Low-Temperature Manufacture of Cubic-Phase Li7La3Zr2O12 Electrolyte for All-Solid-State Batteries by Bed Powder

As the demand for battery technology with enhanced safety and high energy density increases, solid-state batteries are currently attracting attention as a solution to problems such as fire and explosion risks associated with lithium-ion batteries. In this study, experiments were conducted to synthesize and optimize Li7La3Zr2O12 (LLZO), a solid electrolyte that is a key component of lithium-ion batteries with stability and high energy density. Experimental results showed that sintering at a low temperature of 800 °C for 8 h was the optimal synthesis and sintering time. Additionally, the excess lithium-containing bed powder enabled the production of pure cubic-phase LLZO. Through a sintering process that creates a lithium atmosphere on the bottom surface and facilitates lithium replenishment, an additional tunnel was introduced between the specimen and the alumina powder, allowing the bottom surface of the specimen to be exposed to the lithium atmosphere. By manufacturing a uniform cubic electrolyte, the path to manufacturing all-solid-state batteries was opened. These findings provide a new approach to forming cubic-phase LLZO with much higher ionic conductivity than the tetragonal phase at low sintering temperatures.