Garnet Li7La3Zr2O12 Solid-State Electrolyte: Environmental Corrosion, Countermeasures and Applications

Abstract

Garnet-based Li7La3Zr2O12 (LLZO), as a popular solid-state electrolyte, is easily corroded by wet air, leading to failure of mechanical strength, Li-ion conductivity, and wettability. In this work, corrosion behaviors of garnet electrolyte in the air (carbon dioxide, water vapor, CO2+H2O mixed air, actual moist air) and solution (distilled water, NaCl solution, natural seawater) are investigated, and it is determined that the electrolyte has the worst corrosion resistance to water. Prohibition of direct contact between vapor/liquid water and garnet is the basic design standard. We report a straightforward physical deposition methodology to achieve the growth of a poly (vinylidene fluoride) (PVDF) nano-hydrophobic layer on garnet. Grain (Rg) and grain boundary (Rgb) resistances of the electrolyte with PVDF coating are increased by only 14% and 170% at room temperature for 50 hours during a relative humidity of 80%, respectively, which are significantly lower than 930% and 2240% of the unmodified sample. The modified electrolyte presents the original morphology even after being immersed in solution at 353 K for 15 days. Excellent chemical corrosion resistance makes as-prepared garnet have great potential applications in all-solid-state, air-based, and water-based batteries.