Enhanced Electrochemical Performance of LiNi_0.6Co_0.2Mn_0.2O₂ by a Negative‐Thermal‐Expansion Material at Elevated Temperature

Abstract

More measures are being developed to enhance the electrochemical stability of single‐crystal LiNi0.6Co0.2Mn0.2O2 (NCM622), but few focus on improving the stability of NCM622 through heat and deformation management. Herein, a negative‐thermal‐expansion (NTE) material of zirconium tungstate ZrW2O8 is adopted to modify NCM622 via a facile method, and the sample with a proper content of ZrW2O8 exhibits superior cycle performance and rate capability. The capacity retention ratio of modified NCM622 is 86.2% (from 193.6 to 166.8 mAh g−1) after 100 cycles at 2 C between 2.8 and 4.5 V at 60 °C, whereas that of the pristine NCM622 is only 77.5% (from 183.8 to 142.4 mAh g−1). According to various analysis results, the possible enhancing mechanisms of ZrW2O8 for NCM622 are discussed. It is an alternative for the remaining good structure of energy materials using NTE materials.

Reduction of Surface Residual Lithium Compounds for Single-Crystal LiNi0.6Mn0.2Co0.2O2 via Al2O3 Atomic Layer Deposition and Post-Annealing

“…Compared with the bare and the 2AL NCM622 cathode, the 2AL-A NCM622 cathode exhibits the best capacity retention (92.2%) and the highest final capacity (128.4 mAh/g). To the best of our knowledge, the NCM622 cathode modified by Al 2 O 3 ALD and post-annealing shows outstanding capacity retention compared with NCM622 cathodes modified by other methods reported in literature (Table S1) [17,[44][45][46][47][48][49][50]. It shows only 0.026% capacity loss per cycle, which is lower than most NCM622 cathodes modified by other methods.…”