Extraordinarily enhanced rate and stability of Ni-rich cathodes through MXene coating

Abstract

Ni-rich layered cathodes play a crucial role in achieving high energy density in lithium-ion batteries, primarily due to their high theoretical capacity. However, Ni-rich layered cathodes suffer from structural degradation, severe side reactions, and limited cycle life, particularly under conditions of high operating voltage. This study introduces an innovative interfacial engineering strategy employing two-dimensional transition metal carbide (MXene) nanosheets as conformal surface modifiers to significantly improve the structural and electrochemical stability of high-nickel layered oxide cathode materials. The modifying layer enhances the charge and ion transport of the interface for the cathode material, effectively promoting the rate performances. Moreover, the induced cathode–electrolyte interphase (CEI) can mitigate the attack of HF by preferential adsorption of PF₅ onto the MXene, which substantially improves the cycling stability especially at high operating voltage. As a result, the modified material shows excellent electrochemical performance with 96.75% capacity retention at 4.5 V after 100 cycles at 1 C, which is higher than that of bare NCM90 (76.09%). In addition, the rate capability is also enhanced by this coating engineering, which endows the cathode with a high capacity of 142 mAh g⁻¹ at 10 C, compared to 110.6 mAh g⁻¹ for bare NCM90. This work provides a new reference for constructing stable high-energy-density Ni-rich layered cathodes with MXene materials.