Ethanothermal Synthesis of Octahedral-Shaped Doped Mn2O3 Single Crystals as a Precursor for LiMn2O4 Spinel Cathodes in Lithium-Ion Batteries

Micrometer-sized particles of single-crystalline octahedral-shaped Mn2O3 doped with various elements (Al, Ti, Ni, and Zr) have been obtained by an ethanothermal synthesis at 150 degrees C. The doping of other element(s) into the Mn2O3 framework is characterized by energy-dispersive X-ray spectroscopy and Xray powder diffraction. With Ni as a dopant, however, the particle morphology changed dramatically to spheres. The doped Mn2O3 with octahedral morphologies was employed as a precursor for the preparation of doped spinel LiMn2O4 cathodes for lithium-ion batteries. The doped samples exhibit enhanced cycle life, with the Al and Ti codoped sample displaying similar to 90% capacity retention after 100 cycles at C/3 rate in full cells with a graphite anode. In addition, replacing 25 vol % of ethanol with water as the solvent for the solvothermal synthesis gives a rod-shaped gamma-MnOOH structure instead of alpha-Mn2O3, which will be attractive for future studies of unique physicochemical properties originating from the shape.