Enhancing the overcharged performance of Li(Ni0.8Co0.15Al0.05)O2 electrodes by CeO2-Al2O3 surface coating

Abstract

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.