First-principle investigation on stability of Co-doped spinel λ-Mn_4−xCo_xO₈

Abstract

The mechanism of stability of Co-doped spinel λ-MnO₂ that is referred to as spinel Li_xMn₂O₄ (x=0) was studied by using the first-principle calculation method. The total energy and formation enthalpy can be decreased remarkably due to the Co substation, resulting in a more stable structure of λ-Mn_xCr_2−xO₄. The bond order and DOS analysis were given in detail to explain the nature of stability improvement. The calculated results show that as the content of Co dopant increases, the bond order of Mn—O becomes larger and the peak of density of states around Fermi level shifts toward lower energy. The charge density distribution illustrates that the Mn—O bonding is ionic and partially covalent, and the covalent Mn—O bonding becomes stronger with the increase of Co dopant content. The results confirm that the Co-doping will enhance the stability of λ-MnO₂ and hence improve the electrochemistry performance of Li_xMn₂O₄.

Keywords

first-principles / stability / electrochemical performance / Co-doped λ-MnO₂

References

[1] AydinolM. K., KohanA. F., CederG., et al.. Ab initio study of lithium intercalation in metal oxides and metal dichalcogenides[J]. Physical Review B, 1997, 56(3): 1354-1365

[2] AroraP., PopovB. N., WhiteR. E.. Electrochemical investigation of cobalt-doped LiMn₂O₄ as cathode material for Li-ion batteries[J]. Journal of the Electrochemical Society, 1998, 145(3): 807-815

[3] GummowR. J., DekockA., ThackerayM. M.. Improved capacity retention in rechargeable 4 V lithium/lithium-manganese oxide (Spinel) cells[J]. Solid State Ionics, 1994, 69(1): 59-67

[4] LiuY., FujiwararT., YukawaH., et al.. Chemical bonding in lithium intercalation compound Li_xMn₂O₄(x=0, 1, 2)[J]. Electrochimica Acta, 2001, 46: 1151-1159

[5] ShiS.-q., WangD.-s., MengS., et al.. First-principles studies of cation-doped spinel LiMn₂O₄ for lithium ion batteries[J]. Physical Review B, 2003, 67: 115130-115136

[6] GuohuaL., IkutaH., UchidaR., et al.. The spinel phases LiM_yMn_2−yO₄ (M=Co,Cr,Ni) as the cathode for rechargeable lithium batteries[J]. Journal of the Electrochemical Society, 1996, 143(1): 178-182

[7] BanovB., TodorovY., TrifonovaA.. LiMn_2−xCo_xO₄ cathode with enhanced cycle ability[J]. Journal of Power Sources, 1997, 68: 578-581

[8] AmineK., TukamotoH., YasudaH., et al.. Preparation and electrochemical investigation of LiMn_2−xMe_xO₄ (Me:Ni, Fe, and x=0.5, 1) cathode materials for secondary lithium batteries[J]. Journal of Power Sources, 1997, 68: 604-608

[9] MiuraK., YamadaA., TanakaM.. Electric states of spinel Li_xMn₂O₄ as a cathode of the rechargeable battery[J]. Electrochimica Acta, 1996, 41: 249-256

[10] CederG., MishraS. K.. Structural stability of manganese oxides[J]. Physical Review B, 1999, 59: 6120-6130

[11] VanderbiltD.. Soft self-consistent pseudopotentials in generalized eigenvalue formalism[J]. Physical Review B, 1990, 41: 7892-7895

[12] MattssonA. E., SchultzP. A., DesjarlaisM. P., et al.. Designing meaningful density functional theory calculations in materials science—a primer[J]. Modeling and Simulation in Materials Science and Engineering, 2005, 13: 1-31

[13] MonkhorstH. J., PackJ. D.. Special points for Brillouin-zone integrations[J]. Physical Review B, 1976, 13: 5188-5192

[14] LiuW., KowalK., FarringtonG. C.. Electrochemical characteristics of spinel phase LiMn₂O₄-based cathode materials prepared by the Pechini process[J]. Journal of the Electrochemical Society, 1996, 143(11): 3590-3596

[15] StrobelP., PalosA. I., AnneM., et al.. Structural, magnetic and lithium insertion properties of spinel-type Li₂Mn₃MO₈ oxides (M∼Mg, Co, Ni, Cu)[J]. Journal of Materials Chemistry, 2000, 10: 429-436

[16] WolvertonC.. First-principles prediction of vacancy order disorder and intercalation battery voltages Li_xCoO₂[J]. Physical Review Letters, 1998, 81(3): 606-609

[17] HuangY.-d., LiJ., JiaD.-zeng.. Preparation and characterization of LiMn_2−yCo_yO₄ spinel by low heating solid state coordination method[J]. Journal of Colloid and Interface Science, 2005, 286: 263-267

[18] BaderR. W.An Introduction to the Electronic Structure of Atoms and Molecules[M], 1980, Oxford, Oxford Press