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

Lithium sulfide (Li₂S) 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 Li₂S. As a typical example, a Co₉S₈/Li₂S heterostructure is reported here as a novel self-catalytic cathode through a co-recrystallization followed by a one-step carbothermic conversion. Co₉S₈ as the catalyst effectively lowers the Li₂S 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 Co₉S₈/Li₂S heterostructures encapsulated in three-dimensional graphene shows a high capacity, reaching 92.6% of Li₂S 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 Li₂S loading of 12 mg cm⁻² and a low E/S ratio of (Formula presented.), 86% of theoretical capacity can be utilized. (Figure presented.).