Optimization of Pore Structure of Cathodic Carbon Supports for Solvate Ionic Liquid Electrolytes Based Lithium-Sulfur Batteries.
Lithium-sulfur (Li-S) batteries are a promising energy-storage technology owing to their high theoretical capacity and energy density. However, their practical application remains a challenge because of the serve shuttle effect caused by the dissolution of polysulfides in common organic electrolytes. Polysulfide-insoluble electrolytes, such as solvate ionic liquids (ILs), have recently emerged as alternative candidates and shown great potential in suppressing the shuttle effect and improving the cycle stability of Li-S batteries. Redox electrochemical reactions in polysulfide-insoluble electrolytes occur via a solid-state process at the interphase between the electrolyte and the composite cathode; therefore, creating an appropriate interface between sulfur and a carbon support is of great importance. Nevertheless, the porous carbon supports established for conventional organic electrolytes may not be suitable for polysulfide-insoluble electrolytes. In this work, we investigated the effect of the porous structure of carbon materials on the Li-S battery performance in polysulfide-insoluble electrolytes using solvate ILs as a model electrolyte. We determined that the pore volume (rather than the surface area) exerts a major influence on the discharge capacity of S composite cathodes. In particular, inverse opal carbons with three-dimensionally ordered interconnected macropores and a large pore volume deliver the highest discharge capacity. The battery performance in both polysulfide-soluble electrolytes and solvate ILs was used to study the effect of electrolytes. We propose a plausible mechanism to explain the different porous structure requirements in polysulfide-soluble and polysulfide-insoluble electrolytes.
Department of Chemistry and Biotechnology, Yokohama National University , 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Shiguo
S
Zhang
Department of Chemistry and Biotechnology, Yokohama National University , 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Ai
A
Ikoma
Department of Chemistry and Biotechnology, Yokohama National University , 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Zhe
Z
Li
Department of Chemistry and Biotechnology, Yokohama National University , 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Kazuhide
K
Ueno
Department of Chemistry and Biotechnology, Yokohama National University , 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Xiaofeng
X
Ma
Department of Chemistry and Biotechnology, Yokohama National University , 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Kaoru
K
Dokko
Department of Chemistry and Biotechnology, Yokohama National University , 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Masayoshi
M
Watanabe
electrolyte; lithium−sulfur battery; polysulfide-insoluble; pore volume; porous carbon; solvate ionic liquids