POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY

摘要

The present invention provides a positive electrode active material for a lithium secondary battery, wherein the positive electrode active material is a lithium transitional metal oxide having a a-NaFeO2 layered crystal structure, wherein the transitional metal contains a Ni-Mn mixed transitional metal, the average oxidation state of the whole transitional metal excluding lithium is larger than trivalence, and the transitional metal satisfies the following formulas 1 and 2. 1.0 2+)/m(Mn4+) 2+)/m(Mn4+) is a Mn4+ to Ni2+ mole ratio.) The positive electrode active material according to the present invention adjusts the oxidation state of the transitional metal in a transitional metal oxide layer having a layered structure, differently from conventional positive electrode active materials, to thereby form a more uniform and stable layered structure. Thus, the present invention provides a positive electrode active material with overall improvement in electrochemical characteristics containing a battery capacity, and particularly, with improvement in high rate charge and discharge characteristics.