PNNL

Abstract

We demonstrate a cathode formulation using an amorphous PEO10LiTFSI multifunctional binder to enable good cycling performance under lean electrolyte conditions. The PEO10LiTFSI binder traps both the electrolyte and dissolved polysulfides within the conductive cathode scaffold. The Li-S cell with an electrolyte to sulfur ratio (E/S) of 3.3 mLE/gS could deliver a 1200mAh/g, 4.6mAh/cm2 specific capacity and good cycle life. This formulation has been scaled up to a 1Ah pouch cell, with the electrode-stack-level specific energy of 456 Wh/kg at an E/S ratio of 1.7 mLE/gS. Accumulation of polysulfide reduction products, such as Li2S, on the cathode, is identified as the main mechanism for capacity fading under lean electrolyte conditions.