Polyphosphazene Based Inorganic‐Organic Hybrid Cathode Containing Pyrene Tetraone Sides for Aqueous Zinc‐Ion Batteries

Abstract Aqueous rechargeable zinc‐ion batteries (ARZBs) are intriguing for electrochemical energy storage applications because of their safety and cost‐effectiveness. Regarding cathode materials, rapid development has been observed with the organic‐based cathode materials that offer much higher structural integrity upon successive (de‐)insertion of charge carries ions. Even though promising results demonstrated with organic electrodes, they still suffer from the short cycle‐life due to their discharge products solubility in electrolyte. Herein, electrochemical performance and charge storage mechanism of the synthesized polyphosphazene‐based inorganic‐organic hybrid electrode containing pyrene‐4,5,9,10‐tetraone (PTO) redox active lateral group, poly[(bis(2‐amino‐4,5,9,10‐pyrenetetraone)], abbreviated as (PPAPT), were investigated in ARZBs. The charge storage mechanism of PPAPT was examined by various ex‐situ [Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy and energy dispersive X‐ray spectroscopy (SEM‐EDS), X‐ray photoelectron spectroscopy (XPS)] and in‐situ [pH change with bromocresol green indicator and electrochemical quartz crystal microbalance (EQCM)] characterization techniques as well as computational density functional theory (DFT) revealing that the PPAPT electrode (de‐)coordinates both zinc and proton. The electrode and its discharge product are insoluble in the electrolyte demonstrated by UV‐vis analysis and exhibited a stable cycling performance with a discharge capacity of 125.4 mAh g −1 after 1000 cycles at a current density of 10 C.