Self-Formed Electronic/Ionic Conductive Fe₃ S₄  @ S @ 0.9Na₃ SbS₄ ⋅0.1NaI Composite for High-Performance...

Fe₃ S₄  @ S @ 0.9Na₃ SbS₄ ⋅0.1NaI composite cathode is prepared through one-step wet-mechanochemical milling procedure. During milling process, ionic conduction pathway is self-formed in the composite due to the formation of 0.9Na₃ SbS₄ ⋅0.1NaI electrolyte without further annealing treatment. Meanwhile, the introduction of Fe₃ S₄ can increase the electronic conductivity of the composite cathode by one order of magnitude and nearly double enhance the ionic conductivities. Besides, the aggregation of sulfur is effectively suppressed in the obtained Fe₃ S₄  @ S @ 0.9Na₃ SbS₄ ⋅0.1NaI composite, which will enhance the contact between sulfur and 0.9Na₃ SbS₄ ⋅0.1NaI electrolyte, leading to a decreased interfacial resistance and improving the electrochemical kinetics of sulfur. Therefore, the resultant all-solid-state sodium-sulfur battery employing Fe₃ S₄  @ S @ 0.9Na₃ SbS₄ ⋅0.1NaI composite cathode shows discharge capacity of 808.7 mAh g^-1 based on Fe₃ S₄ @S and a normalized discharge capacity of 1040.5 mAh g^-1 for element S at 100 mA g^-1 for 30 cycles at room temperature. Moreover, the battery also exhibits excellent cycling stability with a reversible capacity of 410 mAh g^-1 at 500 mA g^-1 for 50 cycles, and superior rate capability with capacities of 952.4, 796.7, 513.7, and 445.6 mAh g^-1 at 50, 100, 200, and 500 mA g^-1 , respectively. This facile strategy for sulfur-based composite cathode is attractive for achieving room-temperature sodium-sulfur batteries with superior electrochemical performance.