Artificial Amorphous Interface Matters for Boosting High‐Voltage Stable LiCoO 2 Cathode

ABSTRACT The energy density of lithium‐ion batteries (LIBs) can be improved significantly by elevating the working voltage. Nevertheless, serious issues are generally induced at higher cut‐off voltages for LIBs, including structural collapse and oxygen loss on the cathode side. Constructing a stable cathode‐electrolyte interface (CEI) is considered as an effective approach to tackle these issues. Previous research has predominantly focused on designing crystallized interfacial structures. This omits the coating materials with other structures that could potentially surpass crystallized counterparts. Herein, the amorphization of the phosphate interface has been designed for high‐voltage stable LCO by precisely tailored atomic‐level fabrication. The modified LCO cathode exhibits excellent high‐voltage rate capability of 142.1 mAh g −1 at 10 C and significantly improved cycling stability with a capacity retention of 83.3% after 200 cycles at 1 C. The outstanding performance attributes to the conformal high‐voltage stable interface with favorable Li‐ion conducting kinetics at LCO surface. Additionally, synchrotron‐based X‐ray analysis demonstrates that this amorphous layer helps stabilize lattice oxygen and alleviate the variation in the chemical state and local environment of Co at the deep charging state. This work offers new perspectives and possibilities on interphase engineering toward high‐energy and stable LIBs.