Evaluating the feasibility and air stability of high-entropy doping in garnet electrolytes

High-entropy electrolytes have attracted extensive attention for their potential to overcome the limits of traditional materials. However, confirming the accurate synthesis of a single-phase high-entropy electrolyte remains a challenge. Herein, we develop a quinary garnet electrolyte of cubic phase with high resistance to air corrosion. By employing a straightforward method that analyzes the variations of diffraction peak intensity, we can evaluate the feasibility of high-entropy doping, the degree of cubic phase, and the extent of H⁺/Li⁺ exchange. Meanwhile, ambient pressure X-ray photoelectron spectroscopy is utilized to investigate the degradation of garnet electrolyte by H₂O, with the failure mechanism further elucidated by nuclear magnetic resonance analysis. On this basis, the high-entropy garnet electrolyte demonstrated increased cubic phase content and better air stability, compared with traditional counterpart. Consequently, a higher current critical density is achieved, facilitating the integration of commercial cathodes with high area capacities into the quasi-solid-state batteries. Our findings provide an effective method for synthesizing and evaluating high entropy electrolytes.