Preparation And Properties Of Conjugated Carbonyl Polymers As Electrode Materials For Lithium Ion Batteries

Organic electrode materials have become the most alternative candidates for sustainable and green lithium-ion batteries?LIBs?due to their high theorical capacity,abundant resources and non-pollution.Among them,organic conjugated carbonyl compounds have been emerged as the most hopeful organic electrode materials because of their structure diversity,redox stability,multielectron reactions and fast reaction kinetics.However,most organic conjugated carbonyl compounds show high dissolution and poor electronic conductivity in organic electrolytes,which may restrict their further application.In this paper,a serises of conjugated carbonyl polymers are obtained and their electrochemcial performance are studied as LIBs electrode materials.Main contents and results are listed below:?1?A novel conjugated microporous polymer with abundant carbonyl groups?PT-BTA?has been successfully synthesized by Suzuki coupling reaction based on pyrene-4,5,9,10-tetraone?PT?and their extended conjugated structure and increased molecular weight can solve the solubility problem.When applied as cathode materials for LIBs,PT-BTA could deliver a discharge capacity of 156.6 mAh g^-1at 50 mA g^-1and a discharge capacity of 60.0 mA g^-1at 1000 mAh g^-1after 1000 cycles.?2?A series of conjugated carbonyl polymers have been successfully synthesized by the coupling polymerization and then a flexible,binder-free,and free-standing carbonyl-conjugated polymer/carbon nanotube hybrid films?PPTC/PPQC?has been constructed by a vacuum-filtration method.Due to the extended conjugated structure and no introduction of inactive moieties,PPTC exhibited a high capacity and redox potential.Furthermore,the incorporation of CNTs endowed the hybrid films with a flexible feature,which could be served as a flexible,binder-free,and free-standing organic cathode for LIBs.PPTC could deliver a high reversible discharge capacity of 142.3 mAh g^-1at 50 mA g^-1,good cycling stability with a capacity retention of 74.6% at 500 mA g^-1after 300 cycles.?3?A self-polymerized nitro-substituted conjugated carbonyl compound?2,7-dianitropyrene-4,5,9,10-tetraone,PT-2NO₂?has been synthesized for the first time,whose nitro could be irreversibly reduced into azo liked conjugated carbonyl polymer during the electrochemical reaction.The reaction mechanism is proved by detailed characterizations and theorical calculations.Furthermore,the feature of self-polymerization can effectively avoid the reduce of theorical capacity,then both carbonyl and azo groups can be served as active sites during the electrochemical reaction to deliver high capacity.When applied as cathode for LIBs,PT-2NO₂ shows a high reversible capacity of 153.9 mAh g^-1.?4?A novel Cu tetraaminophthalocyanine bridged naphthalenetetracarboxylic anhydride?NTCDA?polymer?CuPcNA-CMP?has been synthesized by Schiff base reaction,which shows extended conjugated structure and excellent chemical stability.Furthermore,phthalocyanine and carbonyl groups in CuPcNA-CMP all show the excellent electrochemical activity.When applied as a cathode material for LIBs,CuPcNA-CMP could deliver high capacity of 133.6 mAh g^-1at 0.2 A g^-1after 100 cycles.When used as an anode material for LIBs,CuPcNA-CMP could deliver 429.7 mAh g^-1at 1 A g^-1after 1000 cycles and a reversible capacity of 171.8 mAh g^-1even at 10 A g^-1.Interestingly,the symmetrical LIBs assembled using CuPcNA-CMP as both cathode and anode materials can also deliver excellent performance.The discharge capacity of 118.8 and 75.2 mAh g^-1and at 0.1 and 5 A g^-1,respectively.