Effect of Mn source and peculiar cycle characterization for LiAl0.1Mn1.9O4 material in the 3 V region

LiAl0.1Mn1.9O4 was synthesized using LiOH, Al(NO3)(3), and two different Mn3O4 sources (Tosoh and Chuodenki, Japan). Rietveld analysis revealed that the two Mn3O4 and LiAl0.1Mn1.9O4 compounds exhibited the same structures, respectively. LiAl0.1Mn1.9O4 materials showed similar physicochemical properties, but they presented very different cycle retention rates in the 3 V region after 50 cycles (Tosoh, 36.2%; Chuodenki, 98.6%). The ex situ X-ray powder diffraction measurements also revealed that the two LiAl0.1Mn1.9O4 materials showed different X-ray patterns after discharge to 2.2 V after 50 cycles. It was seen that LiAl0.1Mn1.9O4 synthesized using Tosoh Mn3O4 showed a mixture of distinct cubic and many tetragonal phases, but the other one using Chuodenki Mn3O4 maintained an almost perfect cubic phase after cycling. We found that the LiAl0.1Mn1.9O4 material might show an entirely different cycle characterization in the 3 V region although it was synthesized using the Mn source of the same crystal structure. (C) 2001 The Electrochemical Society.