Gel Combustion Synthesis of Li(Ni,Mn,Co,Fe)O2 Solid Solutions

Abstract

An option for the homogeneous substitution of iron for cobalt, nickel, and manganese in solid solutions with a α-NaFeO₂-type layered structure formed in the system Li–Ni–Mn–Co–O was studied. Two sets of samples, namely, Li(Ni_0.33Mn_0.33Co_0.33)_1 –xFe_xO₂ and Li(Ni_0.60Mn_0.20Co_0.20)_1 –xFe_xO₂ (0 ≤ х ≤ 1), were prepared by combusting sucrose- or starch-based gels and characterized by X-ray powder diffraction. It is the first time that single-phase Li(Ni,Mn,Co,Fe)O₂ samples containing 15–20% Fe of the total amount of cations were prepared. The position of a metastable area of Li(Ni,Mn,Co,Fe)O₂ solid solutions with respect to the section LiNiO₂–LiMn_0.5Co_0.5O₂–LiFeO₂ was determined in the frame of the isobaric–isothermal tetrahedron LiNiO₂–LiMnO₂–LiCoO₂–LiFeO₂.