Journal of the Korean Crystal Growth and Crystal Technology (한국결정성장학회지)

The Korea Association of Crystal Growth (한국결정성장학회)
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Synthesis and electrochemical properties of $LiCoO_2$ powders by urea hydrolysis

우레아 가수분해법에 의한 리튬이차전지용 $LiCoO_2$의 합성과 전기화학적 특성

  • 정용희 (한양대학교 일반대학원 세라믹공학과) ;
  • 강귀원 (한양대학교 일반대학원 세라믹공학과) ;
  • 정훈 (요업기술원 도자ㆍ구조세라믹본부) ;
  • 백윤규 (한양대학교 일반대학원 세라믹공학과) ;
  • 황광택 (요업기술원 도자ㆍ구조세라믹본부)
  • Published : 2004.12.01
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Abstract

Lithium cobalt oxide $(LiCoO_2)$ cathode powders for rechargeable battery have been successfully prepared using urea hydrolysis method. The obtained hydrolysis-derived precursors with different Li/Co molar ratio were calcined at various temperatures. Low temperature phase $(LT-LiCoO_2)$ and high temperature phase $(HT-LiCoO_2)$ were obtained after calcination at $500^{\circ}C$ for 2 hr, and phase transformation from $LT-LiCoO_2{\;}to{\;}HT-LiCoO_2$ was completely occurred over $700^{\circ}C$. The layered structure of $LiCoO_2$ was well developed with a rise in the calcination temperature. Charge-discharge test show that the lithium cobalt oxide with 1.2 molar ratio prepared at $800^{\circ}C$ has an initial discharge capacity as high as 152 mAh/g, and the relatively stable cycling characteristic with 9.2 % of capacity fading was obtained after 40th charge-discharge test.

우레아 가수분해법을 이용하여 리튬이차전지용 $LiCoO_2$ 양극 분말을 합성하였다. Li/Co 몰비가 다르고 가수분해에 의해 얻어진 전구체는 다양한 온도에서 열처리되었다. 저온상 $LiCoO_2(LT-LiCoO_2)$와 고온상 $LiCoO_2(HT-LiCoO_2)$는 $500^{\circ}C$에서 2시간 열처리 후 합성되었고, 저온상에서 고온상으로 상전이는 $700^{\circ}C$ 이상에서 완전히 일어났다. 열처리 온도가 증가함에 따라 $LiCoO_2$의 층상구조가 잘 발달하였다. 충방전 실험결과 Li/Co의 몰비가 1.2이고 $800^{\circ}C$에서 열처리한 $LiCoO_2$의 초기용량이 152 mAh/g으로 높았으며, 40회 충.방전 후에는 9.2%의 용량감소를 나타내는 상대적으로 안정한 충방전 특성을 나타내었다.

Keywords

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