Wenxi Wang, Vinayak S. Kale, Zhen Cao, Sharath Kandambeth, Wenli Zhang, Jun Ming, Prakash T. Parvatkar, Edy Abou-Hamad, Osama Shekhah, Luigi Cavallo, Mohamed Eddaoudi, Husam N. Alshareef
ACS Energy Letters, (2020)
Aqueous zinc-ion batteries and capacitors are potentially competitive grid-scale energy storage devices because of their great features such as safety, environmental friendliness, and low cost. Herein, a completely new phenanthroline covalent organic framework (PA-COF) was synthesized and introduced in zinc-ion supercapatteries (ZISs) for the first time. Our as-synthesized PA-COF shows a high capacity of 247 mAh g–1 at a current density of 0.1 A g–1, with only 0.38% capacity decay per cycle during 10 000 cycles at a current density of 1.0 A g–1. Although covalent organic frameworks (COFs) are attracting great attention in many fields, our PA-COF has been synthesized using a new strategy involving the condensation reaction of hexaketocyclohexanone and 2,3,7,8-phenazinetetramine. Detailed mechanistic investigations, through experimental and theoretical methods, reveal that the phenanthroline functional groups in PA-COF are the active zinc ion storage sites. Furthermore, we provide evidence for the cointercalation of Zn2+ (60%) and H+ (40%) into PA-COF using inductively coupled plasma atomic emission spectroscopy and deuterium solid-state nuclear magnetic resonance (NMR). We believe that this study opens a new avenue for COF material design for zinc-ion storage in aqueous ZISs.