리튬이차전지의 양극소재로 사용되는 붕산염기반의 Fe, Mn 과 Co 복합소재의 합성과 구조적 연구

Abstract

Polyanionic structured compounds are widely studied as a cathode material for lithium-ion battery (LIB). Among them, lithium metal borate (LiMBO3, M = Mn, Fe, and Co) form has the lowest weight, thus offering the highest theoretical capacity (220 mAhg -1) and providing an advantage of safety. Also, the energy density is expected to be higher than lithium metal phosphate. Among borate-based materials, LiMnBO3 has the highest operating potential, while LiFeBO3 has the highest theoretical capacity. On the other hand, LiCoBO3 has an excellent theoretical capacity (215 mAh g-1) and 4 V operating potential. LiMBO3 (M = Mn, Fe, Co) compounds are crystallized in the monoclinic space group C2/c. In this study, LiFe1-xMnxBO3 and LiFe1 xCoxBO3 (x = 0, 0.25, 0.5, 0.75, and 1.0) composite materials have been synthesized with solid-state reaction method for structural studies according to the amount of d-electrons on metal sites. The morphological and structural studies of synthesized materials have been identified with X-ray diffraction (XRD) and 7Li nuclear magnetic resonance (NMR). Also, quantitative analysis for the ratio of metal has been performed with laser-induced breakdown spectroscopy (LIBS).