Hybrid Solid Electrolyte Composed of Lithium Aluminum Germanium Phosphate and Poly(ethylene oxide) for All Solid-State Lithium Batteries

Lithium-ion batteries have rapidly become the dominant power sources for portable electronic devices and electric vehicles, due to their high energy density and long cycle life [1,2].However, safety issues still prevent full utilization of these batteries owing to the use of flammable liquid electrolytes, and safety problems have become a significant concern especially in large capacity applications such as electric vehicles and energy storage systems. In this respect, fabrication of all solid-state lithium batteries by using solid electrolytes may give a fundamental solution for the safety issue of lithium batteries [3,4]. Glass ceramic electrolytes present potential advantages, such as absence of electrolyte leakage, large electrochemical stability window, absence of problems relating to vaporization of organic solvents and high thermal stability.  However, sheet manufacturing, especially using thin-film technologies for making large-scale batteries, is considered to be difficult because of hard and brittle ceramic materials.  In this work, solvent-free hybrid solid electrolytes composed of lithium aluminum germanium phosphate and poly(ethylene oxide) (PEO) were prepared in the form of flexible film, and their electrochemical characteristics were investigated. Their morphological properties were examined using SEM, EDS and XRD. The ionic conductivities and electrochemical stability of hybrid solid electrolytes were much higher than those of PEO-based polymer electrolyte. The optimized hybrid solid electrolyte was applied to the solid-state Li/LiFePO₄ cell, and its electrochemical performance was evaluated.

References

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4. Y.Li, J.B.Goodenough, Electrochem. Commun., 13, 1289 (2011).