LAYERED CORE.SHELL CATHODE ACTIVE MATERIALS FOR LITHIUM SECONDARY BATTERIES, METHOD FOR PREPARING THEREOF AND LITHIUM SECONDARY BATTERIES USING THE SAME

摘要

Disclosed herein is a layered core-shell cathode active material for secondary lithium batteries, in which the core layer has a structural formula of LiSUB1+a/SUB[MSUBx/SUBMnSUB1-x/SUB]SUB2/SUBOSUB4 /SUB(M is selected from a group consisting of Ni, Co, Mg, Zn, Ca, Sr, Cu, Zr, P, Fe, Al, Ga, In, Cr, Ge, Sn and combinations thereof, 0.01=x=0.25, 0=a=0.1) and the shell layer has a structural formula of LiSUB1+a/SUB[MSUBy/SUBMnSUB1-y/SUB]SUB2/SUBOSUB4 /SUB(M' is selected from a group consisting of Ni, Mg, Cu, Zn and combinations thereof, 0.01=y=0.5, 0=a=0.1). In the layered cathode active material, the core layer, corresponding to a 4V spinel-type manganese cathode, functions to increase the capacity of the active material while the shell layer, corresponding to a 5 V spinel-type transition metal mix-based cathode, is electrochemically stable enough to prevent the reaction of the components with electrolytes and the dissolution of transition metals in electrolytes, thereby improving thermal and lifetime characteristics of the active material.