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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