Specific capacitance-pore texture relationship of biogas slurry mesoporous carbon/MnO2 composite electrodes for supercapacitors

Abstract

Here, we report synthesis of biogas slurry mesoporous carbon/MnO 2 composites by simple co-precipitation route followed by thermal treatment at 250 °C for 6 h. The texture, morphology, crystal structure, and microstructure of the composites are investigated by nitrogen sorption studies, FESEM, HRTEM, X-ray diffraction, and Raman spectroscopy. All samples exhibit type IV isotherms. The BET surface area decreased from 514 to 110 m2 g −1 while total pore volume decreased from 0.52 to 0.17 cm 3 g −1 for samples loaded with 2×10−5 and 2×10−3 moles of Mn. The electrodes fabricated exhibit high specific capacitance of 709 F g−1 at scan rate of 5 mV s−1. The specific capacitance at scan rate of 5 mV s−1 increases with increasing MnO2 content. However, at 50 mV s−1, specific capacitance decreases with increasing MnO2 content. Varying the MnO2 content and hence the textural parameters, strongly influences the specific capacitances of the composite electrodes.