망간과 코발트 함량에 따른 층상형 Li[Ni0.52Co0.16+xMn0.32-x]O2 양극물질의 전기화학적 및 열적 특성 향상에 관한 연구

Abstract

We investigate the effects of the Co and Mn ratio on the structure, morphology, electrochemical properties, and thermal stability of Li[Ni0.52Co0.16+xMn0.32‐ x]O2 cathode materials. Li[Ni0.52Co0.16+xMn0.32‐ x]O2 (x = 0, 0.08, 0.16) cathode materials are prepared via high temperature calcination of LiOH and coprecipitated [Ni0.52Co0.16+xMn0.32‐ x](OH)2 hydroxides. From an X‐ ray diffraction investigation, the prepared materials have a well ordered O3 type α­NaFeO2 layer structure. As the Co content (x) is increased, the initial discharge capacity increase slightly but it is accompanied by severe capacity fading during extensive cycling. Meanwhile, a small increase of Mn enhances the electrochemical stability at high temperature (55oC) as well as the thermal stability. Electrochemical impedance spectroscopy reveals that manganese substitution is effective to reduce the resistance during cycling due to stabilization of the host structure.