Fig. 3
Reversible structural changes of partially dehydrated Na-bir during the cycling. a Ex situ Mn K-edge XANES spectra, b Ex situ k3-weighted Mn K-edge EXAFS spectra of partially dehydrated Na-bir during the initial two cycles. c Ex situ Na K-edge XANES spectra of partially dehydrated Na-bir during the initial 2 cycles. d Ex situ Raman spectra of partially dehydrated Na-bir in the pristine, 1st charge, 1st discharge, 2nd charge, and 2nd discharge state. e In situ XRD patterns of partially dehydrated Na-bir during Na ion insertion/extraction at a current density of 30 mA g−1. High-resolution ADF-STEM images of f pristine, g charged, and h discharged partially dehydrated Na-bir. The scale bars are 2 nm
