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Lithium-sulfur (Li-S) batteries are promising candidates for next generation electrical energy storage devices due to their high specific energy. Despite intense research, there are still a number of technical challenges in developing a high performance Li-S battery. To elucidate the issues, an all solid-state Li-S battery was fabricated using Li 3 PS 4 solid electrolyte. Most of the theoretical capacity of sulfur, 1600 mAhg −1 was attained in the initial discharge-charge cycles with a high coulombic efficiency approaching 99%. To verify the benefit of the solid state electrolyte, galvanostatic stripping-deposition tests were also carried out on a symmetrical Li/Li cell and compared with those of a liquid electrolyte (1 M-lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) in a mixture of 1,3-dioxolane (DOL)-diethoxyethane (DEE)). The kinetics and thermodynamics of the solid-state cell are discussed from the viewpoint of the charge transfer processes. This study demonstrates both the merits and drawbacks of using the solid sulfide electrolyte in a Li-S battery and facilitates the further improvement of this important high energy storage device. Lithium-sulfur (Li-S) batteries are attracting growing interest owing to their high specific energy above 3000 Whkg −1 (active material). However, before this technology can be used in practice, there are some significant challenges to overcome, including red-ox shuttle of polysulfides as well as poor lithium cycle performance.The polysulfide redox shuttle originates from the dissolution of the cathode material into the organic electrolyte. So far, various approaches have been suggested to solve the red-ox shuttle issue. LiNO 3 is a well-known additive for optimizing the solid electrolyte interphase (SEI) on lithium metal electrode, such as to block the deposition of polysulfides.1,2 An ionommer (e.g., Nafion) has also been proposed for preventing the polysulfide migration 3 and a buffer solution containing polysulfides can facilitate a good cycle ability as well. 4 The poor lithium cycle performance is due to the consumption of lithium metal during the charge-discharge process. It is well known that the lithium cycling response is primarily determined by the type of electrolyte to which it is in contact. 5,6 In the development of lithiummetal secondary batteries the Figure of Merit (FOM) is the parameter used to evaluate the lithium cycling ability. 5,6 Although lithium metal has a high specific capacity of 3862 mAhg −1 , its effective degree of utilization (i.e., the lithium loss relative to the amount of total input lithium metal) has to be taken into account. Generally, a valid parameter to determine the cycle ability of the lithium anode is the efficiency. For instance, it is difficult to achieve an efficiency higher than 99% for lithium cycling in a typical liquid electrolyte cell due to losses during its dissolution-deposition reaction. Therefore, the improvement of the FOM of a liquid electrolyte Li-S battery has been a major challenge to enhance the charge-disc...

A thin carbon black (CB) layer on a metal current collector is used as a substrate of a deposition‐type Li metal anode for a sulfide‐based all‐solid‐state battery (ASSB). In this ASSB, the capacity of the CB layer is set to ≈5–10% of the cathode. Therefore, the anode soon overcharges and a large proportion of the Li ions precipitate as Li metal on the anode during the charging process, thus this precipitated Li works as a Li metal anode. This CB‐based anode effectively suppresses short circuit of the cell, and an ASSB with this anode has shown an excellent cycle property of over 150 cycles with good capacity retention. From measurements involving cross‐sectional scanning electron microscopy, deposited Li metal layer at the CB/Ni interface is observed. It is also found that the addition of metal particles in the CB‐based anode drastically improves cell performance by extending the cycle life. An ASSB with an Ag/CB‐based anode is operated over 700 cycles at 3 mA cm−2 current density (0.5 C) with a capacity retention of ≈86% after 700 cycles.

Sulfur-based polymeric materials were obtained from surplus feedstock; elemental sulfur; and sustainable algae oil, Botryococcene, via inverse vulcanization. Reactions of elemental sulfur and Botryococcene at 185 °C produce polymeric materials with various weight ratios of sulfur and Botryococcene (5:5 to 9:1), depending on the feed ratio. In this study, these polymers have been characterized from several aspects using spectral analysis, thermoanalysis, and electrochemical analysis. When the composition of sulfur is more than 70 wt %, the polymer contains a residual sulfur element not incorporated in the polymer chains. The sulfur-based polymers can be pressed into intended shapes when heated at 120 °C. The polymers could serve as active materials for Li−S batteries. This investigation of structure and properties provides basic information for future applications.

ARTICLE This journal isHighly oxygen-enriched electrolytes for a lithium-oxygen (Li-O 2 ) battery were prepared by combining perfluorohexyl bromide as an oxygen-uptake perfluorochemical (PFC) medium with lithium perfluorooctane sulfonate (LiPFOS) as a perfluoro-surfactant and a supporting electrolyte, which allowed exceptionally high miscibility of PFC with tetraethylene glycol dimethyl ether (TEGDME). The electrochemical reduction current of oxygen was three times enhanced in the LiPFOS-TEGDME electrolyte with ca. 60 wt% PFC content in comparison with that of a conventional Li-O 2 battery electrolyte, which was ascribed to high oxygen solubility of the electrolyte. A Li-O 2 cell fabricated with the PFC-based electrolyte exhibited excellent discharging capacity of 6500 mAh/g which was approximately 1.5 times larger than that obtained with the conventional electrolyte.