Positive active material for rechargeable lithium battery and method of preparing same
AssigneeSamsung SDI Co., Ltd.
InventorsJae-Phil Cho, Geun-Bae Kim, Yong-Chul Park
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Abstract
Disclosed is a positive active material for a rechargeable lithium battery having a higher concentration of Co in the surface portion than in the central portion. The surface portion is a region from the outermost surface to a depth of 10 microns. The positive active material is represented Li1+xMn2−yCoyO4 wherein −0.1<x0.1 and 0<y<0.1. The positive active material is produced by obtaining a sol or gel cobalt material by mixing lithium salts, cobalt salts, an alcohol and chelating agents and heating the mixture, mixing the sol or gel cobalt material with LiMn2O4, and heat-treating the resulting mixture.
Claims14
A positive active material for a rechargeable lithium battery represented by the formula Li1+xMn2−yCoyO4, wherein −0.1≦x≦0.1 and 0<y<0.1, having a concentration of Co in a surface portion higher than that in a central portion, with the surface portion being a region from an outermost surface of the positive active material to a depth of 10 microns, wherein the ratio of the concentration of Co in the central portion to that in the surface portion ranges from 1:1.05 to 1:1.30.
A method of preparing a positive active material for a rechargeable lithium battery comprising the steps of:
- obtaining a sol or gel-cobalt material by mixing lithium salts, cobalt salts, an alcohol and chelating agents and heating the mixture;
- mixing the sol or gel-cobalt material with LiMn2O4;
- and
- heat-treating the mixture,
- wherein the positive active material is Li1+xMn2−yCoyO4 where −0.1≦x≦0.1 and 0<y<0.1 and has a concentration of Co in a surface portion higher than that in a central portion, the surface portion being a region from an outermost surface of the positive active material to a depth of 10 microns.
Dependencies are inferred from the claim text.