X-선 흡수실험 및 제일원리계산을 통한 Cr-doped Li_(4)Ti_(5)O_(12)의 미세구조 및 전자구조 해석
Analyses on Fine Structure and Electronic Structure of Cr-doped Li_(4)Ti_(5)O_(12)by Using X-ray Absorption Spectroscopy and First Principle Calculation
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초록
Li_(4)Ti_(5)O_(12)는 우수한 안정성으로 고출력 배터리의 음극 물질로 주목받고 있다. 그러나 절연체로서전도도의 개선이 필요한 상황으로 다양한 방법이 시도되고 있다. 본 연구에서는 Cr 도핑을 통해서Li_(4)Ti_(5)O_(12)의 전도도 향상을 목표로 하였으며, X-선 흡수 실험 및 FEFF 8.4 코드를 이용한 제일원리 계산을 통해서 도핑에 의한 미세 구조 및 전자 구조의 변화를 분석하였다. Cr 도핑은페르미 레벨을 Cr d 밴드의 중심에 위치시켜 전도성을향상시켰으며, Ti d 밴드의 전자밀도를 높여 XANES pre-edge및 White line의 변화를 야기했다.
Abstract
Li_(4)Ti_(5)O_(12) has been considered a potential material for high power lithium batteries. Since Li_(4)Ti_(5)O_(12) is however an insulator having a broad band gap, various methods have been employed to improve the conductivity. In this study, we have investigated the change of fine structure and electronic structure by Cr doping using X-ray absorption spectroscopy and First Principle Calculation. Doping with Cr, we could obtain an enhanced electronic conductivity by locating the Fermi level at the center position of Cr d-band and identify the change of XANES pre-edge and white line peak due to the increase of electron density of Ti d-band.
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