We propose that superconductivity in A^Cw (A=K, Rb) with 77 > 30 K results from a favorable combination of high phonon frequencies and the existence of two different energy scales optimizing the coupling constant X=NV. Calculations show that electron scattering V is dominated by particular onball Jahn-Teller-type modes on the scale of the large on-ball /r-hopping energy, while the density of states N is controlled by the weak interball hopping energy. This factorization has several observed experimental consequences. Crucial differences to intercalated graphite explain the much smaller 77 values in the graphite compounds.

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