High cycling performance electrodes of Co2+-doped sandwich structured woodceramics

Abstract

In order to improve the electrochemical performance of biomass electrodes and prolong their service life, the Co2+ doped sandwich structure woodceramics composite electrode is prepared by utilizing cherry wood veneer and pine needle carbon powder as external cladding layer and core layer, respectively, accompanying with catalyst and dopant Co(NO3)2.6H2O. Scanning electron microscopy (SEM) reveals that a three-dimensional network can be obtained by an external cladding layer which maintains natural pore structures and pine needle toner core layer which possesses the hollow tubular structure attach with the transverse holes tube wall. Transmission electron microscopy (TEM) results exhibit that the doped Co nanoparticles are wrapped by graphitized carbon which improves the corrosion retardancy and prolongs the service life of electrodes. X-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) analysis indicates that the doped Co2+ exists mainly as metallic cobalt (Co) after a series of reactions, but also with a small amount of Co2+. The electrochemical measurements presents that the specific capacitance of the resultant electrodes can reach 319 F g−1 specific capacitance and capacitance retention rate can maintain 98.7% after 15,000 cycles under 0.1 A g−1 current density in the inorganic system (6 mol L−1 KOH). The practical assembled in symmetrical capacitor with the energy density of 33.86 Wh kg−1 has been performed at a power density of 100 W kg−1. Those enhanced performances explain that this novel sustainable sandwich electrode has a good potential for practical application with a long cycle life.