Journal of the Korean Electrochemical Society (전기화학회지)

The Korean Electrochemical Society (한국전기화학회)
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A Synthesis of LiCoO2 using the CoSO4 Recovered from Cathode Material Scrap and its Electrochemical Properties

폐 리튬 이차전지로부터 회수된 황산코발트 제조 및 이를 이용해 합성된 산화리튬코발트 양극활물질의 전기화학적 특성

  • Kim, Mi-So (Dept. of Materials Engineering and Convergence Technology & RIGET, Gyeongsang National University) ;
  • Ha, Jong-Keun (School of Materials Science and Engineering & RIGET, Gyeongsang National University) ;
  • Park, Se-Bin (R&D center, Metal Chemistry Corp.) ;
  • Ahn, Jou-Hyeon (Dept. of Materials Engineering and Convergence Technology & RIGET, Gyeongsang National University) ;
  • Choi, Im-Sic (R&D center, Metal Chemistry Corp.) ;
  • Cho, Kwon-Koo (Dept. of Materials Engineering and Convergence Technology & RIGET, Gyeongsang National University)
  • 김미소 (경상대학교 나노신소재융합공학과 & 그린에너지 융합연구소) ;
  • 하종근 (경상대학교 나노신소재공학부 & 그린에너지 융합연구소) ;
  • 박세빈 (메탈화학(주) 기술연구소) ;
  • 안주현 (경상대학교 나노신소재융합공학과 & 그린에너지 융합연구소) ;
  • 최임식 (메탈화학(주) 기술연구소) ;
  • 조권구 (경상대학교 나노신소재융합공학과 & 그린에너지 융합연구소)
  • Received : 2014.02.17
  • Accepted : 2014.04.27
  • Published : 2014.05.31
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Abstract

The electrochemical properties using the cells assembled with the synthesized $LiCoO_2$(LCO) were evaluated in this study. The LCO was synthesized from high-purity cobalt sulfate($CoSO_4$) which is recovered from the cathode scrap in the wastes lithium ion secondary battery(LIB). The leaching process for dissolving the metallic elements from the LCO scrap was controlled by the quantities of the sulfuric acid and hydrogen peroxide. The metal precipitation to remove the impurities was controlled by the pH value using the caustic soda. And also, D2EHPA and $CYANEX^{(R)}272$ were used in the solvent extraction process in order to remove the impurities again. The high-purity $CoSO_4$ solution was recovered by the processes mentioned above. We made the 6 wt.% $CoSO_4$ solution mixed with distilled water. And the 6 wt.% $CoSO_4$ solution was mixed with oxalic acid by the stirring method and dried in oven. $LiCoO_2$ as a cathode material for LIB was formed by the calcination after the drying and synthesis with the $Li_2CO_3$ powder. We assembled the cells using the $LiCoO_2$ powders and evaluated the electrochemical properties. And then, we confirmed possibility of the recyclability about the cathode materials for LIBs.

본 연구에서는 폐 리튬이차전지의 스크랩으로부터 순도 높은 황산코발트($CoSO_4$) 용액을 회수하고, 회수된 용액을 이용하여 리튬이차전지의 양극활물질인 $LiCoO_2$를 제조하여 전기화학적 특성을 평가하였다. 황산코발트의 제조는 황산과 과산화수소수를 이용하여 원료물질로부터 금속물질을 녹여내기 위한 침출단계, 가성소다를 이용한 pH 조절로 1차 불순물을 제거하기 위한 중화공정 및 D2EHPA와 $CYANEX^{(R)}272$를 이용하여 2차 불순물을 제거하기 위한 용매추출공정을 거쳐 고순도의 용액을 회수한다. 회수된 황산코발트는 증류수와 희석하여 6 wt.% 황산코발트 용액으로 만들고, 다시 옥살산과 혼합 및 교반 후 건조, 하소 및 리튬의 원료가 되는 $Li_2CO_3$ 분말과 혼합 후 합성 공정을 거쳐 이차전지의 양극활물질인 $LiCoO_2$를 제조하였다. 이를 이용하여 전극을 조립하고, 전기화학적 특성을 평가하였다. 전기화학적 특성은 본 실험에서 합성된 $LiCoO_2$와 상업용 $LiCoO_2$(Aldrich사)를 비교하였으며, 결과는 유사하거나 혹은 합성된 $LiCoO_2$가 더 우수한 것을 확인할 수 있었다. 따라서, 본 실험을 통해 양극활물질의 재활용 가능성을 확인하였다.

Keywords

References

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