Stabilizing the Structure of Nickel‐Rich Lithiated Oxides via Cr Doping as Cathode with Boosted High‐Voltage/Temperature Cycling Performance for Li‐Ion Battery

Structural degradation is a crucial issue, accounting for capacity fading and safety concerns of Ni-rich cathodes, especially at high temperature and high cutoff cell potential. Herein, Cr3+ is used as a dopant to stabilize the structure, as well as enhance the cycling life, of LiNi0.6Co0.2Mn0.2O2. The effective bulk Cr3+ doping is confirmed via various analysis characterizations. Results demonstrate that a moderate amount of Cr3+ can not only expand pathways for Li-ion insertion and extraction, but also suppress cation mixing. Electrochemical test results show that the electrochemical performance of the moderate amount of Cr3+-doped material is remarkably improved, especially under harsh conditions. In the cell potential range of 2.7-4.3 V, the 1 mol% Cr-doped LiNi0.6Co0.2Mn0.2O2 exhibits 100.6 g(-1) after 200 cycles at 10 C, corresponding to 93.1% of the initial cycle. In the cell potential range of 2.7-4.5 V, the cathode still exhibits 166.8 mAh g(-1) and keeps 75.0% of the initial value at the 200th cycle at 3 C and 50 degrees C, whereas the discharge capacity of pristine LiNi0.6Co0.2Mn0.2O2 quickly decreases to 31.5 mAh g(-1).