Sodium metal anode has always been regarded as most desirable anode in sodium batteries for its ultrahigh theoretic capacity and low deposition/stripping potential, and researches about improving sodium anodes stability are quite crucial. One of feasible strategies is modification of current collectors via introducing 3D structures on them, while hierarchical structures and high specific surface area synergistically assure uniform deposition/stripping process. However, in-situ growing 3D structures, the electronic conductivity of which is significantly improved compared to surface coating on current collectors for integration, have not been reported yet in sodium metal batteries. Hence, taking copper foam for the substrate, we synthesized Cu nanowires on Cu foam by anode oxidation method and heat reduction (Figure 1a). The Cu nanowires on copper foam delivered ultralong cycle life for more than 50 cycles with a high areal capacity of 12 mAh cm<sup>-2</sup> (coulombic efficiency＞99%) and tiny hysteresis (~40 mV) (Figure 1b). The superb performance can be attributed to elevated surface area, which markedly reducing current density and benefiting Na<sup>+</sup> infusing. Secondly, sodium dendrite can be confined within 3D structure, avoiding infinite growth of dendrite towards specific lattice plane.

Dendrite-free Na metal plating/stripping onto 3D porous Cu hosts

2019 Spring National Meeting

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