Three-Dimensional Flexible SnO₂@Hard Carbon@MoS₂@Soft Carbon Fiber Film Anode toward Ultrafast and Stable Sodium Storage

Developing flexible electrodes for the application in sodium-ion batteries (SIBs) has received great attention and has been still challenging due to their merits of additive-free, lightweight, and high energy density. In this work, a free-standing 3D flexible SIB anode with the composition of SnO₂@hard carbon@MoS₂@soft carbon is designed and successfully synthesized. This electrode combines the energy storage advantages and hybrid sodium storage mechanisms of each material, manifested in the enhanced flexibility, specific capacity, conductivity, rate, cycling performances, etc. Based on the synergistic effects, it exhibits much higher specific capacity than SnO₂ carbon nanofibers, as well as more excellent cycling performance (250 mA h g^-1 after 500 cycles at 1 A g^-1) than MoS₂ nanospheres (32 mA h g^-1). In addition, relevant kinetic mechanisms are also expounded with the aid of theoretical calculation. This work provides a feasible and advantageous strategy for constructing high-performance and flexible energy storage electrodes based on hybrid mechanisms and synergistic effects.