An electrochemical approach galvanostatic intermittent titration technique-electrochemical impedance spectroscopy-distribution of relaxation times is developed, combined with X-ray photoelectron spectroscopy and transmission electron microscope analysis, to investigate the negative electrode surface solid electrolyte interphases (SEI). The relationship between SEI structure, growth/dissolution behavior, and electrochemical performance is established.

The growth and dissolution of solid electrolyte interphases (SEI) on the surfaces of Cu, graphite, T-Nb₂O₅, Co₃O₄, and T-Nb₂O₅/Co₃O₄ as anodes during lithiation/delithiation is systematically investigated using galvanostatic intermittent titration technique-electrochemical impedance spectroscopy-distribution of relaxation times in conjunction with X-ray photoelectron spectroscopy and transmission electron microscope analysis. Whilst traditional SEI analyzes are based on compositional layering and mosaic models, in this article, the growth and ablation behavior of SEI is analyzed in terms of the lithiation potential to distinguish between apparent and effective SEIs, and the SEI undergoes apparent SEI formation, effective SEI flourishing, and SEI reconstruction. The hidden dynamic characteristics of SEI are elucidated, and the effects of interfacial charge transfer and SEI reactions are decoupled. Active materials are used to regulate the concentration polarization to effectively control the competitive reactions involved in SEI formation, considerably increasing the initial Coulombic efficiency (CE) of T-Nb₂O₅ from 35.52% to 75.77% and increasing the stability of the CE. These findings provide a foundational strategy for the targeted control of the SEI reactions by adjusting the rate of SEI formation, enabling the design of high-performance SEI that improve the electrode properties. The insights gained will help advance next-generation batteries.