Effects of coprecipitated manganese on the structure and electrochemical performance of Al-substituted α-nickel hydroxide

The effects of manganese on the structure and electrochemical performance of Al-substituted alpha-Ni(OH)(2) prepared by a chemical co-precipitation method were studied. The results of XRD and IR showed that the Al-substituted Ni(OH)(2) with various Mn contents are typical alpha-phase. The Mn-free sample is labile in alkaline media and partly converted to beta-Ni(OH)(2). The stability of the samples improves with the increase in Mn content. The results of galvanostatic charge-discharge experiments showed that the addition of Mn increases the difference between the oxygen evolution and charge potentials, which improves the charge efficiency and increases the discharge capacity. The Mn-containing samples display better cycle stability than the Ni/Al sample without Mn. The Al-substituted Ni(OH)(2) sample with Mn 9.3% shows the highest discharge capacity during the whole cycle, and the largest discharge capacity is 260 mAh g(-1).The electrochemical transfer resistance (R-t) value decreases with the increase of Mn content.