Electrochemical Properties Of Carbon Nanostructures Derived From Rape Seed Shells

Development the technology of the use of biomass resources.Renewable biomass resources replace non-renewable fossil fuel to produce heat and chemical products is a good way to save energy and improve the environment.Resource-rich,environmentally friendly and renewable biomass has been widespread concern.Unique structure and high carbon content of biomass can be used to prepare bio-carbon materials and used in lithium ion battery anode has become a hot spot.Although Lithium ion batteries have been recognized,there are still security problems,such as cycle life,low temperature performance and high cost.Sodium ion and lithium ion properties have many similarities.Sodium ions can be constructed a lithium-ion battery-like structure,and become a widely used secondary battery.Because of its abundant resources,low cost,high specific energy and good safety performance,sodium ion battery has been paid more and more attention by researchers.However,the anode material is the difficulty in the development of sodium-ion batteries.In this context,this dissertation aims to study the electrochemical properties of carbon nanomaterials derived from rape seed shells by hydrothermal-carbonization and one-step pyrolysis.The spherical,particle self-assembled flakes and sheet-like structure contained particles carbonaceous materials were prepared by hydrothermal carbonization in different acid?H₃PO₄,H₂SO₄,HCl and HNO3?solvent and then pyrolysis in the Ar atmosphere.The sheet-like structure contained particles carbonaceous materials with great electrochemical performance was obtained through 180 oC hydrothermal 24 h with HNO3?10 wt %?solvent,followed 700 oC pyrolysis 2 h.(a high reversible capacity of 143 mAh g^-1 for 200 th cycle at 100 mA g^-1)Porous sheet biomass carbon electrode materials were prepared by hydrothermal carbonization with KOH activation,and then high-temperature pyrolysis.The biological carbon nano-materials is sensitive to the hydrothermal time and hydrothermal temperature.With the increase of hydrothermal time,the graphitization degree of the product increases and the surface folds increase.The hydrothermal time increased from 120 oC to 170 oC,the surface folds of the product decreases.The loose deposited sheet-like structure with a degree of graphitization of carbonaceous materials shows a better electrochemical performance was obtained through 170 oC hydrothermal 12 h by chemical activation with KOH?3 mol/L?,followed 700 oC pyrolysis 2 h.(a high reversible capacity of 139 mAh g^-1 for 400 th cycle at 100 mA g^-1 and 120 mAh g^-1 at 500 mA g^-1)Porous carbon electrode materials were prepared by using KOH as an activator under inert atmosphere.In the study,we found that the morphology of carbon materials changed from lamellar structure to skeletal carbon with the increase of carbonization temperature.The temperature increased further,the nano flake grows on the carbon skeleton surface.This kind of structure shows a good electrochemical performance of lithium ion batteries(458 mAh g^-1).As for sodium ion battery anode materials only 77.3 mAh g^-1 at 100 mA g^-1.