A Cobalt‐ and Manganese‐Free High‐Nickel Layered Oxide Cathode for Long‐Life, Safer Lithium‐Ion Batteries

High-nickel LiNi1−x−yMnxCoyO2 and LiNi1−x−yCoxAlyO2 cathodes are receiving growing attention due to the burgeoning demands on high-energy-density lithium-ion batteries. The presence of both cobalt and manganese in them, however, triggers multiple issues, including high cost, high toxicity, rapid surface deterioration, and severe transition-metal dissolution. Herein, a Co- and Mn-free ultrahigh-nickel LiNi0.93Al0.05Ti0.01Mg0.01O2 (NATM) cathode that exhibits 82% capacity retention over 800 deep cycles in full cells, outperforming two representative high-Ni cathodes LiNi0.94Co0.06O2 (NC, 52%) and LiNi0.90Mn0.05Co0.05O2 (NMC, 60%) is presented. It is demonstrated that a titanium-enriched surface along with aluminum and magnesium as the stabilizing ions in NATM not only ameliorates unwanted side reactions with the electrolyte and structural disintegrity, but also mitigates transition-metal dissolution and active lithium loss on the graphite anode. As a result, the graphite anode paired with NATM displays an ultrathin (≈8 nm), monolayer anode-electrolyte interphase architecture after extensive cycling. Furthermore, NATM displays considerably enhanced thermal stability with an elevated exothermic temperature (213 °C for NATM vs 180 and 190 °C for NC and NMC, respectively) and remarkably reduced heat release. This work sheds light on rational compositional design to adopt ultrahigh-Ni cathodes in lithium-based batteries with low cost, long service life, and improved thermal stability.