Fig. 4
Detection of Cr and S valance state during various charge-discharge stages. a Charge and discharge curves of NaCrS2 electrode for ex situ XAS. b Cr K-edge XANES spectra of NaCrS2 electrodes at various states. c Corresponding FT-EXAFS spectra of the NaCrS2 electrode at various charge and discharge stages. Calculated (solid red line) and experimental (solid and open circle) FT-EXAFS spectra for d pristine and e fully charged samples. f EPR spectra of pristine NaCrS2, fully charged and discharged samples recorded at room temperature. g S K-edge XANES spectra of NaCrS2 at the initial cycle
