Fig. 4. Na-ion electrochemical energy storage performances in half-cell configuration at 25 °C.

Galvanostatic charge/discharge voltage profiles of NLNFM (a) and NLNFMB (b) at 25 mA g⁻¹ between 2.0 and 4.3 V. Cycling performance at 25 mA g⁻¹ (c), rate capability at various charge-discharge rates (d), and cycling performance at 250 mA g⁻¹ (1C = 250 mA g⁻¹) (e).