In-situ Formed All-amorphous Poly (ethylene oxide)-based Electrolytes Enabling Solid-state Zn Electrochemistry

Abstract The revival of rechargeable zinc (Zn)-ion batteries was overshadowed by the deep-seated issues of dendrite growth and intricate side-reactions in routine aqueous electrolytes. Poly (ethylene oxide) (PEO)-based solid-state polymer electrolytes (SPEs) are potentially promising to address these issues, but the valid Zn2+ conduction and proper Zn electrochemistry have been difficult of accomplishment due to the high-degree crystallization of PEO and its interfacial incompatibility with stiff Zn metal. Herein, we bypass these obstacles by the in-situ polymerization of the stark but hand-picked monomer, poly(ethylene glycol) methyl ether acrylate, characterized by the long side-chains with pendant ethylene oxide units, to construct the all-amorphous Zn2+ SPEs for the first time. The long side-chains favor the formation of amorphous matrix while the in-situ process endows compatible electrolyte/electrode interfaces, thus leading to a high ambient ionic conductivity (2.87 × 10−5 S cm−1) as well as low interfacial resistances. The demonstration of this SPE in solid state Zn/Zn symmetrical cells and rechargeable Zn/Mo6S8 cells with long life-spans signifies the highly reversible and dendrite-free Zn electrochemistry. Our results lay groundwork not only for Zn but for other multivalent-metal batteries suffering from poor bulk and interfacial ion transport to construct the rechargeable all-solid-state batteries.