Aqueous Zn-Tetrazine Batteries with Cooperative Zn²⁺/H⁺ Insertion

We present the investigation of 1,2,4,5-tetrazine derivatives as low-cost and synthetically modular organic electrode materials in rechargeable aqueous Zn-ion batteries (AZIBs). The substituents at the 3,6-positions of tetrazine were found to be critical for cycling stability. While heteroatom substituents (chloro, methoxy, and pyrazole) lead to the rapid decomposition of electrode materials in the electrolyte, the installation of phenyl groups enhances the cycling stability via π-π stacking. Spectroscopic characterization suggests a cooperative Zn²⁺ and H⁺ insertion mechanism. This unique cooperativity of Zn²⁺ and H⁺ leads to a steady discharge plateau in contrast to the undesirable sloping voltage profile typically observed in Zn-organic batteries.