Thermal Cyclodebromination of Polybromopyrroles to Polymer with High Performance for Supercapacitor

Abstract

A strategy has been designed for synthesizing a new type of polymer with hierarchical architecture and crystalline CNx (x ≤ 0.25) domains through deep thermal cyclodebromination of polybromopyrroles. The crystalline CNx domain is determined to be a curving sp2-hybridized CNx network cross-linked by the sp3-hybridized N–C bond on the basis of sample characterization and theoretical calculations. N atoms in the CNx network are confirmed to be negatively charged by theoretical calculations, facilitating electrosorption of electrolyte cations. The polymer obtained at the condensation temperature of 500 °C is featured with high tap density, a high degree of graphitization, and a microporous characteristic, exhibiting nearly stable volumetric capacitance (143 and 101 F cm–3) and specific surface capacitance (1.94 and 1.37 mF cm–2) when cycled in 1 mol L–1 KCl at a current density of 1 and 0.5 A g–1 for 2000 cycles with three- and two-electrode systems, respectively.