Surface Al-doped LiNi0.5CO0.2Mn0.3O2 (523) single crystals with a diameter of 2-4 mu m were synthesized by using Ni-Co-Mn hydroxide precursor and combined with further Al3+ coating/annealing operations. Al contents in the surface and the bulk structures of product particles were about 1.05% and 0.02%, respectively. XPS, XRD, and HRTEM results confirm that the Al element exist as a dopant within the layered structures of 523 surface. Coin cell testing of the as-prepared 523 cathode were taken under different voltage ranges of 3.0-4.3 V, 3.0-4.4 V, and 3.0-4.5 V, with corresponding 100 cycles capacity retentions of 91.2%, 74.0%, and 67.8% at 25 degrees C, and 43.1%, 40.1%, and 31.6% at 55 degrees C. The capacity degradation rate was mainly associated with the interfacial structure instabilities of 523 materials under different voltage ranges, which have been investigated by electrochemical impedance spectroscopy (EIS) and XPS.