Pyrazine-based compounds with Zn2+/H+ co-insertion mechanism for aqueous zinc ion batteries with high rate and excellent low-temperature performance.

Developing highly efficient and durable cathode materials is one of the key challenges to achieving high-performance aqueous zinc-ion batteries (AZIBs). Herein, two new imine compounds, Phenanthrenequinone-phenazine (PQNZ) and Diphenazinepyrene-tetraone (PTONZ) were successfully synthesized via a one-step condensation reaction, and used as cathodes for AZIBs. The findings indicate that PTONZ demonstrates markedly enhanced electrochemical characteristics relative to PQNZ. PTONZ delivers a specific capacity of 356.0 mA h g-1 at 0.05 A g-1 and maintains a capacity of 131.3 mA h g-1 even at 25 A g-1. Further investigation into the charge storage mechanism using various ex-situ characterization techniques combined with DFT theoretical calculations have unveiled that during the discharge process, both H+ and Zn2+ are actively involved in the intercalation and deintercalation within the PTONZ cathode material. Moreover, at -20 °C, the PTONZ half-cell owns a capacity retention 86.6% after 4500 cycles at 1 A g-1. This study not only provides an effective molecular engineering strategy for creating high-performance organic cathode materials but also offers a new perspective for understanding the charge storage behavior of AZIBs.