A Cross-Linked Triphenylamine-Based Polymer Cathode Material With Dual Anion-Cation Reversible Insertion For Lithium Ion Battery

A cross-linked triphenylamine polymer poly[N,N'-bis(4-diphenylaminophenyl) naphthalene-1,4,5,8-tetracarboxylic diimide] cathode material with dual anion-cation reversible insertion is polymerized from monomer N,N'-bis(4-diphenylaminophenyl) naphthalene-1,4,5,8-tetracarboxylic diimide by chemical oxidative polymerization, which has a very low solubility in common organic solvents and electrolytes. The triphenylamine unit in the polymer can reversibly dope/dedope the PF6- anion, while the naphthalimide unit can reversibly insert/extract the lithium cation. The lithium ion half-cells with the polymer as a cathode and the lithium foil as an anode are assembled and the electrochemical properties are tested. For comparison, the electrochemical properties of monomer are studied. Thanks to its cross-linked network structure, the electrochemical performance of polymer is much better than that of its monomer. The polymer has excellent cycle performance, the initial discharge specific capacity is 140 mAh g(-1), which is close to its theoretical specific capacity, and the capacity can still be maintained at 125 mAh g(-1) after 100 cycles, suggesting that this polymer is a potential cathode material for lithium ion batteries. (C) 2019 The Electrochemical Society.