Research On The Preparation Of Carbon-based Functional Materials And Their Performance In Batteries

In recent years,with the development and application of new energy materials,the next-generation storage batteries are favored by researchers.Among them,lithium-air battery stands out because of its high theoretical energy density.Sodium-ion batteriy is also developed benefitting from the rich source of sodium metal.Carbon material,as one of the most widely used electrode material,has the advantages of high specific surface area,excellent conductivity and strong electrochemical stability.The research content of this thesis is how to make more efficient use of carbon materials to achieve the best performance in the next generation of energy storage system.Firstly,a new bifunctional catalyst was prerared by anchoring highly dispersed Ir O₂ nanoparticles on nitrogen-doped carbon nanotubes（N/CNTs）via a simple hydrothermal method.Benifitting from the nitrogen element and Ir O₂ nanoparticles,Ir O₂-N/CNTs has high oxygen reduction/oxygenation evolution catalytic activity.Utilizing the structural advantages of the carbon nanotube itself,the Ir O₂-N/CNTs catalyst provided more three-phase contact area and played the role of bifunctional catalyst.The performance of Ir O₂-N/CNTs used in lithium-air battery as cathode catalyst was investigated.The battery shows a high specific capacity(6839 m Ah g^-1),excellent capacity retention rate(88.9%after seven cycles at 100 m A g^-1),and superior cycling stability(160 cycles at 200 m A g^-1 with a limited capacity of 600 m Ah g^-1).Then,the reduced graphene oxide（r GO）was prepared by the improved Hummer’s method,and then we do a nitrogen doping of r GO,which turns out a three-dimensional（3D-N/r GO）wrinkle structure.3D-N/r GO was further combined with ZIF67 to make full use of the ultra-high specific surface area.ZIF67@3D-N/r GO provided more contact area for the three-phase reaction interface.ZIF67 that sticky to the inner wall of 3D-N/r GO played an important role,because it can support the internal space of the catalyst to form a three-dimensional structure,and it is easy to prepare with low cost.The performance of ZIF67@3D-N/r GO in lithium-air batteries as a cathode catalyst was investigated.The discharge specific capacity in first cycle is 8308.7 m Ah g^-1 under the current density of 0.1 A g^-1.After combined with ZIF67,the discharge capacity increased to 12028 m Ah g^-1.Biomass-derived carbon materials are favored by research scholars because of their broad sources and diversified structures.In this thesis,pine pollen was used as a precursor to prepare a biomass-derived carbon with“honeycomb”like structure.The hard carbon material is applied to the negative electrode material of a sodium ion battery and exhibits excellent electrochemical performance.At a current densit y of 0.1A g^-1,the first cycle discharge specific capacity was 370.1 m Ah g^-1,the initial coulombic efficiency reached 59.8%.The reversible capacity after 200 cycles still remained at 203 m Ah g^-1,showing excellent cycle stability.Even at a large current density of 5 A g^-1,a reversible capacity of 87.3 m Ah g^-1 can be achieved,which is superior to other biomass-derived carbon materials.