Positive electrode and lithium battery including the same

A positive electrode for a lithium battery comprising:

• a composite material comprising
• a positive active material as a core of the composite material, and
• a coating layer located on a surface of the positive active material forming a shell on the core of the composite material,
• wherein the coating layer comprises a copolymer comprising a first repeating unit represented by Formula 1, and a second repeating unit represented by Formula 2:
• wherein in Formula 1,
• Ar1 is a substituted or unsubstituted C6-C30 arylene group or a substituted or unsubstituted C6-C30 heteroarylene group,
• R1, R2, and R3 are each independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C6-C30 aryl group, or a substituted or unsubstituted C3-C30 heteroaryl group,
• A is a bond, a substituted or unsubstituted C1-C30 alkylene group, a substituted or unsubstituted C6-C30 arylene group, a substituted or unsubstituted C3-C30 heteroarylene group, a substituted or unsubstituted C4-C30 cycloalkylene group, or a substituted or unsubstituted C3-C30 heterocycloalkylene group,
• is a 3-membered to 31-membered ring system comprising 2 to 30 carbon atoms, and X is —S, —N(R), or —P(R′),
• R and R′ are each independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 heteroalkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C7-C30 arylalkyl group, a substituted or unsubstituted C6-C30 aryloxy group, a substituted or unsubstituted C3-C30 heteroaryl group, a substituted or unsubstituted C4-C30 heteroarylalkyl group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C2-C30 alkenyl group, or a substituted or unsubstituted C3-C30 alkynyl group, and
• Y− is an anion,
• wherein in Formula 2,
• A1 is —C(═O)O—(CH2CH2O)a—R7, wherein R7 is hydrogen, a substituted or unsubstituted C1-C30 alkyl group, or a substituted or unsubstituted C6-C30 aryl group, and a is an integer of 1 to 10, and
• R4, R5, and R6 are each independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C6-C30 aryl group, or a substituted or unsubstituted C3-C30 heteroaryl group, and
• in Formulae 1 and 2, m and n are mole fractions of the first repeating unit represented by Formula 1 and the second repeating unit represented by Formula 2, respectively, wherein a sum of m and n is 1, and m and n are each independently greater than 0 and less than 1.