리튬이차전지 양극소재용 LiMnBO3의 전기화학적 사이클 특성과 용량 저하에 관한 연구

Abstract

Recently polyanion-based materials (PO, BO, silicate, etc.) have been studied as cathode materials for rechargeable lithium-ion batteries due to their advantages over the commercial metal oxide cathode materials (LiCoO, Li(NiCoMn)O, etc.): low cost, thermal and chemical stability and low toxicity. However polyanion-based cathodes, such as LiFePO, have some problems of low theoretical capacity(170 mAh g) due to their high molecular weight compared to other metal oxide cathode materials(~280 mAh g). Therefore, alternative polyanion-based cathode materials of higher energy density, including silicates and borates, have developed due to its relatively low energy density. LiMnBO is highlighted as a prospective cathode materials for their high theoretical capacity of 222 mAh g. Moreover boron is abundance material in the earth’s crust and has slightly less electronegativity than phosphorous. Although LiMnBO has large theoretical capacity, its electrochemical properties have not been satisfied for the lithium rechargeable batteries. In this work we have synthesized LiMnBO and lithium excess LiMnBO to improve the electrochemical properties such as capacity and cycleability by solid-state method. The synthesized materials have been characterized using X-ray diffraction, scanning electron microscope(SEM) image and charge-discharge profile analysis. Also we used Ex-situ X-ray diffraction to compare cycle performance of the synthesized materials and the thermal stability of LiMnBO and LiMnBO was studied using Time-resolved X-ray diffraction.