Study On The Preparation And Properties Of Wood And Bamboo Derived Carbon Based Supercapacior Electrode Materials

Supercapacitor,as an electric energy storage device,has attracted widespread attention in the field of energy and materials.Electrode material is the main contributor to the electric energy storage of the supercapacitor.Carbon materials and carbon based composites are two kinds of supercapacitor electrode materials,which have good potential to realize commercial application.However,some typical carbon materials have a relatively high cost owing to complicated preparation processes and scarce raw materials,which limits the industrial production and application of these electrode materials of carbon materials and carbon based composites.It has become an important research direction to explore a low cost carbon source to prepare carbon material and carbon based composites for supercapacitor electrode materials in this field.Wood and bamboo have been used as alternative carbon source materials for the preparation of supercapacitor electrode materials with low cost in recent years,as they are renewable biomass materials,and the process to prepare carbon materials is simple,and the as-obtained carbons have abundant porous structure.In order to prepare the low cost carbon based electrode materials with good electrochemical performance and achieve the high added value utilization of wood and bamboo,in this thesis,we have designed and implemented the preparation of novel wood and bamboo derived carbon based composite materials,and investigated their supercapacitive performance.The detailed research contents and main results are listed as follows:?1?Bamboo carbon powder was prepared via high temperature pyrolysis of bamboo powder,then activated by high temperature alkali activation method to produce hierarchical porous structure.The boron doping and/or nitrogen doping of as-prepared carbon materials were achieved by hydrothermal method.After that,supercapacitor electrodes were fabricated with the as-prepared doped bamboo derived carbon materials as active materials,then the electrochemical properties of all as-prepared electrodes were tested by cyclic voltammetry?CV?,galvanostatic charge-discharge,and electrochemical impedance spectroscopy?EIS?measurements.Test results show that specific capacitance and energy density of as-prepared boron and nitrogen co-doped bamboo derived carbon materials are significantly higher than those of un-doped carbon,boron-doped carbon and nitrogen-doped carbon.The maximum specific capacitance values were as high as 281 F g^-1 in 1 M KOH and 318 F g^-1 in 1 M H2SO4,and the maximum energy density values were 37.8 W h kg^-1 in 1 M KOH and 42.1 W h kg^-1 in 1 M H2SO4.The maximum specific capacitance values obtained is larger than those of most previously reported bamboo-derived carbons,boron and nitrogen co-doped carbons,and other typical biomass-based carbons.In addition,an asymmetric supercapacitor utilizing a negative electrode based on this novel NBKBC material demonstrated satisfactory energy density and electrochemical cycling stability.This study proves that the as-prepared boron and nitrogen co-doped bamboo derived carbon material is a promising candidate for fabrication of practical supercapacitors.Through employing this fabrication method of materials,the high added value utilization of bamboo is expected to be realized.?2?Boron doped wood derived porous carbons?BAWDC?were prepared by successive high temperature pyrolysis,alkali activation,and hydrothermal doping.Then boron doped wood derived porous carbon/polyaniline?PANI-BAWDC?composites were synthesized by low temperature in-situ oxidation polymerization of aniline in the presence of boron doped wood derived porous carbons.Benefiting from the increased anchoring sites endowed by boron doping and the abundant porous structure in boron doped wood derived porous carbon,an improved dispersion of polyaniline?PANI?component for the composite than pure polyaniline was achieved during the synthesis process.After that,the supercapacitor electrodes were fabricated with these as-prepared composites as active materials,and their electrochemical performance were also investigated.Test results show that compared to pure PANI and BAWDC,the as-prepared PANI-BAWDC displays significantly enhanced specific capacitance,due to the synergetic effect between PANI and BAWDC.Moreover,the obtainable highest specific capacitance(421 F g^-1)and energy density(45.2 W h kg^-1)of this PANI-BAWDC composite are comparable to those of some similar carbon/PANI composites.The present research provides a feasible route for synthesizing carbon based composites with low cost and high electrochemical performance,and also provides a significant reference for the high added value utilization of wood.