Exploration of a Novel Vanadium Source for the Synthesis of a Na<sub>3</sub>V<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> Cathode of Sodium-Ion Batteries
Zhenghao Wang, Liang Chen, Ke Yang, Bin Liang, Xiaodong Guo, Zhenguo Wu, Dongmei Luo
Abstract
The NASICON (sodium super ion conductor)-type Na 3 V 2 (PO 4 ) 3 (NVP) possesses a high voltage plateau and structural robustness and thus demonstrates enormous potential in energy storage applications. Traditionally, high-purity vanadium pentoxide (V 2 O 5 ) and ammonium vanadate (NH 4 VO 3 ) have been employed as vanadium sources for NVP@C synthesis, resulting in lengthy and expensive procedures. This study demonstrates the potential of utilizing sodium vanadate (NaVO 3 ) solution, which can be obtained as an intermediate product during V 2 O 5 extraction from vanadium slag, as a vanadium source through a solid-state method. Two different types of red cakes ( x Na 2 O· y V 2 O 5 · z H 2 O) from a pure NaVO 3 solution and sodium roasting leachate of vanadium slag were analyzed to evaluate their effect on the resulting NVP@C. The findings indicate that phase-pure NVP@C can be synthesized from both red cake sources, demonstrating the feasibility of this new synthesis route. Moreover, the NVP@C material prepared from a red cake of NaVO 3 solution exhibits superior properties, which may be attributed to the sparser particles and narrower particle size distribution. It maintained reversible capacities of 104.7, 101.2, 94.5, and 66.7 mA h g –1 at 0.1, 1, 5, and 10 C, respectively, in the first week. After 500 cycles at 1 C, the capacity retention rate is 93.12%, demonstrating good cycling stability. Using an intermediate product of industrial V 2 O 5 production as a raw material to achieve the synthesis of NVP@C expanded the range of vanadium sources for the synthesis of NVP@C, simplified the production process, avoided the generation of ammonia nitrogen wastewater, and opened up a more industrially viable synthesis pathway for NVP@C.