Study On Organic Carbonyl Compounds As Electrode Materials For Lithium-ion Batteries

Currently,lithium ion batteries have been very broad application prospects in various fields such as portable electronic devices,electrical vehicle,space technology and national defence industry by virtue of high voltage,high capacity,high energy,long cycle life and security.It have became research hotspots which has received much attention in recent years.In the research field of lithium ion battery,The focus on electrode materials of lithium ion battery has still mainly concentrated in the inorganic materials.Due to the limitation of theoretical specific capacity and single structure,it is difficult to further improve the energy density of traditional inorganic electrode materials.Furthermore,The large-scale application of inorganic electrode materials inevitably brings the issue of resource scarcity and serious environmental pollution.However,organic materials are expected to gradually replace inorganic electrode materials due to high theoretical specific capacity,low cost,structural diversity,flexibility and easy processability.More importantly,some organic electrode materials can be directly extracted from natural plants or processed through organic synthesis method,which makes the whole cycle of the lithium battery truly realize the green sustainable development.In this article,organic carbonyl compounds were selected as the active object of electrode materials,the structure and morphology of materials were characterized by scanning electron microscope(SEM),transmission electron microscopy(TEM),infrared spectra(FT-IR)and other advanced analysis method,electrochemical performances including the specific capacity,cycle life and rate capability etc were thoroughly probed using the electrochemical methods of constant current charging-discharging test,cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS).The main work of thesis contains two portions following:1?The purchased tannic acid was selected as the active material for organic electrode,But it may not be able to achieve ideal specific capacity and energy density due to its inherent issues such as poor electrical conductivity,solubility.Concerning this issue,we restrained the dissolution of tannic acid in the organic electrolyte by the substitution of different concentrations of a new lithium salt named lithium bis(trifluoromethylsulfonyl)imide(LiTFSI)for conventional lithium hexafluorophosphate(Li PF6)to form electrolyte,so that the specific capacity,rate capability and cycle life of tannic acid electrode were improved.2?The five-membered ring coordination compounds were prepared by solvothermal synthesis method from folic acid ligand with different metal ions such as Co2+,Ni2+,Fe3+.The coordination compounds acted as the electrode material have robust structure,simple production process,low cost,and crucially,it effectively improved the dissolution of folic acid in the organic electrolyte which resulted in low capacity,bad rate capability,poor cycle performance etc.Therefore good effect was achieved when it was be applied to lithium ion batteries.These results will directly promote attention and understanding to organic carbonyl compound electrode materials,provide the reference value and theoretical support for research and development of other organic electrode materials and electrolyte aspects.Based on it,we will continue to develop more organic electrode materials with broad application prospect and electrolyte to match,apply them to all kinds of new energy storage device.We expect that organic electrode materials can shine brilliantly in the era of new energy and bring more benefits to mankind.