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Studies on the local structures for the trigonal N i 3+ centers in cathode materials L i A l y C o 1–y O 2 ( y = 0, 0.1, 0.5, and 0.8)
Author(s) -
Ding ChangChun,
Wu ShaoYi,
Xu YongQiang,
Zhang LiJuan
Publication year - 2018
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.4738
Subject(s) - chemistry , octahedron , electron paramagnetic resonance , crystallography , non blocking i/o , cathode , transition metal , cluster (spacecraft) , hyperfine structure , nickel , electrochemistry , metal , anisotropy , crystal structure , nuclear magnetic resonance , atomic physics , physics , electrode , biochemistry , organic chemistry , computer science , programming language , catalysis , quantum mechanics
The local angular distortions Δθ are theoretically studied for the various Ni 3+ centers in LiAl y Co 1–y O 2 at different Al concentrations ( y = 0, 0.1, 0.5, and 0.8) based on the perturbation calculations of electron paramagnetic resonance g factors for a trigonally distorted octahedral 3d 7 cluster with low spin (S = 1/2). Due to the Jahn–Teller effect, the [NiO 6 ] 9– clusters are found to experience the local angular distortions (Δθ ≈ 5°–9°) along the C 3 axis. The variation trend of Δθ with y is in accordance with that of anisotropy (Δ g = g || − g ⊥ ). As the substitutions can weaken bond strengths between transition metal and oxygen and the structural stability plays an important role in cathode performances, detailed investigations on the structural properties of the cathode materials LiAl y Co 1–y O 2 can be practically helpful to understand the performances of these materials. The oxy‐redox properties of LiAl y Co 1–y O 2 systems are comprehensible in the framework of Ni 3+ /Ni 4+ couples, and the trigonally compressed octahedral [NiO 6 ] 9– clusters are applicable to the clarification of the electrochemical properties of lithium nickel oxide batteries. It appears that LiAl 0.8 Co 0.2 O 2 with the largest Al concentration may correspond to the smallest distortion among the mixing systems.