Electrochemical oscillation triggered by the doped Mn ions in spinel Li₄Ti₅O₁₂

Phase-transition kinetics is an important concern in the wide application of Li-ion batteries, while its in-depth understanding is still limited by the complexity of real electrode systems. As a derivative phenomenon, electrochemical oscillation is closely coupled with the underlying phase-transition kinetics, providing a direct and sensitive probe to track kinetic variations. Herein, a valence-engineering strategy is presented to modulate the phase-transition kinetics of Mn-doped Li₄Ti₅O₁₂ (LMTO), which can be directly manifested through the characteristic evolution of electrochemical oscillation behaviour. Actually, LMTO-Ar (sintering under Ar) exhibits enhanced oscillatory amplitude during de-lithiation, whereas LMTO-O₂ (sintering under O₂) triggers oscillation at the onset of lithiation, which can be interpreted using the split overpotentials of nucleation and phase transition, owing to the high overpotential of the nucleation step and the hysteresis of the phase-transition step in LMTO. Additionally, the electrochemical oscillation is quantitatively reproduced with a million-particle electrode through tailoring the nucleation and phase-transition kinetics. Therefore, this investigation provides profound insights into the origin of electrochemical oscillation and establishes a generalizable kinetics-oscillation correlation framework for advancing the rational design of phase-transition electrode materials.