Recently, Ni-rich layered Li[Ni_1-2xCo_xMn_x]O₂ (NCM, x ≤ 0.2) cathodes show high capability for increasing the energy densities which is essential to facilitate the penetration of electrified transportation systems into the automobile market. However, the poor thermal stability of these cathodes is retarding their commercialization. In this study, the effect of Ni content and upper cut-off potential on the electrochemical and thermal properties of Ni-rich NCM cathodes (NCM-622, 811, 90) is evaluated to identify the optimum composition of the cathodes and the cycling conditions. This research shows that operating Ni-rich cathodes at higher cut-off potentials (> 4.3 V) rather than progressing to highly nickel enriched compositions can be a better method of enhancing their energy densities and maintaining adequate thermal stability. It is shown that a Li[Ni_0.6Co_0.2Mn_0.2]O₂ (NCM-622) cathode cycled up to 4.5 V exhibits a discharge capacity of 200 mAh g^-1 and capacity retention of 93% after 100 cycles, which are similar to the ones of Li[Ni_0.8Co_0.1Mn_0.1]O₂ (NCM-811) cycled up to 4.3 V. Similar volume change during cycling and comparable NiO-like rocksalt impurity layer after 100 cycles in both of the cathodes may be the reason for their similar cycle lives despite operating at different charge cut-off potentials. In spite of the comparable capacity and retention, NCM-622 cathode exhibits superior thermal stability, in which the occurrence of the exothermic reaction is delayed by 50 °C, than NCM-811. In addition, analogous trends are observed in the cathodes with higher nickel compositions, i.e., NCM-811 and Li[Ni_0.9Co_0.05Mn_0.05]O₂ cycled up to 4.5 V and 4.3 V, respectively.

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