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 × 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 0.05 C via the conversion reaction of sulfur and lithium. During 10 charge-discharge cycles, the discharge capacity decreased to 600 mAh g ^-1 due to the lower utilization ratio of sulfur by agglomeration of Li₂S at the electrode/electrolyte interface.