Preparation Of Nitrogen-containing Organic Porous Polymers And Their Application In Secondary Batteries

Lithium-ion batteries（LIBs）occupy most of the current energy storage markets with the clear advantages of high energy density and long cycle life.Aqueous zinc-ion batteries（AZIBs）are of great interest because of their inherent safety,low cost,eco-friendliness,and resource renewability.However,the boom in electrochemical energy storage has also raised concerns about the widespread use of inorganic electrode materials.In contrast,organic compounds have gained considerable interest because of their ability to have a customizable structure,precise molecular design,affordability,and eco-friendliness.Nitrogen-containing porous polymers are regarded as excellent electrode materials because of their highly efficient nitrogen active sites and large insoluble frameworks,making them an ideal choice among other materials.A series of nitrogen-containing organic porous polymers were prepared through a simple polymerization reaction in this thesis,and their electrochemical properties as electrode materials for secondary batteries were explored.The main research content is as follows:（1）A high surface area and nitrogen-rich covalent triazine framework（TCNQ-CTF）was synthesized by the dynamic trimerization reaction of 7,7,8,8-tetracyanoquinodimethane（TCNQ）under ionothermal conditions.As the positive electrode material,TCNQ-CTF was assembled into a lithium-ion half-cell that exhibited a large reversible capacity(159 m Ah g^-1 at 50 m A g^-1)and long cycle life(still providing a reversible capacity of 67.5 m Ah g^-1after 2000 cycles at 1 A g^-1).Subsequently,it was used as a negative electrode material for LIBs,showing high initial discharge specific capacity(1609 m Ah g^-1 at 50 m A g^-1)and higher rate capacity(321.2 m Ah g^-1 at 2 A g^-1).Based on this,a symmetric all-organic battery was constructed,demonstrating its feasibility for practical applications（2）A covalent triazine framework（BDMI-CTF）with high nitrogen content,large surface area,and large conjugated structure was synthesized by an ionothermal reaction using 1,3-bis（dicyanomethylidene）indane（BDMI）as precursor.When used as a positive electrode material for LIBs,it showed higher initial capacity(186.5 m Ah g^-1 at 50 m A g^-1)and excellent long-term cycling performance(the capacity retention rate was close to 100%after 2000 cycles at 1 A g^-1).In addition,when used as a negative electrode material for LIBs,BDMI-CTF also showed higher initial discharge specific capacity(2073.3 m Ah g^-1 at50 m A g^-1)and long cycling life(still reversible capacity of 337.5 mAh g^-1 after 1000cycles at 1 A g^-1).Based on this,it was tested as both positive/negative electrode materials for all-organic symmetric batteries to prove the feasibility of its practical application.（3）The imine polymer poly（1,5-naphthalenediamine）（p NAPD）was synthesized by simple chemical oxidative polymerization of 1,5-naphthalenediamine（1,5-NAPD）monomer in an acidic aqueous solution,and the composite（p NAPD@CNT）was constructed by adding carbon nanotubes to the reaction process.Among them,the imine structure in the polymer can be used as an active site for redox reactions,and the introduction of carbon nanotubes leads to a significant improvement in electrochemical performance.When used as a positive electrode material in AZIBs,p NAPD@CNT exhibits high reversible capacity(215 m Ah g^-1 at 50 m A g^-1),and remarkable cycling stability(85.1%capacity retention after 1000 cycles at 1 A g^-1).