N-Methyl-(n-butyl) pyrrolidinium bis(trifluoromethanesulfonyl) imide (PYR14TFSI), a kind of ionic liquid, is used as the additive in the electrolyte of Li-S battery. The changing of viscosity and conductivity of the electrolyte with different content of PYR14TFSI addition is tested. And the electrochemical impedance, the cycle performance and the columbic efficiency of the Li-S battery with different content of PYR14TFSI additive in the electrolyte are also tested. The results show that the addition of PYR14TFSI can not only inhibit the dissolution of lithium polysulfides (Li2Sx), but also decrease the migration rate of polysulfides ions in the electrolyte. Therefore, shuttle phenomenon in the lithium-sulfur battery is suppressed effectively with the addition of PYR14TFSI. Consequently, a coulombic efficiency nearing 100% and long cycling stability are achieved. (C) 2013 Elsevier B.V. All rights reserved.