Conducting Polymers With Electro-Active Couples Functional Materails For Lithium Ion Batteries:Preparation And Properties

In this work, pyrrole and aniline were modified by introducing of two kinds of redox-active couples electro-active group (triphenylamine and ferrocene). A series of novel pyrrole and/or aniline derivatives were synthesized, including pyrrole-ferrocene (FcPy), pyrrole-triphenylamine derivative (DPTPA), and aniline-ferrocene derivative (FcAn). The corresponding homopolymers and copolymers (PFcPy, P(FcPy-co-Py), PDPTPA, P(An-co-FcAn)) of these pyrrole and aniline derivatives were prepared by chemical oxidative polymerization. The electrochemical properties and charge/discharge performance of the as-prepared Li-ion battery cathode materials have been studied.Both of the homopolymer and copolymer of pyrrole-ferrocene derivatives electrodes displayed a high discharge capacity. At20mA·g-1, PFcPy and P(FcPy-co-Py) electrodes delivered a high discharge capacity of43.2mAh·g-1and68.1mAh·g-1in the first cycle and expressed varying degree voltage plateau at the voltage of about3.5V, and could still remain 89.5%and72.0%of the initial capacities after50cycles, respectively. Moreover, PFcPy and P(FcPy-co-Py) electrodes still exhibited their flat voltage plateau after50cycles. These excellent electrochemical performances were ascribed to the improved charge carrier transportation, unique microstructure and the stable redox-active couples of the ferrocene modified polypyrrole derivatives.The poly[pyrrole-triphenylamine] derivatives electrodes showed a even higher discharge capacity, compared to that of PTPAn electrode. At20mA·g-1, PDPTPA electrodes delivered high discharge capacity of113.1mAh·g-1in the first cycle. The improved capacity of polymers could be ascribed to the in contrast higher capacity of triphenylamine itself and improvement of polymer particles microstructure, which enhanced the utilization of active material. Moreover, PDPTPA electrodes exhibited perfect rate capability. These electrodes retained over76.5%of the initial capacity and displayed flat voltage plateau with a ten times increase in the current from50to500mA·g-1.Copolymer of aniline-ferrocene derivative P(An-co-FcAn) electrode had a high discharge capacity of107.7mAh·g-1at20mA·g-1and, exhibited an unobvious voltage plateau at the voltage of3.5V. In addition, this electrode maintained about61%of initial capacity and the voltage plateau still exist after50cycles. These high battery performances could be attributed to change of chain structure of the polymer and improvement of particles microstructure after the introduction of ferrocene couple.