Nano-sized Li[Ni0.2Li0.2Mn0.6]O-2 powder is vulnerable to reaction with the electrolyte because it has a wide electrolyte/cathode contact area. In order to avoid this, we modified the surface of the nano-sized Li[Ni0.2Li0.2Mn0.6]O-2 powder by coating it with MgF2. A polydopamine pre-coating layer served as a binding agent for the homogeneous MgF2 coating on the surface of the Li[Ni0.2Li0.2Mn0.6]O-2 nanoparticles. Polydopamine-assisted coating with MgF2 improved the discharge capacity, cyclic performance and thermal stability of the Li[Ni0.2Li0.2Mn0.6]O-2 cathode, possibly by suppressing side reactions between the electrolyte and the cathode. (C) 2014 Elsevier Ltd. All rights reserved.