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 NOx-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.