In Situ X-ray Absorption Spectroscopic Study for α-MoO<sub>3</sub>Electrode upon Discharge/Charge Reaction in Lithium Secondary Batteries

Kang, Joo‐Hee; Paek, Seung‐Min

doi:10.5012/bkcs.2010.31.12.3675

Cited by 15 publications

(6 citation statements)

References 18 publications

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“…As a consequence, a distinct pre-edge peak occurs due to the transition from the core 1s level to the unoccupied 4d state. 47 Therefore, the oxidation state of Mo in this sample was close to +6. To get a better insight into the sample, an extended X-ray absorption fine structure (EXAFS) spectra of MoS 2 electrode before cycling were carried out, after the first discharge process and after 10 discharge–charge cycles, as shown in Fig.…”

Section: Resultsmentioning

confidence: 74%

An experimental and computational study to understand the lithium storage mechanism in molybdenum disulfide

et al. 2014

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The lithium storage mechanism in molybdenum disulfide (MoS(2)) has been comprehensively investigated as the existing conversion-based storage mechanism is unable to explain the reason behind its high practical capacity, high polarization losses, and the change in the discharge profile after the 1(st) charge-discharge cycle. To resolve these issues and to gain a deeper understanding of MoS(2)-based Li-ion batteries, for the first time, we have studied the reaction mechanism of the MoS(2) anode using various experimental techniques such as XRD, Raman spectroscopy, electrochemical impedance spectroscopy, XANES, and EXAFS, as well as ab initio density functional theory based calculations. On the basis of the results presented here, and in line with some experimental findings, we find that the reaction of MoS(2) with Li is not as simple as with usual metal oxide based conversion reactions, but that the pathway of the conversion reaction changes after the first discharge process. In the first discharge process, lithiation is initiated by a limited intercalation process, followed by a conversion reaction that produces molybdenum nanoparticles (Mo) and lithium sulfide (Li(2)S). Whereas, unlike oxide-based conversion materials, MoS(2) does not transverse back during the delithiation process. Indeed, instead of MoS(2) formation, we identified the presence of polysulfur after the complete cycle. In consecutive cycles, polysulfur reacts with lithium and forms Li(2)S/Li(2)S(2), and this Li-S reaction is found to be highly reversible in nature and the only source of the high practical capacity observed in this electrode. To validate our experimental findings, an atomic scale ab initio computational study was also carried out, which likewise suggests that Li first intercalates between the MoS(2) layers but that after a certain concentration, it reacts with MoS(2) to form Li(2)S. The calculations also support the non-reversibility of the conversion reaction, by showing that Mo + Li(2)S formation is energetically more favorable than the re-formation of MoS(2) + Li.

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Section: Resultsmentioning

confidence: 74%

An experimental and computational study to understand the lithium storage mechanism in molybdenum disulfide

et al. 2014

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“…Using the reference spectra of MoO 2 and MoO 3 (Supporting Information Figure S16), the valence state of Mo is estimated to be changed from +4 to around +6 during Li-ion extraction. In addition, the intensity of the pre-edges increases after charge, due to the distortion of the MoO 6 octahedron resulting from the increasing O 2p –Mo 4d hybridization. − These imply that the MoO 6 octahedrons in the Mo 3 O 13 clusters and other parts of the as-prepared Li 2 MoO 3 become more and more distorted with increasing Li removal.…”

Section: Results and Discussionmentioning

confidence: 99%

Feasibility of Using Li₂MoO₃ in Constructing Li-Rich High Energy Density Cathode Materials

et al. 2014

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Layer-structured xLi2MnO3·(1 – x)Li M O2 are promising cathode materials for high energy-density Li-ion batteries because they deliver high capacities due to the stabilizing effect of Li2MnO3. However, the inherent disadvantages of Li2MnO3 make these materials suffer from drawbacks such as fast energy-density decay, poor rate performance and safety hazard. In this paper, we propose to replace Li2MnO3 with Li2MoO3 for constructing novel Li-rich cathode materials and evaluate its feasibility. Comprehensive studies by X-ray diffraction, X-ray absorption spectroscopy, and spherical-aberration-corrected scanning transmission electron microscopy clarify its lithium extraction/insertion mechanism and shows that the Mo4+/Mo6+ redox couple in Li2MoO3 can accomplish the task of charge compensation upon Li removal. Other properties of Li2MoO3 such as the nearly reversible Mo-ion migration to/from the Li vacancies, absence of oxygen evolution, and reversible phase transition during initial (de)lithiation indicate that Li2MoO3 meets the requirements to an ideal replacement of Li2MnO3 in constructing Li2MoO3-based Li-rich cathode materials with superior performances.

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“…The second stage is believed to be a conversion reaction of MoO 3 with Li ions into metallic Mo and Li 2 O as a matrix up to ≈0.7 V. Some metal oxides result in a high capacity by alloying Li ions with the metals after the conversion reactions. While the intercalation of Li + ions in MoO 3 has been reported with strong experimental results, no clear evidence has been provided for the conversion of MoO 3 until now . Even further discharging for abnormal capacities is often found due to an irreversible SEI layer and results in a large loss of Faradaic efficiency in the first discharging of MoO 3 with Li + ions.…”

Section: Introductionmentioning

confidence: 99%

High Capacity and Reversibility of Oxygen‐Vacancy‐Controlled MoO₃ on Cu in Li‐Ion Batteries: Unveiling Storage Mechanism in Binder‐Free MoO_3−x Anodes

et al. 2020

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MoO3 has great potential as an electrode for lithium‐ion batteries due to its unique layered structure that can host Li+. Despite high theoretical capacity (≈1117 mAh g−1), MoO3 is not widely used simply because of poor rate capability due to lower electronic conductivity and severe pulverization. The Li‐storage mechanism in MoO3 is also still unclear. Herein, oxygen‐vacancy‐controlled MoO3 is used without any additional binders and conductive materials to directly examine the Li‐storage mechanism on MoO3−x. Li‐storage capacity based on the reversible formation/decomposition of solid‐electrolyte interphase (SEI) films and the transformation of MoO3−x to amorphous Li2MoO3 is demonstrated. The surfaces of MoO3−x are conjugated with Cu2O nanoparticles via annealing at 200 °C. Cu2O acts as an effective catalyst for the formation of SEI films and the reversible reaction of MoO3−x with Li+ ions. As a result, Cu2O@MoO3−x exhibits a charge capacity of 1100 mAh g−1 after the second cycle and maintains a high reversible capacity, whereas MoO3−x exhibits a charge capacity of 900 mAh g−1 and fades to 590 mAh g−1 after 100 cycles at 1 A g−1.

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In Situ X-ray Absorption Spectroscopic Study for α-MoO₃Electrode upon Discharge/Charge Reaction in Lithium Secondary Batteries

Cited by 15 publications

References 18 publications

An experimental and computational study to understand the lithium storage mechanism in molybdenum disulfide

An experimental and computational study to understand the lithium storage mechanism in molybdenum disulfide

Feasibility of Using Li₂MoO₃ in Constructing Li-Rich High Energy Density Cathode Materials

High Capacity and Reversibility of Oxygen‐Vacancy‐Controlled MoO₃ on Cu in Li‐Ion Batteries: Unveiling Storage Mechanism in Binder‐Free MoO_3−x Anodes

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In Situ X-ray Absorption Spectroscopic Study for α-MoO3Electrode upon Discharge/Charge Reaction in Lithium Secondary Batteries

Cited by 15 publications

References 18 publications

An experimental and computational study to understand the lithium storage mechanism in molybdenum disulfide

An experimental and computational study to understand the lithium storage mechanism in molybdenum disulfide

Feasibility of Using Li2MoO3 in Constructing Li-Rich High Energy Density Cathode Materials

High Capacity and Reversibility of Oxygen‐Vacancy‐Controlled MoO3 on Cu in Li‐Ion Batteries: Unveiling Storage Mechanism in Binder‐Free MoO3−x Anodes

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In Situ X-ray Absorption Spectroscopic Study for α-MoO₃Electrode upon Discharge/Charge Reaction in Lithium Secondary Batteries

Feasibility of Using Li₂MoO₃ in Constructing Li-Rich High Energy Density Cathode Materials

High Capacity and Reversibility of Oxygen‐Vacancy‐Controlled MoO₃ on Cu in Li‐Ion Batteries: Unveiling Storage Mechanism in Binder‐Free MoO_3−x Anodes