The Research On Performance Of Supercapacitor Based On Wood Oriented Tunnel Structure

With the rapid development of the economy,the world energy is continuously consumed,and energy has become one of the most concerned topics in nowadays society.In many application areas,some of the most eff-icient and practical electrochemical energy conversion and storage devices primarily are batteries,conventional capacitors and supercapacitors.Supercapacitors have several orders of magnitude higher energy density compared with conventional capacitors.Besides,it has higher power density and better cycle life than batteries · However,the performance of supercapacitors is affected by many factors,for example,the electrode materials and electrolytes.In this paper,we mainly study the electrode materials which have the greatest influence on the performance of supercapacitors.As a promising renewable resource,biomass possesses some advantages,such as,wide source,low cost and green sustainability.The biomass functional materials used as raw materials is a hot research topic in the field of electrode materials.In particular,the wood used to make supercapacitors has aroused great interest.Wood is a widely sourced,inexpensive material with excellent mechanical properties.It can be carbonized at the high temperature under the inert gas condition and maintain its interconnected multi-channel porous structure,providing a large transport surface area for the ions.In this paper,two kinds of wood with different pore sizes,cell sizes and shapes were used to prepare supercapacitor electrode materials,and they both demonstrated excellent performance ·First,we used fir as a raw material to explore the physical activation time and material thickness.It was found that the optimum activation time was 10 h and the optimum thickness of the material was 0.8 mm.We also used nitric acid and potassium hydroxide to etch some mesopores and micropores on the wood tube wall,to further increase the specific surface of the electrode and expand its specific capacitance.Second,Manganese dioxide pseudocapacitor material was used to fill the wood tube by two methos to further improve the electrochemical performance of the capacitor.Manganese dioxide is an inexpensive,non-toxic metal oxide and its theoretical specific capacitance is up to 1370 F g-1.Based on the above research,potassium permanganate(KMnO4)was directly used as a reducing agent to transport MnO2 in the poplar trough according to potassium hydrothermal reaction method on the temperature condition of 140 0C.The composite electrode area specific capacitance can reach 3.497 F cm-2 at a concentration of 10 mM L-1.Thirdly,The hydrothermal electrode material can be used for large-scale preparation and be convenient for mass production.However,the quality of the manganese dioxide is uncontrollable to upload on the composite electrode by hydrothermal method.Potentiostatic electrochemical deposition can accurately control the quality of the uploaded manganese dioxide.Using this method,we synthesized manganese dioxide nanosheets in Chinese fir tube cells,which can further increase the specific surface area of the electrode material and improve the electrochemical properties of Chinese fir chips.When the loading amount of manganese dioxide is 10 mg cm-2,the specific capacitance of the composite electrode material can reach 187.5 F g-1.In this paper,an electrode material with high energy density,power density and specific capacitance was prepared by using green sustainable biomass carbon material.According to our research,the supercapacitor which used wood as the electrode material,can go into mass production,which may further promote the green development of supercapacitors.