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

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(Ni0.33Mn0.33Co0.33)1 –xFexO2 and Li(Ni0.60Mn0.20Co0.20)1 –xFexO2 (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–LiMn0.5Co0.5O2–LiFeO2 was determined in the frame of the isobaric–isothermal tetrahedron LiNiO2–LiMnO2–LiCoO2–LiFeO2.