Investigation into the origin of high stability of δ-MnO2 pseudo-capacitive electrode using operando Raman spectroscopy

MnO2 coated Ga-doped ZnO electrodes demonstrate a specific capacitance of 1068 F g−1 and unprecedented stability in Na2SO4, the charge storage mechanism of which was dominated by an interlayer spacing contraction/expansion due to Na+ intercalation/deintercalation without the involvement of proton, which was illuminated by a joint experimental and theoretical study.295