Amorphous Niobium Sulfides as Novel Positive-Electrode Materials

Sakuda, Atsushi; Taguchi, Noboru; Takeuchi, Tomonari; Kobayashi, Hironori; Sakaebe, Hikarí; Tatsumi, Kuniaki; Ogumi, Zempachi

doi:10.1149/2.0091407eel

Cited by 44 publications

(42 citation statements)

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“…Moreover, amorphous TiS 4 and amorphous NbS x (x = 3, 4, 5) were reported by Sakuda et al [23][24][25] The liquid-type cells using amorphous NbS x (x = 3, 4, 5) showed high discharge capacities. 25 Their initial discharge capacities were 281, 446, and 596 mAh g ¹1 , respectively. Therefore, amorphization of active materials is effective for batteries with both organic liquid electrolytes and solid electrolytes.…”

Section: Introductionmentioning

confidence: 82%

Structure Analyses of Amorphous MoS<sub>3</sub> Active Materials in All-solid-state Lithium Batteries

et al. 2015

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We have successfully prepared amorphous MoS 3 (a-MoS 3 ) by ball milling a mixture of Mo metal and sulfur and investigated structural changes during the charge-discharge processes. The XPS measurements revealed that a-MoS 3 should consist of Mo 4+ , S 2 2− , and S 2− . In the XRD profiles of the a-MoS 3 electrodes after the initial discharge and charge tests, only the halo patterns due to the amorphous state were observed without crystalline diffraction peaks. The HR-TEM observations of a-MoS 3 electrodes during the 1st discharge process revealed that the lattice fringes due to MoS 2 layer structure disappeared gradually. However, the lattice fringes like MoS 2 were also observed after the 1st charge. The HR-TEM image after the 10th charge did not show the lattice fringes of MoS 2 . These results of HR-TEM observations suggested that the reversible structural changes of a-MoS 3 occurred.

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Section: Introductionmentioning

confidence: 82%

Structure Analyses of Amorphous MoS<sub>3</sub> Active Materials in All-solid-state Lithium Batteries

et al. 2015

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“…Amorphous NbSx (x = 3, 4, 5) are prepared mechanochemically. Electrochemical cells with an organic liquid electrolyte using the amorphous NbSx (x = 3, 4, 5) show higher discharge capacities with an increase in the sulfur content of NbSx (Sakuda et al, 2014). Amorphous TiS3 (a-TiS3) retains a higher capacity than crystalline TiS3 in all-solid-state lithium cells.…”

Section: Transition Metal Sulfide Positive Electrodesmentioning

confidence: 99%

Development of Sulfide Solid Electrolytes and Interface Formation Processes for Bulk-Type All-Solid-State Li and Na Batteries

2016

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All-solid-state batteries with inorganic solid electrolytes (SEs) are recognized as an ultimate goal of rechargeable batteries because of their high safety, versatile geometry, and good cycle life. Compared with thin-film batteries, increasing the reversible capacity of bulk-type all-solid-state batteries using electrode active material particles is difficult because contact areas at solid-solid interfaces between the electrode and electrolyte particles are limited. Sulfide SEs have several advantages of high conductivity, wide electrochemical window, and appropriate mechanical properties, such as formability, processability, and elastic modulus. Sulfide electrolyte with Li7P3S11 crystal has a high Li + ion conductivity of 1.7 × 10 −2 S cm −1 at 25°C. It is far beyond the Li + ion conductivity of conventional organic liquid electrolytes. The Na + ion conductivity of 7.4 × 10 −4 S cmis achieved for Na3.06P0.94Si0.06S4 with cubic structure. Moreover, formation of favorable solid-solid interfaces between electrode and electrolyte is important for realizing solid-state batteries. Sulfide electrolytes have better formability than oxide electrolytes. Consequently, a dense electrolyte separator and closely attached interfaces with active material particles are achieved via "room-temperature sintering" of sulfides merely by cold pressing without heat treatment. Elastic moduli for sulfide electrolytes are smaller than that of oxide electrolytes, and Na2S-P2S5 glass electrolytes have smaller Young's modulus than Li2S-P2S5 electrolytes. Cross-sectional SEM observations for a positive electrode layer reveal that sulfide electrolyte coating on active material particles increases interface areas even with a minimum volume of electrolyte, indicating that the energy density of bulk-type solid-state batteries is enhanced. Both surface coating of electrode particles and preparation of nanocomposite are effective for increasing the reversible capacity of the batteries. Our approaches to form solid-solid interfaces are demonstrated.

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“…A recent review on amorphous nature of materials suggests to distinguish between disordered and amorphous materials, as the latter ones do not necessarily may be transferred into an ordered state, in contrast to the former ones. Good examples of this concept are sulfur‐rich transition metal compounds, which exist only in an amorphous state and have never been obtained in crystalline form: MoS 3 ,– MoS x (x=4–6), TiS 4 , NbS 4 and NbS 5 , etc. The family of amorphous transition metal polychalcogenides has drawn a considerable attention lately, owing to the enhanced activity of its members as hydrogen evolution catalysts, sensors and components of battery electrodes and supercapacitors .…”

Section: Introductionmentioning

confidence: 99%

Revealing the Flexible 1D Primary and Globular Secondary Structures of Sulfur‐Rich Amorphous Transition Metal Polysulfides

et al. 2019

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Sulfur‐rich transition metal polysulfides MS5 (M=Mo, W) are synthesized by a low‐temperature solution method from corresponding carbonyls M(CO)6 and elemental sulfur. Extensive characterization reveals that all sulfur atoms are assembled into disulfide ligands (S−S) within the structure of the amorphous spherical particles. Their thermodynamic stabilities are estimated for the first time using density functional theory (DFT) calculations, indicating two stable chain models composed either of binuclear [M2S8] or trinuclear [M3S12] fragments linked through S−S units. Molecular dynamics (MD) DFTB simulation proves that the S−S bridges predetermine the supreme flexibility of the polysulfide chains as primary structures of MS5 and their globular secondary arrangements. Interestingly, this type of structural organization is reminiscent of that for classical polymers. Thus, the reasons for MS5 forming exclusively as amorphous phases are uncovered, which may be extended to many other sulfur‐rich polysulfides. The potential of these materials as increased capacity cathodes for lithium‐ion batteries is shown.

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Amorphous Niobium Sulfides as Novel Positive-Electrode Materials

Cited by 44 publications

References 1 publication

Structure Analyses of Amorphous MoS<sub>3</sub> Active Materials in All-solid-state Lithium Batteries

Structure Analyses of Amorphous MoS<sub>3</sub> Active Materials in All-solid-state Lithium Batteries

Development of Sulfide Solid Electrolytes and Interface Formation Processes for Bulk-Type All-Solid-State Li and Na Batteries

Revealing the Flexible 1D Primary and Globular Secondary Structures of Sulfur‐Rich Amorphous Transition Metal Polysulfides

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