Evaluating biomass-derived hierarchically porous carbon as the positive electrode material for hybrid Na-ion capacitors

摘要

As a promising renewable resource, biomass has several advantages such as wide availability, low cost, and versatility. In this study, we use peanut shell, wheat straw, rice straw, corn stalk, cotton stalk, and soybean stalk as the precursors to synthesize hierarchically porous carbon as the positive electrode material for hybrid Na-ion capacitors, aiming to establish a criterion of choosing suitable biomass precursors. The carbon derived from wood-like cotton stalk has abundant interconnected macropores, high surface area of 1994 m(2) g(-1), and large pore volume of 1.107 cm(3) g(-1), thanks to which it exhibits high reversible capacitance of 160.5 F g(-1) at 0.2 A g(-1) and great rate capability, along with excellent cyclability. The carbonaceous positive electrode material is combined with a Na2Ti2,(97)Nb0.03,O-7 negative electrode material to assemble a hybrid Na-ion capacitor, which delivers a high specific energy of 169.4 Wh kg(-1) at 120.5 W kg(-1), ranking among the best-performed hybrid ion capacitors. (C) 2016 Elsevier B.V. All rights reserved.