Al2O3-coated layered oxide Li1.2Mn0.54Ni0.13Co0.13O2 (AO-LMNCO) is synthesized by a facile sol-gel reaction to prepare a preliminary formation of Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO), and then coating process with Al2O3 nano layer is followed via a chemical deposition route. Galvanostatic charge-discharge tests show that 1.5wt% Al2O3 coated sample presents the optimum electrochemical performance. It delivers a discharge capacity 285mAhg−1 in the potential window of 2.0–4.8V at 0.2C, which is superior to that 274mAhg−1 for the pristine one. The initial columbic efficiency is significantly enhanced from 80.60% to 87.40% after the coating process. Moreover, the optimal sample presents a superior high-rate capacity of 120mAhg−1 at 10C, and the value is much greater than the pristine one. Physical characterization results show that the as-prepared Li-rich oxide has a typical layered structure, and the Al2O3 nano layer (~4nm thick) is coated on the surface of the cathode grains. We could ascribe the remarkably enhancement of cycling stability and high-rate capability to the Al2O3 protective coat, which could obstruct the electrolyte from the close contact with the active material. Thus the corrosion of the electrode structure effectively decreases and the dissolution of Mn from the pristine material greatly suppresses.