Preparation and Electrochemical Performance of Microporous Carbon Microspheres Obtained from Potato Starch

Abstract

Potato starch,an extensive biomass with natural globular structure,has been used to prepare microporous carbon microspheres by way of H3PO4 promotion of starch pyrolysis and activation by KOH.Nitrogen adsorption/desorption at 77 K indicate that micropores were the major structural component in the samples.The micropore structure provides accessible surfaces for capacitive storage.Scanning electron microscopy(SEM) revealed that the globular shape of starch remained after carbonization and activation procedures,due to the important role of H3PO4 in the process.Fourier transform infrared(FTIR) spectroscopy confirmed the acceleration effect of H3PO4 on starch pyrolysis.Electrochemical measurements in 6 mol · L-1 KOH electrolyte showed that the product had excellent capacitive characteristics,with a specific capacitance as high as 363.6 F · g-1 at a current density of 50 mA · g-1.Furthermore,it exhibited a high charging rate such that the cyclic voltammetry(CV) curve still remained rectangular and highly symmetric shape even when the scan rate was 300 mV · s-1.All the results demonstrate that the potato starch-based microporous carbon is a promising electrode material for high performance electrochemical capacitors.