A major goal of intercalation chemistry is to intercalate high densities of guest species without disrupting the host lattice. Many intercalant concentrations, however, are limited by the charge of the guest species. Here we have developed a general solution-based chemical method for intercalating extraordinarily high densities of zero-valent copper metal into layered Bi2Se3 nanoribbons. Up to 60 atom % copper (Cu7.5Bi2Se3) can be intercalated with no disruption to the host lattice using a solution disproportionation redox reaction.