Ceramic-Based Flexible Sheet Electrolyte for Li Batteries

The increasing demand for high-energy-density batteries stimulated the revival of research interest in Li-metal batteries. The garnet-type ceramic Li7La3Zr2O12 (LLZO) is one of the few solid-state fast-ion conductors that are stable against Li metal. However, the densification of LLZO powders usually requires high sintering temperatures (e.g., 1200 degrees C), which likely result in Li loss and various side reactions. From an engineering point of view, high-temperature sintering of thin LLZO electrolytes (brittle) at a large scale is difficult. Moreover, the high interfacial resistance between the solid LLZO electrolytes and electrodes is a notorious problem. Here, we report a practical synthesis of a flexible composite Al-doped LLZO (Al-LLZO) sheet electrolyte (75 mu m in thickness), which can be mass-produced at room temperature. This ceramic-based flexible sheet electrolyte enables Li-metal batteries to operate at both 60 and 30 degrees C, demonstrating its potential application for developing practical Li-metal batteries.