Abstract
Quasi-solid-state electrolytes are one of the most promising alternative candidates for traditional liquid state electrolytes with a fast ion transport rate, high mechanical strength and wide temperature adaptation. Here, we have designed a biomimicking electrolyte film with a Janus-faced honeycomb-like structure and applied it to sodium ion batteries. The advanced quasi-solid-state sodium ion batteries show an initial coulombic efficiency of 105% and stable charge-discharge cycles over a wide temperature range from -20 °C to 60 °C. Additionally, operando observations of the chemical structure and interfacial evolution have been carried out, demonstrating a robust and stable quasi-solid-state electrolyte film.