Exchange current densities at Li | Li7La3Zr2O12 interface

Abstract

Solid electrolyte Li₇La₃Zr₂O₁₂ was synthesized by a citrate-nitrate technique. Single-phase of the synthesized compound was established by X-ray diffraction method. The pellets of Li₇La₃Zr₂O₁₂ were hydrostatic pressed at 500 MPa and annealed at 1180°C for 1 h. Absence of through porosity in the obtained samples was confirmed by a kerosene technique at room temperature. Symmetrical electrochemical cell with reversible lithium electrodes was assembled to determine the current exchange densities at Li | Li₇La₃Zr₂O₁₂ interface. Polarization curves were obtained by the linear potential sweep for the studied cell. The form of the obtained curves is close to the Tafel form. So, it was concluded that a rate-determining step in the system Li | Li₇La₃Zr₂O₁₂ | Li refers to the process of lithium transfer at the interface. From the obtained polarization curves exchange current densities was calculated. The exchange current densities reach values of 30 mA/cm² at temperatures above 400°C. The obtained values of the current densities are sufficient for practical application of Li₇La₃Zr₂O₁₂ as solid electrolyte in primary and secondary lithium current sources.