High-Areal-Capacity\nAll-Solid-State Lithium Batteries\nEnabled by Electronically Conductive Li-Deficient LiNiO<sub>2</sub> Cathode

All-solid-state lithium batteries (ASSLBs) with Ni-rich\ncathodes\nare promising candidates for achieving high energy and improved safety.\nHowever, their electrochemical performance is limited by cathode loading,\nespecially in the absence of conductive agents. Herein, we utilize\nelectronically conductive Li-deficient LiNiO<sub>2</sub> (LD-LNO)\nto construct high-areal-capacity ASSLBs under high cathode loading.\nThis LD-LNO shows an inherent enhanced electronic conductivity and\nminimal surface impurities. Electrochemical analysis combined with\nsolid-state nuclear magnetic resonance spectroscopy demonstrates the\nmitigation of the detrimental H3 phase transition and the side reactions\nat the LD-LNO/Li<sub>6</sub>PS<sub>5</sub>Cl interface. As a result,\nLD-LNO-based ASSLBs achieve competitive cyclability and rate capability\nwithout the need for cathode modifications. A high reversible areal\ncapacity of 15.2 mAh cm<sup>–2</sup> is attained at 35 °C\nunder a 133.8 mg cm<sup>–2</sup> LD-LNO mass loading. This\nwork sheds light on electronically conductive cathodes, providing\na perspective for addressing the high cathode loading issue in ASSLBs.