Analysed current trends in development of garnet-type structured Li7La3Zr2O12-based oxides as solid electrolytes for next-generation all-solid-state lithium batteries.

No abstract

An economical and simple technique to mitigate the solid electrolyte–lithium metal anode interfacial charge transfer resistance.

Interest toward developing all-solid-state batteries incorporating lithium-stuffed garnet electrolytes (LSGEs) has been on the constant rise. However, LSGEs are known to react with humidity, and subsequently, CO 2 during preparation or storage, leading to Li 2 CO 3 formation. In this study, we report the long-term exposure effects of CO 2 and humidity on the lithium-ion conductivity of typical garnettype Li 7 La 2.75 Ca 0.25 Zr 1.75 Nb 0.25 O 12 with and without Al 2 O 3 deposited by atomic layer deposition (ALD). The ionic conductivity of the samples was investigated by electrochemical impedance spectroscopy as a function of time for up to 1000 h. The impedance spectra of ALD-coated garnet-type Li 7 La 2.75 Ca 0.25 Zr 1.75 Nb 0.25 O 12 sample was unaffected by long-term exposure to 400 ppm up to pure CO 2 while the uncoated garnet-type sample show at least 8% increase in total resistance. Both samples show increased resistance in the presence of humidity, but the resistance recovers upon removal of the humidity.

Ni; y = 0.1, 0.2, referred to as yM-LLCZNO) were synthesized in air by ceramic synthesis at different sintering temperatures. The resulting compositions were characterized for their phase formation and microstructure, and their ionic and electronic conductivities in air and 7% H 2 /N 2 . Powder X-ray diffraction showed that transition metal-doped LLCZNO garnets contain several impurity phases. The transition metal-substituted samples have lower conductivities than that of the parent LLCZNO. The electronic conductivities of selected transition metal-doped LLCZNO samples were found to be about 4 to 5 orders of magnitude lower than their corresponding ionic conductivity, highlighting the challenge to design single-phase mixed electronic and ionic conducting Li-stuffed garnets in both oxidizing and reducing atmospheres. The research area of single-phase mixed conducting Li-garnet is relatively unexplored at the moment, and a theoretical study will help to elucidate the underlying challenge in doping transition metal in Li-based garnets structure and its effect on transport properties.