Recent developments in garnet based solid state electrolytes for thin film batteries

•Recent advances in solid state electrolytes for lithium ion batteries are reviewed.•A novel laser annealing process of synthesizing cubic Li7La3Zr2O12 is discussed.•Cubic Li7La3Zr2O12 exhibits a very high Li ion conductivity of 1.0 × 10−4 S/cm.

This paper reviews the current status of, and new progress in, the field of solid state electrolytes (SSE) for lithium ion batteries. In addition to a review of current technologies, we are also presenting our novel results on pulsed laser processing of garnet based SSEs, specifically Li7La3Zr2O12 (LLZO). LLZO powders with a tetragonal structure were prepared by a sol–gel technique, then a pulsed laser annealing process was employed to covert the powders to cubic LLZO without any loss of lithium. The tetragonal LLZO exhibited a Li ion conductivity of 1.8 × 10−7 S/cm, whereas the laser annealed cubic LLZO showed a Li ion conductivity of 1.0×10−4 S/cm at room temperature. A systematic study of the effect of pulsed laser annealing (PLA) on the crystal structure, morphology, composition, and ionic conductivity of LLZO was performed via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS) measurements. These results demonstrate that PLA is a powerful processing technique for synthesizing the high ionic conductivity cubic phase of LLZO at relatively low temperatures, as compared to conventional methods.

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