In LiMn1.5+xNi0.5-xO4, the amount of Mn3+ was experimentally reported to increase with increasing the Mn/Ni ratio, which is likely due to the antiparallel spin alignment between Mn4+ and Mn3+.  In this talk, we will present theoretical evidence for Mn3+-concentration dependence of spin alignments, through density functional theory/Hubbard model (DFT+U) calculations.  For this study, U parameters for Mn, Ni and O were first optimized by fitting to the predicted electronic structures from hybrid-DFT, which turns out to be very effective.  With the newly optimized U values, we have successfully reproduced relevant experimental results.  This talk will also touch on the behavior of dopants (Cr, Fe, Co) near the surface of LiMn1.5Ni0.5O4, together with underlying reasons; our calculations show that Cr and Fe undergo surface segregation while Co doesn't.  We will finally discuss how the cycling performance and rate capability of LiMn1.5Ni0.5O4 can be enhanced by doping of certain 3d elements.

Magnetic and electronic properties of doped LiMn1.5Ni0.5O4: A first principles study

245th National Meeting (2013)

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