A multifunctional super‐sodiophilic coating on aluminum current collector for high-performance anode-free Na-metal batteries

Na-metal batteries (NMBs) are drawing soaring research interest as next-generation high-energy and low-cost batteries. However, the pursuit of high-reversibility Na metal anode with controllable and uniform Na plating/stripping remains a formidable challenge owing to the inhomogeneity of mass/charge transfer and high activity of Na. Herein, a 3D Zn@Al current collector is proposed by coating a 3D nanofiber-like Zn layer on the Al foil, which can suppress the dendritic Na growth to enable the high reversibility of Na plating/stripping. Experimental studies and theoretical calculations demonstrate that the 3D Zn@Al current collector greatly enhances the sodiophilicity due to the larger binding energy of Zn/NaZn13 with Na, and homogenizes electric field distribution owing to the 3D nanofiber-like Zn layer. Benefiting from such favorable properties, extraordinary electrochemical performances with low nucleation overpotential (5 mV at 1 mA cm−2), long cycle lifespan (1500 h) together with small polarization voltage (10 mV at 1 mA cm−2) have been achieved. Most noticeably, an anode-free NMBs with Na3V2(PO4)3 as cathode can achieve excellent cycle life (with the capacity retention of 98.8% for 100 cycles). Our findings provide a simple and efficient strategy for designing functional current collector for Na anode to build high-performance anode-free NMBs.