“Water-in-montmorillonite” quasi-solid electrolyte for ultra-low self-discharge aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) face challenges including zinc dendrites, parasitic reactions, and self-discharge, limiting their practical application. While quasi-solid-state electrolytes (QSSEs) are promising solutions, existing QSSEs often suffer from high cost, low conductivity, or inadequate self-discharge suppression. This study introduces a novel “water-in-montmorillonite” (WiME) electrolyte to address these limitations. WiME leverages the layered structure of inexpensive montmorillonite (Mont) to confine water, achieving a high ionic conductivity of 64.82 mS/cm alongside remarkable self-discharge suppression, maintaining 92.7% capacity retention after 720 hours. WiME architecture facilitates uniform Zn deposition, promoting cycling stability at high utilization. WiME-based symmetric cells show excellent long-term cycling, surpassing 1900 hours. Full Zn||MnOOH cells display stable cycling for 500 cycles without capacity decay, demonstrating the synergy between mitigated parasitic reactions, homogenous zinc deposition, and enhanced interfacial stability enabled by WiME. These findings present a low-cost, high-performance strategy for advancing the practicality of AZIBs for various applications.