包覆Y(OH)3的球形Ni(OH)2的电化学性能

利用软嵌式粉末电极技术研究了Y(OH)3包覆对球形Ni(OH)2电化学性能的影响. 循环伏安结果表明, 在球形Ni(OH)2的氧化过程中存在Ni(Ⅲ)和Ni(Ⅳ)的两步氧化反应, 产生的Ni(Ⅳ)不稳定, 能分解产生NiOOH和氧气, 所以可将Ni(Ⅲ)→Ni(Ⅳ)看作副反应. Y(OH)3包覆层对Ni(OH)2氧化过程后期的副反应, 特别是Ni(Ⅲ)→Ni(Ⅳ)具有较好的抑制作用. 由包覆后的Ni(OH)2制成的模拟电池表现出很好的高温性能, 在1C充放电条件下, 当Y的摩尔分数为1.61%时, 在60 ℃时所对应的容量保持率可达到25 ℃的92.7％; 当Y的摩尔分数仅为0.55 %时, 在60 ℃时所对应的质量比容量也可达到241.3 mA·h/g.

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 voltammetry(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)2 coated with 1.61%(mass fraction) Y as the positive active material can reach 92.7% at 60 ℃. The specific capacity of Ni(OH)2 coated with 0.55%(mass fraction) Y can reach 241.3 mA·h/g at 60 ℃.