Incorporating a lithium-deficient layer and interfacial-confined catalysis enables the reversible redox of surface oxygen species in lithium-rich manganese-based oxides†

Lithium-rich manganese-based oxides (LRMOs) are promising next-generation candidate cathode materials, offering a high discharge capacity exceeding 300 mA h g⁻¹. This exceptional capacity is attributed to the synergistic redox activity of transition metals and lattice oxygen. Nevertheless, the over-oxidation of lattice oxygen in LRMOs leads to capacity fading, severe lattice strain, and sluggish oxygen redox reaction kinetics. Herein, we introduce a lithium-deficient layer and a RuO₂-promoted interface-confined catalysis network on the surface of LRMO (Ru-1). The lithium-deficient layer effectively passivates the surface lattice oxygen by reducing the Li–O–Li configurations at the atomic level. The RuO₂-promoted interface-confined catalysis network successfully captures trace amounts of lost lattice oxygen and catalyzes the reversible reduction of activated O species. This configuration yields a specific discharge capacity of 307 mA h g⁻¹ at 0.1C, with an impressive capacity retention rate of 97% after 300 cycles at 1C. The Ru-1‖graphite pouch cell exhibits a superior capacity retention rate of 85% after 450 cycles at C/3 and the Ru-1‖Li pouch cell exhibits a high energy density of 513 W h kg⁻¹. Our strategies involving the lithium-deficient layer and interface-confined catalysis offer novel insights into protecting the surface and enhancing oxygen reusability within the LRMOs.