Soybean root-derived heteroatoms co-doped porous carbon with ultra-high specific surface area for high performance supercapacitors

Abstract

In this work, a strategy consisting of a two-step carbonization and high temperature activation is developed to derive N, S and O co-doped carbon with three-dimensional pores from soybean roots. An optimized porous carbon activated at 700 °C (HSRC-700) displays an ultra-high specific surface area of 3107 m2 g−1 with rational 3-dimensional pores, contributing to a high capacitance of 486.8 F g−1 at 0.5 A g−1, which maintains 230 F g−1 even at 100 A g−1. Also, a stable life over 18,400 cycles at 20 A g−1 with a retention of 92.5% is delivered. Meanwhile, the energy density of a coin-type symmetric supercapacitor with HSRC-700 in 1 M LiPF6 is as high as 59.4 W h kg−1 at 1500 W kg−1, and the value remains 33.3 W h kg−1 at 30,000 W kg−1. The findings above indicate that green and eco-friendly soybean root-derived porous carbon exhibits great potential in supercapacitors.