Preparation Of Sunflower Seed Shell-based Novel Anode Material And Study On Its Electrochemical Performance

With the consumption of petroleum resources and the increasingly prominent environmental problems,in order to meet the current and future energy needs,it has become an urgent task to find alternative clean energy.Biomass materials have many advantages,such as abundant sources,economic and environmental protection,simple preparation process,etc.,which have attracted the attention of many experts and scholars.At present,biomass-carbon nanomaterials have been successfully applied in soil improvement,sewage treatment,heavy metal adsorption,greenhouse gas adsorption,photocatalysis,chemical catalysis,biodegradation of polymer composite materials,etc.Biomass carbon materials also show great potential in electrochemical applications.Using biomass as raw material to prepare lithium-ion battery anode material not only realizes the utilization of agricultural and forestry waste resources,but also provides a new idea for the preparation of new energy materials.Among them,sunflower seed,as one of the five widely used oil crops,provides a rich source for sunflower seed shell,and the carbon content of sunflower seed shell is about 41～51%,which has great application potential.In this paper,sunflower seed shell was used as raw material to prepare amorphous biomass carbon with specific morphology by chemical activation method and hydrothermal carbonization method respectively,which was used as anode material for lithium-ion battery.The physical characterization and electrochemical performance analysis of the prepared materials were carried out,and the main research contents were as follows:（1）Sunflower seed shell was prepared by physical carbonization and chemical activation with Ca Cl₂as the activator and PMA as the processing aid.The effects of Ca Cl₂dosage and activation temperature on the structure and properties of the porous were investigated,and the promoting effects of PMA on the carbonization and activation process were also researched.The results show that when the activation temperature is 600℃and the impregnation ratio is1:2.5（sunflower seed shell:Ca Cl₂）,the porous carbon material has more abundant pore structure,excellent electrochemical performance but poor cycling stability.PMA can improve the specific surface area and structural stability at the same time,and the prepared porous carbon material has the best electrochemical performance.The BET specific surface area of the material is up to 404.216 m²g^-1,and the specific discharge capacity of the material can be maintained at 590.3 m Ahg^-1after 450 cycles at 2 C.（2）The cellulose was extracted by alkaline boiling and acid boiling,and the sunflower husk cellulose-based carbon nanospheres were prepared by the hydrothermal carbonization method.The hydrothermal reaction time was used as the experimental variable,which were set as 24 h,36 h,48 h and 60 h,respectively.Then a strong oxidant（ammonium persulfate）was used to change the process of cellulose hydrolysis and spheroidization,and ammonium persulfate was added at a ratio of 1:5（sunflower seed hull:ammonium persulfate）to successfully prepare sunflower seed hull-based carbon nanospheres,Simplify the experiment and increase the yield.The influence of hydrothermal time and ammonium persulfate on the formation process of carbon nanospheres and the influence of the microstructure of carbon nanospheres on the electrochemical properties were investigated.When the hydrothermal time was 60 h,the maximum specific surface area(356.125 m²g^-1)and the best electrochemical performance were obtained.The specific discharge capacity of sunflower seed shell-based carbon spheres was 729.6 m Ahg^-1after 100 cycles at 0.2 C.