Li2S nanocomposites underlying high-capacity and cycling stability in all-solid-state lithium–sulfur batteries

Nagao, Motohiro; Hayashi, Akitoshi; Tatsumisago, Masahiro; Ichinose, Takahiro; Ozaki, Tomoatsu; Togawa, Yoshihiko; Mori, Shigeo

doi:10.1016/j.jpowsour.2014.10.043

Cited by 87 publications

(63 citation statements)

References 17 publications

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“…The cell retained 750 mAh g −1 for 10 cycles. Charge-discharge reaction mechanisms were examined using high-resolution TEM observation (Nagao et al, 2015). Figure 9 shows TEM images for the Li2S electrodes; Figure 9A before charge-discharge test, Figure 9B after the initial charge, and Figure 9C after the initial discharge.…”

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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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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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“…12 Recently, we reported structural and morphological changes of Li 2 S at the nanoscale during the fullelectrochemical cycles in all-solid-state cells by using a highresolution transmission electron microscope (TEM). 13 A reversible reaction proceeded in Li 2 S particles with a smaller size (less than 10 nm), and an irreversible reaction occurred in the particles with a larger size (50200 nm). 13 An alternative approach to enhance the utilization of Li 2 S is an inherent increase of Li + ion conductivity for Li 2 S. However, studies for increasing the ionic conductivity of Li 2 S have not been reported.…”

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“…13 An alternative approach to enhance the utilization of Li 2 S is an inherent increase of Li + ion conductivity for Li 2 S. However, studies for increasing the ionic conductivity of Li 2 S have not been reported.…”

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Highly Utilized Lithium Sulfide Active Material by Enhancing Conductivity in All-solid-state Batteries

2015

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To improve the utilization of Li 2 S active material, an essential increase of Li + ion conductivity for Li 2 S itself was investigated by modifying the crystal structure of Li 2 S. Li 2 SLiI solid solutions were prepared by mechanical milling and their ionic conductivities were remarkably increased. All-solid-state cells with Li 2 SLiI composite electrodes exhibited the highest utilization of Li 2 S with high reversibility and cyclability in allsolid-state cells with Li 2 S reported so far.Development of rechargeable batteries with high energy density and high safety is desired. Elemental sulfur with a high theoretical capacity (1672 mA h g ¹1 ) attracts much attention as a positive electrode for a Li/S battery with high energy density. However, Li/S batteries with an organic liquid electrolyte suffered from rapid capacity fading, mainly due to the dissolution of polysulfides, which are formed during charge discharge processes in the sulfur electrode. In order to suppress the dissolution of polysulfides into the liquid electrolyte, various approaches such as trapping in pore in carbon, 1 the use of solid polymers, 2,3 ionic liquid-based electrolytes, 4,5 and protection of lithium anodes 6 have been examined. We reported that allsolid-state Li/S cells with composite electrodes prepared by the mechanical milling (MM) of a mixture of sulfur active material, acetylene black, and Li 2 SP 2 S 5 solid electrolyte (SE) showed a high reversible capacity with good cyclability.7 However, the sulfur positive electrode requires the use of a lithium metal negative electrode because the sulfur positive electrode has no lithium, which poses serious safety hazards and may not be practical. Li 2 S active material, with a theoretical capacity of 1167 mA h g ¹1 , has received much attention because of its potential to use a non-lithium negative electrode such as highcapacity negative electrodes (e.g., silicon-or tin-based compounds, which can form alloys with lithium).8 We reported that all-solid-state cells with Li 2 S nanocomposite electrodes showed high capacity of 600 mA h g ¹1 at 0.13 mA cm ¹2 (0.07 C). However, the utilization of Li 2 S was still 50%, and thus, further improvement of the utilization is important for increasing the energy density of all-solid-state cells. To resolve the insulating nature of Li 2 S that prevents the achievement of high utilization, various efforts have been made to improve the contact between Li 2 S and electrical conductive materials such as carbon, metal, and solid electrolyte for all-solid-state batteries with Li 2 S as the active material. 911 On the other hand, shortening the Li + ion diffusion distance in Li 2 S by decreasing the Li 2 S particle size was also investigated for improving the utilization.9,12 The utilization of Li 2 S was increased from 43% to 50% by using pulverized Li 2 S as an active material for all-solid-state cells. 12 The all-solid-state Li/S batteries with the Li 2 S nanoparticle composite exhibited an initial discharge capacity of 848 mA h g ¹1 at a rate of 0.1 C ...

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“…TEM observation of the Li 2 S electrodes in the all-solid-state batteries revealed that the crystalline Li 2 S nanoparticles were changed to the amorphous sulfur by delithiation. 22) Very recently, we have investigated the structural changes of a-MoS 3 during chargedischarge process by high-resolution TEM (HR-TEM).…”

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confidence: 99%

Improved electrochemical performance of amorphous TiS<sub>3</sub> electrodes compared to its crystal for all-solid-state rechargeable lithium batteries

Matsuyama

Hayashi

Ozaki

et al. 2016

J. Ceram. Soc. Japan

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Crystalline and amorphous TiS 3 active materials were prepared. The all-solid-state lithium secondary batteries with crystalline and amorphous TiS 3 showed the initial discharge capacity of about 560 mAh g ¹1 , corresponding to the theoretical capacity of TiS 3 . However, the battery using crystalline TiS 3 had an irreversible capacity at the 1st cycle. The battery showed the reversible capacity of about 400 mAh g ¹1 from the 2nd to 10th cycle. On the other hand, irreversible capacities were not observed for 10 cycles in the battery with amorphous TiS 3 . The structural changes of crystalline and amorphous TiS 3 were observed by XRD and HR-TEM during cycling. Crystalline TiS 3 became partially amorphous during the cycling. Amorphous TiS 3 maintained amorphous state for 10 cycles and thus had the better cyclability compared to crystalline TiS 3 .

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Li2S nanocomposites underlying high-capacity and cycling stability in all-solid-state lithium–sulfur batteries

Cited by 87 publications

References 17 publications

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

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

Highly Utilized Lithium Sulfide Active Material by Enhancing Conductivity in All-solid-state Batteries

Improved electrochemical performance of amorphous TiS<sub>3</sub> electrodes compared to its crystal for all-solid-state rechargeable lithium batteries

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