Electrochemical performances of supercapacitors from carbon-ZrO2 composites

Abstract

Carbon xerogel-ZrO2 composites (CZrX) were successfully synthesized through a one-pot sol-gel synthesis. The XRD results confirm the presence of well dispersed (<4.5 nm) cubic ZrO2 on the carbon support, homogeneously distributed on the carbon surface. Gas adsorption and mercury porosimetry measurement pointed out that the increase of ZrO2 in the carbon matrix produces an increase in the mesopore volume as well as a widening of the microporosity at the expense of the narrow micropores (W0 (CO2)) that decreases causing simultaneously the progressive surface area decrease. The obtained composite materials possess specific surface areas ranging from 423 to 539 m2 g−1 and a very well-developed micro and mesoporosity with a total pore volume ranging from 0.361 to 0.480 cm3 g−1.A two-electrode symmetric supercapacitor based on the carbon xerogel-ZrO2 composites exhibits a high electrochemical performance better than other similar materials from the literature with high capacitances (up to 180 F g−1 at 0.125 A g−1 for 30% ZrO2 composite), a high retention capacitance and high energy density, 27.1 Wh kg−1, at a power density of 140 W kg−1 in the voltage range of 0 V–1.2 V. The presence of zirconium oxide in the carbon matrix improves in all case the capacitive behavior of samples in spite of the decrease of the surface area and micropore volume of the samples. That has been explained on the base of different textural properties and/or chemical characteristic of the material.