transition metal such as Mn, Ni, Co, Cu etc are more likely used as positive electrode
whereas some others such as Bi, Fe, Mo, Carbon etc are more likely used as negative electrode materials.
Until high school course, element was known to lose its properties as it forms compound. Maybe it is wrong in reality.
What makes that element have certain potential window for capacitance no matter what element they are combined with?
What determines the potential window?