From Biocarbon To Three-dimensional Porous Graphene-like And Its Application In Supercapacitor

Biomass is an abundant renewable material in nature,and it is a common raw material for carbon materials.Biocarbon carbonized from biomass is hard carbon,and it is composed of turbulent graphite microcrystals and the amorphous crosslinking carbon atoms between them.Owing to this constrained and disordered structure,the application of biocarbon is severely limited.In contrast,graphene has larger area of two-dimensional crystal lattice,which possess high specific surface area and high conductivity,so as has wide application in many areas.Thus,it is a promising research to convert biocarbon to graphene material via changing its structure.This paper used biomass as the raw material,proposed a low-temperature graphitization reaction to prepare three-dimensional porous graphene-like:firstly pyrolyzed biomass at 400 ? for 3 h to get the biocarbon,then mixed the biocarbon with potassium carbonate,ground the mixture for 5 min and transferred it to the cube oven,reacted for 2 h at 900 ?,then took it out after natural cooling,finally washed with deionized water and dilute hydrochloric acid.3DPGL prepared by this method is composed of crosslinking graphene-like sheets.Through a series of characterizations,it has been proved that 3DPGL possess high specific surface area(1506.09 m2 g-1)and high conductivity(32.14 S cm-1).To test the electrochemical performance of 3DPGL,1 M TEMABF4/propylene carbonate was used as electrolyte to assemble the two-electrode symmetry supercapacitor.The electrochemical test result shows that 3DPGL has good electrical double-layer capacitor performance,the gravitational specific capacitance of 3DPGL was 91.15 F g-1 at a current density of 0.2 A g-1,and the electrode material kept 85.1%of the initial capacitance at a current density of 0.1 A g'1 after 5000 cycles,reveals the good supercapacitor performance.This paper also carried out deep exploration and promotion of low-temperature graphitization,through the single factor experiments,different carbonized samples were obtained via changing the carbonization temperature in the preparing process,then test the structure and properties of biocarbons obtained via different carbonization temperature and the corresponding samples after low-temperature graphitization reaction,the results shows that with the increasing of carbonization temperature at the range of 400?900 ?,the samples after low-temperature graphitization all possessed good graphene-like morphology,but the pore volume and the specific surface area decreased with the increasing of carbonization temperature,and the structure of carbonized samples obtained via different carbonization temperature also has corresponding differences.Though the promoting exploration of this reaction,we found that low-temperature graphitization reaction is also applicable to other biomass materials and sodium carbonate reactant,demonstrated the universality and huge space of this research.