Surface Li+/Ni2+ Antisite Defects Construction for Achieving High‐Voltage Stable Single‐Crystal Ni‐Rich Cathode by Anion/Cation Co‐Doping

Abstract

AbstractNi‐rich cathode material possesses a considerable theoretical capacity, yet achieving their full capacity potential remains challenging. Elevating its operation voltage is an effective approach, while the stability of Ni‐rich cathode material is relatively poor, which is limited by Li+/Ni2+ mixing. Herein, a strategy of cation/anion co‐doping is proposed for single‐crystal ultrahigh‐nickel cathode LiNi0.92Co0.04Mn0.04O2 operated at 4.5 V. The enhancement mechanism is explicitly revealed by in situ/ex situ tests and theory calculations. Specifically, Mo6+ and F− are introduced to construct an appropriate Li+/Ni2+ antisite defects structure at the particle surface, which can maintain the low‐defect Li+ layered channel inside the bulk simultaneously, inducing a stable access portal for Li+ transport from the cathode/electrolyte interface. More importantly, the Li+/Ni2+ antisite passivation layer on the surface can uphold the stability of Li‐layer and optimize the reactive behavior of Ni2+, thus boosting the interfacial stability and reducing the lattice mismatch. As a result, it can achieve high capacity (204 mAh g−1 at 1 C) and stable retention during long‐term high‐voltage measurements both in half‐cell (87.1% after 200 cycles) and full‐cell (91.9% after 400 cycles). This facile strategy provides a feasible technical reference for further exploiting the ultrahigh‐capacity of Ni‐rich cathode for commercial application.