Black Aspergillus-derived Highly Porous Carbon Fibers For Capacitive Applications

In the 21st century,with the rapid development of economy,demands for energy are also increasing in various countries around the world,so energy has become the indispensable important component in the modern society development.And traditional fossil fuels such as coal,oil,natural gas and other resources are excessive consumption,which not only caused serious energy crisis,also since the acidity in its use a lot of harmful gases and liquids,caused great environmental pollution.Not only that,as countries continue to build industrialized and modernized countries,the consumption of fossil fuels will be even more impressive.This is undoubtedly a further deterioration of the environment and energy issues.So solving this problem becomes imminent.Scientists are always looking for renewable energy sources that can replace traditional fossil fuels to reduce the environmental crisis.For now,renewable clean energy sources such as wind power and solar energy,tidal power has been widely used,but they also exist some disadvantages,such as the clean energy itself characteristics of intermittent and low energy density,which makes the clean energy have certain limitation in application.If we want to apply these new energy sources reasonably and efficiently,the first issue is to store these energy sources and release them until they are needed.In recent years,several new type energy storage device:secondary battery,fuel cell,lithium battery and super capacitor,etc.,and through comparison and practical application,the super capacitor with fast charge and discharge,long cycle life,high power density obvious advantage has received the widespread attention at home and abroad.Supercapacitors,which is also called Electrochemical capacitors,compared with the ordinary traditional capacitor,this new type of energy storage device has higher energy density,compared with the battery they have a better cycle stability and power density.Ordinary storage device converts electrical energy into chemical energy in charge,discharge and convert chemical energy into electricity,in this process,the energy loss lead to that the highest energy conversion rate only reach80%,however super capacitor is perfect to overcome the shortcomings,it does not exist in the process of charging and discharging in the form of energy conversion,the energy of the highest conversion efficiency can reach 98%.It is because of its high energy density and power density that it fills the gap between the plate capacitor and battery.In this paper,we study a kind of porous activated carbon（PAC）,it comes from renewable inert gas in the pyrolysis of filamentous fungi.PAC has a high specific surface area of 1800m²g^-1,with micropores,mesopores and macroporous stratification structures.The N-doped PAC electrode shows a high specific capacitance of 298 Fg^-1.And after 10000 cycles,it has 100%capacity retention and excellent cycle stability.In addition,the assembled symmetric supercapacitor device has 10.32 Wh Kg^-1 energy density.This work provided a new source of renewable filamentous fungi for the production of high performance porous carbon materials for supercapacitors.The main contents include the following aspects:（1）The filamentous fungus was first carbonized and reactivated,and the effect of the carbonization temperature on the performance of the capacitor was studied.The influence of adding Ni on the final performance was explored,the effect of activation on the porosity of the material and the effect of the specific surface area on the performance of the capacitor were clarified.（2）The effect of N doping on the performance of the capacitor was studied.（3）The influence of the comparison capacitance after the composite of carbon material and metal oxide was studied.