3D Porous Garnet/Gel Polymer Hybrid Electrolyte for Safe Solid-State Li–O2 Batteries with Long Lifetimes

Li–O2 battery is a promising rechargeable battery candidate due to its ultrahigh theoretical energy density. However, safety issues and poor cycling stability of Li–O2 batteries caused by the formation of Li dendrites and the use of organic liquid electrolytes inhibit their practical applications. Here, we propose a hybrid solid electrolyte composed of three-dimensional (3D) porous garnet microstructure (PSSE) infused with gel polymer electrolyte (GPE) (PSSE/GPE) to enhance the safety and cycling stability of Li–O2 batteries. In this hybrid solid electrolyte, the 3D garnet microstructure serves as a rigid backbone to suppress Li dendrites, while the consecutive GPE in PSSE serves as an ionic highway, ensuring a high ionic conductivity (1.06 × 10–3 S cm–1) in the bulk. Besides, the hybrid electrolyte offers the ability to block O2 crossover and maintain good compatibility with Li metal anode and advanced air electrode. As a result, the cycle life of Li symmetric cell is dramatically improved almost 60 times (6000 h, 250 days) by replacing GPE with PSSE/GPE. The Li–O2 battery based on PSSE/GPE shows a long cycle life of 194 cycles with a high cycling capacity of 1250 mA h g–1. The present study demonstrates a novel class of hybrid solid electrolyte for high-performance solid-state Li–O2 batteries.