title: Pseudo-binary electrolyte, LiBH4-LiCl, for bulk-type all-solid-state lithium-sulfur battery.
abstract: The ionic conduction and electrochemical and thermal stabilities of the LiBH4-LiCl solid-state electrolyte were investigated for use in bulk-type all-solid-state lithium-sulfur batteries. The LiBH4-LiCl solid-state electrolyte exhibiting a lithium ionic conductivity of [Formula: see text] at 373 K, forms a reversible interface with a lithium metal electrode and has a wide electrochemical potential window up to 5 V. By means of the high-energy mechanical ball-milling technique, we prepared a composite powder consisting of elemental sulfur and mixed conductive additive, i.e., Ketjen black and Maxsorb. In that composite powder, homogeneous dispersion of the materials is achieved on a nanometer scale, and thereby a high concentration of the interface among them is induced. Such nanometer-scale dispersals of both elemental sulfur and carbon materials play an important role in enhancing the electrochemical reaction of elemental sulfur. The highly deformable LiBH4-LiCl electrolyte assists in the formation of a high concentration of tight interfaces with the sulfur-carbon composite powder. The LiBH4-LiCl electrolyte also allows the formation of the interface between the positive electrode and the electrolyte layers, and thus the Li-ion transport paths are established at that interface. As a result, our battery exhibits high discharge capacities of 1377, 856, and 636 mAh g(-1) for the 1st, 2nd, and 5th discharges, respectively, at 373 K. These results imply that complex hydride-based solid-state electrolytes that contain Cl-ions in the crystal would be integrated into rechargeable batteries.
authors.affiliation: WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Unemoto
authors.forename: ChunLin
authors.initials: C
authors.lastname: Chen
authors.forename: Zhongchang
authors.initials: Z
authors.lastname: Wang
authors.forename: Motoaki
authors.initials: M
authors.lastname: Matsuo
authors.forename: Tamio
authors.initials: T
authors.lastname: Ikeshoji
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Orimo