Study On The Morphology Control Of Super-crosslinked Microporous Polymers And The Electrochemical Properties Of Their Derivatives

Hypercrosslinked microporous polymers(HCP),as an important class of organic porous materials,it has a good physicochemical stability,rich pore structure,high specific surface area,wide range of monomer sources,low cost,and mild reaction conditions,which make HCPs become a new type of organic porous material with great research value.The idea of synthesis of HCPs is mainly based on Friedel-Crafts chemistry,using its high crosslinking degree to prevent the flexible polymer chain contraction and "hole" between the polymer chain.Compared with other organic microporous polymers,HCPs have lower synthesis costs and can achieve large-scale production.In the research field of HCPs.there are still few researches on the morphology of HCPs.In general,there are two main ways to construct HCPs morphology,one is template method.the other is self template method.Overall,the template method to construct the polymer morphology can be extended to a certain extent.but the synthesis process is complex,the template removal is time-consuming,and it needs to consider the impact of template and other factors that limit the need for large-scale production of industrial production requirements.However,for the existing self-template method.a narrow range of monomers for its morphology control,a complex monomer structure,and the reaction condition that does not have applicability.Therefore,several tubular HCPs and its derivatives were synthesized and we studied its electrochemical properties:1.We first chose pyrene,pyridine and triphenylamine as the reaction monomers,successfully passed the "low concentration" of simple,low cost.no template.no additives and mild reaction conditions realizes the control of the morphology of the HCPs based on pyrene,pyrrole and triphenylamine.Through the morphological characterization techniques,it was proved that the polymer grown mainly by "low concentration polymerization" is a one-dimensional hollow tubular nanostructure.Among them,the specific surface area of tubular HCPs constructed with triphenylamine as a monomer is 870 m2·g-1.Through the one-step carbonization of a tubular HCPs constructed with triphenylamine as a monomer,we obtained nitrogen-doped porous carbon nanotubes(N-PCNT).We studied the electrochemical performance of N-PCNTs.The rate performance indicates that the first-cycle discharge specific capacity of N-PCNTs is 859 mAh g-1 at a current density of 100 mA g-1,and there is still 203 mAh g-1 at a high current density of 1000 mA g-1.This shows that at high current densities,the material structure remains stable.This laid the foundation for the later research.2.In order to solve the problem that the conductivity of MnO is poor and the volume expansion and crystal structure collapse will occur during the long term charge and discharge process,which leads to the rapid attenuation of the capacity of lithium ion batteries.A kind of MnO/Nitrogen-doped porous carbon nanotubes(MnO/N-PCNTs)was successfully synthesized by one-step thermolysis Mn(CHCOO)2 adsorbed hyper-crosslinked polymers nanotubes.The MnO/N-PCNTs nano-composite show good performance(high reversible specific capacity of 512 mAh g-1 after 250 discharge/charge cycles at 500 mA g-1)as andoe materials for lithium-ion batteries.3.In order to solve the utilization of sulfur is not high because of its poor conductivity,and during the charge and discharge of the lithium-sulfur battery,the formed lithium sulfide will be further dissolved,resulting in poor cycling performance of the battery.A kind of HCP/S material was successfully synthesized by one-step melting sulfur and uniform spherical HCPs based on triphenyl borate.The electrochemical performance test of HCP/S composites shows that the structure of HCP/S remains stable after continuous charge and discharge.The initial capacity of HCP/S-43%is the highest,and the discharge capacity in the first cycle is 1067 mAh g-1,while the other two high-sulfur HCP/S have lower capacity in the first cycle.In general,the recycling of composite materials is not very well.The best performance of the HCP/S-43%is only 426 mAh-1 g after 50 cycles.However,because of the diversity of the structure design and synthesis methods of the HCP/S,we believe that we can design a more suitable HCPs to fix sulfur and prepare the cathode material for the lithium sulfur battery with more stable cycling performance.