고분자 도포를 이용한 실리콘-탄소의 합성 및 Si-C Li Cell의 전기화학적 특성
Synthesis of Silicon-Carbon by Polymer Coating andElectrochemical Properties of Si-C|Li Cell
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초록
실리콘 분말에 polyaniline(PAn)을 중합하고 탄화하여 Si-C 재료를 개발하고 물리적 특성 및 전기화학적 특성을 분석 하였다. 평균입도는 PAn의 중합으로 증가하였으며 탄화로 일부 감소하였다. XRD 분석으로 결정질의 실리콘과 비결정 성의 탄소 재료가 공존함을 확인 하였다. Si-PAn 전구체로 부터 개발한 Si-C 재료를 이용한 Si-C|Li cell은 Si|Li cell에 비하여 우수한 특성을 나타내었으며, 탄소 전구체인 PAn의 HCl 탈도핑에 의해 전기화학적 특성을 개선할 수 있었다. 전해액 중 FEC 첨가한 경우 초기 방전 용량이 증가하였다. GISOC 시험으로 구한 가역 비용량 범위는 Si- C(Si:PAn=50:50 wt. ratio)|Li 전지의 경우 약 414 mAh/g를 나타내었으며, 가역 범위에 대한 초기 충방전의 intercalation 효율(IIE)는 75.7%였으며, 표면 비가역 비용량은 35.4 mAh/g을 나타내었다.
Abstract
Abstract : Si-C composites were prepared by the carbonization of silicon powder covered by polyaniline(PAn). Physical and electrochemical properties of the Si-C composites were characterized by the particle size analysis, X-ray diffraction technique, scanning electron microscope, and electrochemical test of battery. The average particle size of the Si was increased by the coating of PAn and somewhat reduced by the carbonization to give silicone-carbon composites. XRD analysis' results were confirmed co-existence of crystalline silicon and amorphous-like carbon. SEM photos showed that the silicon particle were well covered with carbonacious materials depend on the PAn content. Si-C|Li cells were fabricated using the Si-C composites and were tested using the galvanostatic charge-discharge test. Si-C|Li cells gave better electrochemical properties than that of Si|Li cell. Si-C|Li cell using the Si-C from HCl undoped PAn Precursor showed better electrochemical properties than that from HCl doped PAn Precursor. Using the electrolyte containing FEC as an additive, the initial discharge capacity was increased. After that the galvanostatic charge-discharge test with the GISOC(gradual increasing of the state of charge) condition was carried out. Si- C(Si:PAn=50:50 wt. ratio)|Li cell showed 414 mAh/g of the reversible specific capacity, 75.7% of IIE(initial intercalation efficiency), 35.4 mAh/g of IICs(surface irreversible specific capacity).
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