Porous MnO$_{2}$ prepared by sol-gel method for electrochemical supercapacitor

MnO$_{2}$ has attracted great attention as material for electrochemical pseudocapacitor due to its high theoretical specific faradic capacitance ($\sim$ 1370 F$\cdot $g$^{-1})$, environmental friendliness and wide potential window in both aqueous and nonaqueous electrolytes. However, the MnO$_{2}$ has a low surface area which depresses its electrochemical performance. The amorphous $\alpha $-MnO$_{2}$ composite was synthesized by sol gel method in the presence of the tri-block copolymer P123. Our aim is to investigate the role of P123 on the electrochemical performance of MnO$_{2}$. The samples with and without P123 were prepared and characterized by x-ray diffraction (XRD), SEM, TEM and Brunauer--Emmett--Teller (BET) method. The electrochemical performances of the amorphous MnO$_{2}$ composites as the electrode materials for supercapacitors were evaluated by cyclic voltammetry~and AC impedance measurements in a 1M Na$_{2}$SO$_{4}$ solution. The results show that the sample prepared without P123 exhibited a relatively low specific capacitance of 28F$\cdot $g$^{-1}$, whereas the porous MnO$_{2}$ prepared with P123 exhibited 117 F$\cdot $g$^{-1\, }$at 5 mV/s. The results of crystalline MnO$_{2}$ composites will also be presented.