Search for: All records

Abstract With the aid of neutron diffraction and electrochemical impedance spectroscopy, we have demonstrated the effect of the increase in lithium concentration and distribution on Li‐ion conductivity. This has been done through the synthesis of a layered oxide Li₂(La_0.75Li_0.25)(Ta_1.5Ti_0.5)O₇, with the so‐called Ruddlesden‐Popper type structure, where bilayer stacks of (Ta/Ti)O₆octahedra are separated by lithium ions, located in inter‐stack spaces. There are also intra‐stack spaces that are occupied by a mixture of La and Li, as confirmed by neutron diffraction. The distribution of lithium over both inter‐ and intra‐stack positions leads to the enhancement of Li‐ion conductivity in Li₂(La_0.75Li_0.25)(Ta_1.5Ti_0.5)O₇compared to Li₂La(TaTi)O₇, which has a lower concentration of lithium ions, located only in inter‐stack spaces. The analyses of real and imaginary components of electrochemical impedance data confirm the enhanced mobility of ions in Li₂(La_0.75Li_0.25)(Ta_1.5Ti_0.5)O₇. While the Li‐ion conductivity needs further improvement for practical applications, the success of the strategy implemented in this work offers a useful methodology for the design of layered ionic conductors.