POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND MANUFACTURING METHOD THEREFOR

The present invention relates to a positive electrode active material which has a new composition, a non-rocksalt-type structure, and a new local structure, has significantly increased electrochemical activity, and thus can achieve high-capacity energy and significantly improved electrochemical performance, and a method of preparing the same. The positive electrode active material according to the present invention has a composition of [Formula 1] below, and the layered non-rocksalt-type structure, wherein excess lithium is present to be inappropriate for a site balance, and the excess lithium enters an octahedral site and a tetrahedral site LiMO [Formula 1] (x is an amount in which the excess lithium enters the tetrahedral site between a lithium layer and a transition metal layer, y is an amount in which the excess lithium enters the octahedral site of the transition metal layer, x and y are values that satisfy the charge balance, 0