We present first-principles calculations of a new type hybrid phases composed by buckled germanene with saturated or half-saturated alkali metal atoms adsorption. Our energetics and electronic structure analysis suggests that adsorbed alkali metal atoms (Li, Na, K) can be used as covered adatoms to synthesize germanene based new phases in two dimensional. The predicted new phases of Ge2X2 and Ge2X1 (X = Li, Na, K) relative to the single germanene sheet could exist at room temperature. The formation energy of Ge2Li2 configuration obtained from complete lithiation is even more favorable than that of germanane. Charge transfer is significant between the alkali metal atoms and Ge, indicating the ionic interactions between them. Furthermore, our charge density analysis indicates that covalent component in some extent exists in Ge2X2 and Ge2X1 (X = Li, Na, K) 2D phases, which even leads the complete lithiated germanene into a semiconductor with an energy gap of 0.14 eV. We report that 2D phases of Ge2X1 (X = Li, Na, K) are metallic with weak polarization on the Fermi level and in unoccupied states. It is found that half-lithiated germanene exhibits local magnetic moments of 0.48 mu(B) on the Ge atoms neighbored with Li adatoms. (C) 2015 Elsevier B.V. All rights reserved.