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HOME > No.21, May 2020 > All-Solid-State Lithium-Sulfur batteries with high capacity and long life

All-Solid-State Lithium-Sulfur batteries with high capacity and long life

First milestone toward next-generation batteries By Nguyen Huu Huy Phuc
Takeshi Kawano

Assistant Professor Nguyen Huu Huy Phuc and his research team at the Department of Electrical and Electronic Information Engineering of Toyohashi University of Technology have made an active sulfur material and carbon nanofiber (CNF) composite using a low-cost and straightforward liquid phase process. All-solid-state lithium-sulfur batteries using a sulfur-CNF composite material obtained by liquid phase process show a higher discharge capacity and better cycle stability than those of lithium-ion secondary batteries. It is anticipated that these new all-solid-state lithium-sulfur batteries will have a wide range of practical applications such as in large scale batteries for electric vehicles.

Lithium-ion secondary batteries have been used as power sources in a wide variety of applications such as smartphones and electric vehicles. All-solid-state batteries have also attracted attention as a candidate for next-generation batteries in recent years because of the increase in the use of hybrid and electric vehicles. In particular, all-solid-state lithium-sulfur batteries have attracted attention because they have a five times higher energy density than conventional lithium-ion secondary batteries. However, sulfur is an insulator, which thus limits their application in battery devices. In order to solve this issue, sulfur must be provided with an ionic and electron-conductive path.

Schematic images and electron microscope photograph of sulfur-carbon composites (upper). Schematic images and cycle characteristics of all-solid-state sulfur battery (lower)
Schematic images and electron microscope photograph of sulfur-carbon composites (upper). Schematic images and cycle characteristics of all-solid-state sulfur battery (lower)

Therefore, the research group prepared a cathode composite of sulfur active material and carbon nanofibers (CNF) by a novel liquid phase synthesis process. All-solid-state lithium sulfur batteries using sulfur-CNF composites and electrochemically stable Li2S-P2S5-LiI solid electrolytes synthesized by liquid phase process showed high discharge capacity equivalent to the theoretical capacity of sulfur and maintained high capacity after repeated charge-discharge cycles.

"In order to produce high-performance all-solid-state lithium sulfur batteries, the, the sulfur and carbon materials must be properly compounded. Conventionally, sulfur-carbon composites were synthesized by mechanical pulverization using a ball milling, or by a complex process of liquid mixing using a special organic solvent, in which sulfur is combined with a porous carbon material with a high specific surface area. However, few batteries have been reported that exhibit a high capacity and high cycling stability which approaches the theoretical capacity of sulfur. Therefore, we focused on finding a simple process for fabrication of carbonaceous materials and sulfur composite. In the sulfur-carbon complex obtained by the newly developed process, it was confirmed that sulfur is accumulated on the carbon in a thin sheet form, suggesting that sulfur is fully utilized as an active material. In addition, the process is easier to manufacture than the conventional process", explained the first author of the paper, Assistant Prof. Nguyen Huu Huy Phuc.

The composite was successfully synthesis by a – two – step – process in which sulfur nano sheet was nucleated and grown on CNF by a newly discovered chemical reaction.

This method is relatively simple for preparing sulfur-carbon composites, so it is suitable for mass production. The practical application of this method to high energy density all-solid-state lithium sulfur batteries is expected to lead to a dramatic increase in the popularity of storage batteries for large power sources, especially for electric vehicles and home and office applications.

This study was supported by the Advanced Low Carbon Technology Specially Promoted Research for Innovative Next Generation Batteries (ALCA-SPRING, JPMJAL1301) program of the Japan Science and Technology Agency (JST).


Nguyen Huu Huy Phuc, Maeda Takaki, Hiroyuki Muto, Matsuda Reiko, Hikima Kazuhiro, and Atsunori Matsuda (2020). Sulfur-Carbon Nano Fiber Composite Solid Electrolyte for all-solid-state Li-S Batteries, ACS Applied Energy Materials, DOI: 10.1021/acsaem.9b02062


By Nguyen Huu Huy Phuc

豊橋技術科学大学 電気・電子情報工学系のNguyen Huu Huy Phuc特任助教らの研究チームは、安価で簡便な液相プロセスを利用することで、硫黄活物質とカーボンナノファイバー(CNF)の複合体の作製に成功しました。このプロセスで得られる硫黄-CNF複合体を用いた全固体リチウム硫黄電池は、現行のリチウムイオン二次電池よりも高い放電容量と優れたサイクル安定性を示すため、電気自動車や大型電源用蓄電池などへの応用が期待されます。








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Researcher Profile

Nguyen Huu Huy Phuc
Name Nguyen Huu Huy Phuc
Affiliation Department of Electrical and Electronic Information Engineering
Title Project Assistant Professor
Fields of Research Li-S battery/ sulfide solid electrolytes/ all solid state batteries