Sodiophilic Decoration of a Three-Dimensional Conductive Scaffold toward a Stable Na Metal Anode

Although Na metal is regarded as one of the most promising anode materials for Na-based batteries because of its high specific capacity (1166 mA h g–1) and low redox potential (−2.71 V versus the standard hydrogen electrode), many issues, such as dendrite-induced safety concerns, low efficiency, and poor cyclability, severely impede its practical application. Herein, to alleviate the abovementioned problems, a nitrogen-doped graphene-modified three dimensional nickel foam framework was constructed as the host material for Na plating. The sodiophilic N-containing functional groups in the graphene structure can effectively reduce the nucleation overpotential of Na, guide the homogeneous Na-ion flux, regularize the electric field distribution, and eventually inhibit Na dendrite formation. As a result, the Na composite metal anode can be cycled reversibly free from dendrite obsessions with a high Coulombic efficiency exceeding 99% at 0.5 mA cm–2, 1 mA h cm–2 for at least 800 cycles and 99% at 1 mA cm–2, 2 mA h cm–2 for at least 200 cycles. Based on this anode, a symmetric cell with ultralow voltage polarization (∼11 mV) and long-running lifespan (1000 h at 1 mA cm–2 for 1 mA h cm–2) can be realized. Furthermore, a full cell coupled with a Na3V2(PO4)3 cathode delivers a prolonged lifespan (250 cycles at 2 C) and excellent rate performances, demonstrating a facile but effective avenue to achieve Na metal anode stabilization.