Redox-active phthalocyanine-based frameworks produced by pyrolysis: Promising electrode materials for low-cost potassium batteries

In this manuscript, we present a scalable approach to the design of advanced organic redox-active materials by pyrolysis of simple low molecular weight precursors. A cascade of condensation reactions occurring under pyrolysis of 3,6-dihydroxyphthalodinitrile produced a covalent organic framework with phthalocyanine units. Spectroscopic characterization supported by DFT calculations revealed that the obtained material has a porous membrane-like structure, which is favorable for ionic transport. The potassium batteries using the designed organic redox-active material as a working electrode delivered a specific discharge capacity of ∼100 mAh g⁻¹ at the high current density of 1 A g⁻¹ with the average discharge potential of ∼3 V. These characteristics, in combination with the simple synthesis, pave the way to the practical implementation of the designed material in ultrafast, scalable and low-cost stationary batteries, which are urgently needed for electric grids operating with any considerable contribution from renewable energy sources due to their high variability. The proposed material design concept deserves further exploration and might lead to a big family of redox-active organic frameworks with superior electrochemical characteristics.