Straining copper foils to regulate the nucleation of lithium for stable lithium metal anode

Although lithium metal (Li) has been considered as the ideal anode material for next generation batteries, its practical applications are hindered by detrimental dendrite growth due to non-uniform Li deposition. It is reported that the substrate materials and their lattice mismatch have significant roles on Li nucleation. However, the defects such as dislocations resulted from the applied strain on substrate materials, have been seldomly investigated. Hence, strained copper current collectors (CuCCs) are used as the substrate to investigate the defects (mainly dislocations) on the nucleation and growth behaviors of Li. It is found that the variation of dislocation density and structure can significantly influence the nucleation behaviors of Li. The increase of dislocation density can effectively reduce the nucleation energy barrier and favors the uniform nucleation of Li. The lowered nucleation energy barrier and critical nuclei size promote the subsequent growth of Li. The subsequent growth of Li embryos on CuCCs with 5% strain becomes orderly and forms the compact Li thin film through intergranular fusion rather than the generation of dendrites via 1D growth. As anodes in both half and symmetric cells, the compact deposited Li layer exhibits high Coulombic efficiencies and long cycling stability indicating its great potential as a stable Li metal anode.