Zero‐Strain Na₃V₂(PO₄)₂F₃@Rgo/CNT Composite as a Wide‐Temperature‐Tolerance Cathode for Na‐Ion Batteries with Ultrahigh‐Rate Performance

Abstract

Abstract Sodium‐ion batteries (SIBs) are widely considered a hopeful alternative to lithium‐ion battery technology. However, they still face challenges, such as low rate capability, unsatisfactory cycling stability, and inferior variable‐temperature performance. In this study, a hierarchical Na 3 V 2 (PO 4 ) 2 F 3 (NVPF) @reduced graphene oxide (rGO)/carbon nanotube (CNT) composite (NVPF@rGO/CNT) is successfully constructed. This composite features 0D Na 3 V 2 (PO 4 ) 2 F 3 nanoparticles are coated by a cross‐linked 3D conductive network composed of 2D rGO and 1D CNT. Furthermore, the intrinsic Na + storage mechanism of NVPF@rGO/CNT through comprehensive characterizations is unveiled. The synthesized NVPF@rGO/CNT exhibits fast ionic/electronic transport and excellent structural stability within wide working temperatures (−40–50 °C), owing to the zero‐strain NVPF and the coated rGO/CNT conductive network that reduces diffusion distance for ions and electrons. Moreover, the stable integration between NVPF and rGO/CNT enables outstanding structural stability to alleviate strain and stress induced during the cycle. Additionally, a practice full cell is assembled employing a hard carbon anode paired with an NVPF@rGO/CNT cathode, which provides a decent capacity of 105.2 mAh g −1 at 0.2 C, thereby attaining an ideal energy density of 242.7 Wh kg −1 . This work provides valuable insights into developing high‐energy and power‐density cathode materials for SIBs.