Fig. 6.

Morphology and components analysis of the Na metal anode after cycling at 1 C using ANs–GPE and GFs–GPE at 60 °C. a–d SEM and EDS images of the Na metal anode surface after 200 cycles. e–h SEM and EDS images of cross-section of the NVP/ANs–GPE/Na cell after 1000 cycles. i, j Atomic concentration of various elements with sputtering time. k, l High-resolution C1s and O1s XPS spectra of Na anodes after 200 cycles. Scale bars, 5 μm in a, c; and 50 μm in e