Effect of Na-ion incorporation on charge storage dynamics of manganese oxide in symmetric supercapacitor devices

Alkali-metal incorporation in transition-metal oxides is an effective approach for improving electrochemical charge-storage behavior. In this work, Na-ion-incorporated manganese oxide was synthesized via a low-cost chemical precipitation route and systematically examined for its structural, morphological, and electrochemical properties. X-ray diffraction confirmed the Mn 2 O 3 and NaMnO 2 phases, while FTIR spectra revealed characteristic Mn-O vibrational modes. SEM and EDS investigations demonstrated granular morphology and successful Na incorporation. Electrochemical measurements carried out in a three-electrode configuration using 1 M KOH electrolyte showed a significant enhancement in capacitive performance upon Na incorporation. The specific capacitance increased from 74.54 F g −1 for Mn 2 O 3 to 401.9 F g −1 at 2 mV s −1 . Furthermore, a symmetric Swagelok-type supercapacitor based on NaMnO 2 delivered a specific capacitance of 52.98 F g −1 with an energy density of 128.83 Wh kg −1 at a power density of 2000 kg −1 , retaining ∼75% capacitance after 10,000 cycles.