Rechargeable lithium-ion batteries (LIBs) are one of the dominant technologies for electrochemical energy storage. They are widely used in portable electronics, electrical vehicles, and large-scale energy storage systems. Current LIBs use organic polymer based electrolytes and they have several problems such as dendrite formation, flammability and leakage.¹ Therefore, there is much attention on developing a solid-state Li-ion electrolyte that is thermally and chemically stable. Among the various inorganic solid Li-ion conducting electrolytes, garnet structured compounds have shown great promise as potential electrolytes for all-solid-state lithium batteries due to their high ionic conductivities (10^-4 S/cm), compatibility with Li metal anode, and wide electrochemical window (~ 6V vs Li/Li⁺).² The present study reports a comparison of the experimental and theoretical data of garnet type Li-ion solid electrolytes. The solid electrolytes, Li_6.5La_2.9A_0.1Ta_0.6Zr_1.4O₁₂ (A = Ca, Sr, Ba) were prepared by conventional solid state sintering and spark plasma sintering method. The formation of the ‘‘single-phase’’ garnet-type structure was analysed by powder X-ray diffraction (PXRD). Li-ion conductivity was determined using electrochemical impedance spectroscopy (EIS) and all the members have exhibited ionic conductivity in the order of 10⁴ S/cm at 25 °C. Interfacial resistance of the garnet samples and Li metal was measured using EIS and the interfacial stability of the same was confirmed by DC galvanostatic cycling experiments. Li-ion conductivity and activation energy of the prepared compounds were also calculated using a statistical mechanical approach and the estimated values are in good agreement with the experimental values.

References

1. S. Chen, K. Wen, J. Fan, Y. Bando and D. Golberg, J. Mater. Chem. A, 2018, 6, 11631–11663.

2. R. Murugan, V. Thangadurai and W. Weppner, Angew. Chem. Int. Ed., 2007, 46, 7778–7781.