Fig. 5: Characterization and electrochemical properties of NMT-10 after different days of air exposure.

a Schematic diagram of the changes in the surface and crystal structure of the material after exposure to air. SEM images exposure to air for (b) 1 day, (c) 7 days, (d) 15 days, (e) 30 days. Scale bar, 2 μm. HR-TEM, and SAED results of air exposure samples for (f) 1 day, (g) 7 days, (h) 15 days, (i) 30 days. Scale bar, 10 nm, 1/10 nm. j Statistical analysis based on TEM measurements after different exposure durations. Error bars represent the standard deviation (SD) from at least four measurements. k, XRD patterns: * indicates the hydrated phase in the sample. Pristine and exposed samples XPS of (l) C 1 s, (m) O 1 s. n Rate performance of exposed samples for different days at 0.02 A g⁻¹ in 1.5-4.3 V. Schematic of sodium ion migration paths of water molecules on the surfaces of (o) NMO, (p) NMT-10, and water molecules at the interlayer of (q) NMO, (r) NMT-10. s The sodium ion migration energy barrier for water molecules at the surface and the interlayer.