Premium
Thermodynamic Stability of Transition‐Metal‐Substituted LiMn 2− x M x O 4 (M=Cr, Fe, Co, and Ni) Spinels
Author(s) -
Lai Chenying,
Chen Jiewei,
Knight James C.,
Manthiram Arumugam,
Navrotsky Alexandra
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201600120
Subject(s) - transition metal , chemical stability , materials science , crystallography , x ray crystallography , chemistry , mineralogy , thermodynamics , physics , diffraction , catalysis , optics , biochemistry
The formation enthalpies from binary oxides of LiMn 2 O 4 , LiMn 2− x Cr x O 4 ( x= 0.25, 0.5, 0.75 and 1), LiMn 2− x Fe x O 4 ( x= 0.25 and 0.5), LiMn 2− x Co x O 4 ( x= 0.25, 0.5, and 0.75) and LiMn 1.75 Ni 0.25 O 4 at 25 °C were measured by high temperature oxide melt solution calorimetry and were found to be strongly exothermic. Increasing the Cr, Co, and Ni content leads to more thermodynamically stable spinels, but increasing the Fe content does not significantly affect the stability. The formation enthalpies from oxides of the fully substituted spinels, LiMnMO 4 (M=Cr, Fe and Co), become more exothermic (implying increasing stability) with decreasing ionic radius of the metal and lattice parameters of the spinel. The trend in enthalpy versus metal content is roughly linear, suggesting a close‐to‐zero heat of mixing in LiMn 2 O 4 —LiMnMO 4 solid solutions. These data confirm that transition‐metal doping is beneficial for stabilizing these potential cathode materials for lithium‐ion batteries.