
• heating the third composition at a temperature of about 160° C. or greater to prepare a third polymer.