Numerous endeavors have been dedicated to the development of composite polymer electrolyte (CPE) membranes for all-solid-state batteries (SSBs). However, insufficient ionic conductivity and mechanical properties still pose great challenges in practical applications. In this study, a flexible composite electrolyte membrane (FCPE) with fast ion transport channels was prepared using a phase conversion process combined with in situ polymerization. The polyvinylidene fluoride-hexafluoro propylene (PVDF-HFP) polymer matrix incorporated with lithium lanthanum zirconate (LLZTO) formed a 3D net-like structure, and the in situ polymerized polyvinyl ethylene carbonate (PVEC) enhanced the interface connection. This 3D network, with multiple rapid pathways for Li⁺ that effectively control Li⁺ flux, led to uniform lithium deposition. Moreover, the symmetrical lithium cells that used FCPE exhibited high stability after 1200 h of cycling at 0.1 mA cm⁻². Specifically, all-solid-state lithium batteries coupled with LiFePO₄ cathodes can stably cycle for over 100 cycles at room temperature with high Coulombic efficiencies. Furthermore, after 100 cycles, the infrared spectrum shows that the structure of FCPE remains stable. This work demonstrates a novel insight for designing a flexible composite electrolyte for highly safe SSBs.

The nitrogen doped carbon (NC) encapsulating metal particles (metal/NC) are promising low-cost bifunctional oxygen electrocatalysts for rechargeable Zn-air batteries. However, the states of the art catalytic performance are still significantly restricted by the limited content of active sites for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, a series of NC encapsulating CoNi samples as a bifunctional catalyst for both ORR and OER were synthesized via a simple pyrolysis method. Large surface area and high content M–N _x active sites promote the ORR activity and accelerate the surface reconstruction layer for high OER performance. The NC encapsulating CoNi with optimized Co/Ni ratio (2:1) shows high ORR activity with a half-wave of potential (0.85 V) and a low overpotential of 309 mV for OER. Rechargeable Zn-air battery assembled by an air cathode with the NC encapsulating CoNi exhibits a power density of 143 mW cm⁻² and good cyclability over 100 h at 10 mA cm⁻². This mechanism work provides a feasible strategy for developing high activity and low cost bifunctional oxygen electrocatalysts.