Recent development on low temperature synthesis of cubic-phase LLZO electrolyte particles for application in all-solid-state batteries

Oxide-based solid-state electrolytes (SSEs) are a group of compound materials consisting of lithium and oxygen along with various other metal/non-metal elements forming particular crystalline, amorphous and glassy structures. Recently, significant research interest has been given to develop garnet-type oxide SSEs considering excellent ionic conductivity of the cubic-phase, suitability as a separator and better thermal stability among other oxide electrolytes. In this review, we discuss on the recent progress in synthesis of cubic-phase Li7La3Zr2O12 (LLZO) SSEs ultrafine particles, particularly on the low temperature synthesis processes of submicron particles and nanoparticles with cubic-phase crystal structure. The synthesis of cubic-phase LLZO particles with incorporation of particular dopant cations has been explored by the solid phase reactions, solution process techniques, such as, sol-gel and fuel combustion techniques and molten-salt methods. In this context, the present challenges and future scopes of synthesizing ultrafine cubic-phase LLZO particles are discussed in details to achieve high relative density pellet formation with excellent ionic conductivity. This review provides a detail discussion for understanding on various synthesis methods to obtain ultrafine cubic-phase LLZO particles toward application in all-solid-state batteries (ASSBs).