Charge–discharge reaction mechanism of manganese molybdenum vanadium oxide as a high capacity anode material for Li secondary battery

Abstract

The compound system, Mn 12x Mo 2x V 2(12x) O 6 (0 ¡ x ¡ 0.4), synthesized by solid state reaction forms the brannerite structure. The electrochemical reaction mechanism as the anode for Li secondary batteries was investigated. X-ray diffraction (XRD) analysis clearly indicated that Mn 0.6 Mo 0.8 V 1.2 O 6 anode irreversibly transformed from crystalline brannerite to amorphous phase via a rock-salt type structure during the first lithium insertion/removal reaction. The charge compensation and the change in the local environmental structure during the Li insertion/removal were confirmed by X-ray absorption fine structure (XAFS) of manganese, vanadium and molybdenum.

A new class of high capacity cation-disordered oxides for rechargeable lithium batteries: Li–Ni–Ti–Mo oxides

“…It has been previously shown that the intensity of the pre-edge peak increases as the site symmetry of the TM ions decreases from a centrosymmetric to a non-centrosymmetric environment. [40][41][42] This is because an electric dipole-forbidden transition from the Mo 1s to the Mo 4d orbital (corresponding to the pre-edge peak) becomes partially allowed in a non-centrosymmetric environment which leads to stronger 4d-5p mixing. [40][41][42] For example, the pre-edge peak observed in MoO 3 (grey dot-dashed line) originates from highly distorted Mo-O octahedra.…”

“…[40][41][42] This is because an electric dipole-forbidden transition from the Mo 1s to the Mo 4d orbital (corresponding to the pre-edge peak) becomes partially allowed in a non-centrosymmetric environment which leads to stronger 4d-5p mixing. [40][41][42] For example, the pre-edge peak observed in MoO 3 (grey dot-dashed line) originates from highly distorted Mo-O octahedra. 42 Therefore, the intensity increase of Mo pre-edge peak of LNTMO20 shows that the Mo environment deviates from the regular octahedral coordination upon cycling, 42 which may originate from a distortion of the Mo-O octahedra, or from some degree of Mo 6+ migration from octahedral to tetrahedral sites.…”

“…[40][41][42] For example, the pre-edge peak observed in MoO 3 (grey dot-dashed line) originates from highly distorted Mo-O octahedra. 42 Therefore, the intensity increase of Mo pre-edge peak of LNTMO20 shows that the Mo environment deviates from the regular octahedral coordination upon cycling, 42 which may originate from a distortion of the Mo-O octahedra, or from some degree of Mo 6+ migration from octahedral to tetrahedral sites. Comparison with the spectra of MoO 2 and MoO 3 -shows that the Mo edge position of LNTMO20 does not shift down in energy after the first discharge, which strongly suggests that the majority of the Mo ions remain 6+.…”

Nanotube Li2MoO4: a novel and high-capacity material as a lithium-ion battery anode

“…3a, can be inferred to describe this delithiation product. [16][17][18][19][20][21][22][23] It is believed that this O-phase is responsible for electrochemical performance in the following cycles.…”

Beyond Intercalation‐Based Li‐Ion Batteries: The State of the Art and Challenges of Electrode Materials Reacting Through Conversion Reactions

“…In addition, electrochemical reduction of Mn 2 + to Mn has been observed for Mn 0.6 Mo 0.8 V 1.2 O 6 by X-ray absorption spectroscopy (XAS). [ 49 ] On the other hand, analysis of electron energy loss spectroscopy (EELS) data on β -MnO 2 electrodes, coupled with electron diffraction (ED), suggest that manganese is indeed not completely reduced and that LiMn 3 O 4 is formed upon discharge down to 0 V. [ 50 , 51 ] Since the formation of such oxide cannot explain the huge capacity of 1600 mAh g − 1 observed for this process, an alternative mechanism of interfacial storage, which is overviewed below, is speculated. Considering that long voltage plateaus are observed for both γ -and β -MnO 2 (albeit separated by 100 mV), it is not likely that the difference in manganese dioxide polytype will have a fundamental effect.…”