Conformal Conversion of Polyphosphazene@Sb₂MoO₆ Nanowires to N/S-Doped/Carbon-Coated SbPO₄/MoO_x for High-performance Lithium Storage

Alloy-type antimony (Sb) and conversion-type molybdenum (Mo) anodes have attracted extensive attention in the application of lithium-ion batteries (LIBs) owing to their high theoretical capacity. In this study, Sb₂MoO₆ nanowires are prepared via a hydrothermal method and assessed their thermal behavior upon heat treatment, observing an intriguing transformation from nanowire to Sb₂O₃/MoO_x nanosheets. To enhance structure stability, the Sb₂MoO₆ nanowires are successfully coated with a polyphosphazene layer (referred to as PZS@Sb₂MoO₆), which not only preserved the nanowires form but also yielded N/S co-doped carbon-coated SbPO₄/MoO_x (NS-C@SbPO₄/MoO_x) nanowires following annealing in an inert environment. This composite benefits from the stable PO₄³⁻ anion that serve as a buffer against volume expansion and form a Li₃PO₄ matrix during cycling, both of which substantially bolster ion transport and cycle endurance. Doping with heteroatoms introduces numerous oxygen vacancies, augmenting the number of electrochemically active sites, and carbon integration considerably enhances the electronic conductivity of the electrode and alleviates the volume-change-induced electrode pulverization. Employed as anode materials in LIBs, the NS-C@SbPO₄/MoO_x electrode exhibits remarkable cycling performance (449.8 mA h g⁻¹ at 1000 mA g⁻¹ over 700 cycles) along with superior rate capability (394.2 mA h g⁻¹ at 2000 mA g⁻¹).