Reductive Treatment of δ-MnO2 with Sodium Borohydride: Method for Increasing the Electrode Material Capacitance

The effect of reductive treatment on the phase composition, morphology, and electrochemical parameters of delta-MnO2 produced by the hydrothermal method from KMnO4 at a temperature of 160 degrees C in the presence of HNO3 was studied. delta-MnO2 processing with 3 M NaBH4 aqueous solution leads to partial reduction of Mn(IV) to Mn(III) and Mn(II). The electrochemical characteristics of the obtained electrode materials were examined by cyclic voltammetry, galvanostatic charge-discharge measurements, and impedance spectroscopy. Reductive treatment increases the specific capacitance of delta-MnO2 in 1 M Na2SO4 up to 204 F g(-1) at a current density of 0.1 A g(-1), and also reduces diffusion limitations during cycling due to an increase in the specific surface area. The loss of specific capacitance after 2000 charge-discharge cycles does not exceed 2.6%, which confirms the high electrochemical stability of the obtained electrode materials.

Automated summary

The effect of reductive treatment on the phase composition, morphology, and electrochemical parameters of delta-MnO2 was studied. Reductive treatment increased the specific capacitance and reduced diffusion limitations during cycling.