Interaction between formation protocol and electrolyte composition during solid-electrolyte interphase formation: A model-supported investigation

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The formation process affects lithium-ion battery (LIB) performance, safety, and lifetime, yet its optimization remains challenging due to complex material–process interactions. This study investigates the interplay between electrolyte composition and formation protocol using four carbonate-based electrolytes and two protocols in three-electrode cells during formation. Differential voltage analysis (DVA), incremental capacity analysis (ICA), and electrochemical impedance spectroscopy (EIS) reveal electrolyte- and protocol-specific differences in solid-electrolyte interphase (SEI) growth, interfacial kinetics, energy-, and active material loss. The DVA-derived SEI growth curves show electrolyte-dependent responses to the two formation protocols that qualitatively align with the electrolyte’s solubility of SEI constituents, supporting an initial SEI growth via a near-shore aggregation mechanism. Furthermore, the SEI growth curves are utilized to parameterize a mechanistic SEI growth model. The model captures cell-specific capacity losses during formation and ten subsequent cycles, enabling quantitative assessment of transport limitations and interpretation of protocol- and electrolyte-induced differences. Overall, this work contributes to the understanding of electrolyte–protocol interactions and demonstrates a practical strategy to parameterize mechanistic SEI growth models.