Architectural engineering of MoS2/Fe2O3@carbon fiber heterostructures to obtain ultra-stable anodes for sodium-ion batteries

Metal sulfides based on a conversion mechanism possess high theoretical specific capacity, making them suitable for high-energy-density sodium-ion batteries (SIBs). However, they suffer from rapid capacity decay when assembled into full batteries due to dynamic hysteresis and large volume expansion. In this paper, the architectural engineering approach to construct MoS2/Fe2O3 @ carbon fiber heterostructures is proposed to overcome the above issues. The heterojunction formed by MoS2 and Fe2O3 would promote ion/electron transfer, while the carbon nano-fibers serve as a holder to maintain structural stability and ensure the rapid transport of electrons. The full battery in which the as-prepared MoS2/Fe2O3 @ carbon fiber anode is paired with a Na3V2(PO4)3/C cathode delivers a reversible capacity of 61.1 mAh g−1 at 500 mA g−1 for 1600 cycles without attenuation. Experimental characterization and theoretical calculation results show that this structural engineering approach improves the ion diffusion efficiency, enhances the conductivity, provides a more appropriate sodium ion adsorption energy, and thus extends the cycling life of the SIB. This work demonstrates the efficiency of architectural engineering and paves the way to design ultra-long-cycling Na-ion batteries.