Reversible phase transformation of MnO2nanosheets in an electrochemical capacitor investigated by in situRaman spectroscopy

Abstract
The reversible phase transformation is reported from hexagonal to monoclinic structure responding to the intercalation/deintercalation of Na+ between MnO2 nanosheets upon potential cycling in aqueous electrolyte via an in situ Raman technique. This structural evolution will influence the Na+ diffusion process in MnO2 nanosheets and cause phase retention during the self-discharge process.