Design and synthesis of п-conjugated aromatic heterocyclic materials with dual active sites and ultra-high rate performance for aqueous zinc-organic batteries.

1,4,5,8-naphthalene tetracarboxylic acid dianhydride-2,3-diamino phenothiazine (NTDP) with multiple active sites (6 with C N and 2 with C O) and synthesized as cathode for aqueous zinc ion batteries using solid-phase method. DFT verified that NTDP has the smallest energy gap (ΔE), the lowest LUMO levels (against monomers) and multiple active sites, therefore it exhibited excellent specific capacity (307.5 mA h/g under 0.05 A/g), ultra-high rate performance (194.9 mA h/g under 20 A/g) and impressive stability (190.0 mA h/g for 9000 cycles with a capacity retention of 91.2% at 15 A/g). Several characterizations reveal that the mechanism of NTDP is the reversible redox reactions of Zn2+ based on the dual active centers (C O and C N). This work will provide chances for organic electrodes with reasonable molecular structure design for use of batteries. [Display omitted] • NTDP with multiple active sites (6 with C N, 2 with C O) was designed for AZIBs. • DFT verified that NTDP had the smallest energy gap (ΔE) and multiple active sites. • NTDP showed excellent ultra-high rate performance and long cycle life. • NTDP could store 4 zinc ions and transport 8 electrons from mechanism analysis. • The NTDP//Zn flexible battery successfully powered fan and lit a bulb. Acid anhydride cathode materials garner considerable interest for aqueous zinc ion batteries (AZIBs) due to ideal specific capacity and structural diversity, however, serious solubility leads to capacity degradation. Herein, 1,4,5,8-naphthalene tetracarboxylic acid dianhydride − 2,3-diamino phenothiazine (NTDP) featuring multiple active sites (6 with C N and 2 with C O) and large π-conjugated backbone, was designed and synthesized utilizing solid-phase method. The smallest energy gap (ΔE) and the lowest LUMO levels (against monomers) induced by multiple active sites and п-conjugated backbone with high aromaticity, NTDP exhibited excellent specific capacity (307.5 mA h g−1 under 0.05 A/g), ultrahigh rate performance (194.9 mA h g−1 under 20 A/g) and impressive cycling stability (190.0 mA h g−1 over 9000 cycles with a capacity retention of 91.2 % at 15 A/g). The reversible Zn2+ insertion/removal mechanism on multiple active centers (C O and C N) was proposed through XPS, FT-IR, and Raman. The specific capacity of the NTDP//zinc flexible cell was 112.6 mA h g−1 at 3 A/g under various folding angles (45°, 90°, 135°, and 180° bends), suggesting its practical potential for flexible devices. This work will offer opportunities for the rational design of battery structures. [ABSTRACT FROM AUTHOR]