Constructing nitrogen/sulfur co-doped hierarchical porous cellulose-based carbon derived from larch via regeneration by dissolution approach for supercapacitor

The effective strategies to increase the energy density of carbon-based supercapacitors are increasing the specific surface area (SSA) and heteroatom doping, however the methods to achieve such outcomes are often time-consuming and complicated. Herein, a time-saving and facile method was adopted to fabricate hierarchical carbonized wood electrodes with both delignification and partly dissolution/regeneration through NaOH/thiourea solution followed by carbonization. The partial dissolution/regeneration treatment not only generates the interconnected network structures on the surface of the regenerated wood and improves the porosity, but also achieves the efficient co-doping of nitrogen/sulfur heteroatoms. A relatively excellent activation was achieved by dissolving for only 3 h, with a SSA of 1416.25 m2/g, which was 2.86 times higher than the SSA of the samples carbonized directly with delignified wood. Remarkably, the as prepared electrode exhibits superior areal (specific) capacitance of 6.11 F/cm2 (413.6 F/g, 1.0 mA/cm2) and durability (98.9%, 12,000 cycles, 50 mA/cm2). In addition, a symmetrical supercapacitor (SSC) assembled from carbonized regenerated wood has an excellent energy density of 1.15 mWh/cm2 (51.24 Wh/kg) at a power density of 699 mW/cm (31.11 W/kg). This facile doping and activation method may be able to provide a new concept for the carbon electrode preparation of bio-based materials.