Controllable Preparation Of P-Benzoquinone Bridged Conjugated Microporous Polymer And Its Application In Li-Ion Batteries

Conjugated polymers are a class of organic polymers that are composed of covalent bonds and have stable structures.The designability of their structure make them show great application potential as electrode materials for lithium-ion batteries.In order to solve the structural instability and solubility in organic electrolytes of organic quinone-based electrode materials,this thesis innovatively proposed using Diels-Alder reaction to prepare a p-benzoquinone-bridged conjugated microporous polymer(CMP)and a p-benzoquinone-bridged linear conjugated polymer(LCP).The successful preparation of the material was proved by model reaction and a series of structural characterization methods.The stable fused structure and abundant benzoquinone content endow the prepared material with excellent electronic properties.The application of the prepared two polymer materials as cathode materials in lithium-ion batteries was studied.Meanwhile,the electrochemical mechanism and electrochemical reaction kinetics were discussed.This study provides a new synthetic route for the preparation of quinone-enriched conjugated polymers,and provides new insights for understanding the relationship between the electrode microstructure and the performance of lithium batteries.The research content is as follows,(1)The p-benzoquinone bridged conjugated microporous polymer was prepared by Diels-Alder reaction of hexa(bromomethyl)benzene and p-benzoquinone.The theoretical feasibility of the reaction was verified by the model reaction,and the structure of the as-prepared conjugated microporous polymer was characterized by Fourier transform infrared reflectance spectroscopy,solid-state ¹³C nuclear magnetism,and X-ray electron energy spectroscopy.At the same time,the electronic properties of it were evaluated by solid-state ultraviolet,ultraviolet photoelectron spectroscopy,and theoretical calculations.The rate performance and cycle stability performance of the lithium-ion batteries using the as-prepared conjugated microporous polymer as the cathodes were tested.When the current was 1.0 A g^-1,the capacity retention rate after 1500cycles was as high as 94.8%.The results showed that the battery has excellent electrochemical performance.X-ray photoelectron spectroscopy,infrared spectroscopy and other tests on fully charged/discharged electrodes revealed the redox mechanism of the battery.The reaction kinetics of the battery was also discussed by electrochemical methods.(2)A new p-benzoquinone bridged linear conjugated polymer was preparedthroughDiels-Alderreactionof1,2,4,5-tetra(bromomethyl)benzene and p-benzoquinone.The successfully preparation of the polymer was proved by Fourier-transform infrared reflectance spectroscopy,solid-state ¹³C Nnuclear magnetic resonance,X-ray photoelectron spectroscopy,elemental analysis,and other characterization methods.The as-prepared linear conjugated polymer exhibited excellent insolubility in various organic solvents.Therefore,it exhibited excellent cycle performance when used as a lithium-ion battery cathode material.When the current was 1.0 A g^-1,the specific discharge capacity can still reach 59.9 m Ah g^-1 after 2500 cycles.Through the X-ray photoelectron spectroscopy and infrared spectroscopy tests of the electrodes before and after the battery cycle,the composition changes of the electrodes were characterized.The reaction kinetics of the battery was discussed by electrochemical means.