Hierarchical MoS₂/Carbon microspheres as long-life and high-rate anodes for sodium-ion batteries

Sodium-ion batteries (SIBs) are considered promising low-cost alternatives to prevailing lithium-ion batteries (LIBs). The inherently sluggish kinetics of their anode materials, however, poses a great challenge to the SIBs' rate capabilities. This work reports the synthesis of novel MoS₂/Carbon (MoS₂/C) microspheres with three-dimensional (3D) architecture as an anode for SIBs using a facile hydrothermal strategy. The MoS₂/C electrode delivers a reversible capacity of 498 mA h g^-1 at 100 mA g^-1, which stabilizes at 450 mA h g^-1 after 100 cycles. Even at 4 A g^-1, the electrode maintains a high reversible capacity above 310 mA h g^-1 after 600 cycles, demonstrating its superior rate capability and long-term cyclic stability. Quantitative kinetics analysis reveals a pseudocapacitance-dominated Na⁺ storage mechanism, especially at high current densities. Furthermore, density functional theory (DFT) calculations show that the Na transport rates are faster through the MoS₂/C heterointerface, due to a low diffusion energy barrier, than along the MoS₂/MoS₂ bilayers.