Ti Substitution Strategy Improves Electrochemical Performance of Na<sub>3</sub>V<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>F<sub>3</sub> Cathode
Qiu‐Fen Hu, Mengjiao Sun, Yunchun Zha, Guiquan Zhao, Hanlin Tang, Yang Li, Mou Yang, Bohuai Pang, Yongjiang Sun, Hong Guo
Abstract
NASICON-type Na 3 V 2 (PO 4 ) 2 F 3 (NVPF) is a promising cathode for sodium-ion batteries (SIBs), but its performance is hindered by Na 3 V 2 (PO 4 ) 3 (NVP) impurities and intrinsic limitations. To overcome these challenges, Ti-substituted NVPF cathodes are successfully synthesized using the sol–gel method in this study. Theoretical calculations and advanced analyses confirm that substituting Ti ions for V in the NVPF lattice effectively eliminates NVP impurities, mitigates the low-voltage plateau issue, and enhances both electronic conductivity and sodium-ion diffusion kinetics. Hence, the optimized Na 3 V 1 . 95 Ti 0 . 05 (PO 4 ) 2 F 3 cathode demonstrated a high initial capacity of 129.10 mAh g –1 at 0.2 C. Notably, it exhibited excellent cycling stability, with capacity retentions of 91.98% after 500 cycles at 5 C and 81.14% after 6000 cycles at 30 C, significantly outperforming the unsubstituted NVPF sample. This study provides a practical new approach for the development of high-performance cathode materials for SIBs and is expected to accelerate the commercialization process of SIBs.