Why second ionization enthalpy is always higher than the first ionisation enthalpy for every element?

Explanation

Electron is more tightly bound by the nucleus in an cation (i.e `M^(+))` as the number of proton remains the same as in neutral atom whereas number of electron is one less than the proton. This increases the attraction between the valence sheel electrons and the nucleus `(Z_(eff)` increases). So, second ionization enthalpy is always higher than the first ionisation enthalpy for every element.