Liquid‐free all‐solid‐state Zn batteries and encapsulation‐free flexible batteries enabled by in‐situ constructed polymer electrolyte

Zn batteries are usually considered as safe aqueous system promising for flexible batteries. On the other hand, any liquids, including water, being encapsulated in a deformable battery may result in potential troubles. Developing completely liquid-free all-solid-state Zn batteries needs high-quality solid-state electrolytes (SSEs). Here, we demonstrate the in-situ polymerized amorphous solid poly(1,3-dioxolane) electrolytes, which shows high Zn ion conductivity of 19.6 mS ×cm -1 at room temperature, low interfacial impedance, highly reversible Zn plating/stripping over 1800 h cycles, uniform & dendrite-free Zn deposition, and non-dry properties. The in-plane interdigital-structure device with electrolyte completely exposed to open atmosphere can be stably operated for over 30 days almost without weight loss and electrochemical performance decay. Furthermore, the sandwich-structure device can normally operate over 40 min under fire condition. Meanwhile, the interfacial impedance and the capacity using in-situ-formed SPEs retain almost unchanged after various bending tests, a key criterion for flexible/wearable devices. Our study demonstrates an approach for SSEs that fulfill the requirement of no liquid and mechanical robustness for practical solid-state Zn batteries.