As the only commercialized negative current collector, copper (Cu) foil possesses insurmountable applicational advantages as a lithium metal anode (LMA) substrate. However, the successful usage of Cu foil is limited by the poor Li affinity and crystal face variation, which will lead to severe lithium dendrite growth and poor cyclability. Herein, an industrial-popular ion implantation technique is first adopted for Cu surface modification. With the high-energy implantations of N+ plasma, the unique N-rich transition interface can be formed, among which the lithiophilic CuxNy with extended crystal domains can have uniform Cu crystal faces and offer benefit for Li nucleation/deposition; besides, the induced Li3N-rich SEI with high ionic conductivity can support Li-ion transport kinetics, suppress Li dendrite growth, and mitigate the side reaction to improve LMA stability. Consequently, a uniform Li nucleation/deposition is achieved, with obviously enhanced cycling stability and rate capability for the full cells. This technological maturity ion implantation method can be readily extended to any non/metallic ion species, or joint implantation of bi/multiple ions, and other substrates, demonstrating a possible route to surmount the metal anode challenges.
Keywords: Li3N; SEI; copper foil; lithium metal anode; nitrogen ion implantation.