Composite copper-based current collector, preparation method thereof and lithium ion battery

The invention provides a composite copper-based current collector, a preparation method thereof and a lithium ion battery, and belongs to the technical field of battery materials. The composite copper-based current collector comprises: a polymer-based film; the modified copper layer is arranged on at least one surface of the polymer base film; and the modified copper layer comprises a C-Cu heterogeneous microstructure with dispersed carbon quantum dots. According to the invention, the carbon quantum dots are introduced, so that the carbon quantum dots are uniformly dispersed at copper grains and copper grain boundaries, a C-Cu heterogeneous microstructure with dispersed carbon quantum dots is formed, and the existence of the carbon quantum dots can apply resistance to grain coarsening, inhibit grain coarsening and promote grain refinement, so that the tensile strength of the composite copper-based current collector is improved; the C-Cu heterogeneous microstructure can increase the dislocation storage capacit