Coordination Polymer Derived Porous Carbon Activated in Situ by the ZnCl₂ Dot: Capacitances Greatly Enhanced by...

Herein, a 1D zinc coordination polymer [Zn(bibp)Cl₂]_∞ (CP-2-ZX) was assembled from the reaction of 4,4'-bis(imidazol-1-yl)-biphenyl (bibp) with ZnCl₂. Through a calcination-thermolysis strategy, sponge-like highly porous carbon AC-Zn-CP was prepared by employing the coralloid sample of CP-2-ZX as the precursor. For comparisons, a series of activated carbon (AC-n) was obtained by the similar heating process on the mixture of bibp with ZnCl₂ at different mass ratios. The results illustrate that the atomically dispersed ZnCl₂ dot in the 1D chain of CP-2-ZX has an in situ activation effect on the generation of AC-Zn-CP, which can greatly promote the porosity and achieve high-efficiency utilization of ZnCl₂. Therefore, the atomically dispersed activating agent provides a new method for environmentally friendly production of porous carbon materials. Significantly, the AC-Zn-CP electrode displays specific capacitance of 215 F g^-1 in 3 M KOH solution, which will be largely promoted to 1419 F g^-1 in the redox active electrolyte of K₃[Fe(CN)₆]/KOH. AC-Zn-CP also shows remarkable cycling stability (the capacity retention is 89.0% after 5000 cycles). Moreover, the fabricated symmetric supercapacitor owns a high energy density of 34.8 Wh kg^-1 at 785.5 W kg^-1. So, the AC-Zn-CP∩K₃[Fe(CN)₆] system has wide application prospects in supercapacitors.