| Title |
On the degradation of vanadium-based phosphate framework electrode materials in aqueous environments |
| Authors |
Tediashvili, Davit ; Pilipavičius, Jurgis ; Juodkazytė, Jurga ; Vilčiauskas, Linas |
| DOI |
10.1149/1945-7111/ad13fa |
| Full Text |
|
| Is Part of |
Journal of The Electrochemical Society.. Pennington : The Electrochemical Society. 2023, vol. 170, iss. 12, art. no. 120529, p. 1-10.. ISSN 0013-4651. eISSN 1945-7111 |
| Keywords [eng] |
aqueous batteries ; sodium ion ; NVP ; NVPF ; degradation |
| Abstract [eng] |
Na 3 V 2 (PO 4 ) 3 and Na 3 V 2 (PO 4 ) 2 F 3 with their relatively high capacities and redox potentials are among the most studied and applied positive electrode materials in non-aqueous sodium-ion batteries. However, their stability in aqueous environments is relatively low limiting the application of these materials in aqueous batteries or deionization cells. In this study, we provide a comprehensive analysis of Na 3 V 2 (PO 4 ) 3 and Na 3 V 2 (PO 4 ) 2 F 3 degradation in aqueous media using a number of techniques such as standard electrochemical methods, elemental analysis, powder X-ray diffractometry, and rotating ring-disc electrode method. The latter allows for real time in situ/operando degradation analysis. The results show that Na 3 V 2 (PO 4 ) 3 suffers from chemical vanadium dissolution in neutral pH, whereas it is negligible in Na 3 V 2 (PO 4 ) 2 F 3 . The results obtained in unbuffered electrolytes by the ring-disc electrode technique explicitly show that Na 3 V 2 (PO 4 ) 3 and Na 3 V 2 (PO 4 ) 2 F 3 generate most of the soluble V (V) species during the charging process. Whereas at lower pH, there is an additional electrochemically-induced generation of soluble V (IV) species during discharging as well. The overall results suggest that fluoride ions significantly increase the structural stability of phosphate materials in aqueous environments and a careful electrolyte design with controlled proton and water activity could enable the use of Na 3 V 2 (PO 4 ) 2 F 3 in water-based electrochemical devices. |
| Published |
Pennington : The Electrochemical Society |
| Type |
Journal article |
| Language |
English |
| Publication date |
2023 |
| CC license |
|
