A multifunctional MXene additive for enhancing the mechanical and electrochemical performances of the LiNi0.8Co0.1Mn0.1O2 cathode in lithium-ion batteries

摘要

LiNi0.8Co0.1Mn0.1O2 (NCM811) has attracted increasing attention owing to its extremely high discharge capacity (>200 mA h g(-1)). However, poor mechanical strength, cycling stability, and rate capability impose limitations on its large-scale practical applications. Here, we report that few-layer and rod-like MXene (Ti2C3Tx) as a multifunctional additive significantly enhances the mechanical property, cycling performance, and rate capability of the Li/NCM811 cells. Thus, NCM811 added with 2.5 wt% MXene (2.5-MXene) delivers the highest discharge capacity of 209 mA h g(-1) at 0.2C as well as the best rate performance with a high reversible capacity of 95 mA h g(-1) at 8C. Moreover, the capacity retention of 2.5-MXene can reach 77.0% after 100 cycles at a 0.5C rate, while it is only 53.6% for pristine NCM811 without MXene (0-MXene). Such superior performances result from the effective and multifunctional MXene additive, which is helpful to establish a better conductive network, store/release Li(+)via cation intercalation, offer more deformation space, form a physical protection CEI layer, and suppress the M <-> H2 phase transformation for the NCM811 electrodes. In addition, the DFT calculation indicates that the MXene additive can prohibit the irreversible Ni/Co/Mn elements' migration via the absorption process. Therefore, the few-layer/rod-like MXene can be a facile and efficient approach to enhance the mechanical and electrochemical performance of the NCM811 materials for large-scale applications in the next-generation energy density lithium-ion batteries by considering its multifunctional properties, low cost, and convenient accessibility.