Co‐recrystallization induced self‐catalytic Li2S cathode fully interfaced with sulfide catalyst toward a high‐performance lithium‐free sulfur battery

Abstract Lithium sulfide (Li 2 S) is a promising cathode for a practical lithium‐sulfur battery as it can be coupled with various safe lithium‐free anodes. However, the high activation potential (>3.5 V) together with the shuttling of lithium polysulfides (LiPSs) bottleneck its practical uses. We are trying to present a catalysis solution to solve both problems simultaneously, specially with twinborn heterostructure to shoot off the trouble in interfacial contact between two solids, catalyst and Li 2 S. As a typical example, a Co 9 S 8 /Li 2 S heterostructure is reported here as a novel self‐catalytic cathode through a co‐recrystallization followed by a one‐step carbothermic conversion. Co 9 S 8 as the catalyst effectively lowers the Li 2 S activation potential (<2.4 V) due to fully integrated and contacted interfaces and consistently promotes the conversion of LiPSs to suppress the shuttling. The obtained freestanding cathode of Co 9 S 8 /Li 2 S heterostructures encapsulated in three‐dimensional graphene shows a high capacity, reaching 92.6% of Li 2 S theoretical capacity, high rate performance (739 mAh g −1 at 2 C), and a low capacity fading (0.039% per cycle at 1 C over 900 cycles). Even under a high Li 2 S loading of 12 mg cm −2 and a low E/S ratio of , 86% of theoretical capacity can be utilized. image