METHOD OF PREPARING MATERIAL FOR LITHIUM SECONDARY BATTERY OF HIGH PERFORMANCE

摘要

Provided is a method for preparing a lithium mixed transition metal oxide, comprising subjecting Li2CO3 and a mixed transition metal precursor to a solid-state reaction under an oxygen-deficient atmosphere with an oxygen concentration of 10 to 50% to thereby prepare a powdered lithium mixed transition metal oxide having a composition represented by Formula I of LixMyO2 wherein M, x and y are as defined in the specification. Therefore, since the high-Ni lithium mixed transition metal oxide having a given composition can be prepared by a simple solid-state reaction in air, using a raw material that is cheap and easy to handle, the present invention enables industrial-scale production of the lithium mixed transition metal oxide with significantly decreased production costs and high production efficiency. Further, the thus-produced lithium mixed transition metal oxide is substantially free of impurities, and therefore can exert a high capacity and excellent cycle stability, in conjunction with significantly improved storage stability and high-temperature stability.

主权项

1. A method for preparing a lithium mixed transition metal oxide, comprising subjecting Li2CO3 and a mixed transition metal precursor to a solid-state reaction under an oxygen-deficient atmosphere with an oxygen concentration of 10 to 50% by volume; and forming a powdered lithium mixed transition metal oxide having a composition represented by Formula I below:
LixMyO2  (I) wherein: M=M′1-kAk, wherein M′ is Ni1−a-b(Ni1/2Mn1/2)aCob, 0.65≦a+b≦0.85 and 0.1≦b≦0.4; A is a dopant; 0≦k≦0.05; and x+y=about 2 and 0.95≦x≦1.05,the lithium mixed transition metal oxide being substantially free of water soluble bases such that less than 20 ml of 0.1M HCl is necessary to titrate 200 ml of a solution containing substantially all of the soluble bases present in 10 g of the lithium mixed transition metal oxide to a pH less than 5, the solution being prepared by repeated soaking and decanting of the lithium mixed transition metal oxide, and wherein the solid-state reaction is a single heat treatment.