Application of three-electrode technology in Li4Ti5O12 electrochemical oscillation system

The electrochemical oscillation of Li-ion batteries is a novel electrochemical phenomenon, which has been discovered in two-phase materials of Li4Ti5O12 and LiCrTiO4. To analyze the electrochemical oscillation in this work, a three-electrode coin cell was designed and assembled with a specialized reference electrode, based on the conventional two-electrode coin cell. In the three-electrode coin cell, a Li-deficient Li4Ti5O12 material exhibits a distinct electrochemical oscillation during the galvanostatic charge process, and its electrochemical kinetics was studied by in-situ electrochemical impedance spectroscopy (EIS). Compared with two other Li4Ti5O12 materials without electrochemical oscillation, the Li-deficient Li4Ti5O12 material had an evidently larger resistance of the SEI layer (R-sei) and charge transfer resistance (R-ct) in the EIS spectra. When the electrochemical oscillation emerged, the Warburg impedance (W-s) dramatically transformed into the capacitive impedance in the EIS spectra, indicating that the intraparticle phase separation had been replaced by the interparticle phase separation. This study further confirmed the reaction process of electrochemical oscillation proposed in our previous work, so as to finally reveal the underlying mechanism of this novel phenomenon.

Automated summary

This article describes the electrochemical oscillation phenomenon of Li-ion batteries and its impact on the electrochemical kinetics of materials. Through the study of a three-electrode coin cell and in-situ electrochemical impedance spectroscopy, it was found that a Li-deficient Li4Ti5O12 material exhibited distinct electrochemical oscillation during the charge process, compared with two other materials without oscillation. This study further confirmed the reaction process of electrochemical oscillation and revealed its underlying mechanism.