Effects of Aluminum Doping on The Phase Stability and Electrochemical Properties of LiCoO2 and LiMnO2

1997 ◽  
Vol 496 ◽  
Author(s):  
Y.-I. Jang ◽  
B. Huang ◽  
H. Wang ◽  
Y.-M. Chiang ◽  
D. R. Sadoway
Keyword(s):  
Single Phase ◽  
Low Cost ◽  
Reversible Capacity ◽  
Open Circuit ◽  
Teller Distortion ◽  
Al Content ◽  
Jahn Teller ◽  
Li Battery ◽  
Low Mass ◽  
Jahn Teller Distortion

ABSTRACTAluminum is of interest as a constituent for Li battery electrodes due to its low cost and low mass, and because ab initio calculations indicate that solid solution of LiAlO2 with LiMO2 (M = transition metal) in the α-NaFeO2 structure can increase intercalation voltage [1]. In this study, we investigated the effect of Al doping on LiCoO2 and LiMnO2. Single phase LiAlyCo1-yO2 has been synthesized up to y = 0.5 by firing homogenous hydroxide precursors. A systematic increase in the open circuit voltage is observed with Al content. In LiAlyMn1-yO2, the addition of LiAlO2 stabilizes LiMnO2 in the α-NaFeO2 structure under conditions where neither endmember is stable in the structure. High reversible capacity was obtained over both a 4 V and 3 V plateau, indicating that the compound transforms to a spinel-related structure during cycling, but that the cooperative Jahn-Teller distortion is suppressed.

scholarly journals Enhanced Cycling Stability through Erbium Doping of LiMn2O4 Cathode Material Synthesized by Sol-Gel Technique

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1558 ◽  
Author(s):  
Hongyuan Zhao ◽  
Xiuzhi Bai ◽  
Jing Wang ◽  
Dongdong Li ◽  
Bo Li ◽  
...  
Keyword(s):  
Spinel Structure ◽  
Sol Gel ◽  
Reversible Capacity ◽  
Narrow Particle Size Distribution ◽  
Substantial Impact ◽  
Teller Distortion ◽  
Er Doping ◽  
Jahn Teller ◽  
Limn2o4 Cathode ◽  
Jahn Teller Distortion

In this work, LiMn2−xErxO4 (x ≤ 0.05) samples were obtained by sol-gel processing with erbium nitrate as the erbium source. XRD measurements showed that the Er-doping had no substantial impact on the crystalline structure of the sample. The optimal LiMn1.97Er0.03O4 sample exhibited an intrinsic spinel structure and a narrow particle size distribution. The introduction of Er3+ ions reduced the content of Mn3+ ions, which seemed to efficiently suppress the Jahn–Teller distortion. Moreover, the decreased lattice parameters suggested that a more stable spinel structure was obtained, because the Er3+ ions in a ErO6 octahedra have stronger bonding energy (615 kJ/mol) than that of the Mn3+ ions in a MnO6 octahedra (402 kJ/mol). The present results suggest that the excellent cycling life of the optimal LiMn1.97Er0.03O4 sample is because of the inhibition of the Jahn-Teller distortion and the improvement of the structural stability. When cycled at 0.5 C, the optimal LiMn1.97Er0.03O4 sample exhibited a high initial capacity of 130.2 mAh g−1 with an excellent retention of 95.2% after 100 cycles. More significantly, this sample showed 83.1 mAh g−1 at 10 C, while the undoped sample showed a much lower capacity. Additionally, when cycled at 55 °C, a satisfactory retention of 91.4% could be achieved at 0.5 C after 100 cycles with a first reversible capacity of 130.1 mAh g−1.

The Interplay of Open-Shell Spin-Coupling and Jahn-Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

2020 ◽  
Author(s):  
Marta L. Vidal ◽  
Michael Epshtein ◽  
Valeriu Scutelnic ◽  
Zheyue Yang ◽  
Tian Xue ◽  
...  
Keyword(s):  
High Harmonic ◽  
Open Shell ◽  
Spin Coupling ◽  
High Symmetry ◽  
Teller Distortion ◽  
Spectral Window ◽  
X Ray ◽  
Jahn Teller ◽  
X Ray Absorption ◽  
Jahn Teller Distortion

We report a theoretical investigation and elucidation of the x-ray absorption spectra of neutral benzene and of the benzene cation. The generation of the cation by multiphoton ultraviolet (UV) ionization as well as the measurement of<br>the carbon K-edge spectra of both species using a table-top high-harmonic generation (HHG) source are described in the companion experimental paper [M. Epshtein et al., J. Phys.<br>Chem. A., submitted. Available on ChemRxiv]. We show that the 1sC -> pi transition serves as a sensitive signature of the transient cation formation, as it occurs outside of the spectral window of the parent neutral species. Moreover, the presence<br>of the unpaired (spectator) electron in the pi-subshell of the cation and the high symmetry of the system result in significant differences relative to neutral benzene in the spectral features associated with the 1sC ->pi* transitions. High-level calculations using equation-of-motion coupled-cluster theory provide the interpretation of the experimental spectra and insight into the electronic structure of benzene and its cation.<br>The prominent split structure of the 1sC -> pi* band of the cation is attributed to the interplay between the coupling of the core -> pi* excitation with the unpaired electron<br>in the pi-subshell and the Jahn-Teller distortion. The calculations attribute most of<br>the splitting (~1-1.2 eV) to the spin coupling, which is visible already at the Franck-Condon structure, and estimate the additional splitting due to structural relaxation to<br>be around ~0.1-0.2 eV. These results suggest that x-ray absorption with increased resolution might be able to disentangle electronic and structural aspects of the Jahn-Teller<br>effect in benzene cation.<br>

Jahn-Teller Effect in Hexahydroxocuprate(II) Complexes

1995 ◽  
Vol 60 (9) ◽  
pp. 1429-1434
Author(s):  
Martin Breza
Keyword(s):  
Hydrogen Bonding ◽  
Quantum Chemical ◽  
Potential Surface ◽  
Hydroxyl Group ◽  
Chemical Calculation ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Extremal Values ◽  
Jahn Teller Distortion

Using semiempirical CNDO-UHF method the adiabatic potential surface of 2[Cu(OH)6]4- complexes is investigated. The values of vibration and vibronic constants for Eg - (a1g + eg) vibronic interaction attain extremal values for the optimal O-H distance. The Jahn-Teller distortion decreases with increasing O-H distance. The discrepancy between experimentally observed elongated bipyramid of [Cu(OH)6]4- in Ba2[Cu(OH)6] and the compressed one obtained by quantum-chemical calculation is explainable by hydrogen bonding of the axial hydroxyl group.

Unveiling the role of Mn-interstitial defect and particle size on the Jahn-Teller distortion of the LiMn2O4 cathode material

2021 ◽  
Vol 490 ◽  
pp. 229519
Author(s):  
Renier Arabolla Rodríguez ◽  
Nelcy Della Santina Mohallem ◽  
Manuel Avila Santos ◽  
Demetrio A. Sena Costa ◽  
Luciano Andrey Montoro ◽  
...  
Keyword(s):  
Particle Size ◽  
Cathode Material ◽  
Teller Distortion ◽  
Interstitial Defect ◽  
Jahn Teller ◽  
Limn2o4 Cathode ◽  
Jahn Teller Distortion

OBSERVATION OF THE ESR FOR HIGH-Tc SUPERCONDUCTORS Bi-Sr-Ca-Cu-O

1989 ◽  
Vol 03 (04) ◽  
pp. 355-359 ◽  
Author(s):  
S.L. YUAN ◽  
B.H. HOU ◽  
S.Z. JIN ◽  
W. WANG ◽  
G.G. ZHENG ◽  
...  
Keyword(s):  
Superconducting Transition ◽  
Teller Distortion ◽  
High Tc ◽  
Spin Resonance ◽  
Jahn Teller ◽  
Zero Resistance ◽  
Magnetic Ions ◽  
Preliminary Study ◽  
Perpendicular Component ◽  
Jahn Teller Distortion

The preliminary study on the electron spin resonance (ESR) for the Bi-Sr-Ca-Cu-O system with different superconducting transition temperatures has been made at room temperature. It is found that the Lande factor g-values are increased with increasing zero resistance temperature T c0 but width between peaks ΔH pp of the ESR spectrum decreased with increasing T c0 . These might be attributed to the spin-orbit coupling of the magnetic ions and the Jahn-Teller distortion in the perpendicular component.

Experimental Evidence for a Jahn-Teller Distortion in AuCl3

2005 ◽  
Vol 117 (41) ◽  
pp. 6904-6908 ◽  
Author(s):  
Ian J. Blackmore ◽  
Adam J. Bridgeman ◽  
Neil Harris ◽  
Mark A. Holdaway ◽  
John F. Rooms ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Distortion
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