LiF-Rich Cathode Electrolyte Interphases Homogenizing Li+ Fluxes toward Stable Interface in Li-Rich Mn-Based Cathodes

Abstract

Constructing a stable cathode-electrolyte interphase (CEI) is crucial to enhance the battery performance of Li-rich Mn-based oxide (LMO) cathodes. To achieve an ideal CEI, a gas-phase fluorination technique is proposed to pre-structure a robust LiF layer (≈1 nm) on the LMO surface. The designed LiF layer effectively modulates the electric field distribution on the electrode surface and mitigates undesirable side reactions between the electrode and electrolyte, thereby promoting the formation of a uniform LiF-rich CEI layer on the LMO-F-1. The optimized CEI facilitates homogeneous Li⁺ fluxes across the electrode surface and enhances Li⁺ diffusion in the electrode during (de)intercalation, contributing to a stable electrode-electrolyte interface. Moreover, the robust LiF-rich CEI layer effectively suppresses the decomposition of lithium salts in the electrolyte and reduces autocatalytic side reactions triggered by the by-products. In addition, it improves the structural stability of LMO by increasing the formation energies of oxygen and manganese vacancies. As a result, the modified LMO with the LiF-rich CEI retains 95% of its initial capacity after 100 cycles, demonstrating remarkable electrochemical stability. The proposed gas-phase Li⁺ flux homogenization strategy offers a promising avenue for enhancing the interface stability of high-voltage cathode materials with lithium storage.