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Positive active material for rechargeable lithium battery and method of preparing same

Inactive Publication Date: 2005-04-21
KWEON HO JIN +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006] It is an object of the present invention to provide a manganese-based positive active material for rechargeable lithium batteries which exhibits a good cycle life characteristic at high temperatures.

Problems solved by technology

However, as compared to other lithiated transition metal oxides such as LiCoO2 and LiNiO2, LiMn2O4 has a relatively low discharge capacity.
Furthermore, when high rate of charge and discharge operations are cycled, the discharge capacity is excessively reduced.
In particular, when the charge and discharge operations are continuously performed at high temperatures, manganese distributed in the surface of LiMn2O4 readily elutes to the electrolyte, causing a disproportionation reaction.
This reaction seriously deteriorates the cycle life characteristic of the battery.

Method used

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  • Positive active material for rechargeable lithium battery and method of preparing same
  • Positive active material for rechargeable lithium battery and method of preparing same
  • Positive active material for rechargeable lithium battery and method of preparing same

Examples

Experimental program
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Effect test

example 1

[0018] An aluminum isopropoxide solution having a 5 weight-percent concentration was prepared by refluxing an aluminum isopropoxide powder in ethanol at about 100° C. for about half an hour. The aluminum isopropoxide solution was then mixed with a powder of LixMn2-yAlyO4-zFz where 06 for a solute.

example 2

[0019] The positive electrode preparing procedure was performed in the same way as in Example 1 with the exception that the heat-treating temperature was heightened up to 900° C. A coin-type half cell was fabricated with the resulting positive electrode in combination with other components as described in Example 1.

example 3

[0020] An aluminum isopropoxide solution having a 5 weight-percent concentration was prepared by refluxing an aluminum isopropoxide powder in ethanol at about 100° C. for about half an hour. The aluminum isopropoxide solution was then mixed with a powder of LixMn2O4 where 0<x≦1.5 at an identical volume ratio in a moisture free dry room such that an overall surface of the power became wet sufficiently by the solution, and dried in the same room. Thereafter, the mixture was heat-treated at about 300° C. for about 10 hours under a dry air atmosphere to thereby prepare a metallic oxide-coated active material. The subsequent positive electrode processing steps were performed in the same way as in Example 1. A coin-type half cell was fabricated with the resulting positive electrode in combination with other components as described in Example 1.

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Abstract

A positive active material for rechargeable lithium batteries includes an active material component processed from a manganese-based compound. The transition metal compound is selected from LixMnO2, LixMnF2, LixMnS2, LixMnO2-zFz, LixMnO2-zSz, LixMn1-yMyO2, LixMn1-yMyF2, LixMn1-yMyS2, LixMn1-yMyO2-zFz, LixMn1-yO2-zSz, LixMn2O4, LixMn2F4, LixMn2S4, LixMn2O4-zFz, LixMn2O4-zSz, LixMn2-yMyO4, LixMn2-yMyF4, LixMn2-yMyS4, LixMn2-yMyO4-zFz, or LixMn2-yMyO4-zSz where 0<x≦1.5, 0.05≦y≦0.3, z≦1.0 and M is selected from Al, Co, Cr, Mg, Fe or La. A metallic oxide is coated on the active material component.

Description

BACKGROUND OF THE INVENTION [0001] (a) Field of the Invention [0002] The present invention relates to a positive active material for rechargeable lithium batteries and a method of preparing the same and, more particularly, to a manganese-based positive active material for rechargeable lithium batteries which has a good cycle life characteristic. [0003] (b) Description of the Related Art [0004] Generally, manganese-based compounds such as LiMn2O4 and LiMnO2 are the positive active material of choice for rechargeable lithium batteries because of their low cost, abundance and environmentally friendly characteristics. Among such manganese-based compounds, LiMn2O4 is particularly stable for the battery use and thus attractive for the electric vehicle application. [0005] However, as compared to other lithiated transition metal oxides such as LiCoO2 and LiNiO2, LiMn2O4 has a relatively low discharge capacity. Furthermore, when high rate of charge and discharge operations are cycled, the di...

Claims

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Application Information

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IPC IPC(8): H01M10/05B82Y99/00H01M4/131H01M4/1315H01M4/50H01M4/505H01M4/58H01M10/0525H01M10/36
CPCH01M4/131H01M4/1315H01M4/505H01M4/581Y10T29/49108Y02E60/122Y02T10/7011Y10T29/49115H01M10/0525Y02E60/10H01M4/36H01M4/04
Inventor KWEON, HO-JINKIM, GEUN-BAEPARK, DONG-GONNOH, HYUNG-GON
Owner KWEON HO JIN
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