Preparation and electrochemical performances of in-situ growth of δ-MnO2 on hierarchical porous carbon derived from LNP
Lignin based porous carbon have been widely studied as the electrode materials for supercapacitors device owing to its low-cost,renewable and simple preparation process.In this paper,lignin nanoparticles(LNP)isolated from wheat straw biomass was used as the carbon precursor,pretreated by activation with ZnCO3,and then prepared to LNP based hierarchical porous carbon(LPC)through slow pyrolysis at different temperatures(600-800℃).Furthermore,in-situ growth of δ-MnO2 was loaded onto the surfaces of LPC by the lights of solution reaction method.The resultant MnO2/LPC nanocomposite with three-dimensional(3D)nano-lamellar structure was successfully synthesized.The micromorphology,chemical composition,and electrochemical performances of MnO2/LPC were characterized by means of SEM,XRD,FTIR and electrochemical tests.The study results suggested that the behaviors of MnO2 in-situ growing on LPC were significantly affected by the pyrolysis temperature of LPC preparation.As the pyrolysis temperature of LPC increased from 600℃ to 800℃,the pattern of δ-MnO2 nanocrystals evolved from the clustered particles to 3D cross-linked porous lamellar nanostructure.In addition,the as-prepared MnO2/LPC electrode had shown excellent electrochemical performances.The specific capacitance of MnO2/LPC at 800℃ could reach 145F/g at 1A/g,yet maintained 110F/g as the current density increasing to 5A/g,indicating that it had also a better rate performance(75.9％).Meanwhile,the symmetric supercapacitor assembled from this composite material had a high specific capacitance of 87F/g and energy density of 3.03W·h/kg in the two electrode system.
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