Preparation Of Nano-Hierarchical Porous Carbon And Study On Electrochemical Performance

With the deterioration of the energy crisis,new energy storage devices have received much attention,especially supercapacitors?SCs?with high power density and long cycling term and lithium-ion batteries?LIBs?with high stability.SCs and LIBs have complementary advantages and are combined in the application of new energy vehicles.However,the energy density and fading rate are expected to be promoted simultaneously,and nano-hierarchical porous carbon is a potential candidate.This work is based on the crosslink between sodium alginate?SA?and metal cations,assisted by freeze-drying and chemical activation,to prepare hierarchical porous carbon with a combination of micro-,meso-and macropore.The structural characteristics were tested by SEM,TEM,N₂ sorption and so on,and electrochemical performances were tested by constant current density and cyclic voltammetry.Carbons crosslinked with Ca?CaA-HPC?aimed to prepare electrodes of SCs and carbons crosslinked with Fe to form the Fe₃O₄/C composite were used as electrodes of LIBs.CaA-HPC owned high specific surface area up to 3077 m² g^-1 with a combination of micro-,meso-and macropores.The diameter of mesopores was around 3-5 nm.The capacitance reached 270 F g^-1 at current density of0.1 A g^-1,and the fading rate was 88%when current density was elevated to 10 A g^-1.The capacitance remained 90.5%after 10000 circles.Fe₃O₄/C composite owned macroporous structure with a few mesopores and no micropores.Control groups under different temperatures of carbonization were conducted,and it was demonstrated that higher temperature could benefit the porous structure and the electrochemical performances of electrodes of LIBs.The samples under the carbonizing temperature of 750?showed capacitance around 750 F g^-1 at current density of 0.1 A g^-1.