Towards a safe lithium-sulfur battery with a flame-inhibiting electrolyte and a sulfur-based composite cathode.

Of the various beyond-lithium-ion batteries, lithium-sulfur (Li-S) batteries were recently reported as possibly being the closest to market. However, its theoretically high energy density makes it potentially hazardous under conditions of abuse. Therefore, addressing the safety issues of Li-S cells is necessary before they can be used in practical applications. Here, we report a concept to build a safe and highly efficient Li-S battery with a flame-inhibiting electrolyte and a sulfur-based composite cathode. The flame retardant not only makes the carbonates nonflammable but also dramatically enhances the electrochemical performance of the sulfur-based composite cathode, without an apparent capacity decline over 750 cycles, and with a capacity greater than 800 mA h(-1)  g(-1) (sulfur) at a rate of 10 C.