POSITIVE ELECTRODE MATERIAL COMPRISING CRYSTAL OF LAYERED STRUCTURE COMPRISING SECONDARY PARTICLE FORMED BY AGGLOMERATION OF PRIMARY PARTICLES HAVING IMPROVED PARTICLE STRUCTURE, PREPARATION METHOD THEREOF, AND LITHIUM SECONDARY BATTERY USING THE MATERIAL

摘要

PURPOSE: Provided are a positive electrode material which comprises a crystal of a layered structure having an improved particle structure and is excellent in discharge rate characteristics and battery capacity, its preparation method and a lithium secondary battery using the positive electrode material which has high output and high energy density. CONSTITUTION: The positive electrode material comprises a secondary particle(2) which is formed by the agglomeration of a plurality of primary particles(1), wherein the length which the primary particles are combined together at the cross-section of a secondary particle, is 10-70 % to the length of total circumference of a primary particle at the cross-section. The void fraction of the secondary particle is 2.5-35 %. Preferably the secondary particle comprises a crystal having a composite oxide layered structure represented by LiaMnxNiyCozO2, wherein 1=a=1.2, 0=x=0.65, 0.35=y0.5, 0=z=0.65, and x+y+z=1. The method comprises the steps of sintering a source material comprising Li, Ni, Mn and Co at a temperature of 950-1,100 deg.C; and pulverizing the sintered one.