Distinct lithium plating mechanisms in lithium-ion batteries under alternating current operation

초록

Lithium-ion batteries (LIBs) suffer from performance degradation and safety risks caused by lithium plating during operation, which poses a significant challenge to the widespread adoption of electric vehicles (EVs). Among the various causes of lithium plating, overpotential arising from the formation of ion concentration gradients within the cell has been identified as a dominant factor. To address this issue, this study introduces an approach that compares the conventional direct current with an alternating current (AC) method, which can potentially be implemented for internal heating or fast charging applications. The AC application reduces internal concentration gradients through charge-discharge alternating cycles, thereby extending the boundary conditions before lithium plating onset. The resultant yield surfaces across different states of charge (SOCs), frequencies, and temperatures are presented and experimentally validated by electrochemical impedance spectroscopy and scanning electron microscopy analysis. This study establishes the fundamentals of lithium plating behavior under AC operation and how AC can broaden the safe operating range of LIBs while improving their thermal and electrochemical stability.

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