Electrochemical performance of spherical Ni(OH)2 coated with Y(OH)3

The effects of surface coating of Y(OH)(3) on the electrochemical performance of spherical Ni(OH)(2) were studied by cyclic voltarnmetry (CV) with soft-embedded electrode (SE-E). The results show that a two-step oxidation process exists in the oxidation procedure of Ni(OH)(2) corresponding to the formation of Ni(III) and Ni(IV), respectively, in which Ni(IV) species is not stable and can dissociate into NiOOH and oxygen. Therefore, the conversion of Ni(III) to Ni(IV) is regarded as a side reaction. The presence of Y(OH)(3) on the particle surface could restrain the side reactions, especially the formation of Ni(IV). The charge acceptance of the battery with Ni(OH), coated with 1.61% (mass fraction) Y as the positive active material can reach 92.7% at 60 degrees C. The specific capacity of Ni(OH)(2) coated with 0.55% (mass fraction) Y can reach 241.3 mA.h/g at 60 degrees C.