Synthesis of nano-Na3V2(PO4)2F3 cathodes with excess Na+ intercalation for enhanced capacity. (June 2020)

• Record Type: Journal Article
• Authors: Peng, Manhua; Wang, Xiayan; Guo, Guangsheng
• Is Part Of: Applied materials today. Volume 19(2020)
• Publication Date: 2020-06
• Subjects: SIB sodium ion battery -- SG material material prepared by a modified sol–gel reaction -- SS material material prepared by a standard solid-state reaction -- XRD X-ray diffraction -- SEM scanning electron microscopy -- TEM transmission electron microscopy -- XPS X-ray photoelectron spectroscopy -- EIS impedance spectroscopy -- GITT galvanostatic intermittent titration technique -- TGA Thermogravimetric analysis; Sodium-ion battery -- Vanadium cathode -- High capacity -- Na+ intercalation; Materials science -- Periodicals; Materials -- Research -- Periodicals; 620.1105
• DOI: 10.1016/j.apmt.2020.100554
• Languages: English
• ISSNs: 2352-9407

Abstract

Highlights: Nano-Na3 V2 (PO4 )2 F3 cathode materials with an enlarged interlayer spacing were synthesized. Weakened electrostatic repulsion in Na3 V2 (PO4 )2 F3 allowed formation of Na4 V2 (PO4 )2 F3 . The capacity (250 mA h·g −1 ) was higher than that of highly crystallined Na3 V2 (PO4 )2 F3 . The capacity retention of Nano-Na3 V2 (PO4 )2 F3 after 20 cycles was 72%. Abstract: Vanadium-based materials are promising as cathodes for sodium-ion batteries owing to their superior cycling behavior and rate performance. However, there is a critical need for the rational implementation of Na + intercalation to enhance the capacity. Herein, nano-Na3 V2 (PO4 )2 F3 materials were synthesized via bulk dismemberment by gas released by the decomposition of excess citric acid to trigger some degree of lattice distortion and defects. Owing to the weakened electrostatic repulsion between sodium ions in Na3 V2 (PO4 )2 F3 with an enlarged interlayer spacing, one more Na + ion could be readily embedded to form Na4 V2 (PO4 )2 F3 . A new reaction plateau at 1.38 V/1.56 V accompanied the V 3+ /V 2+ redox reaction, inducing a capacity of 250 mA h·g −1, which is higher than that of highly crystallined Na3 V2 (PO4 )2 F3 . A noteworthy reversible redox phenomenon involving three sodium ions was confirmed during the cycling process. The nano-Na3 V2 (PO4 )2 F3 electrode exhibited a capacity retention of 72% at 1.3–4.5 V after 20 cycles. Thus, this novel synthesis routine can provide vanadium-based cathode materials with enhanced Na + intercalation properties, which can be applied to improve the capacity of sodium-ion batteries.