Ionic liquid-based electrolyte with binary lithium salts for high performance lithium-sulfur batteries

摘要: Abstract Rechargeable Li–S batteries have suffered several technical obstacles, such as rapid capacity fading and low coulombic efficiency. To overcome these problems, we design new electrolytes containing N-methoxyethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)-imide (Pyr 1,2O1 TFSI) tri(ethylene glycol)dimethyl ether (TEGDME) in mass ratio of 7:3. Moreover, Lithium difluoro(oxalate)borate (LiODFB) is introduced for the modification. Although addition LiODFB additive lead to extremely high viscosity electrolyte inferior performance cells, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, 0.84 nm) (0.60 nm) mixture with a total molar concentration 0.4 mol kg −1 binary salt shows excellent electrochemical performance. The Pyr TFSI/TEGDME LiTFSI/LiODFB salts mole 6:4 obtained after optimizing ratio. cells this system show cycle performance, whose initial discharge 1264.4 mAh g , retains 911.4 mAh g 50 cycles efficiency more than 95%. It can be attributed solid-electrolyte interphase (SEI)-forming ability which protect Li anode from suffering dendrites prevent shuttle phenomenon. novel provide good cycling stability batteries, suggested promising batteries.