| Lithium ion battery has already occupied the main market of portable electronic products because of its high energy density,small volume and no pollution.However,with the large-scale application of lithium ion batteries,we are face with serious shortage of lithium resources.The sodium of the same main group as lithium is rich in resources and low in price,the physical and chemical properties of the two are similar,the sodium-ion battery and the lithium-ion battery have similar working principles,however,the radius of sodium ions is much larger than that of lithium ions,therefore,the materials is suitable for lithium ion deintercalation are not suitable for the deintercalation of sodium ions.Finding the right electrode material is the research hotspot of the current sodium ion battery.The anode electrode material is an important part of the battery,and its performance largely determines the performance of the battery.Carbon materials are rich,stable,safe and it is one of the most promising anode materials for sodium ion batteries.Its main problems are low specific capacity and low initial coulombic efficiency,hindering its practical application.Designing porous structure and heteroatom doping is an effective method to improve the sodium storage performance.This dissertation mainly focuses on the preparation and modification of carbon materials by introducing template and heteroatom doping and can prepare the anode material of sodium ion battery with excellent electrochemical performance,we discussed the intrinsic connection and regularity about the morphology,structure,composition and electrochemical performance of carbon materials.The main research content is as follows:1.With the biomass of Phoenix tree fruits as the precursor,the fruit was peeled off to obtain phoenix tree fruit filaments and phoenix tree fruit cudgels,respectively,and calcined under a nitrogen atmosphere to prepare a sheet-like structure of hard carbon material,exhibiting better electrochemical sodium storage.performance.The the filamentous and rod-derived hard carbon materials can deliver a reversible capacity of 230 mA h g-1,190 mA h g-11 at a current density of 0.2 A g-1 and the first Coulomb efficiencies were 61%and 67%,respectively.These jobs not only help solve the energy crisis,but also reduce biomass waste.2.Using renewable biomass gelatin as a carbon source and nitrogen source,phosphoric acid as a phosphorus source,and polystyrene nanospheres as templates for the preparation of N/P co-doped porous carbons.The product can deliver a reversible capacity of 230 mA h g-1 at a current density of 0.2 A g-1 and even a high capacity of 113 mA h g-1 at 10 A g-1.The synergistic effect of the porous structure and N/P co-doping contributes to the improvement of the sodium storage performance.In general,N,P co-doped porous carbon has been shown to be a promising electrode material for sodium-ion batteries.Also,this method can be used to prepare other types of heteroatom-doped?single-doped,double-doped and multi-doped?porous carbon materials and applied in the energy storage field.3.Taking sucrose as carbon source,phosphoric acid as phosphorus source and PS as template and the phosphorus-doped porous carbon was prepared by one-step synthesis.The morphology and structure of the material are regulateed by controlling the sintering temperature.It was found that the material prepared at 800?C has a very uniform pore structure.The product can deliver a reversible capacity of 270 mA h g-1at a current density of 0.2 A g-1 and even a high capacity of 140 mA h g-1 at 10 A g-1.On the one hand,a uniform three-dimensional porous framework structure can provide sufficient space for the diffusion of sodium ions.On the other hand,phosphorus doping can increase the interlayer spacing of carbon materials,establish a good conductive network,and thus improve the electrochemical storage of materials.performance.This study has opened up a new method for the further development of high-capacity,long-lived carbon-based sodium ion battery anode materials. |
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