Synthesis and Electrochemical Properties of Layered Li[Li0.15NixAl0.55-2xMn0.3+x]O2 Cathode Materials for Lithium Secondary Batteries

Abstract

The presently commercialized lithium-ion batteries use layer structured LiCoO2 cathodes. Because of the high cost and toxicity of cobalt, an intensive search for new cathode materials has been underway in recent years. The Mn-based materials have attracted wide attention as intercalation cathode materials because of their low cost and non-toxicity. Many research groups have been studied to prepare layered LiMnO2 with the α-NaFeO2 structure as LiCoO2 and LiNiO2. However, the LiMnO2 materials transform to spinel-like phase during cycling only by a minor cationic arrangement. One of promising cathode materials is layered Li[Li0.2Cr0.4Mn0.4]O2 which can be consisted of solid solution between LiCrO2 and Li2MnO3 [1]. Recently, some research groups have studied to stabilize layered structure by using solid solution between Li2MnO3 and LiMO2 (M = Cr, Ni, Co) such as Li[Li(1-2x)/3 Nix Mn(2-x)/3]O2 and Li[Li(1-x)/3Co(Cr)xMn(2-2x)/3]O2 [2,3]. In this system, M is the redox-active species from Mn+ to M(n+1)+ or M(n+2) or M(n+3)+, while Li1/3Mn2/3 clusters with tetravalent manganese act as inert matrix. In this work, we report the structural and electrochemical properties of a layered Li[Li0.15NixAl0.55-2xMn0.3+x]O2 materials.