Controllable Synthesis And Energy Storage Performance Of Multi-stage Pore Carbon Materials Based On Canola

Along with the development of the society,people have stricter demand for the new portable storage equipment.Specifically,Lithium ion batteries?LIBs?and super capacitor?SCs?as the leading electrode material for energy storage have aroused great interest in field of advanced materials with high performance.In recent few decades,activated carbon?AC?has been applied as energy storage material for its high specific surface area,good electrical conductivity and chemical stability.However,the non-hierarchical pore structure of AC constrains its application.Large number of micropores?<2 nm?significantly increase the surface area of AC,but the incompatibility between the micropores material and electrolyte ion results in obviously decreasing the available specific surface area.Therefore,the preparation of hierarchical pore carbon?HPC?with high specific surface area is crucial for improvement of energy storage of carbon electrode materials.The biomass material is an ideal carbon source for HPC materials because of its unique 3D structure,renewable,and environmentally friendly characteristics.Herein,we choose a hazardous algae biomass,enteromorpha prolifera?EP?,as the carbon source.Proceed from the unique tubular porous structure of EP,hierarchical porous carbonaceous aerogel?HPCA?with high specific surface area was prepared by freeze-drying and activation process.Meanwhile,the Co₃O₄@HPCA composite and PANI@HPCA composite were prepared using the HPCA as the substrate.The content of this research is as follows:1.The controllable synthesis of HPCA and its energy storage performanceThe synthesized HPCA contains a large amount of micro/meso/macro-pores and huge specific surface area(1900²200 m2g^-1),which was made through freeze-drying,carbonization and activation by KOH.The ionic conductivity of HPCA was enhanced due to the existence of a large number of mesoporous.Meanwhile,the available surface area was increased which remarkably increases the performance of lithium ion batteries and supercapacitors.HPCA exhibits a reversible lithium storagecapacity of 827.1 mAhg^-1 at current density of 0.1 Ag^-1.It also possess high specific capacitance and excellent rate performance for electric double layer capacitors(260.6Fg^-1 at 1 Ag^-1 and long cycle life with 91.7% capacitance retentionafter 10 000 cycles at 10 Ag^-1),which is attributed to the hierarchical pore structure of HPCA.2.The controllable synthesis of Co₃O₄@HPCA and its energy storage performanceCo₃O₄@HPCA composite material was synthesized through in situ composite by hydrothermal method,in which HPCA is the substrate.The introduction of HPCA can not only elevate the conductivity of Co₃O₄ nanowires,but also raise the power density and stability of electrode materials.In this way,pseudocapacitive performance of Co₃O₄ could be fully demonstrated,which shows a highperformance pseudocapacitor with the maximum specific capacitance of1167.6 Fg^-1 at the current density of 1 Ag^-1 and 500 Fg^-1 at a high current density of 50 Ag^-1.In addition,the capacity retention rate is 92.4% after 10,000 cycles at 10 Ag^-1.Co₃O₄@HPCA composite material exhibits much higher performance than the Co₃O₄ nanowires.3.The controllable synthesis ofPANI@HPCA and its energy storage performancePANI@HPCA was produced by in situ grow of polyaniline?PANI?on the surface of HPCA,in which HPCA was used as framework support that increases the mechanical properties of PANI during the charge/discharge process,and also prolong the long cycle life.In addition,the introduction of HPCA can also improve the power density of the composite material.PANI@HPCA shows a specific capacity of 427.8 Fg^-1 at 1 Ag^-1 and long cycle life with 83.2% capacitance retentionafter 10 000 cycles at 10 Ag^-1.The energy storage performance of the composite has been boosted comparing with the pure PANI.