Preparation of Sb nanoparticles in molten salt and their potassium storage performance and mechanism.

Sb nanoparticles with a size of 55 nm are fabricated via the reduction of SbCl3 by metallic Al in the molten salt of SbCl3 at 80 °C. In situ XRD patterns and ex situ Raman spectra show that the potassium storage mechanism is an alloying-type with the formation of a cubic K3Sb phase when fully potassiated and an amorphous phase when fully depotassiated. As an anode for potassium-ion batteries, Sb nanoparticles coated with graphene could deliver a reversible capacity of 381 mA h g-1 at 100 mA g-1, and maintain a capacity of 210 mA h g-1 at 500 mA g-1 for 200 cycles.