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Phase separation tendencies of aluminum-doped transition-metal oxides (LiAl{sub 1{minus}x}M{sub x}O{sub 2}) in the {alpha}-NaFeO{sub 2} crystal structure

Journal Article · · Journal of the Electrochemical Society
DOI:https://doi.org/10.1149/1.1392639· OSTI ID:20013016
There has recently been considerable interest in Al doping of lithium intercalation oxides. Al substitution of the transition-metal cation has been shown theoretically and experimentally to increase the cell voltage. First-principles methods are used to calculate the miscibility of eight aluminum-doped transition-metal oxides in the layered {alpha}-NaFeO{sub 2} structure. This study finds that for all Li(Al,M)O{sub 2} compounds investigated (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu) the enthalpy of mixing is positive. In addition, detailed analyses were performed on LiAl{sub 1{minus}x}Co{sub x}O{sub 2} and LiAl{sub 1{minus}x}Cr{sub x}O{sub 2} by calculating full temperature-composition phase diagrams. For the Li(Al,Co)O{sub 2} system, the authors find regions of immiscibility below {minus}173 C and above 600 C. For both Li(Al,Co)O{sub 2} and Li(Al,Cr)O{sub 2} above 600 C, Al-doping is limited by the formation of {gamma}-LiAlO{sub 2}.
Research Organization:
Massachusetts Inst. of Tech., Cambridge, MA (US)
Sponsoring Organization:
US Department of Energy
DOE Contract Number:
FG02-96ER45571
OSTI ID:
20013016
Journal Information:
Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 12 Vol. 146; ISSN 0013-4651; ISSN JESOAN
Country of Publication:
United States
Language:
English