MoS 2 Hollow Multishelled Nanospheres Doped Fe Single Atoms Capable of Fast Phase Transformation for Fast-charging Na-ion Batteries.

Low Na + and electron diffusion kinetics severely restrain the rate capability of MoS 2 as anode for sodium-ion batteries (SIBs). Slow phase transitions between 2H and 1T, and from Na x MoS 2 to Mo and Na 2 S as well as the volume change during cycling, induce a poor cycling stability. Herein, an original Fe single atom doped MoS 2 hollow multishelled structure (HoMS) is designed for the first time to address the above challenges. The Fe single atom in MoS 2 promotes the electron transfer, companying with shortened charge diffusion path from unique HoMS, thereby achieving excellent rate capability. The strong adsorption with Na + and self-catalysis of Fe single atom facilitates the reversible conversion between 2H and 1T, and from Na x MoS 2 to Mo and Na 2 S. Moreover, the buffering effect of HoMS on volume change during cycling improves the cyclic stability. Consequently, the Fe single atom doped MoS 2 quadruple-shelled sphere exhibits a high specific capacity of 213.3 mAh g -1 at an ultrahigh current density of 30 A g -1 , which is superior to previously-reported results. Even at 5 A g -1 , 259.4 mAh g -1 (83.68 %) was reserved after 500 cycles. Such elaborate catalytic site decorated HoMS is also promising to realize other "fast-charging" high-energy-density rechargeable batteries.