Multifunctional composite interfacial layer based on aluminum and boron for single crystal LiNi0.8Co0.1Mn0.1O2 with enhanced electrochemical performance at high voltage and temperature

Nickel-rich cathodes are unable to meet the requirements of widespread commercialization due to rapid capacity decay and poor thermal stability. This work greatly improves the capacity retention of the cathode with high cut-off voltage and high temperature by constructing a multifunctional composite interfacial layer of LiAlO2, LiBO2, Al2O3 and B2O3 on the surface of single crystal LiNi0.8Co0.1Mn0.1O2 (NCM811). The formation of the composite layer consumes the surface residual lithium and reduces the interfacial side reactions, contributing to further formation of a stable cathode-electrolyte interface. The fast ion conductor layer improves Li+ transport pathways and rate performance is enhanced. The oxide layer effectively resists the erosion of HF, inhibits the irreversible phase change and oxygen evolution reaction of the cathode. The thermal stability of the material is significantly improved. Ultimately, modified cathode exhibits excellent capacity retention of 78.4 % and 70.4 % after 100 cycles at high cutoff voltage (4.5 V) and high temperature (55 °C) at a rate of 0.5C, respectively.