Preparation And Electrochemical Properties Of Polytriphenylamine Derivatives

In this paper,a series of triphenylamine derivative functional monomers and organic polymers containing triphenylamine structural units were prepared and the novel electrochemically active polymers were prepared by copolymerizing between dopants and other functional monomers.The electrochemical and battery properties of polymers as electrode materials for lithium batteries were investigated.The polymer mainly contains:?1?The composite material?PPy-Li-TCPA₂?was prepared by doping polypyrrole with triphenylamine derivative organic acid and then its electrochemical and battery properties were studied.?2?Preparation of polyimide polymer containing triphenylamine unit and then its electrochemical and battery performance were studied.?3?A novel quinone-amine polymer?PAQ?was prepared containing triphenylamine structural units and then its electrochemical and battery properties were studied.The specific research contents are as follows:Tri-?4-cyanophenyl?amine and tris-?4-carboxyphenyl?amine monomers were successfully prepared by redox method.composite electrode materials were prepared with different molar ratios?Li-TCPA₂:pyrrole?by using lithiated tris-?4-carboxyphenyl?amine?Li-TCPA₂?as dopant.The composite materials are PPy-Li-TCPA₂?6:1?,PPy-Li-TCPA₂?4:1?and PPy-Li-TCPA₂?2:1?,respectively.The results show that polypyrrole is large particle packing morphology,and the doping of triphenylamine structural unit makes the composite uniform particle distribution and the particle diameter is smaller.The PPy-Li-TCPA₂?4:1?particle diameter was 100nm,but the composite exhibited a bulk distribution when Li-TCPA₂ was excessively added.At the same time,compared with polypyrrole,the composite?PPy-Li-TCPA₂?itself has a larger pore volume and a specific surface area of 68.58 m²·g^-1.Battery test studies have shown that PPy-Li-TCPA₂ has a higher specific capacity after doping polypyrrole.In particular,PPy-Li-TCPA₂?4:1?exhibited a higher discharge specific capacity(91.1 mAh·g^-1)at constant current charge and discharge rate of 30 mA/g.Moreover,PPy-Li-TCPA₂?4:1?has more excellent cycle rate,and the discharge specific capacity can reach 80.1 mAh·g^-1 even at a high rate of 500 mA/g.At the same time,the specific capacity loss is only 9.5%.Electrochemical AC impedance studies show that PPy-Li-TCPA₂?4:1?has a good charge transport capability.The excellent electrochemical performance of PPy-Li-TCPA₂?4:1?is mainly attributed to the fact that the composite material PPy-Li-TCPA₂?4:1?has its own uniform distribution of particle morphology and the Increasing in specific surface area for providing a large contact area between electrolyte and electrode materials.Tris-?4-aminophenyl?amine monomers were prepared.Two different structures of polyimide electrode materials?N1 and N2?were prepared by the functional monomers with pyromellitic dianhydride?PMDA?and naphthalene tetracarboxylic dianhydride?NDTA?,respectively.From the test results,it can be concluded that the N1 and N2 polyimide materials are high temperature resistant materials containing five-membered ring and six-membered ring structural units,respectively.This indicates that the polyimide polymer has been successfully prepared.The N1 material is a loose particle deposited topography.The N2 polymer material is a bulk deposition morphology which affects the electrochemical properties of the polymer.Electrochemical and battery performance studies have shown that as a negative electrode for lithium batteries,both N1 and N2 materials have distinct two pairs of voltage platforms,which correspond to electron gains and losses of carbonyl groups in the five/six-membered ring,respectively.At the same time,at 30 mA/g constant current charge and discharge rate,the specific discharge capacity of N1 polymer electrode material increased to 434.1 mAh·g^-1 after 50 laps.This is due to the process of progressive activation of the electrode active material during charge and discharge.Moreover,N1 has more excellent rate cycling.Even at a high rate of 500 mA/g,the specific discharge capacity of N1 is still increasing,eventually reaching 412.2mAh·g^-1.The impedance test results show that the N1 electrode material exhibits more excellent ion mobilitycompared to the N2 polymer,which is consistent with its high battery performance.Two different structures of the quinone-amine polymer electrode materials?PAQ1 and PAQ2?were prepared by using the michael addition reaction of tris-?4-aminophenyl?amine and p-phenylenediamine monomer with p-benzoquinone monomer,respectively.From the test results,it can be concluded that the electrode materials PAQ1 and PAQ2 polymers all contain benzene ring and carbonyl group and C-N structural unit.It is indicated that the quinone-amine polymerr has been successfully prepared.The PAQ1 polymer material is uniformly distributed particle morphology,while the PAQ2 polymer material is a blocky morphology.Electrochemical tests show that PAQ1 has distinct voltage platform of 3.912V and3.184V,corresponding to the double electron gain and loss of the carbonyl group.The voltage platform of PAQ2 is 3.754V and 2.915V,which also corresponds to the double electron gain and loss of carbonyl.At constant current charge and discharge rate of 30 mA/g,the PAQ1 polymer electrode material has a hgher discharge specific capacity than PAQ2.At the same time,the discharge specific capacities of PAQ1 and PAQ2 were 449.2mAh·g^-1 and 124.6mAh·g^-1,respectively.The specific discharge capacities of PAQ1 and PAQ2 were 88.1mAh·g^-11 and 66.9mAh·g^-1,respectively.At the same time,high-rate charge-discharge performance studies showed that the specific discharge capacity of PAQ1 and PAQ2 polymer electrode materials were47.6 mAh·g^-1 and 31.9 mAh·g^-1 at the high rate of 500 mAh·g^-1.At the same time,the active electrode material has a remarkable capacity recovery capability.This is consistent with the high electrochemical activity of the prepared novel materials and the open structural morphology.