Quasi-Solid-State Lithium-Sulfur Battery Using Room Temperature Ionic Liquid-Li-salt-Fumed Silica Nanoparticle Composites as Electrolytes

A quasi-solid-state composite electrolyte, consisting of N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)amide (DEME-TFSA)-lithium bis(trifluoromethanesulfonyl)amide (Li-TFSA)-fumed silica nanoparticles, has been prepared for use in the electrolyte of a lithium-sulfur battery. Regardless of the solid-state like appearance, the quasi-solid-state electrolyte exhibited a high liquid-like apparent conductivity of 1.2 x 10(-4)S cm(-1) at 308 K when the volume ratio of DEME-TFSA-Li-TFSA is 75% in the quasi-solid-state composite. By using the quasi-solid-state electrolyte, a quasi-solid-state lithium-sulfur battery was developed and the cell performance was evaluated. The cell has successfully exhibited initial discharge capacities of 1370 mAh g(-1) at 308 K with a 0.05C via the conversion reaction of sulfur and lithium. During 10 charge-discharge cycles, the discharge capacity decreased to 600 mAhg(-1) due to the lower utilization ratio of sulfur by agglomeration of Li2S at the electrode/electrolyte interface. (C) The Electrochemical Society of Japan, All rights reserved.