Tuning Surface Reconfiguration for Durable Cathode/Electrolyte Interphase of LiCoO2 at 45 °C

Abstract

AbstractRecently, strategies of optimizing cathode/electrolyte interphase (CEI) have been applied to enhance the durability of LiCoO2 (LCO) at high voltages (≥4.55 V vs Li/Li+) and high temperatures (≥45 °C), but the underlying mechanism is still in debate. Herein, a durable CEI on LCO that operates at 45 °C is achieved via tuning the chemical and morphological properties at the surface. Specifically, an artificial CEI layer composing of island‐shaped AlPO4/Li3PO4 deposits is constructed on LCO surface, i.e., AP‐LCO. Upon cycle, a progressive chemical evolution from AlPO4 to Li3AlF6/Li3PO4 takes place, and a robust CEI enriching with ion‐conductive Li3AlF6 species is formed, leading to a uniform and compact CEI to provide a comprehensive coverage on LCO surface. Therefore, the AP‐LCO displays outstanding improvements in the resistance to HF corrosion, the suppression of surface degradation, and the kinetics of Li+ transport, along with an unprecedentedly high thermal stability. Benefited from the above advantages, the Li||AP‐LCO cell shows high capacity retention of 84.0% in 500 cycles at 45 °C and 4.6 V. This work provides a new insight into the role of robust CEI for high‐temperature durability of LCO cathodes.