Effect of chromium doping on Na3V2(PO4)2F3@C as promising positive electrode for sodium-ion batteries

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 856; p. 113694
• Main Authors: Criado, A., Lavela, P., Pérez-Vicente, C., Ortiz, G.F., Tirado, J.L.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-01-2020; Elsevier Science Ltd
• Subjects: Cathodes; Chromium; Correlation analysis; Doping; Electrode materials; Electrode polarization; Electrodes; Energy storage; Fluorophosphate; Intercalation reactions; Lithium; Rechargeable batteries; Reliability aspects; Sodium-ion batteries; Sol-gel processes; X ray photoelectron spectroscopy; Intercalation reactions; Sodium-ion batteries; Fluorophosphate; Energy storage
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2019.113694

Cr-doped Na3V2(PO4)2F3@C samples, obtained by a one-step sol-gel method, are studied as cathode materials for sodium-ion batteries. Their structural and morphological properties induced by Cr incorporation are determined by powerful solid-state techniques including X-ray diffraction, electron microscopy, and Raman and XPS spectroscopies. Galvanostatic tests reveal the beneficial effects of low-level Cr doping in Na3V2(PO4)2F3, mainly improving the kinetic response of the electrode materials at the highest studied rates. These results are correlated to low cell internal resistances and cell polarization between charge and discharge. Eventually, a full sodium-ion cell is essayed as a proof of concept to evidence the reliability of these cathode materials in practical conditions.
Cr doping Na3V2(PO4)2F3@C samples decreased the low cell internal resistances and cell polarization of sodium half cells. A full sodium-ion cell evidenced the reliability of these cathode materials in practical conditions. [Display omitted]
•Cr-doped Na3V2(PO4)2F3@C samples were prepared by a one-step sol-gel method.•Cr doped samples showed low cell polarization and charge transfer resistance values.•Cr doped samples evidenced good rate capabilities when cycled at increasing rates.•A full sodium-ion cell delivered 75 mA h g−1 and an energy density of 277 W h kg−1.