LITHIUM SECONDARY BATTERY WITH IMPROVED ELECTRODE EFFICIENCY AND ENERGY DENSITY CHARACTERISTICS

Provided is a cathode mix for lithium secondary batteries, comprising a cathode active material having a composition represented by the following Formula I: LiFe(P 1-X O 4 ) (I) wherein a molar fraction (1-x) of phosphorus (P) is in the range of 0.910 to 0.999, to allow operational efficiency of the cathode active material to be leveled to a lower operational efficiency of an anode active material and improve energy density of the cathode active material. The cathode mix maximizes operational efficiency of batteries, minimizes electrode waste and thus reduces manufacturing costs of batteries. Furthermore, The cathode active material, wherein a molar fraction (1-x) of phosphorus (P) is lower than 1, according to the present invention contains both Fe 2+ and Fe 3+ , thus advantageously causing no structural deformation, improving ionic conductivity, exhibiting superior rate properties, inhibiting IR drop upon charge/discharge, thereby imparting high energy density to batteries.