Al-substituted nickel hydroxides with the Al3+/Ni2+ molar ratio of 0%, 5%, 10%, 15% and 20% were prepared by a chemical co-precipitation method. Tap density tests demonstrate that the tap-density of samples increases obviously with the increasing of the Al content when the Al content is less than 10%; the sample presents the highest tap-density when the Al content is 10%; however, further increasing of Al content leads to the decrease of tap density. X-ray diffraction (XRD) analysis reveals that the sample shows β phase when the Al content is less than 5%, and α/β mixed phase when the Al content is between 5% and 10%, but when the Al content is higher than 10% the samples show α phase. The results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge-discharge tests indicate that Al-substituted nickel hydroxide has higher electrochemical activity and smaller electrochemical reaction resistance than the pure nickel hydroxide. In particular, the Al-substituted nickel hydroxide with Al3+/Ni2+ molar ratio of 15% exhibits the best electrochemical performance. For example, the stable specific discharge capacity is up to 324 mAh/g (516 mAh/cm3) at the charge-discharge current density of 100 mA/g. Meanwhile, the samples also possess excellent cycling performance