Stabilizing SPAN in Non‐Flammable Acetonitrile Electrolytes for Long‐Life Graphite||SPAN Batteries

Abstract Sulfurized polyacrylonitrile (SPAN) presents an opportunity to replace elemental sulfur as a “shuttle‐free” cathode for secondary Li−S batteries, which can be an ideal choice for stationary energy storage due to its abundance, low cost, and sustainability. The electrolyte options for the state‐of‐the‐art SPAN batteries have been limited to the flammable carbonate and ether ones, which raises safety concerns. Here, we explored the use of a non‐flammable acetonitrile (AN) electrolyte for SPAN battery for the first time and identified the irreversible cleavage of C−S bonds of SPAN as the main reason for the failure of SPAN in AN electrolyte. Fortunately, by introducing 10 wt % fluoroethylene carbonate into the AN electrolyte, the bond cleavage in SPAN is suppressed and a stable cathode electrolyte interface is formed, both contributing to stabilizing the structure of SPAN during electrochemical process. Consequently, we achieved a stable cycling for 900 cycles in Li||SPAN cells. Moreover, by pairing with a pre‐lithiated graphite (pGr) anode, the newly formulated electrolyte enables extended cycle life for 1500 cycles with a capacity retention of 91 % and superb safety in pGr||SPAN full cell. The present exploitation broadens the electrolyte choices of SPAN‐based batteries and paves the way for future applications for these batteries.