Studies On The Biomass-based Three Dimensional Porous Carbon Materials And Flexible Energy Storage

In recent years,with the tremendously breakthrough of flexible materials,the field of wearable electronic devices has entered a rapid development stage.Therefore,more and more energy storage devices need to be miniaturized,lightweight and have practical flexibility.Supercapacitors have become an indisoensable energy storage devices due to their high power density,cycle stability and extremely short charging time,and exploring the electrode materials of supercapacitors with flexibility have naturally become hot topic in current research.A variety of materials can be used as electrode materials for supercapacitors,such as metal oxides,conductive polymers and carbon materials.In the above materials,carbon materials with excellent electrochemical stability,large specific surface area and high conductivity are considered to be one of the most promising electrode materials.On the other hand,considering the preparation cost and yield of various carbon materials,biomass porous carbon materials are undoubtedly the best choice at present.Different biological structures and methods of preparing biomass carbon materials are different,so the structure of biomass carbon materials is different.In this paper,different biomass are used as carbon source,and four kind of activated carbon materials with different structures are prepared by different activation methods,and explored the structure-activity relationship between their structures and flexible electrical properties.In addition,the introduction of metal oxides into the biomass based carbon materials make them have pseudocapacitance properties,thus further improved their electrical properties.Finally,the planar flexible supercapacitor is fabricated by the device design.The main work contents are as follows:?1?Cotton straw and Cellulose were used as carbon sources by molten-salt method to synthesis carbon precursor.Saussurea involucrata and Cotton as carbon sources by carbonization to synthesis carbon precursor.Then four kinds of precursor was activated by potassium hydroxide at high temperature in a tubular furnace to obtain three dimensional porous carbon materials.The structure of biomass carbon is regulated by changing the ratio of carbon source to potassium hydroxide and the activation temperature.All solid state supercapacitors with sandwich structure were assembled by the four materials,and it was found that Saussurea involucrata-based carbon materials shown excellent flexibility and electrochemical properties due to high specific surface area and high degree of graphitization,the specific capacitance was 129 F g^-1 at the rate scan of 2 mV s^-1,the capacitance barely changed after bending 100 times.?2?Algae was carbonized in a CVD tube furnace at high temperature to obtain algin-based carbon.After that,Cobalt nitrate was used as a precursor,CoO was grown on algin-based carbon by hydrothermal method,the resulting product was named ADC@CoO.Then ADC@CoO surface was coated with a layer of polyaniline in situ polymerization to obtain ADC@CoO@PANI.Finally,the ADC@CoO@PANI was carbonized in a tubular furnace to obtain algin-based ADC@CoO@CP composites.As the biomass material was modified by cobalt oxide and doped with N,the working voltage of a symmetrical supercapacitor which prepared by the electrode material is increased to 1.4V.?3?Cotton stalk-based carbon was used as electrode material.The electrode was etched into comb electrode by laser marking machine to synthetize micro supercapacitor device with polyvinyl alcohol and sulfuric acid as solid electrolytes.The planar micro supercapacitor shown good flexibility and high specific capacitance,and the fabrication process is compatible with traditional micro-nano technology,so it is more suitable for the preparation and integration of micro electrical devices.