Investigation of the lithium plating triggering criterion in graphite electrodes

Abstract

Lithium plating is considered an undesirable side reaction because it can induce capacity fading and pose safety concerns in Li-ion batteries. The timely detection of lithium plating onset is crucial for both mechanistic investigations and ensuring the safe and durable operation of batteries. In this study, discharging tests were conducted by varying the set capacity in graphite/Li cells to induce lithium plating on the graphite electrode. Based on a comprehensive analysis of the voltage curves and the morphological characterization of disassembled cells, the inflection point on the differential voltage curve during the discharging process was identified as the precise onset time of lithium plating. Electrochemical models were developed to further elucidate the mechanisms governing the onset of lithium plating. Compared with the model based on the potential criterion, the model employing the concentration criterion demonstrated enhanced precision in predicting lithium plating, particularly under high C rates. Based on the model with the concentration criterion, the discharging protocol was optimized parametrically to achieve high discharging efficiency and restrain lithium plating. This nuanced understanding contributes to determining the onset of lithium plating more accurately, thereby facilitating a more robust battery design and durable yet fast charging protocols.