A novel coral-like garnet for high-performance PEO-based all solid-state batteries

As one of the most promising next-generation energy storage devices, the lithium-metal battery has been extensively investigated. However, safety issues and undesired lithium dendrite growth hinder its development. The application of solid-state electrolytes has attracted increasing attention as they can solve safety issues and show great potential to inhibit the growth of lithium dendrites. Polyethylene oxide (PEO)-based electrolytes are very promising due to their enhanced safety and excellent flexibility. However, they suffer from low ionic conductivity at room temperature and cannot effectively inhibit lithium dendrites at high temperatures due to the intrinsic semicrystalline properties and poor mechanical strength. In this work, a novel coral-like Li_6.25Al_0.25La₃Zr₂-O₁₂ (C-LALZO) is synthesized to serve as an active ceramic filler in PEO. The PEO with LALZO coral (PLC) exhibits increased ionic conductivity and mechanical strength, which leads to uniform deposition/stripping of lithium metal. The Li symmetric cells with PLC do not cause a short circuit after cycling for 1500 h at 60°C. The assembled LiFePO₄/PLC/Li batteries display excellent cycling stability at both 60 and 50°C. This work reveals that the electrochemical properties of the composite electrolyte can be effectively improved by tuning the microstructure of the filler, such as the C-LALZO architecture. [Figure not available: see fulltext.]