TY - JOUR
T1 - Systematic calculations of On (n = 1 to 6) polytypes of LiCoO2
AU - Fisher, Craig A.J.
AU - Kuwabara, Akihide
AU - Moriwake, Hiroki
AU - Oki, Hideki
AU - Kohama, Keiichi
AU - Ikuhara, Yuichi
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2014/6
Y1 - 2014/6
N2 - Six different polytypes On (n = 1 to 6) of the conventional lithium-ion battery cathode material LiCoO2 are examined systematically using first-principles calculations within the framework of density functional theory. The calculations correctly predict the most stable form to be O3-LiCoO2, and indicate that the recently synthesized O4 polytype is slightly more stable than O2-LiCoO2, with a lattice energy per formula unit intermediate between O2- and O3-LiCoO2. Extending the calculations to the as-yet unobserved O5 polytype suggests that this is also slightly more stable than the O2 form. The potential differences of each polytype relative to lithium metal are found to decrease as the concentration of stacking faults (and volumetric mass density) increases, with a maximum of 3.89 eV for the polytype with optimum crystal packing (cubic-close-packing, ccp), namely O3-ABCABC, and a minimum for the highest concentration of stacking faults, corresponding to a hexagonal close-packed structure, i.e., O1. Other polytypes can be considered as intergrowths of these two configurations, so that for n beyond 6 the most stable form of each polytype is expected to display properties increasingly similar to those of O3 as the proportion of ccp sequences will increase.
AB - Six different polytypes On (n = 1 to 6) of the conventional lithium-ion battery cathode material LiCoO2 are examined systematically using first-principles calculations within the framework of density functional theory. The calculations correctly predict the most stable form to be O3-LiCoO2, and indicate that the recently synthesized O4 polytype is slightly more stable than O2-LiCoO2, with a lattice energy per formula unit intermediate between O2- and O3-LiCoO2. Extending the calculations to the as-yet unobserved O5 polytype suggests that this is also slightly more stable than the O2 form. The potential differences of each polytype relative to lithium metal are found to decrease as the concentration of stacking faults (and volumetric mass density) increases, with a maximum of 3.89 eV for the polytype with optimum crystal packing (cubic-close-packing, ccp), namely O3-ABCABC, and a minimum for the highest concentration of stacking faults, corresponding to a hexagonal close-packed structure, i.e., O1. Other polytypes can be considered as intergrowths of these two configurations, so that for n beyond 6 the most stable form of each polytype is expected to display properties increasingly similar to those of O3 as the proportion of ccp sequences will increase.
KW - Density functional theory
KW - Electrode potentials
KW - Lithium cobalt oxides
KW - Lithium-ion batteries
KW - Polytypes,
KW - Stacking faults
UR - http://www.scopus.com/inward/record.url?scp=84902650369&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84902650369&partnerID=8YFLogxK
U2 - 10.1002/pssr.201409167
DO - 10.1002/pssr.201409167
M3 - Article
AN - SCOPUS:84902650369
VL - 8
SP - 545
EP - 548
JO - Physica Status Solidi - Rapid Research Letters
JF - Physica Status Solidi - Rapid Research Letters
SN - 1862-6254
IS - 6
ER -