Electrochemical Performances on Both poly(Phenylenediamine) Derivatives as Anode of Lithium-Ion Batteries

In the present work, both poly(phenylenediamine) derivatives of poly(o-phenylenediamine) (PoPD) and poly(m-phenylenediamine) (PmPD) were prepared by in situ chemical oxidation method, and the their chemical characteristics and electrochemical performances were explored in detail. Under the same polymerization conditions, two poly(phenylenediamine) derivatives exhibited the different morphology, conjugated structure, and thermal stability, which was attributed to the different chemical structure of phenazine and polyaniline-like units in polymer backbone. As explored as the anode of lithium ion batteries, the PmPD, compared to the PoPD, demonstrated the remarkably improved electrochemical performances with superior high capacity, good rate capability and cyclic performance. Specially, PmPD presented the gradually increased specific capacity with cyclic process, and after the 46th cycle the developed discharge capacity reached to 973.6 mAh g(-1), which was evidently higher than 447.2 mAh g(-1) of PoPD. Its stable and representative discharge specific capacities were 477.1, 436.6, 468.7 and 374.4 mAh.g(-1) at the current rate of 50, 100, 200, and 500 mAh g(-1), respectively, which were superior to that of PoPD. The improved electrochemical performances can be attributed to the improved conjugated structure and the open morphology for PmPD, which benefited to the charge migration and the utilization of the electrochemical active material during the charge/discharge process. (C) 2019 The Electrochemical Society.