Regulating Anion‐Cation Band Centers to Inhibit Oxygen Escape and Phase Transition for Stable Single‐Crystalline Ultrahigh‐Ni Layered Cathodes

Abstract The high‐voltage ultrahigh‐Ni (Ni ≥ 0.9) layered cathodes featuring high capacity and low‐cost have captured widespread interest in developing high‐energy lithium‐ion batteries. Nevertheless, their commercial deployment is hindered by the challenges of phase transition and lattice oxygen release (LOR)‐induced thermal runaway. Herein, an efficient strategy of adjusting anion‐cation band centers by Ta 5+ and Br − co‐doping is proposed to achieve an ultrastable single‐crystal ultrahigh‐Ni cathode (i.e., LiNi 0.92 Co 0.04 Mn 0.04 O 2 (SN92)). The strong Ta‐O bond and the low electrochemical negativity of Br − cooperation can reduce electrostatic repulsion in O‐transition metal‐O structures and tackle capacity fading caused by the Co 3d and O 2p orbital hybridization. Additionally, introducing the Ta 5+ cation into the single‐crystalline framework can decrease the band centers of Ni 3d and O 2p and suppress detrimental phase transitions, thus improving cycling stability. Moreover, the suppressed LOR and phase transition can prevent the continuous electrolyte decomposition to enable a thinner cathode‐electrolyte interphase layer on the cycled cathode. Consequently, the Ta and Br co‐doped SN92 delivers a high energy density of 742.1 Wh kg −1 and assures long‐term cyclic stability with 87.5% capacity over 1000 cycles for the 6.8 Ah‐class pouch‐type full battery, showing great promise for practical applications.