Zero‐Strain Na<sub>3</sub>V<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>F<sub>3</sub>@Rgo/CNT Composite as a Wide‐Temperature‐Tolerance Cathode for Na‐Ion Batteries with Ultrahigh‐Rate Performance
Chenglong Shi, Junling Xu, Tao Tao, Xiaoyi Lü, Guoping Liu, Fuqiang Xie, Sheng Wu, Yanxue Wu, Zhipeng Sun
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.