Hybrid Ceramic-Gel Polymer Electrolyte with a 3D Cross-Linked Polymer Network for Lithium–Oxygen Batteries

Electrolyte plays a crucial role in constructing the ionic transport paths and oxygen diffusion routes along with maintaining the interfacial stability based on the open working environment of lithium–oxygen batteries. Herein, on the basis of a succinonitrile-based gel polymer electrolyte prepared by in situ thermal-cross-linking ethoxylate trimethylolpropane triacrylate monomer, the SLFE-5%LAGP formed by further adding Li1+xAlxGe2–x(PO4)3 (LAGP) has high ionic conductivity at room temperature (3.71 mS cm–1 at 25 °C), high lithium-ion transference number (tLi+ = 0.644), and excellent long-term stability of the Li/SLFE-5%LAGP/Li symmetric cell at a current density of 0.1 mA cm–2 for over 600 h. More importantly, LAGP can provide adsorption sites for oxygen molecules on its surface followed by the reduction of oxygen and the formation of Li2O2. Consequently, the cell equipped with the SLFE-5%LAGP has an ultrahigh discharge capacity (5652.8 mAh g–1) that exceeds the liquid electrolyte system and achieves an ultralong stable cycling of 52 cycles. This work deepens the understanding of the solid-state lithium–oxygen batteries through the integrated design of electrolytes and electrodes to realize the superior solid–solid contact interface and achieve stable long-term cycling processes.