Effect of Graphite Mixing Method on Electrode Characteristics in Cathode Resynthesis of Lithium Battery

리튬전지(電池) 양극(陽極) 재합성시(再合成時) 흑연(黑鉛) 도전재(導電材) 혼합방법(混合方法)이 전극특성(電極特性)에 미치는 영향(影響)

  • 이철경 (금오공과대학교 신소재시스템공학부) ;
  • 김태현 (자원재활용기술개발사업단)
  • Published : 2010.02.26

Abstract

To improve electronic conductivity of cathodic active materials of lithium ion battery, carbonaceous materials is usually added. New mixing method of abrasive milling has been investigated in mixing of graphite and $LiCoO_2$ powders. It would be expected that uniform mixing of graphite reduces capacity fading of cathode of lithium battery. Abrasion milled $LiCoO_2$ composite showed the best electrochemical performance as a cathode material with 1 wt% of graphite content, 300 rpm of milling speed, and 10 min of milling time. The improvement of the electrochemical performances such as cycleability and charge/discharge capacity retention would be mainly attributed to increase of the electronic conductivity and/or prevention of the active materials by uniform dispersion and coating of graphite on $LiCoO_2$.

리튬이온전지의 양극 전자전도도를 향상시키기 위하여 탄소제를 첨가할 때 기존의 혼합법과는 다르게 abrasive milling에 의하여 $LiCoO_2$ 양극 활물질에 흑연을 균일하게 분산시켜서 충방전시 용량감소를 줄이고자 하였다. 밀링 조건은 300 rpm, 10min으로 하였으며, 흑연 농도는 전기 전도성 향상과 용량의 관계를 고려해 볼 때, 1 wt% 경우가 가장 우수한 전극특성을 보여주었다. Abrasion법은 기존 혼합법에 비하여 10% 이상 capacity retention의 향상을 가져올 수 있었으며, 비가역적인 용량에 있어서도 초기 방전 용량의 효율도 높아 비가역 용량이 감소되는 효과를 얻을 수 있었다. 이는 첨가한 흑연이 균일하게 혼합되고 일부는 $LiCoO_2$ 표면에 코팅되어 전자전도도를 향상시키고 산화물인 활물질의 용해를 억제하기 때문으로 생각된다.

Keywords

References

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