Application of three-electrode technology in Li4Ti5O12 electrochemical oscillation system

Abstract

Studying the kinetics of electrochemical oscillation by using the in-situ EIS spectra in a three-electrode coin cell. • Three-electrode coin cells with reference electrodes of lithium are designed and assembled. • The kinetics of electrochemical oscillation in a three-electrode cells are studied by in-suit electrochemical impedance spectroscopy. • The reaction process of electrochemical oscillation are further confirmed with experimental data. The electrochemical oscillation of Li-ion batteries is a novel electrochemical phenomenon, which has been discovered in two-phase materials of Li 4 Ti 5 O 12 and LiCrTiO 4 . 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 Li 4 Ti 5 O 12 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 Li 4 Ti 5 O 12 materials without electrochemical oscillation, the Li-deficient Li 4 Ti 5 O 12 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transformed into the capacitive impedance in the EIS spectra, indicating that the intraparticle phase separation had been replaced by the interparticle phase separation.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.