What are the factors that affect the redox reactions?

In my work, I used $\ce{Co(OH)2}$ and $\ce{Ni(OH)2}$ as an active materials to fabricate as symmetric supercapacitors in which I used 1-butyl-1-methylpyrrolidinium dicyanamide as an electrolyte.


From my CVs curve, I found that $\ce{Co(OH)2}$ have a high redox peaks while for $\ce{Ni(OH)2}$, it shows no redox reaction peaks. What might be the factor that affects this? As I've known both active materials have similar layered liked-structure. Is it the electronegativity differences between an electrolyte and the materials? 


What could possibly affect the redox reactions and how could I study more on the reaction mechanism?


