Ionic Liquid Enabled FeS2 for High‐Energy‐Density Lithium‐Ion Batteries

High-energy-density FeS2cathodes en­abled by a bis(trifluoromethanesulfonyl)imide (TFSI−) anion-based room temperature ionic liquid (RTIL) electrolyte are demonstrated. A TFSI-based ionic liquid (IL) significantly mitigates polysulfide dissolution, and therefore the parasitic redox shuttle mechanism, that plagues sulfur-based electrode chemistries. FeS2 stabilization with a TFSI−-based IL results in one of the highest energy density cathodes, 542 W h kg−1 (normalized to cathode composite mass), reported to date.