Supercapacitor performance gains from structural modification of carbon electrodes using gamma radiations

Abstract

The performance of supercapacitors (SC) strongly depends on how their activated carbon (AC) electrodes were synthesized from precursor materials and pretreatments applied to them. This study investigates the effect of direct and filtered gamma radiations applied as pretreatments to the AC. The exposure doses used were from 0.1 kGy to 6 kGy. The high gamma-energy and high dose of the pretreatment broke the randomly orientated graphitic crystal lattices inside AC particles and disturbed the existing functional group populations. The filtered radiation pretreatment at 1 kGy, which contains a higher composition of secondary electrons than direct radiation pretreatment, yields AC with the best overall SC performance. The SC cell made from 1 kGy filtered radiation pretreatment AC showed higher specific capacitance 73.1 % (218.58 F g-1), specific energy 73.54 % (10.96 W h kg-1) and specific power of 8.36 % (155.67 W kg-1) compared to the sample without any radiation pretreatment. This study explicitly shows the benefit of secondary electrons in the radiation field, which produce decisively defect sites on the AC lattices for gains in SC performance.