Preparation And Study Of Porous Supercapacitor Materials From Biomass

In 21st century,with decreasing traditional petrochemical energy reserves but increasing energy demanding,sustainable energy and efficient energy storage device become hot research topics.Supercapacitors have drawn extensive attention as a new type of energy storage device due to their high power density,long service life and environmental friendship.In recent years,great progress has been achieved in this field.A large number of electrode materials have been reported,but still remains many problems such as difficult processing,high cost and poor stability.In this paper,binary and ternary composite supercapacitor electrode materials with low cost and outstanding electrochemical properties were prepared via simple hydrothermal and in-situ polymerization process using bacterial cellulose with porous three-dimensional network structure or its derivative carbon aerogels as a template.1.Manganese dioxide/bacterial cellulose aerogel(MnO2/BC)electrode material was prepared with bacterial cellulose as a template.Morphology and electrochemical properties of porous composites were studied.The results of scanning electron microscope(SEM)and wide angle X-ray diffraction(WAXD)show that morphology of manganese dioxide is petaloid and has ? crystal form.morphology and size of the samples were tailored by changing mass ratio of manganese dioxide and bacterial celluloseElectrochemical properties of the samples with different mass ratios are discussed.The electrochemical test results show that MnO2/BC composite electrode materials have pseudo-capacitance properties.When the mass ratio of manganese dioxide to bacterial cellulose is 1.8:1,electrochemical properties of the composites are better than other samples.The specific capacitance of MnO2/BC(1.8:1)composite reaches 129 F/g at a scanning speed of 1 mV/s,showing a good electrochemical stability.2.Polypyrrole/manganese dioxide/bacterial cellulose(PPy/MnO2/BC)aerogel ternary electrode materials were prepared via simple in situ chemical oxidation polymerization.The effect of polymerization time of pyrrole monomer on the morphology and electrochemical properties of the composite electrode materials was studied.SEM and WAXD analysis confirms that the components in the samples are polypyrrole,manganese dioxide and bacterial cellulose,and the composites maintain a porous three-dimensional network structure.The electrochemical test results show that when the mass ratio of polypyrrole to iron hexahydrate is 1:7.8,the specific capacitance of the samples obtained at a polymerization time of polypyrrole for 4 h(Ppy/MnO2/BC-4h)is higher than that of other samples.At 0.75 A/g current density,the specific capacitance can reach 158 F/g.After 500 times of constant current charge and discharge,Ppy/MnO2/BC-4h still has a good specific capacitance retention rate,which is 78.2%of the initial specific capacitance.3.Polypyrrole/manganese dioxide/carbon aerogel ternary composites were prepared using carbon aerogels as template which is obtained by carbonation treating bacterial cellulose aerogels under high temperature in oxygen-free calcination.The effect of polypyrrole monomer on the properties of composites is investigated by adjusting mass ratio of polypyrrole monomer to carbon aerogel.The prepared carbon aerogel is completely carbonized and maintains a three-dimensional porous network structure.Specific capacitance of the prepared carbon aerogel can reach 163 F/g.When the mass ratio of polypyrrole to carbon aerogel is 0.2:1,the specific capacitance of the compositereasches its maxmum,333 F/g.After 1000 times of constant current charge and discharge,the specific capacitance loss rate is only 5.7%,which has superior cycle stability than other materials prepared above.