First-Principles Calculations for
Co-Doped LiMn1.5Ni0.5O4 and LiMn2O4
Battery Electrodes
R. Benedek, C. S. Johnson, and M. M. Thackeray
Argonne National Laboratory, Electrochemical Technology Program, Chemical
Engineering Division, Argonne, Illinois 60439, USA
Abstract
Cobalt is a widely used dopant in lithium-manganese-spinel-based electrode
materials for lithium batteries. Ambiguity exists, however, as to the valence of
Co in these spinels, as well as in numerous other oxides. First-principles
calculations with the generalized gradient approximation plus coulombic
interaction parameter U (GGA+U) method are performed for LiMn1.5Ni0.5O4
with and without Co substitutions, and for Co–substituted lithium manganese
spinel, LiMn2O4, to elucidate electronic and structural
properties of these high energy-density materials. The results indicate that Co
is divalent in these systems for low dopant concentrations, but divalent and
trivalent Co coexist at higher concentrations. This behavior is consistent with
available experimental results.
©2006 The Electrochemical Society
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