RegulatingPolysulfide Clustering with an Anion Acceptorfor Low-Temperature Sulfur Batteries

The performance of the lithium–sulfur battery at harsh conditions of lean electrolyte and low temperature is impeded by nanometric clustering of lithium polysulfides (LiPSs), which inherently hinders sulfur reaction kinetics. Here we describe a cluster-disrupting strategy wherein a fluorinated borane anion acceptor, tris­(perfluorophenyl)­borane, is exploited to regulate the LiPSs solvation structure and to promote their reactions under harsh conditions. The electron-deficient anion acceptor molecules bond with the electron-rich LiPSs via soft Lewis acid–base interactions, which disrupts LiPSs’ clustering and promotes Li₂S solvation, facilitating a three-dimensional Li₂S growth via solution-mediated mechanism at low temperatures. With the borane anion acceptor, the cell shows a significantly improved capacity at −25 °C. Impressively, this strategy enables stable cycling of a 1.83 Ah pouch cell at 0 °C retaining 96.0% capacity over 50 cycles. Our study provides a general methodology for manipulating the fundamental electrolyte chemistry to regulate LiPSs clustering and improve sulfur batteries at harsh conditions.