Enhancing Electrochemical Characteristics of Li-Metal Electrodes: The Impact of Pre-Treatment via CO₂ Gas Reaction

초록

Regulation of the surface film characteristics of Li-metal is a pivotal strategy for augmenting the electrochemical performance of Li-metal batteries. This investigation elucidates a straightforward approach to surface film modification, namely, pre-treatment via a CO2 gas reaction, and its subsequent impact on the electrochemical attributes of Li-metal electrodes. Analysis of the topography and composition of the Li metal surfaces revealed the transformation of the surface film into a more uniform layer enriched with inorganic compounds, including Li2CO3 and Li2O, by pre-treatment. This pre-treatment process significantly enhances the electrochemical properties, such as cyclability and overpotential, in Li/Li symmetric cells, primarily because of the formation of an improved solid-electrolyte interphase (SEI) derived from the altered surface film on Li metal electrodes. The reformed SEI significantly increases the mobility of Li ions through the interphase, thereby attenuating the impedance associated with Li-ion migration within the SEI. This resistance attenuation is instrumental in alleviating the overpotentials, thereby significantly refining the electrochemical plating and stripping dynamics of Li metal electrodes.

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