Interfacial Engineering of LiNiO ₂ via an Atomic Layer Deposition‐Deposited Mg _x Zn _y O _z Layer for Enhanced Electrochemical Performance

Lithium nickel oxide (LNO) is a promising cathode material for next‐generation high‐energy‐density lithium‐ion batteries owing to its high specific capacity and cost‐effectiveness. However, LNO cathodes suffer from significant interfacial instability due to structural issues, cation mixing, and aggressive reactions with the electrolyte, which leads to rapid capacity loss. Herein, we report a surface‐stabilization strategy employing atomic layer deposition (ALD) to fabricate an ultrathin (ca. 4 nm), conformal dual‐metal oxide (Mg and Zn) Mg _x Zn _y O _z (MZO) protective layer on model LNO particles. Comprehensive characterization, including time‐of‐flight secondary‐ion mass spectrometry and scanning transmission electron microscopy–energy‐dispersive X‐ray spectroscopy, reveals a unique chemical distribution: the Zn species remain localized at the surface, whereas Mg partially diffuses into the superstructure. Electrochemical experiments demonstrate that the MZO‐coated LNO particles exhibit significantly enhanced stability, achieving a ca. 22% improvement in capacity retention after 100 cycles over the pristine LNO, alongside a reduction in voltage hysteresis and an increase in round‐trip efficiency. These findings indicate that ALD‐derived dual‐metal surface engineering can improve the early‐stage interfacial stability of cobalt‐free LNO cathodes.