Enhancing the overcharged performance of Li(Ni0.8Co0.15Al0.05)O-2 electrodes by CeO2-Al2O3 surface coating

The nickel-rich cathode materials (LiNi0.8Co0.15Al0.05O2, NCAs) in Lithium ion batteries often suffer from oxygen loss problems under partially overcharged conditions (> 4.3 V), leading to capacity fading and safety problem. Herein, we utilize a facile ball-milling method to coat the NCAs with a shell of cerium aluminum composite oxide (CeO2-Al2O3), which is commonly used as oxygen storage material. Proved by in situ X-ray diffraction results, the coating CeO2-Al2O3 layer is capable to suppress the lattice volume change and irreversible phase transition of NCAs. The CeO2-Al2O3 coating layer can adsorb released oxygen under overcharged conditions and replenish lattice oxygen of NCAs under oxygen-leaned conditions. The protective layer can also prevent dissolution of the transition metals caused by HF attack in electrolytes. As a result, the as prepared electrode presents high specific capacity of 186.4 mA h g(-1) and excellent cycle stability with capacity retention of 94.1% after 300 cycles at a rate of 0.5 C under overcharged conditions (3.0-4.5 V). Coating CeO2-Al2O3 is an efficient strategy to solve capacity fading problem and safety problem caused by partially overcharge, and such strategy shows significant promise for practical applications. (c) 2021 Elsevier B.V. All rights reserved