Lithium Distribution in Aluminum-Free Cubic Li7La3Zr2O12

摘要

Limitation of the flammable organic liquid-carbonate electrolytes of the Li-ion battery have stimulated interest in Li~+-ion solid electrolytes having a conductivity σ_(li) > 10~(-4)S cm~(-1) that are stable on contact with a lithium anode on one side and with water of variable pH on the other side. The "stuffed" Li garnets are promising candidates. The garnet structure A3B3C_2O_(12) contains a B3C2O12 framework structure of B cations in 8-co-ordination sites and C cations in octahedral sites. The framework contains a 3D-connected interstitial space consisting of the tetrahedral 24d-A sites bridged by a single octahedron sharing on opposite sides a common face with each of the two neighboring 24d-A sites. The existence of only face-sharing sites, 3 tetrahedral A and 6 bridging octahedral sites for a total of 9 sites per formula unit, can provide a low activation energy for motion of guest Li~+ ions if the Li~+ ions are disordered with partial occupancies of both sites.