Yolk–Shell MoS₂ Nanosphere-Doped Electron-Rich Iron Heteroatoms for Ultralong Lifespan Na-Ion Batteries

Molybdenum disulfide (MoS2) has been extensively studied as an anode for sodium-ion batteries owing to its large theoretical specific capacity and steady crystal texture. Nevertheless, the unsatisfactory rate capability and short cycling lifespan of MoS2 derived from its inferior electrical conductivity and extensive volume variation among Na+ insertion and extraction have greatly impeded its practical exploitation. Hence, we proposed an electron coupling strategy with the rational incorporation of iron heteroatoms in a novel yolk–shell MoS2 nanostructure (FMS@C) through an advanced micelle-confined microemulsion technology. In this configuration, the doping of electron-rich Fe heteroatoms breaks the long-range ordered texture of pristine MoS2 with extensively activated electronic structures, thus enabling accelerated mass transfer and charge diffusion. Meanwhile, the novel yolk–shell nanoarchitecture with enough inner room can efficiently accommodate the volume variation during repeated charge/discharge cycles, thus favoring the high stability of the structure. Consequently, the prepared FMS@C anode delivers superior rate capability and impressive reversible capacity retention, and it can achieve 201.5 mA h–1 after 5500 cycles at 5 A g–1 with a low capacity decay of 0.0057% per cycle. Accordingly, this work opens up a brilliant way to improve the performance of metal sulfur compounds as advanced energy storage electrodes.