Invoking Interfacial Engineering Boosts Structural Stability Empowering Exceptional Cyclability of Ni-Rich Cathode.

ABSTRACT

The cycling stability of LiNi0.8Co0.1Mn0.1O2 under high voltages is hindered by the occurrence of hybrid anion- and cation-redox processes, leading to oxygen escape and uncontrolled phase collapse. In this study, an interfacial engineering strategy involving a straightforward mechanical ball milling and low-temperature calcination, employing a Se-doped and FeSe2&Fe2O3-modified approach is proposed to design a stable Ni-rich cathode. Se2- are selectively adsorbed within oxygen vacancies to form O─TM─Se bond, effectively stabilizing lattice oxygen, and preventing structural distortion. Simultaneously, the Se-NCM811//FeSe2//Fe2O3 self-assembled electric field is activated, improving interfacial charge transfer and coupling. Furthermore, FeSe2 accelerates Li+ diffusion and reacts with oxygen to form Fe2O3 and SeO2. The Fe2O3 coating mitigates hydrofluoric acid erosion and acts as an electrostatic shield layer, limiting the outward migration of oxygen anions. Impressively, the modified materials exhibit significantly improved electrochemical performance, with a capacity retention of 79.7% after 500 cycles at 1C under 4.5 V. Furthermore, it provides an extraordinary capacity retention of 94.6% in 3-4.25 V after 550 cycles in pouch-type full battery. This dual-modification approach demonstrates its feasibility and opens new perspective for the development of stable lithium-ion batteries operating at high voltages.