Potentiodynamic and galvanostatic testing of NaFe<inf>0.95</inf>V<inf>0.05</inf>PO<inf>4</inf>/C composite in aqueous NaNO<inf>3</inf> solution, and the properties of aqueous Na<inf>1.2</inf>V<inf>3</inf>O<inf>8</inf>/NaNO<inf>3</inf>/NaFe<inf>0.95</inf>V<inf>0.05</inf>PO<inf>4</inf>/C battery

Abstract

The NaFe0.95V0.05PO4/C composite is synthesized by electrochemical ion displacement from LiFe0.95V0.05PO4/C composite in aqueous NaNO3 solution. A coulombic capacity amounting to ∼105 and ∼82 mAh g-1 at sodiation/desodiation rate of 500 and 5000 mAg-1, respectively, is evidenced. For the sake of comparison the same investigations is performed with LiFe0.95V0.05PO4/C composite in LiNO3 solution, and better capacity retention and rate performance is evidenced for NaFe0.95V0.05PO4/C one. This advancement is found to be due a higher participation of pseudocapacity in the sodiation/desodiation charge storage process. An aqueous battery composed of NaFe0.95V0.05PO4/C cathode, belt-like Na1.2V3O8 anode and NaNO3 solution as an electrolyte, tested galvanostatically, displays long-life performance with only 10% of capacity fade after 1000 charge/discharge cycles.