Sustainable organic quinone-based polymers exhibit numerous promising advantages in cathode application, and suitable structure design is important to improve their electrochemical performances. In this work, a designed organic material structure of redox units linked by auxiliary coordination chains poly(quinone-thiourea) is achieved and used as a cathode for aqueous zinc ion batteries. The cell displays improved electrochemical performances with a maximum discharge specific capacity of 211 mA h g −1 at 0.02 A g −1 and long cycle performance of 83% capacity retention after 1000 cycles under 0.1 A g −1 (118 mA h g −1 initial discharge capacity). The Zn 2+ storage mechanism through the ex situ XPS investigations proves that the oxygen atoms of phenol and the sulfur and nitrogen atoms of the thiourea group all contribute to the Zn 2+ intercalation, which stabilizes the Zn 2+ coordination and improve the specific capacity. The ex situ FT-IR also supports the redox of quinone carbonyl and the coordination of the thiourea group with Zn 2+ . Furtherly, the thiourea groups acting as auxiliary coordination sites can alleviate the zinc deposition on the cathode surface and improve the redox reversibility and long cycle performance. Such a structural design is expected to be a promising strategy for developing high-performance organic cathode materials for multivalent ion batteries.

Even though electrochromism has been around for more than 50 years, it still has several issues. Multi-layered films, high manufacturing costs, and a short lifetime are present in existing electrochromic devices. We demonstrate a unique high-performance device with a basic structure and no solid electrochromic sheets in this work. In this device, the electrolyte layer is also avoided. The device uses an electrochromic solution prepared from a mixture of ammonium metatungstate and iron (II) chloride solution as a functional layer with reversible redox properties. The tungstate ions on the electrode surface are reduced when the device is colored, and the Fe2+ on the electrode surface is oxidized on another electrode surface. The generated Fe3+ in the mixed functional layer oxidizes the previously reduced tungstate ions as the device fades. We determined the ΔT (transmittance modulation) and response time among ammonium metatungstate ratios, iron (II) chloride ratios, and driven current density using DOE (design of experiment) trials. Using 0.175 mol/L ammonium metatungstate and 0.30 mol/L iron (II) chloride, a device with outstanding ΔT (more than 57% at 700 nm), a short response time (less than 10 s), and high coloring efficiency (160.04 cm2/C at 700 nm) is demonstrated.

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