Overcoming Obstacles in Zn‐Ion Batteries Development: Application of Conductive Redox‐Active Polypyrrole/Tiron Anolyte Interphase

Abstract This study is focused on overcoming obstacles in the implementation of metallic Zn for zinc‐ion batteries. The major limiting factors of Zn anodes include dendrite growth, hydrogen evolution, and by‐product formation. Herein, the challenges are addressed by the application of a redox‐active electrode‐electrolyte interphase. Cationic polypyrrole(PPy)/anionic Tiron anolyte is formulated as the mixed conducting interphase to push the limits of zinc‐based energy storage. The doping/de‐doping behavior of PPy stimulates the surface adsorption/desorption of Tiron attributed to the ion‐induced nucleation. Testing results show that PPy as a passivating corrosive‐resistant layer improves the interfacial stability of Zn metal; while releasing the redox‐active anolyte boosts the charge transfer of cells by the phenol‐quinone transformations. The Zn//Zn cells demonstrate an improved life from 50 to 2500 cycles with a reduced overpotential at 2 mA cm −2 and 1 mAh cm −2 . In situ UV–vis spectroscopic measurements, combined with density functional theory calculations, address the redox mechanisms of PPy/Tiron anolyte. The testing of α‐MnO 2 //Zn cells shows that the PPy/Tiron anolyte exhibits enhanced capacity and rate performance due to the pseudocapacitive effects. This study unveils a conceptually new approach based on the modification of conducting polymer with redox‐active dopants toward the fabrication of high‐performance Zn‐anolyte batteries.