The second ionisation energy of the alkali metals is much higher than the first as the second-most loosely held electron is part of a fully filled electron shell and is thus difficult to remove.
ðə sˈɛkənd ˌaɪənəzˈeɪʃən ˈɛnɚdʒi ʌvðɪ ˈælkəlˌaɪ mˈɛɾəlz ɪz mˈʌtʃ hˈaɪɚ ðɐn ðə fˈɜːst æz ðə sˈɛkəndmˈoʊst lˈuːsli hˈɛld ᵻlˈɛktɹɑːn ɪz pˈɑːɹt əvə fˈʊli fˈɪld ᵻlˈɛktɹɑːn ʃˈɛl ænd ɪz ðˈʌs dˈɪfɪkəlt tə ɹᵻmˈuːv.