Stabilizing the Lithium-Rich Manganese-Based Oxide Cathode via Regulating a CEI Film

Targeting high-energy-density batteries, lithium-rich manganese oxide (LMO), with its merits of high working voltage (∼4.8 V vs Li/Li + ) and high capacity (∼250 mAh g –1 ), was considered a promising cathode for a 500 Wh kg –1 project. However, the practical application of LMO was hindered by the parasitic reaction between the electrolyte and the electrode, such as dissolution of surface lattice oxygen. Herein, N -methyl- N -trimethylsilyl trifluoroacetamide (MSTFA) is introduced as an additive in a common carbonate ester electrolyte to modify the cathode-electrolyte interphase (CEI) for blocking the undesirable side reaction. The preferential decomposition of MSTFA results in silicon and NO x -containing CEI, which greatly enhances the high-voltage stability of the LMO cathode. Moreover, the designed CEI enables providing a homogeneous interphase within 5 nm, which is responsible for the long-time stability of the cathode. Herein, the assembled LMO||Li battery yields a high-capacity retention of 93.1% after 200 cycles at a current density of 100 mA g –1 .