Ultrafast Sodium‐Ion Storage in Self‐Doped 2D PVP‐VS ₄ /Ti ₃ C ₂ T _x Hybrids for High‐Performance Sodium‐Ion Half/Full Batteries

ABSTRACT Transition metal sulfides demonstrate remarkable theoretical specific capacities, making them highly desirable anode materials for sodium‐ion batteries (SIBs). Nevertheless, low electrical conductivity and restacking seriously limit their electrochemical activity, resulting in suboptimal specific capacity and cycling stability. Herein, it is demonstrated that self‐doped PVP‐VS ₄ /Ti ₃ C ₂ T _x presents multidirectional open conductive channels and sufficient vacancies for reversible and fast Na ⁺ insertion/extraction. The PVP‐VS ₄ /Ti ₃ C ₂ T _x exhibits excellent rate performance (80.5% capacity retention from 0.1 to 10.0 A g ⁻¹ ) and superior cycling stability (711 mAh g ⁻¹ after 1000 cycles at 5 A g ⁻¹ and 518 mAh g ⁻¹ after 600 cycles at 10 A g ⁻¹ ). The sodium storage mechanism of the PVP‐VS ₄ /Ti ₃ C ₂ T _x anode was elucidated through in situ XRD, ex situ HRTEM, and ex situ XPS analyses. The DFT calculation demonstrates that the interfacial structure of PVP‐VS ₄ /Ti ₃ C ₂ T _x significantly enhances the electronic conductivity as an anode. Impressively, the assembled NaFePO ₄ //PVP‐VS ₄ /Ti ₃ C ₂ T _x full cell retained 87.2% of capacity after 500 cycles at 0.5 C, and still allowed the LEDs to remain lighted after cycling. This study offers a fresh perspective on improving the electrochemical performance of vanadium tetrasulfide through Ti ₃ C ₂ T _x as a conductive base to support PVP‐induced VS ₄ .