Achievable fast charge transfer by tuning reasonable solid-electrolyte interphase structures

Abstract

The structure of solid electrolyte interphase (SEI) and electrode dynamics of lithium metal anode are very crucial to improve its performance. In this study, artificial SEIs with different structures are constructed, and the corresponding kinetic evolution of the lithium plating/stripping process is decoupled by in situ electrochemical impedance spectroscopy (ISEIS) in association with the distribution of relaxation time. The results show that although lithiophilic aluminum simple substance introduced by simple immersion improves the nucleation kinetics of lithium, large electrochemical polarization resulting from the sluggish charge transfer at the end of lithium plating/stripping aggravates the growth of dendrite lithium and further accelerates the failure of lithium anode. Subsequently, the issue is solved well by the key annealing of the obtained electrodes. The facile annealing not only promotes the formation of highly crystalline Al₄Li₉ but also welds isolated Al₄Li₉ to form an orderly conductive network. The elaborate SEI structure homogenizes the electric field on the electrode surface, which improves the charge transfer during lithium plating/stripping and thus stabilizes the lithium anode. Our study reveals the potential relationship among SEI structure, electrode kinetics, and electrochemical performance of lithium anodes and sheds new light on the design and kinetic characterization of lithium anode interface.