In situ simultaneous encapsulation of defective MoS2 nanolayers and sulfur nanodots into SPAN fibers for high rate sodium-ion batteries

Abstract Molybdenum sulfide (MoS2) with layered structure has emerged as a promising anode material for sodium ion batteries (SIBs) in light of its particular surface chemistry and physical structures. However, the MoS2-based SIBs usually suffered from the weaknesses of the low rate capability and poor cycling stability induced by the sluggish kinetics of Na+ intercalation and the diffluent discharge products. Herein, the defective MoS2 nanocrystals and sulfur nanodots simultaneously embedded in sulfurized polyacrylonitrile (SPAN) fibers were fabricated via an electrospunning technology, followed by a simple annealing treatment. The unique architecture, in which MoS2 nanolayers and sulfur nanodots were mounted inside the SPAN fiber, provided multi-entry and short-range channel for sodium ion to ensure a fast kinetics. Besides, sulfur defects within MoS2 produced the strong chemical interaction for fixing soluble discharge products. As a result, the electrode performed outstanding sodium-storage performance with a superior long cycling life (8000 cycles at 5 A g-1, 15000 cycles at 10 A g-1) and excellent rate capability (212 mAh g-1 at 25 A g-1). The full cell fabricated by using Na3V2(PO4)3 as the cathode also delivered good energy storage performance and successfully powered a group of light-emitting diode.