Gel electrolyte with flame retardant polymer stabilizing lithium metal towards lithium-sulfur battery

Gel polymer electrolytes have the advantages of both solid and liquid electrolytes. Generally speaking, the liquid electrolyte is physically stored in the porous structure of polymer matrix which cannot block the reactions between the liquid electrolyte and the thermodynamically unstable lithium metal. At the same time, the stored liquid electrolyte still presents a safety hazard. This work designed and prepared a flame-retardant polymer Polyimide (PI) that can gelatinize the classic carbonate liquid electrolyte to form a flame-retardant gel polymer electrolyte, which greatly improved the safety of the battery. More importantly, there was CH/π interaction between the PI and the carbonate solvents which obviously reduced electrolyte consumption and side reactions with lithium metal. The proposed gel polymer electrolyte achieved a high lithium ion transference number of 0.727 and ensured remarkably stable lithium-sulfur batteries with SPAN cathodes.