Herein, we report a novel strategy for preparing a highly homogeneous nanocoating for Li-rich Mn-based layered oxides by the elemental Al doping followed by chemical conversion in phosphate buffer solution. X-ray photoelectron spectroscopy, soft X-ray absorption spectroscopy and transmission electron microscopy results exhibit that there exist AlPO4 nanocoating on the surface of particles. The resultant AlPO4-nanocoated Li[Li0.2Ni0.11Co0.11Mn0.54Al0.04]O2 particles exhibit a greatly enhanced reversible capacity with superior thermal stabilities in relative to pristine Li[Li0.2Ni0.13Co0.13Mn0.54]O2. Under a current density of 30 mA g−1, the AlPO4-nanocoated Li[Li0.2Ni0.11Co0.11Mn0.54Al0.04]O2 can deliver a specific capacity of 282.1 mAh g−1 with capacity retention of 89% after 35 cycles.