In-situ Characterizations of the Dynamics of Cathode Electrolyte Interfaces at Different Current Densities

LiNi0.8Mn0.1Co0.1O2 with high nickel content plays a critical role in enabling lithium metal batteries (LMBs) to achieve high specific energy density, making it a prominent choice for electric vehicles (EVs). However, ensuring the long-term cycling stability of the cathode electrolyte interfaces (CEIs), particularly at fast-charge conditions, remains an unsolved challenge. The decay mechanism associated with CEIs and electrolyte in LMB at high current densities is still not fully understood. To address this issues, in-situ Fourier transform infrared (FTIR) is employed to observe the dynamic process of formation/disappearance/regeneration of CEIs during charge and discharge cycles. These dynamic processes further exacerbate the instability of CEIs as current density increases, leading to rupture and dissolution of CEIs and subsequent deterioration in battery performance because of continuous electrolyte reactions. Additionally, the dynamic changes occurring within individual components of CEIs at different cycling stages and various current densities are also discussed. The results demonstrate that excellent capacity retention at small current density is attributed to the enrichment of inorganic compounds (Li2CO3, LiF, etc.) and rendering better stability and smaller expansion of CEIs. This study aims to provide insights into modifying the CEIs under high current densities for achieving stable and sustainable cycling performance of LMBs.