Enhanced performance of solid-state lithium-air batteries with continuous 3D garnet network added composite polymer electrolyte

Lithium air batteries (LABs) highly desire stable and dense solid-state electrolytes (SSEs) instead of liquid organic electrolytes for suppressing lithium dendrite penetration, resisting attack from active oxygen species, and blocking the diffusion of CO2, moisture as well as O2 in air to the anode side. Herein, we report the preparation and application of composite polymer electrolytes (CPEs) based on a three-dimensional and interconnected Li7La3Zr2O12 (LLZO) garnet network in polyethylene oxide matrix (denoted as 3D-CPE) for LABs. The 3D-CPE achieves high electrochemical stability and ionic conductivity at room temperature, surpassing the conventional CPEs prepared by LLZO particles (denoted as C-CPE). The uniform macro-porous structure in LLZO network is conducive to accommodating PEO polymers and suppressing polymer crystallization. Furthermore, the integrated structure of 3D LLZO network can contribute the lithium ion conduction through LLZO bulk phases and along the continuous interfaces between PEO matrix and LLZO fillers. The solid-state LAB using 3D-CPE delivers high efficiency of discharge and charge performance under 300 mA h g−1 capacity for 50 cycles in ambient air at room temperature. In contrast, the LAB with C-CPE only gives 23 cycles with rapid voltage attenuation under the same conditions. [Display omitted] •3D LLZO-based CPE shows higher conductivity than conventional CPE.•3D-CPE possesses high thermal and electrochemical stability.•LABs with 3D-CPE achieves good cycle performance.•3D-CPE can effectively protect lithium metal anodes.•3D-CPE maintains its morphology and structure after cycling.