Zinc Monofluorophosphate: a New Zinc‐Ion Conductor for Constructing Solid Electrolytes and In‐Situ Modifying Zinc Metal Electrodes

Abstract Aqueous zinc‐ion batteries (AZIBs) are increasingly recognized as a sustainable and cost‐effective energy storage option, but challenges of zinc dendrite formation, parasitic reactions, and corrosion limit their practical use. In this work, zinc monofluorophosphate (ZPOF) is first introduced to modify zinc‐based batteries. The ZPOF exhibits a large ionic conductivity of 3.8 mS cm −1 , facilitating efficient Zn 2+ ‐ion transport and reducing Zn 2+ ‐ion buildup at the zinc/electrolyte interface. Besides, ZPOF's exceptional zincophilic characteristic promotes uniform zinc deposition. The ZPOF‐based solid electrolyte membrane enables AZIB to offer a capacity of 322.2 mAh g −1 at 0.2 A g −1 and operate stably for over 500 h at 1 A g −1 . The ZPOF can also be in situ generated on the zinc surface to form a robust and conformal coating layer, which can prominently enhance electrolyte affinity, corrosion resistance, and electrochemical kinetics, while facilitating the desolvation process and restraining Zn 2+ ion planar diffusion. As a result, the Zn//Zn symmetric cell achieves stable cycling for over 550 h under substantial capacity of 25 mAh cm −2 and large depth‐of‐discharge of 85.4%. Furthermore, the performance of various full‐cell configurations is dramatically improved. This study underscores the potential of ZPOF as a novel Zn 2+ ‐ion conductor for advancing the performance of zinc‐based batteries.