Unveiling the Mechanism of Mn Dissolution Through a Dynamic Cathode‐Electrolyte Interphase on LiMn2O4

Advanced Energy Materials, EarlyView.

Feb 15, 2025 - 10:22
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Unveiling the Mechanism of Mn Dissolution Through a Dynamic Cathode-Electrolyte Interphase on LiMn2O4

This study uncovers the formation and dissolution of Mn3O4 on LiMn2O4 (LMO) surfaces during cycling, linking it to potential-dependent electrolyte decomposition and the evolution of the cathode-electrolyte interphase (CEI). The results emphasize the critical roles of electrolyte stability and cathode surface structure in CEI degradation and Mn dissolution, providing key insights into the dynamic interphase chemistry on cathode materials.

Abstract

Understanding the formation and evolution of the cathode-electrolyte interphase (CEI), which forms at the interface between the cathode and electrolyte, is crucial for revealing degradation mechanisms in cathode materials, especially for developing strategies to stabilize the interphase in the strongly oxidizing conditions that evolve at high operating voltages in next-generation Li-ion batteries. However, The present understanding of the CEI is challenged by its complex and dynamic nature. In this work, near-edge X-ray absorption fine structure spectroscopy, electrochemical characterization, and reactive molecular dynamics simulations are combined to reveal a mechanism for CEI formation and evolution above model LiMn2O4 (LMO) thin-film electrodes in contact with conventional carbonate-based electrolytes. It is found that Mn dissolution from LMO can be understood in terms of repetitive Mn3O4 formation and dissolution behavior during cycling, which is closely connected to electrolyte decomposition and a key aspect of the CEI formation and growth. The behavior of the CEI in this model system offers detailed insight into the dynamic chemistry of the interphase, underscoring the important role of electrolyte composition and cathode surface structure in interphase degradation.