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• 3D Cu current collectors were gained by painting-alloying-dealloying and annealing. • The porous structure of 3D Cu was regulated by altering Ga mass and annealing. • The relationships between porous layer depth and performance were explored. • The Li deposition behaviors on 3D/2D Cu were clarified. Lithium metal anode has shown great potentials for achieving high energy density due to its high theoretical capacity and low redox potential, but its application is impeded by the dendrite proliferation and unstable solid electrolyte interface. Herein, three-dimensional (3D) porous Cu current collectors were fabricated via the combination of painting-alloying-dealloying with subsequent annealing, where the depth and length scale of the porous layer can be facilely regulated by controlling the alloying and annealing processes. In lithium metal batteries, the relationship between the Li deposition behavior and the porous layer depth was explored in detail via electrochemical measurements and ex-situ scanning electron microscopy. Notably, the A-3D Cu-14 current collector with the porous layer depth of around 34.5 µm exhibits long lifespan over 430 h at 1 mA cm−2 and low voltage hysteresis, in comparison with the pristine Cu foil and the porous Cu with thinner porous layers. The superior electrochemical performance of A-3D Cu-14 can be attributed to the enhanced suppression effect upon the Li dendrite deriving from the more accommodation capability of its thick porous layer, as well as the better homogenization of the Li+ ion flux caused by the porous structure. Furthermore, the Li@A-3D Cu-14 | LiFePO 4 full cell shows excellent cycling stability and rate capability in full battery tests. Dealloying-induced modulation upon porous layer depth of three-dimensional copper current collector to stabilize the lithium batteries. [Display omitted] [ABSTRACT FROM AUTHOR]