Crystal structure, migration mechanism and electrochemical performance of Cr-stabilized garnet

• It is the first time to demonstrate that chromium has function of stabilizing cubic-structured LLZO garnet by this work.
• The lithium-ion conductivity is 5.2 × 10− 4 S/cm at 27 °C, rising by 2 times compared with pure LLZO.
• The migration mechanism is dependent on the hopping of Li-ion sites. Three possible migration pathways are proposed, in which lithium ions transport via the tetrahedral sites.

Garnet-structured Li7La3Zr2O12 is stabilized through Cr3 + doping at Zr4 + sites. The Rietveld refinement of powder XRD data is used to analyze the crystal structure and Cr site. The migration mechanisms of lithium ions are dependent on the hopping of lithium ions at different sites. Three possible migration pathways are proposed, in which lithium ions transport via the tetrahedral sites. Small doping of Cr3 + at Zr4 + sites leads to high total conductivity of the 0.1 mol Cr-stabilized Li7.1La3Zr1.9Cr0.1O12 to be 5.2 × 10− 4 S cm− 1 at 27 °C. The sample shows a wide electrochemical stability up to 6 V.