Realizing high-performance Na3V2(PO4)2O2F cathode for sodium-ion batteries via Nb-doping

• Published in: International journal of minerals, metallurgy and materials metallurgy and materials, 2023-10, Vol.30 (10), p.1859-1867
• Main Authors: Wang, Jie, Yuan, Yifeng, Rao, Xianhui, Yang, Min’an, Wang, Doudou, Zhang, Ailing, Chen, Yan, Li, Zhaolin, Zhao, Hailei
• Format: Article
• Language: English
• Subjects: Batteries; Cathodes; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Conductivity; Corrosion and Coatings; Crystal structure; Doping; Electrochemical analysis; Electrochemistry; Electrode materials; Electrodes; Electrons; Energy storage; Glass; Graphene; Materials Science; Metallic Materials; Natural Materials; Niobium; Reaction kinetics; Sodium; Sodium-ion batteries; Specific capacity; Structural stability; Surfaces and Interfaces; Thermal stability; Thin Films; Tribology
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-023-2666-x

Na 3 V 2 (PO 4 ) 2 O 2 F (NVPOF) has received considerable interest as a promising cathode material for sodium-ion batteries because of its high working voltage and good structural/thermal stability. However, the sluggish electrode reaction resulting from its low intrinsic electronic conductivity significantly restricts its electrochemical performance and thus its practical application. Herein, Nb-doped Na 3 V 2− x Nb x (PO 4 ) 2 O 2 F/graphene (rGO) composites ( x = 0, 0.05, 0.1) were prepared using a solvothermal method followed by calcination. Compared to the un-doped NVPOF/rGO, doping V-site with high-valence Nb element (Nb 5+ ) (Na 3 V 1.95 Nb 0.05 (PO 4 ) 2 O 2 F/rGO (NVN05POF/rGO)) can result in the generated V 4+ /V 3+ mixed-valence, ensuring the lower bandgap and thus the increased intrinsic electronic conductivity. Besides, the expanded lattice space favors the Na + migration. With the structure feature where NVN05POF particles are attached to the rGO sheets, the electrode reaction kinetics is further accelerated owing to the well-constructed electron conductive network. As a consequence, the as-prepared NVN05POF/rGO sample exhibits a high specific capacity of ∼72 mAh·g −1 at 10C (capacity retention of 65.2% (vs. 0.5C)) and excellent long-term cycling stability with the capacity fading rate of ∼0.099% per cycle in 500 cycles at 5C.