Preparation and electrochemical performance of Mn and Al Co-doped nickel hydroxide

Abstract

The buffer solution method was used to prepare Mn- and Al-doped nickel hydroxide, labeled as Ni0.8-0.8xMn0.2-0.2xAlx(OH)2(x = 0.10, 0.14, 0.18, 0.22). XRD, SEM, TEM, and BET tests were used to characterize the crystal structure and morphology of the samples. Cyclic voltammetry and constant current charge-discharge tests were used to study the influence of Mn and Al doping on the electrochemical performance of Ni(OH)2. The results showed that the samples doped Mn and Al were mixed phases with α and β and the crystal particle sizes were smaller and significantly increase the specific surface area. Cyclic voltammetry tests showed that the difference between oxidation peak potential and reduction peak potential of Mn and Al co-doped samples was smaller; constant current charge-discharge results showed that the sample x = 0.18 yielded the highest discharge specific capacity, the best cycle stability with discharge specific capacity of 285.5 mAh·g−1 at 100 mA·g−1, while the discharge specific capacity of commercial β-Ni(OH)2 was 256 mAh·g−1. When the sample x = 0.18 was cycled at 800 mA·g−1 for 30 cycles, the discharge specific capacity did not decrease, and its cycling performance was better than that of commercial β-Ni(OH)2. It can be seen that the positive electrode material doped with Mn and Al has good rate capability and cycling stability.