Lithium metal is a promising anode for high-energy-density batteries owing to its high theoretical capacity and highly negative electrochemical potential. However, its commercial application is stalled by the undesired dendritic growth of lithium during cycling.^[1]Among all kinds of promising approaches (e.g. electrolyte engineering, interfacial engineering, use of solid electrolyte and use of 3-D structured current collectors, etc. )^[2], 3-D structured current collectors represent some new promises as they can effectively increase Li nucleation sites and reduce local current. However, most of these successes are at lab-scale with coin cells and most of the methods are sophisticated and expensive, not scalable and compatible with the roll-to-roll manufacturing processes of current Li-ion battery industry.

Here we report a facile electrodeposition process for low- cost, scalable fabrication of copper current collectors with 3-D architected porous structures composed of interconnected Cu nanoparticles.^[3]Compared to flat foil current collectors, the deposited 3-D nanostructured Cu current collector has much larger active surfaces area, thus effectively reduces the actual current density for the same apparent current and lowers the possibility of triggering dendritic growth. During Li plating process, Li can be accommodated in the porous structure and on the top surface of the 3-D nanostructured Cu current collector, which effectively suppresses Li dendrite formation and provides a very high practical Li storage areal capacity. The nanoporous electrodeposition coated Cu foil can be produced with very low cost and this foil can be seamlessly incorporated into current Li-ion battery production with no major modifications required. The electrodeposition method also provides great flexibility and tunability of the deposited structure, which suggests more Li may be accommodated and ultrahigh energy density batteries may be developed along this promising approach.

1. Harry, K.J., et al., Detection of subsurface structures underneath dendrites formed on cycled lithium metal electrodes.Nat. Mater., 2014. 13(1): p. 69-73.
2. Lin, D., Y. Liu, and Y. Cui, Reviving the lithium metal anode for high-energy batteries.Nat. Nanotechnol, 2017. 12(3): p. 194-206.
3. Ma, X., Z. Liu, and H. Chen, Facile and scalable electrodeposition of copper current collectors for high-performance Li-metal batteries.Nano Energy, 2019. 59: p. 500-507.