Enhanced electrochemical performance of Li1.2Mn0.54Ni0.13Co0.13O2 cathode by surface modification using La–Co–O compound

Abstract Li-rich cathode materials have higher discharge capacity and lower cost than conventional electrode materials such as LiCoO2. However, they suffer from rapid capacity fading caused by irreversible phase transition and interfacial instability during the electrochemical cycling. La–Co–O (denoted as LC) compound possess good electronic conductivity and superior thermal stability, which could be used as a promising coating layer to suppress Mn dissolution as well as to facilitate electrical transfer. Furthermore, La–Co–O (LC) coating layer could decrease the Mn3+ ions on the surface of Li1.2Mn0.54Ni0.13Co0.13O2 (denoted as LMNC), thus stabilize the surface structure. Herein, we present La–Co–O (LC) coating layer on the surface of LMNC via an artful sol-gel-based method with a thickness below 50 nm. XPS, EDS and TEM tests were applied to confirm the existence of LC coating layer. 2 mol% LC coated LMNC sample shows much improved cycle stability at 1C (206.3 mAh g−1, 86.2% capacity retention after 100 cycles) and good rate capability especially at high rates. In addition, LC coating could effectively suppress voltage fading of LMNC. EIS results reveal that the LC modified LMNC materials exhibit better electrochemical kinetics than the pristine one.