In this research, a cyclic voltammetry (CV) method was applied to intercalate Na + into an FePO4/Al substrate to produce NaFePO4/Al as a potential cathode material. The sodiation was conducted directly to FePO4 instead of applying delithiation to LiFePO4 followed by sodiation, as was done in previous research. CV was conducted within a potential window of 2.0-4.0 V using a scan rate of 0.05 mVs -1 . The result was compared to LiFePO4/Al treated with a similar method. The various scan rate was

more »

... en applied to understand its effect on the electrochemical activity recorded in the voltammogram and its impedance profile. The results show that the CV product of FePO4/Al (NFP(A)) was crystallized in an orthorhombic olivine NaFePO4, as a result of Le Bail refinement. Orthorhombic Na0.7FePO4, trigonal FePO4, and monoclinic FePO4 were presented as secondary phases. Meanwhile, the CV product of LiFePO4/Al (NFP(B)) was also crystallized in olivine NaFePO4 and possessed secondary phases similar to NFP(A) with an additional Fe2O3 phase. NFP(A) showed two significant peaks at 2.442 V and 3.534 V, confirming sodiation/de-sodiation and Fe 3+ /Fe 2+ activity, respectively. Meanwhile, NFP(B) showed two peaks at 3.183 V and 3.04 V, corresponding to de-lithiation and sodiation, respectively. The Nyquist plots of both materials show a similar profile, with the impedance value of NFP(A) being lower than that of NFP(B). This confirms that the CV treatment of FePO4/Al is more facile than the treatment of the LiFePO4 layer, while also producing a cathode with higher electrical conductivity. Scan rate reduction to 0.04 mVs -1 produced a much lower impedance value, confirming higher electrical conductivity.